The Tumescent Technique By Jeffrey A. Klein MD
Surgical Technique: Microcannular Tumescent Liposuction
No “orthodox” technique exists for performing tumescent liposuction surgery. Individual surgeons have personal methods of performing their own techniques. In liposuction surgery, personal preferences and variations in a technique may reflect artistic style as much as technical change. In developing an approach to liposuction, a surgeon first observes the methods and strategies of other surgeons, then mimics the helpful aspects and rejects others.
This process of “customizing” a technique to fit the surgeon’s personal preferences is a natural part of the evolution and improvement of surgery. Over the years I have made many changes in my own technique, and other surgeons have added their own personal preferences to what is now widely known as tumescent liposuction.
Three criteria can be used to judge any surgeon’s tumescent technique: safety, aesthetic results, and ethics. All patients should be able to judge surgeons’ aesthetic results. Evaluating safety and ethics can be more elusive. If one surgeon’s technique appears to offer greater patient safety than that of another surgeon, the second surgeon’s technique must be scrutinized and criticized. If a surgeon intentionally uses “tumescent technique” merely to attract prospective patients but actually performs a relatively antiquated and dangerous procedure, such verbal deception is unethical and deserves criticism.
My preferences and biases regarding the relative safety of various techniques for anesthesia in liposuction are discussed in other chapters. This chapter outlines my step-by-step surgical technique for doing the actual liposuction, that is, aspirating adipocytes. I hope surgeons consider the relative merits of this technique and adapt those aspects that seem most helpful.
Microcannulas can be used with either systemic or local anesthesia. Microcannular liposuction has many advantages, especially the remarkably smooth results and fewer secondary touch-up procedures that are required to improve irregularities. The technique of microcannular tumescent liposuction described next has many subtle aspects that are specifically designed to facilitate liposuction totally by local anesthesia. For example, surgeons who do not infiltrate slowly and carefully or who do not use microcannulas will find it impossible to do liposuction totally by local anesthesia.
For optimal cosmetic results of liposuction, smoothness is more important than the volume of fat removed. The most common cause of patient dissatisfaction after liposuction is skin irregularities that suggest an unnatural deformity. Successful liposuction requires continuous efforts to maintain a smooth surface in every treated area. A surgeon who is careless, inattentive to details, overconfident, or too aggressive will have many dissatisfied patients. This chapter focuses on techniques that optimize smoothness, symmetry, artistic proportion, efficiency, patient comfort, and patient satisfaction.
In addition to the actual technique for using the cannulas, important aspects of surgical technique include patient selection, patient monitoring, choice of cannulas, vacuum source, preoperative patient markings, and intraoperative positioning. Since it is closely associated with the determination of surgical technique, patient selection is extensively reviewed later in this chapter.
On the day of surgery, surface contour lines are drawn on the skin overlying the targeted fat using a felt-tipped pen. These contour lines are the surgeon’s shorthand notation for designating surgical targets. They are the artistic blueprints for modifying human surface anatomy. The contour lines communicate the planned modifications to the patient, nurses, and other surgeons. Carefully drawn contour lines improve the likelihood of achieving the desired results.
The contour lines typically resemble a topographic map showing the relative altitude of the terrain. The topographic lines appear as a nested or concentric ellipsoids, with the central rings indicating the deepest areas of fat. Individual ellipsoids may be drawn to indicate subtle or isolated bulges within a larger area.
Any preexisting focal depressions or dimples should be marked by drawing an outline of the affected area, then filling the geometric shape with a solid color. Documentary preoperative photographs of the markings are recommended (Figure 28-1).
The preoperative markings on the skin are preferably drawn with the patient standing erect in the anatomic position. The markings are an important means of keeping track of the relative depth of a targeted fat compartment despite subsequent distortions caused by body positioning or tumescent infiltration. The surgeon can compensate for such deformations by paying careful attention to accurate topographic markings.
Such a deformation in shape and depth of a fatty compartment is a topologic isomorphism, a reversible one-to-one mapping from one geometric domain to another. By visualizing the deformation induced by any deviation from the anatomic position, the surgeon can compensate to some degree. Thus, when the patient resumes the standing anatomic position after liposuction, the results will be proportionate and aesthetically pleasing.
After the topographic contour lines are drawn, the patient should examine the drawings and verbally approve the areas to be liposuctioned. Precise preoperative drawings on the patient with good photographic documentation are in the best interests of both the patient and the surgeon.
The liposuction surgeon should have a specialized informed-consent form specifically written for liposuction.
After the patient has been given preoperative sedation, the surgeon cannot obtain “reasonable informed consent” for a last-minute addition to the list of areas to be treated. “Doing a little extra liposuction at no charge” is a common pitfall for the well-intentioned but naive liposuction surgeon.
It is inappropriate to liposuction an area without the patient’s explicit signed consent clearly documented in the patient’s chart. It is only reasonable to extend liposuction into an area not requested by the patient (1) if the area is immediately adjacent to an area where the patient has requested liposuction or (2) if doing so is necessary to achieve the cosmetic result desired by the patient.
The surgeon might be accused of battery if liposuction is done in an area that is relatively distant from areas requested by the patient.
Lipotrops and Liponots
An iatrogenic depression of the skin caused by localized excessive liposuction is designated a lipotrop. Without careful attention, a lipotrop can occur very quickly, before the surgeon realizes what is happening (see Chapter 8).
A liponot is a focal area of insufficient liposuction. Liponots may be caused by focal areas of increased adipose tissue density, such as in the periumbilical region, or may result from uneven removal of fat. Although less common and easier to correct than a lipotrop, a liponot causes considerable patient discontent.
The use of microcannulas and attention to details minimize the risk of lipotrops and liponots. Superior liposuction results require removal of enough fat to achieve significant cosmetic improvement while cautiously avoiding excessive extraction. Careful patient positioning improves the surgeon’s confidence in this regard.
Sequence of Areas
When planning to do iterative or sequential liposuction over a period of months, the surgeon must not treat an area that will leave the patient looking temporarily distorted. The patient will be unhappy and the surgeon chagrined if the patient decides not to proceed with liposuction of the remaining areas.
Goals Versus Predictions
The goal of liposuction is to provide an aesthetic improvement in the shape of a patient’s body. When the patient looks in the mirror and sees an obvious and pleasing improvement in size and shape, the liposuction should be judged a success.
The surgeon must avoid quantitative predictions about the results of liposuction and should avoid making an estimate of the volume of fat to be aspirated during liposuction. One should not predict how a patient’s clothing size will change after liposuction. Little if any reason exists to measure the circumference of a patient’s thigh or torso before or after liposuction.
A quantitative prediction is not in the best interest of the patient or the surgeon for the following reasons:
- If the goal is to remove a specific volume of fat, the surgeon may perform liposuction in excess of the amount required for optimal cosmetic results.
- Despite excellent cosmetic results, some patients will be disappointed and feel cheated if a quantitative prediction is not realized.
Successful tumescent liposuction is nursing intensive. Liposuction totally by local anesthesia is impossible without excellent nursing. Nurses are responsible for ensuring that the awake patient is comfortable at all times. Nurses often perform tumescent infiltration, thus allowing the surgeon to be more time efficient. Nurses are typically not as “rushed” as a surgeon and therefore are often more patient and precise with infiltration.
Nurses are responsible for taking a thorough history immediately before surgery to verify that the clinical situation has not significantly changed. The nurse who provides effective preoperative education and aftercare instructions will prevent many postoperative problems. With the low incidence of postoperative problems as a result of using open drainage and bimodal compression, nurses may be responsible for most of the postoperative follow-up, primarily by telephone.
Patient Comfort and Modesty
Any surgical procedure by local anesthesia is more easily accomplished when the patient is calm and relaxed. If a patient is subjected to unnecessary discomfort, anxiety, fear, and embarrassment, liposuction is more difficult for all concerned. A patient’s attitude is more likely to be relaxed and tranquil if the surgical staff is sensitive to the patient’s physical and psychologic comfort.
Efforts to maintain the patient’s physical comfort and warmth might include covering the patient with drapes or even warm towels that have been kept in a blanket warmer. A water bath can be used to warm the bottles of surgical soap used to scrub the patient and the bottle of sterile saline used to rinse after the scrub. The tumescent local anesthetic solution that will be infiltrated into the subcutaneous fat should be warmer than room temperature and never chilled.
The surgical staff must be aware of patient’s feelings of vulnerability and concerns about being undressed and naked. Some patients may feel embarrassed and humiliated by being undressed in an operating room. The surgical team should be protective of the patient’s modesty. A female patient should be provided with bra, panties, and gown, when consistent with good surgical technique. Similarly, male patients should be provided with appropriate cover.
Sterile Absorbent Gauze Sponges
The surgeon should have an ample supply of sterile absorbent gauze sponges always readily available and within easy reach. A large number of sponges are used during tumescent liposuction (Figure 28-2).
Gauze sponges are used to absorb any excessive flow of tumescent anesthetic solution draining from the many adit sites. Gauze sponges frequently are used to wipe the wet skin surface and thereby facilitate a secure, nonslippery grip by the sensory hand during liposuction.
When fibrous adipose tissue adheres to a microcannula, the cannula can be wiped clean with unsoiled sterile gauze. To minimize the risk of infection, the surgeon should not allow the cannula shaft to contact anything other than clean sterile gauze, subcutaneous fat, or adit sites. The surgeon should avoid touching the microcannula shaft with a surgical glove if the glove has already touched the patient’s skin.
In the anatomic position a person stands erect, with the upper and lower extremities slightly abducted. The anatomic position is traditionally used as a frame of reference when describing the relative location of any point on or in the body. The anatomic position is also the most common position for critically evaluating a human figure, especially before and after liposuction.
Distortions of the body during surgery that deviate significantly from the anatomic position can lead to inaccurate intraoperative assessments of results and unintentional aesthetic defects. The optimal intraoperative position minimizes risks of unintentional iatrogenic aesthetic defects. Although large volumes of subcutaneous tumescent anesthetic solution magnify the targeted fat compartment, they should not disproportionately distort the fat compartment.
When the body’s position deviates from the anatomic position, the body’s fat compartments are stretched, compressed, or twisted to some degree. The risk of inaccurate liposuction is increased when the patient’s intraoperative position distorts the targeted fat compartment. Positioning pillows can be used to place liposuction patients in a position that approximates the anatomic position, thus minimizing the risk of liposuction causing skin irregularities. For example, the optimal position for liposuction of the thighs is a modified lateral decubitus that approximates the anatomic position (see Chapter 32).
Lipowarp. A lipowarp is a distortion of the subcutaneous fat that is caused by the body assuming a position different from the anatomic position. Lipowarps can be caused by a flexion, extension, or rotation of a body part. For example, when the hip is flexed, the fat compartment of the lateral thigh is distorted; the posterolateral aspect is stretched and the anterolateral aspect compressed. A lipowarp of the lateral thigh can also be caused by the effects of gravity when the patient is lying supine; the lateral thigh is compressed in the anteroposterior direction and bulges in the lateral direction (see Chapters 32 and 34).
Pseudobulge. A pseudobulge is a special case of a lipowarp in which a distortion of subcutaneous fat is caused by the localized protrusion of a skeletal part. The most important example is the trochanteric pseudobulge of the lateral thigh. Deviating from the anatomic position by flexing and adducting the hip joint causes the protuberance of the greater trochanter to distend the overlying fat and skin. Failing to compensate for a pseudobulge during liposuction results in excessive localized fat extraction and creation of a lipotrop.
Anesthetic Technique. The method of anesthesia can affect the cosmetic results of liposuction. With liposuction totally by local anesthesia, patients are alert and cooperative in conforming to optimal intraoperative positions (see Chapter 26). Under either intravenous (IV) or inhalation anesthesia, patients are unconscious and cannot cooperate in assuming an optimal position. With endotracheal intubation, considerations of airway management and safety often preclude certain intraoperative positions. Compromises in patient positioning increase the risks of lipotrops and liponots. Attempting to do lateral thigh liposuction with the patient only in the supine position may lead to insufficient and disappointing results (see Chapter 32).
Detumescence Before Liposuction
After completing tumescent infiltration of an area, it is best to wait at least 20 to 30 minutes before commencing liposuction of an area (see Chapter 26). Fully tumescent subcutaneous tissue is difficult to grasp. With decreased tumescence the surgeon can more easily grasp the targeted fat, and liposuction becomes easier to accomplish.
Surgeons who rely on systemic anesthesia for tumescent liposuction tend to infiltrate less than the optimum volume of tumescent anesthetic solution, which then allows liposuction to be initiated as soon as the infiltration is completed.
A liposuction adit is a 1.0-, 1.5-, or 2.0-mm skin biopsy punch excision. Adits provide access for liposuction cannulas into the subcutaneous fat and facilitate postoperative drainage of residual blood-tinged anesthetic solution. The optimal choice of location, size, and number of adits or incisions requires an artful skill and experience. The choice must depend on the surgeon’s technique, expertise, and artistry (see Chapter 27).
Size. The size of an adit or incision must be sufficiently large to permit easy, almost frictionless passage of the cannula.
Number. The number of tiny adits required for microcannular tumescent liposuction is not fixed or constant. Tumescent liposuction with microcannulas requires more adits or incisions than are typically made when larger cannulas are used. The number of adits should not be excessive. Whereas two to four incisions might be used for traditional liposuction of the lateral thigh using large cannulas (3 to 6 mm), six or eight 1.5-mm adits might be created for microcannular liposuction of the thigh using 14-gauge microcannulas. A large thigh typically requires a few more 1.5-mm adits than a small thigh and perhaps one or more 2-mm adits to accommodate a 12-gauge microcannula.
In general, the number of adits for a particular area is determined by the need to minimize the potential scars and maximize the smoothness and completeness of results. The number of required adits or incisions is often increased when the subcutaneous fatty tissue is excessively fibrous.
Location. When determining the sites for placing adits, the surgeon gives priority to sites that permit optimal access to fat and sites that facilitate and encourage postoperative drainage. The surgeon also must consider that some skin areas are at increased risk of postinflammatory hyperpigmentation (see later discussion).
Placement and number of adits should be equally influenced by (1) the goal of optimizing the smoothness and precision of the liposuction and (2) the need to minimize visibility of scars.
Advantages. Adits are not closed with sutures. Eliminating the use of sutures facilitates postliposuction drainage. This in turn reduces postoperative tenderness, swelling, and edema. With no need to remove sutures, patients usually need not return until 6 weeks for postoperative photographs.
Surgeons who use large cannulas usually find that tumescent local anesthesia alone is insufficient for most liposuction patients and that the tumescent technique is better tolerated when used in conjunction with either systemic or epidural anesthesia.1 These surgeons are unaware that consistently painless tumescent liposuction totally by local anesthesia requires the use of microcannulas (see Chapter 27).
Techniques. Microcannulas are made with relatively lightweight hypodermic needle stock and must be used with a certain degree of finesse. They cannot be used as aggressively as one might use larger cannulas. If a microcannula is used too roughly, it will bend and possibly break. If a large vector of force is exerted perpendicular to the long axis of the cannula, the microcannula may bend.
Microcannulas require a delicate touch and a straight in-and-out, pistonlike motion. The surgeon will find that achieving straight-in, straight-out strokes requires considerable concentration to coordinate the simultaneous motion of the shoulder, elbow, and wrist. With a little practice, achieving this motion becomes second nature.
Advantages. Microcannulas remove more fat per stroke than might be expected and save the surgeon a significant amount of time.
Microcannulas produce smoother results and thus decrease the number of secondary touch-up procedures. Microcannulas also facilitate postoperative care and largely eliminate the need for time-consuming follow-up visits. Fat removal is often more thorough than with larger cannulas.
Types. The choice of cannula is a matter of clinical judgment. No precise formulas tell the surgeon which microcannulas to use at each step of a procedure. The Capistrano microcannula offers maximum efficiency (amount of fat removed per in-and-out stroke cycle of the cannula). The Finesse microcannula allows greater liposuction precision; fat is removed with less risk of excessive fat removal and injury to the dermis. Other microcannula designs are also available for tumescent liposuction.
Sizes. The choice of a cannula should be determined by the smoothness of the liposuction results that it produces. The 12-, 14-, and 16-gauge microcannulas are used for body liposuction. The 14-, 16-, and 18-gauge microcannulas are used for liposuction of the chin, necks, and jowls. The 20-gauge microcannula is specifically intended for precision liposuction of the cheeks.
Handles. Microcannula handles permit the surgeon to change the microcannula easily and rapidly whenever necessary during surgery. A variety of larger aspirating tubes can be attached, as well as IV extension tubing for delicate, small-volume liposuction (Figure 28-3).
By removing the thumb from the hole and opening the air vent in the handle, the vacuum tubing can be cleared of fat without removing the cannula from an incision. Also, by opening the air vent as the cannula tip is retracted toward the incision site, the surgeon can avoid excessive liposuction and minimize the risk of creating a spoke wheel deformity (see later discussion).
Successful tumescent liposuction totally by local anesthesia requires a modification of the standard liposuction techniques used with systemic anesthesia. Five absolute requirements for consistently comfortable liposuction by local anesthesia are as follows:
- Use of microcannulas
- Highly sophisticated infiltration technique
- Tumescent anesthetic solutions that vary in concentration according to the area being suctioned
- Gentle surgical technique
- Empathetic nursing staff
If any of these five ingredients is missing, liposuction totally by local anesthesia will be difficult, if not impossible, to achieve.
The hands-on surgical technique for microcannular tumescent liposuction is different from traditional liposuction with larger cannulas.
The process of liposuction requires that the surgeon’s two hands work in concert. One hand is designated the sensory hand (grips the fat) and the other the motor hand (grips the microcannula handle; Figure 28-4).
Sensory Hand. The sensory hand has several functions. By carefully gripping the fatty tissue, it senses the location and relative depth of the cannula tip during the process of liposuction. By maintaining the cannula tip between the thumb and fingers of the sensory hand, the surgeon can ensure that the cannula will not penetrate any tissue that is deep to the adipose tissue (Figure 28-5).
The sensory hand also gently squeezes and palpates the treated area to follow the progress of the liposuction and to determine when sufficient liposuction has been accomplished. It facilitates the safe and gentle liposuction of the fat located along the deepest plane of the fat compartment. While simultaneously gripping and lifting, the sensory hand can stretch the deeper strata, elevating fat away from the subjacent muscle. By vertically stretching the fat in a direction perpendicular to the muscle fascia, fat normally adjacent to the muscle fascia can be suctioned more safely while being elevated away from muscle.
The sensory hand helps maximize the efficiency of liposuction by immobilizing the targeted fat. When a vacuum is applied to a stationary liposuction cannula, fat aspiration does not occur. Similarly, when liposuction is attempted without the sensory hand gripping and immobilizing the fat, relatively little fat is aspirated. Maximally efficient liposuction occurs only when the sensory hand grips the targeted fat and prevents it from oscillating to and fro in unison with the cannula.
Motor Hand. The motor hand grips the cannula handle and provides the force that moves the microcannula through the targeted subcutaneous fat. The motion is most efficient when the microcannula moves in and out along a straight line.
The motor hand also has some sensory function. The motor hand can detect the rasping sensation that is transmitted from the microcannula tip as fat is detached from the surrounding fat. The motor hand can sense the degree of fibrous resistance to a cannula’s progress through fat.
The thumb of the motor hand controls the vacuum applied to the microcannula by either occluding or opening the vent hole located in the thumb depression. Occluding the vent with the thumb permits full suction within the cannula. When the thumb is lifted from the hole, air is vented into the side port, and no suction occurs in the cannula.
Index Finger. The index finger of the motor hand can be used to cushion the impact of the microcannula hub against the skin. The index finger of the hand gripping the microcannula handle can be extended so that the fingertip just covers the distal portion of the hub, where the cannula tube inserts into the hub. Acting as a cushion, the index finger reduces the risk of mechanical trauma from the hub repeatedly bumping against the adit or incision site (Figure 28-6).
Pitch and Yaw
To minimize trauma to the surrounding skin as the microcannula is pushed and pulled through the subcutaneous fat, the surgeon must move the cannula along a straight-line path through the adit or incision. This minimizes both the friction and the posttraumatic hyperpigmentation.
Coordinating the simultaneous movement of the shoulder, elbow, and wrist to achieve a straight in-and-out motion of the microcannula through an adit requires effort and practice. Inattentive or unsteady guidance will allow the direction of the cannula to deviate temporarily from a straight course, turning either to one side or from side to side as it is advanced. Without experience using microcannulas, the surgeon tends to advance the cannula with slight pitch and yaw.
A cannula is moving with a slight pitch if the tip of the cannula does not move along a line that is congruent with its long axis. The cannula is said to yaw as it moves through the adit if the cannula rotates about an axis that is perpendicular to its long axis. Both motions cause unnecessary friction to the skin surrounding the adit.
Regardless of the technique used to change cannula direction, the surgeon must avoid applying excessive pressure or friction to the skin at the adit or incision site.
When the microcannula direction is altered while it is in the subcutaneous fat, it is turned or rotated about an axis that is perpendicular to its long axis. The point where this axis of rotation and the long axis of the cannula intersect is referred to as the fulcrum of rotation. Ideally, the fulcrum of cannula rotation should coincide with the adit, thereby minimizing the trauma and friction applied to the skin surrounding the adit.
In reality, when an experienced surgeon redirects a microcannula, the maneuver involves a coordinated effort of the surgeon’s hands. As the sensory hand grips and displaces the targeted fatty tissue, the motor hand directs and propels the cannula in and out of the adit. The pattern of action and motion of the surgeon’s hands is typically some combination of at least three different movements, as follows:
- The cannula is almost completely withdrawn from the subcutaneous tissue, and the cannula is rotated about a fulcrum near the cannula tip. To avoid excessive liposuction at or near the adit, the thumb of the motor hand can be lifted from the side port on the cannula handle, thereby terminating the vacuum within the cannula.
- While the sensory hand grips, pushes, pulls, and moves the fat laterally or vertically, the motor hand simply continues to reciprocate with a pistonlike motion. The cannula continues to move in and out without changing direction, while the targeted fat is moved from side to side and up or down. The surgeon is careful not to allow the cannula to rub the skin surrounding the adit.
- Small incremental rotations and slight changes in cannula direction are accomplished with each stroke (thrust and retraction) of the cannula. This maneuver requires a coordinated effort of both hands to change the cannula direction with minimal trauma to the adit and minimal lateral pressure on the cannula shaft.
Excessive lateral forces to the long, flexible tube of the microcannula may bend the cannula. Too much lateral pressure repeatedly applied to the microcannula causes repetitive flexion, metal fatigue, and possible fracture where the cannula inserts into the hub.
Microcannular liposuction, using multiple adits or incisions, is accomplished using a fanlike pattern for directing cannulas. The cannula is repeatedly moved from one incision to another, doing five to 20 strokes in a fanlike pattern of tunnels radiating out from each incision site. The pattern of tunnels that radiate from adjacent incisions are intended to interdigitate, overlap, and intersect. Only a limited volume of fat is removed by liposuction through any one incision before moving to another incision. Using multiple incision sites, adjacent patterns fan out radially and overlap in a shingled configuration and interdigitate on all levels throughout the fat.
The essential goal is to remove fat decrementally in a step-by-step process that removes approximately 10% to 20% of the fat uniformly across the entire targeted fat compartment. This process is repeated several times until the desired amount of liposuction is accomplished. The technique of switching incision sites ensures that fat is removed in relatively small decrements over a large area, yielding smooth results. This repeated shifting from one incision to another makes a liposuction pump somewhat more efficient than a hand-held syringe technique.
Initial Liposuction. When initiating liposuction, small-gauge microcannulas are preferred over larger microcannulas. Small-diameter cannulas cause less pain than large-diameter cannulas. After first using small-diameter cannulas, large-diameter cannulas subsequently cause much less discomfort when they follow the path made by a small-gauge cannula. The smaller microcannulas are also useful to “check” that all areas are adequately anesthetized.
The surgeon must minimize the degree of lateral force placed on a microcannula shaft. A microcannula cannot be used to lift or move adipose tissue. The force applied to a microcannula is directed along a vector congruent with its long axis.
The longer the cannula, the greater is its relative flexibility. A long, flexible microcannula is more difficult to direct with accuracy as it progresses through the fat. Thus a 16-gauge microcannula that is 12 cm long is often easier to use than one 15 cm (6 inches) long.
The smallest microcannulas can more easily penetrate and perforate fibrous adipose tissue. Thus smaller microcannulas are also useful for initial stages of liposuction of the deep periumbilical fat, the fibrous tissue extending transversely across the midabdomen just superior to the umbilicus, the male breast, the epigastric abdomen near costal margin, the waist, and the back. After first using the smaller microcannulas to tunnel through fibrous fatty tissue, the surgeon can then use a larger microcannula to remove fat more efficiently.
Progressively Larger Microcannulas. Sixteen-gauge microcannulas are ideal for initiating liposuction in a new area. Microcannulas with smaller cross sections encounter resistance as they are advanced through adipose tissue. By using 16-gauge microcannulas, the surgeon can easily and accurately place adjacent cannula paths very close to one another and achieve a uniform extraction of fat.
Next, the existing tiny tunnels can be enlarged incrementally, first using 14-gauge and then 12-gauge microcannulas. This technique of using progressively larger microcannulas is especially useful for the initial stages of liposuction of relatively fibrous areas, such as the medial knees, periumbilical area, breasts, and scapular back.
Determining the appropriate time to switch to a larger cannula depends on clinical judgment and the surgeon’s personal style and experience. On accomplishing a sufficient amount of liposuction throughout an area using a microcannula of a particular gauge, the surgeon will notice that the cannula begins to encounter less and less resistance. When little resistance is encountered in a targeted area using a small microcannula, the surgeon might use a microcannula with a greater outside diameter.
Progressing from small to large cannulas differs from the traditional strategy of first using large cannulas to remove fat quickly and then switching to a smaller cannula to smooth out irregularities. The microcannular technique starts with smaller cannulas to prevent irregularities rather than repair them. By first creating a network of narrow, closely spaced tunnels that are later enlarged, the surgeon improves the uniformity of the results.
If a large cannula is used first, it becomes more difficult to direct any cannula along a new path. A large cannula tends to follow the path of least resistance and enter an existing tunnel rather than follow a new direction through intact adipose tissue. Thus, when liposuction is initiated using large cannulas, the surgeon tends to do too much liposuction in discrete or focal locations. After using a large cannula, it is more difficult to remove a small lump of residual fat without exacerbating areas where too much fat has already been removed.
Deep Liposuction. The deepest plane within a compartment of fat should be the first to be liposuctioned. If tumescent liposuction is initiated along a plane that is too superficial, it becomes more difficult to palpate and precisely determine the depth of the residual fat. As with infiltration, once a plane of liposuction has been created, it is difficult to judge by palpation the thickness of deeper layers of fat or to distinguish the interface between deep tumescent fat and muscle fascia. Initiating liposuction along the deepest plane facilitates a more complete and homogenous removal of fat (Figure 28-7).
As a general rule the surgeon should use a 16-gauge or 14-gauge microcannula to establish the deep plane and then suction the more superficial levels, creating a meshwork of crisscrossing tunnels from different adits. Once the deepest plane of liposuction has been created and a meshwork of tiny paths has been established throughout the fat, larger diameter (14 or 12 gauge) and longer microcannulas can be used with less resistance, less patient discomfort, and greater accuracy. Only a small amount of liposuction in the deepest plane is necessary to establish the deep cleavage plane.
If the initial tunnels are created at the midlevel strata of the fat compartment, this plane tends to act as a natural cleavage plane. Subsequently, as the surgeon attempts to detect the level of the interface between fat and muscle by using the sensory hand to grip, palpate, and stretch the fat, the initial cleavage plane can be mistaken for the deep fat-muscle interface. The fatty tissue at the initial plane of liposuction is easily stretched and elevated away from the residual deep, firm, tumescent fat. As a result, the sensory hand may mistakenly determine that the tumescent fat deep to the cleavage plane is muscle. Thus the initial cleavage plane becomes a “pseudointerface” between fat and muscle, and the surgeon becomes less confident about attempting liposuction deep to the initial plane of liposuction.
The actual depth of the deepest plane of liposuction is not intended to be precisely at the level of muscle fascia. If too close to muscle, the cannula might puncture muscle and produce significant bleeding. The surgeon can increase the safety of doing liposuction relatively close to muscle fascia by lifting the fat away from deep fascia.
Stretching Deep Fat. The tumescent fat can be elevated away from the deep muscle fascia by using the sensory hand to gently grasp and lift a handful of skin and subjacent tumescent fat. The degree of stretching of the fat at the deepest plane can be augmented by simultaneously elevating the tumescent fat and doing liposuction through the deepest layers of fat. Each new cannula tunnel in the deepest plane incrementally produces laxity of the fat across that plane.
When a microcannula perforates fibrous septa within adipose tissue, the holes in the septa are easily elongated by traction on the adipose tissue. As a consequence, both the septa and the deep fat become more stretchable. This allows the surgeon to accomplish liposuction within the deepest planes of subcutaneous fat while minimizing the risk that the microcannula might encounter and injure a structure deep to fat, such as muscle. Once the deepest plane is established in this manner, the surgeon can more easily and accurately do liposuction throughout the more superficial fat.
Preventing Residual Deep Fat. Initiating liposuction too superficially may result in a deeper layer of undetected fat. The surgeon tends to limit the depth of liposuction to the volume of fat that is superficial to the initial plane of liposuction. The layers of fat that remain deep to the initial plane of liposuction remain tumescent and relatively firm. It becomes difficult to detect, by squeezing and palpation, the depth of the muscle-fat interface (see Figure 28-7).
If liposuction of an area is not initiated at the deepest plane, the surgeon may misjudge the end point of liposuction in that area. When the sensory hand squeezes a mound of subcutaneous fat, the surgeon may grasp only the tissue superficial to the initial plane of liposuction. Because the fat located deep to the initial plane of liposuction is not easily detected by the grasp of the sensory hand, it may not be treated.
By initiating the liposuction too superficially, the surgeon may have a false sense of when liposuction is complete.
Excessive Superficial Liposuction. Conservative superficial liposuction with microcannulas allows the surgeon to remove more fat with fewer irregularities than when using a larger cannula (Figure 28-8).
All liposuction surgeons should know superficial liposuction that is so superficial that it damages the undersurface of the dermis is not necessary for optimal contraction of skin. Furthermore, excessive superficial liposuction is associated with a high risk of injuring the subdermal vascular and lymphatic vessels, which can result in either full-thickness dermal necrosis or chronic erythema ab liporaspiration (see Chapter 8).
The larger the diameter of the cannula, the greater is the risk that excessively superficial liposuction will cause dermal injury. This is particularly true with Capistrano-style cannulas that are 10 gauge or greater in size.
An ability to achieve consistently the smoothest possible result is the mark of a skillful liposuction surgeon. One means of achieving smooth, natural results involves a technique known as decremental liposuction.
With decremental liposuction the total thickness of a fat compartment is gradually and uniformly reduced in small proportions or small decrements. The goal is to decrease the “thickness” of the targeted fat compartment in repeated steps, each time removing approximately 10% to 20% of the intended result. Throughout this decremental process the surgeon must repeatedly check to ensure the liposuction is producing the desired, uniformly smooth result. Smoothness and uniformity are assessed by vision and by palpation at each step of the decremental process.
Through each adit the surgeon performs a limited number of cannula thrusts, with patterns of cannula paths radiating from the adit. The tunnels or paths created by doing liposuction from one adit should crisscross with other cannula paths that radiate from adjacent adits. After a limited number of cannula strokes through a given adit, the cannula is withdrawn and placed in another incision, and the process is repeated.
At each decremental stage, the entire targeted area is partially liposuctioned using all the adits. Moving from adit to adit, the microcannula is directed each time in a fanning pattern, with strokes from adjacent adits overlapping, crisscrossing, and interdigitating. Little by little, the entire compartment of subcutaneous fat is reduced decrementally.
At each step the surgeon must check the surface for smoothness and shapeliness. Any apparent irregularity is corrected, and the desired smoothness is achieved before continuing with the next decremental stage of the liposuction. This process is repeated several times until the fat compartment has been reduced to the desired thickness.
Using too few incisions or doing too much liposuction through one incision before switching to another incision will predispose to postoperative liposuction irregularities. If the surgeon attempts to treat an area segmentally by suctioning all the fat in one segment of an area before treating the adjacent segment, there is a risk of creating cobblestone-like irregularities or lipotrops. It is difficult to match the thickness of adjacent segments of fat when using the segmental approach to liposuction.
Feathering the Periphery. The technique used to achieve a smooth, imperceptible transition from an area treated by liposuction to an untreated area is called feathering the periphery. The surgeon can produce feathering simply by doing proportionately less liposuction at the periphery of the treated area. Feathering can be accomplished using either microcannulas with the same gauge as those being used for liposuction or smaller microcannulas.
Assessment of Symmetry
Humans are rarely perfectly symmetric. It is unrealistic for a patient to expect that liposuction will produce perfectly symmetric results. Results that are less symmetric than the preoperative condition, however, are not acceptable. Thus the ability to judge the degree of symmetry during liposuction surgery is important.
Although it is intuitively appealing to analyze the results of liposuction for symmetry with the patient in a standing position, this maneuver is unnecessary and has potential pitfalls. At the conclusion of tumescent liposuction, if the patient has been lying on one side for an extended time, the dependent areas will become compressed by the patient’s own weight. This transient compression may distort the treated areas and falsely give the appearance of asymmetry. The surgeon must be careful not to overcompensate for a perceived asymmetry that does not exist.
With tumescent liposuction, assessing symmetry can be easily and accurately accomplished while the patient is recumbent. Areas of residual fat are more easily detected by a careful tactile squeeze than by visual examination. The tactile squeeze consists of gently grasping the skin and subcutaneous tissue between the thumb and the flat surface of all four opposed fingers.
The tactile squeeze technique is an accurate means of assessing uniformity of the liposuction. It is important in detecting subtle areas of insufficient liposuction or liponots. Achieving smooth, uniform results on one side and reproducing the same result on the opposite side is an accurate means of attaining symmetry. With experience and attention to detail, uniformity of results consistently leads to symmetric results.
Linear abdominal scars, even those that are depressed or moderately retracted, can be diminished by careful liposuction of the surrounding fat. Abdominal surgical scars that do not involve direct adherence of the dermis onto muscle fascia can usually be penetrated using microcannulas. The vertical sheet of fibrous scar tissue within fat is punctured and penetrated by the infiltration spinal needle while producing tumescent anesthesia. Then, using a relatively short and less flexible 16-gauge microcannula, the surgeon penetrates the scar along a path that is parallel to the skin and at an angle of incidence to the long axis of the scar that is approximately 45 to 90 degrees.
After fenestrating the scar with this smaller cannula, larger microcannulas can be passed more easily through the scar tissue. To avoid inadvertent penetration of tissue beyond the subcutaneous fat, the surgeon must avoid using too much force when pushing the cannula through a scar.
Dermal scars that are adherent to muscle fascia cannot be eliminated by liposuction. Linear dermal scars that are adherent directly to muscle fascia can be excised as a secondary procedure done months after the liposuction. The surgeon makes a narrow fusiform incision about the scar and deepithelializes the scar by a tangential excision of the epidermis, allowing the deeper portions of the scar to remain. After undermining the lateral wound margin deeply just above the deep fascia, the wound is closed by suturing the wound margins and burying the residual scar tissue beneath unaffected fat and skin.
Vulnerable Vascular Structures
If large varicose veins are within an area of subcutaneous fat, the surgeon should consider treating the varicosities before liposuction. The surgeon should know the paths of the larger (named) veins in areas targeted for liposuction.
Significant vascular injury is rarely associated with liposuction, but several major vascular structures are potentially vulnerable to liposuction. In the lower abdomen the anterior superior epigastric veins, the lateral circumflex veins, and the medial neurovascular bundles provide the arterial supply to the midabdominal skin and subcutaneous fat. Other areas with vulnerable venous structures are the breasts and medial thigh (greater saphenous vein).
A liposuction cannula should never enter the popliteal fossa or axilla because of the danger to important neurovascular structures. Similarly, the volar arms should be approached with great caution. Although the important vascular structures in the neck are deep to the platysma muscles, liposuction of the neck region also requires great care.
Preventing Surgical Defects
Depressed Incision Site. This complication is preventable by minimizing trauma to the skin surrounding the incision or adit. A slit incision produced by a scalpel blade is more susceptible to cannula-induced friction than a round adit hole produced by a skin biopsy punch. If an incision or adit hole is too small, excessive friction from the back-and-forth motion of the cannula will injure the skin, resulting in excessive postsurgical scarring and pigmentation.
Incisions and adit sites must not be too small or unnecessarily large. Excessively long incisions result in scars that are unnecessarily long and therefore more visible.
Spoke Wheel Deformity. This defect is the result of disproportionately excessive liposuction and appears as a focal depression in the area of an incision site. The surgeon can avoid creating a spoke wheel deformity by carefully eliminating the suction when the cannula apertures are near the incision; the suction is eliminated whenever the surgeon’s thumb is lifted from the air vent on the cannula handle.
Keloids and Hypertrophic Scars. A liposuction adit or small incision rarely causes these scars. A hypertrophic scar is raised above the surrounding skin but is confined within the area of the wound. A keloid scar is a special case of a hypertrophic scar that extends beyond the site of the initial wound. Certain individuals have a genetic predisposition for keloid formation.
A hypertrophic scar may be hyperemic and pink or may be hypopigmented. Hypertrophic scars may occur in any patient and are more likely to develop on the chest, neck, shoulders, and deltoid surface of the proximal extensor arm.
A decision to do liposuction on a patient with a history of excessive scarring must consider additional clinical history. Patients with keloid scars or hypertrophic scars may still be good candidates for liposuction. For example, a patient with a keloid scar on the deltoid area of the shoulder but normal scars elsewhere on the body will probably have no problem with keloid formation after liposuction of an area known to be at low risk for keloids, such as the abdomen or thighs.
Patients who have hypertrophic scars must be carefully examined and informed about the risks for scarring.
Erythema Ab Liporaspiration. This chronic reticulated erythema is produced by excessive superficial liposuction, with permanent damage to the subdermal vascular plexus. It is analogous to erythema ab igne, the mottled cutaneous vascular pattern that results from chronic thermal injury to the dermis. Liposuction should not be too superficial and should not rasp the dermis. Superficial liposuction must not aggressively involve the dermis. Optimal aesthetic results and rapid healing require at least a thin blanket of atraumatic, uniform residual fat attached to the dermis (see Chapter 8).
Inadequate Local Anesthesia
Any clinician (surgeon, anesthesiologist, registered nurse) who is well trained and experienced in tumescent infiltration should be able to achieve profound local anesthesia in virtually all patients. In as many as 20% to 30% of patients, however, the surgeon may encounter one or more small areas where anesthesia is less than complete. Surgeons must be able to recognize inadequate local anesthesia and to correct the situation.
When a patient experiences pain during liposuction by local anesthesia, two common solutions exist. One approach is simply to infiltrate additional local anesthetic solution into the affected tissue, using either a 15-cm (6-inch), 18-gauge intradiscal needle or a 9-cm (3½-inch), 20-gauge spinal needle. Alternatively, the surgeon can use a smaller microcannula, which is less painful. Thus, whenever an area of discomfort is encountered, simply reducing the size of the cannula may be sufficient to allow continued suction in that area.
Distinct Types of Pain and Discomfort. Common usage has imparted an imprecise meaning to “local anesthesia.” For tumescent local anesthesia, dilute lidocaine produces local analgesia (absence of pain) but not true anesthesia (absence of all sensation).
Adequate tumescent lidocaine can be expected to block sensory nerve fibers that transmit pain and temperature sensation. Usually, however, it does not block sensory fibers that transmit the sensations of vibration, proprioception, and pressure. Thus nerve fibers associated with the periosteum that transmit vibration, proprioception, and pressure sensation are not completely blocked by lidocaine. An alert patient may feel a “strange” sensation during liposuction over a bony prominence, such as the medial malleolus, iliac crest, and trochanteric tubercle of the outer thigh. Some patients describe the “bizarre” sensation of liposuction as a vague rasping or washboardlike vibration and may perceive it as unpleasant or uncomfortable.
If a patient complains of pain during tumescent liposuction totally by local anesthesia, the clinician must distinguish between true pain and intolerance to vibratory and pressure sensations. True pain is typically described as a “sharp,” “needlelike,” or “burning” sensation and is the result of insufficient local anesthesia. When a patient complains of a sharp or burning pain, more local anesthesia should be given or a smaller microcannula used.
Intolerance to vibratory and pressure sensations is typically described as “dull,” “unpleasant,” “rasping,” or “a heavy pressure.” This type of discomfort usually will not diminish with additional tumescent anesthesia. The surgeons can allay much of the patient’s anxiety by explaining the cause of the sensation and giving reassurance that muscle or bone is not being traumatized. The surgeon can minimize the “rasping” sensation by using the sensory hand to grip and elevate the subcutaneous tissue away from the deeper tissues while carefully directing the cannula away from the deep fascia.
A number of factors affect the ultimate result of tumescent liposuction. The surgeon must be aware of these factors to achieve the best liposuction results and adequate documentation.
Supranatant Fat Volume
Documentation. The volume of supranatant fat and the volume of infranatant blood-tinged anesthetic solution should be documented in every operative report. Recording the total volume of aspirate (supranatant plus infranatant) is less clinically relevant.
Merely recording the total volume of the aspirate provides little relevant information regarding the surgical trauma and the risk of surgical complications. The volume of total aspirate is not a good indicator of surgical trauma. A liposuction that yields 2800 ml of supranatant fat and 200 ml of infranatant blood-tinged anesthetic solution is a greater surgical insult than a liposuction that yields 1500 ml of supranatant and 1500 ml of infranatant fluid.
Infranatant Volumes. For more than 30 minutes after completion of liposuction, the supranatant fat and the infranatant solution continue to settle into two separate layers as a result of the difference in densities.
Supranatant fat floats on the top of the aspirate in the collection canister after tumescent liposuction. Before measuring the volume of supranatant fat, sufficient time must pass for fat and water to separate. Thirty minutes after routine tumescent liposuction the volume of supranatant fat consists of approximately 84% fat and 16% saline. When properly measured and recorded, the supranatant fat provides a general indication of the volume of fat actually aspirated.
Internal ultrasound-assisted liposuction (internal UAL) causes the apparent volume of supranatant fat to increase as a result of the fat emulsification. With internal UAL the fat and water are so thoroughly mixed that they do not separate for more than 24 hours. This volume of supranatant fat does not give a reliable estimate of the amount of fat that was actually removed.
Several other factors help determine the volume of infranatant fluid after surgery. The ratio of supranatant fat to infranatant blood-tinged anesthetic solution will vary as a function of the elapsed time between the completion of infiltration and the initiation of liposuction. If the suction is performed within 10 to 15 minutes after infiltration, the supranatant volume/infranatant volume ratio may be 1:1 to 2:1, but if the elapsed time is more than an hour, the ratio may be 6:1 to 12:1. The greater the time interval between completion of infiltration and initiation of liposuction, the smaller is the volume of infranatant solution.
Furthermore, in patients whose fat is exceptionally fibrous (e.g., males) and in those who were obese and have subsequently lost significant weight, the aspirate will contain more than the usual amount of infranatant solution.
A 48-hour postoperative hematocrit is generally unnecessary with true tumescent liposuction, especially if the patient is feeling well, with virtually no symptoms referable to anemia or hypovolemia.
Surgeons who do titanic tumescent liposuction (which is not recommended) need to be familiar with the diagnosis and management of severe perioperative blood loss. In these cases, postoperative hematocrits may be required regularly.
With proper microcannular technique and the goal of achieving smooth results rather than removing a maximal amount of fat, significant liposuction-induced irregularities should not occur.
A skillful surgeon must nevertheless be able to help patients who have been treated elsewhere and may have been disfigured by significant lipotrops. In my experience a lipotrop is most effectively repaired by cautiously doing liposuction to remove the relative excess fat that surrounds a lipotrop. The strategy of using autologous fat transplantation is not only inconsistently successful but also supported only by anecdotal reports. A healthy skepticism is justified when contemplating reports about the skillful use of autologous fat transplantation to compensate for unskillful liposuction technique.
Repairing lipotrops and liponots should be done in a careful and conservative manner. The use of 16-gauge Capistrano microcannulas and 14-gauge Finesse microcannulas is often sufficient.
Inflammation and Infection
Significant inflammation or drainage typically persists for no more than 4 days in the immediate postliposuction period. An occasional patient has tumescent drainage that persists for more than a week. Others may experience an unusual, progressive degree of sterile (noninfectious) inflammation with onset several days after liposuction.
With careful observation the surgeon can identify two types of postoperative inflammation associated with tumescent liposuction. Both the frequency and intensity of these types are reduced by using open drainage and bimodal compression.
Soreness. Prostaglandin-mediated inflammation is the probable cause of the most common type of postliposuction inflammation. It seems to affect all patients to some degree. Even with open drainage and bimodal compression, an observant patient may notice increased postliposuction inflammation affecting all treated areas, with onset 4 to 5 days after surgery.
This delayed inflammatory response is self-limited and rarely elicits a telephone call to the surgeon. Most patients seem to accept this transient increased soreness as part of the normal healing process. Acetaminophen is sufficient treatment for most patients.
Lesions. Petite seromas appear to be the cause of the second type of postliposuction inflammation. Typically with an onset 4 to 7 days after tumescent liposuction, this type of inflammation presents as discrete, focal, erythematous, pink subcutaneous nodules that are firm, tender, and warm to the touch. Often there is only a single lesion. When several lesions are present, they usually become symptomatic and are noticed by the patient within a day or two of each other.
These lesions do not respond to antibiotics alone but do improve quickly when prednisone, 10 mg daily, is added to the antibiotic treatment. On the rare occasions when such a lesion has been opened and drained, all bacterial cultures have had negative results.
The incidence of these petite seromas has fallen precipitously with the use of open drainage and assiduous bimodal compression.
Patient Evaluation. Although fewer than one in every 300 patients returns for examination because of significant local inflammation, all such patients must be carefully evaluated. One approach to the patient who returns for evaluation because of a marked postoperative increase in swelling and pain (inflammation) is as follows:
- Evaluate for infection, including cellulitis and necrotizing fasciitis (see Chapter 12). Most patients first report the problem and concern by telephone. The clinician usually can establish that the likelihood of an infection is remote by taking a careful history by telephone. If the patient is alert, feels afebrile, has a good appetite, is drinking fluids, is urinating regularly, and is otherwise feeling well and participating in routine activities, a serious infection is less likely. If inflammation and discomfort are symmetric and uniformly distributed over all the areas treated by liposuction, a focal infection is relatively unlikely.
If an examination is deemed necessary, the clinician should record the patient’s body temperature and consider a complete blood count. Any suspicious exudate indicates the need for bacterial culture and sensitivity and possibly a Gram stain. The patient is treated with antibiotics if clinically indicated. If necrotizing fasciitis is suspected, the patient must be admitted to a hospital for emergency evaluation by a general surgeon.
- Evaluate for a possible deep venous thrombosis (DVT). The probability of a DVT is more likely if lower extremity pain is unilateral and if the lower extremity was not treated by liposuction. If a DVT is suspected, an emergency consultation by an appropriate specialist should be obtained (see Chapter 10).
After the surgeon has ruled out an obvious infection and DVT, treatment depends on the nature and severity of the symptoms.
- Evaluate the degree to which the patient’s physical activity is impaired as a result of the inflammation. If the patient is able to function without any unusual limitation of activity, treatment with antiinflammatory drugs is less urgent.
- Evaluate the patient’s ability to tolerate discomfort and pain. If the patient has an unusually low threshold for complaining about discomfort, giving the patient reassurance and mild analgesics may be sufficient. If the patient is normally stoic, antiinflammatory drugs may be appropriate.
When treatment of the pain and inflammation is indicated, the clinician should consider the following steps:
- Empiric treatment with antibiotics for possible infection
- Administration of prednisone, 10 mg by mouth daily for 2 to 7 days
- Daily follow-up of the patient’s clinical progress, either by telephone or in the surgeon’s office
Because antiinflammatory drugs may suppress a patient’s immune response to an infection, they should be used with caution in the immediate postoperative period. Both corticosteroids and nonsteroidal antiinflammatory drugs (NSAIDs) suppress leukocyte function and may decrease a patient’s resistance to infection. When antiinflammatory drugs are used, concomitant treatment with antibiotics may be indicated.
The problem of persistent drainage that lasts more than a week is unusual and rarely of any serious concern. Persistent drainage tends to be associated with the following:
- Liposuction of a large area, particularly the thigh or inner thigh/knee areas and abdomen
- Discontinuation of postliposuction compression garments before all drainage has stopped
The drainage typically appears as a pale-yellow, clear, plasmalike liquid and probably represents a combination of increased lymphatic flow associated with inflammation and ruptured lymphatic vessels resulting from liposuction.
Treatment of persistent drainage includes the three steps listed on p. 261 for treatment of inflammation as well as use of absorptive pads and firm compression of the treated area.
Dyschromia and Hyperpigmentation
Avoiding hyperpigmented liposuction adits or incisions is a challenge to a surgeon’s skill. Inexperience and carelessness increase the risk of inadvertent trauma to the portal of entry for the liposuction cannula.
The more darkly pigmented a patient’s natural skin color, the greater is the risk of postinflammatory dyschromia (hyperpigmentation or hypopigmentation) at adit or incision sites. Preventing postinflammatory hyperpigmentation in susceptible patients requires extra care to avoid unnecessary friction and trauma to the skin, particularly the dermalepidermal (D-E) junction near incisions or adits. Prevention of dyschromia at adit and incision sites is much easier than later treatment. The following strategies have proved useful in minimizing the frequency and degree of postinflammatory pigmentation:
- Avoid excessively small adits or incisions to minimize friction at the portal of entry. Using patulous round adits rather than narrow slit incisions will reduce the friction between skin and cannula. An incision that is too small for a cannula will result in a friction burn and mechanical trauma to the D-E junction, which causes injury to pigment. Melanocytes form at the D-E junction, which leads to postinflammatory localized hyperpigmentation and hypopigmentation. Hyperpigmentation is the result of melanocyte death and disgorgement of melanin granules, with subsequent phagocytosis by junctional and papillary melanophages. Melanophages are macrophages or histocytes that have ingested melanin granules or melanosomes.2
- Minimize friction from the cannula as it rubs the epidermis within several millimeters of the incision. Lift the skin with the gripping hand so that the cannula enters the adit at an angle, which avoids rubbing the cannula against the periincisional skin.
- Do not allow the cannula hub to contuse and bruise the incision site. With cannulas that are too short, the surgeon tends to advance or push the cannula too far, thus causing the hub to impact the skin around the adit. Gripping the cannula handle with the index finger extended slightly beyond the cannula hub helps to cushion the hub and minimize skin trauma (see Figure 28-6).
- Optimize the number of adits or incisions. Too few incisions tend to limit the thoroughness and smoothness of liposuction results. Too many unnecessary incisions may result in unnecessary scars. Microcannulas require a few more adits than the minimal number of incisions needed when using larger, traditional cannulas. Multiple adits are usually less visible than a smaller number of larger incisions.
- Optimize the placement of incisions. Minimize the number of incisions or adits placed in sites that are predisposed to dyschromia, such as the epigastrium and the back. Pigmented adit or incision sites tend to be most visible on the back and upper abdomen. When feasible, liposuction of the back should be approached from lateral incisions on the hip and waist.
For liposuction of the upper abdomen, only a few microincisions should be used to allow initial fenestration of the dense subcutaneous fat with the smallest microcannulas. Subsequently, most upper abdominal liposuction can be accomplished from incisions in the lower abdomen. For example, 12-gauge microcannulas can be advanced to the epigastrium from adits located laterally and inferiorly.
Similarly, using 12-gauge microcannulas for liposuction of the subscapular back can be accomplished through incisions placed laterally. Microincisions are preferentially placed where they tend to disappear. In patients of Northern European ancestry, the incisions required for microcannulas usually become invisible on the breasts, arms, thighs, chin and neck, and particularly the inner thighs.
All liposuction surgeons must remember the following caveats:
- It is inappropriate for nurses to do liposuction. Allowing a nurse to do the initial debulking liposuction can be viewed as “partaking in a conspiracy to practice medicine without a license.”
- A surgeon should never allow the administration of systemic anesthesia without adequately trained personnel in attendance.
- Cold sterilization of liposuction cannulas, other liposuction instrumentation, and tubing is dangerous and below surgical standards of care.
- Excessive liposuction is unwise and more dangerous than many surgeons realize.
Patient selection in cosmetic surgery requires both a precise knowledge of the patient’s health status and current medications (prescription and nonprescription) and an insightful awareness of important psychologic factors. Training and skill in careful patient selection are prerequisites for any liposuction surgeon. Patients must be much healthier to qualify as candidates for cosmetic surgery than for therapeutic surgery.
Cosmetic surgery patients should be healthy and at minimal risk for perioperative complications. Candidates for liposuction should have American Society of Anesthesiologists (ASA) class I or II anesthesia risk.3 Liposuction is ideally suited for healthy patients with localized deposits of fat.
If a potential liposuction patient has an unusual coexisting medical problem with which the surgeon has had little experience, preoperative consultation and medical clearance from an appropriate specialist are recommended.
An ethical cosmetic surgeon must be alert to avoid situations that involve real or apparent conflicts of interest. A potential conflict of interest exists for the surgeon making a decision about cosmetic surgery for a patient who is not completely healthy. Against the obligation to fulfill the ethical imperative of “above all, do no harm,” the surgeon must weigh (1) the desire to satisfy a patient’s request for the cosmetic procedure and (2) the desire to receive a fee for performing the surgery.
When the patient has a potentially serious medical problem that might be exacerbated by liposuction, the surgeon’s decision depends on a balance between desire to satisfy a patient’s request for surgery and an obligation to avoid significant risks. Concern for such a patient’s safety and the surgeon’s enlightened self-interest require that the patient’s specialists provide a formal letter giving preoperative clearance before liposuction.
The more precarious the patient’s health, the more important it is to have the advice and consent of a knowledgeable clinical expert. For example, if a patient has a significant but well-controlled cardiovascular condition, connective tissue disease, endocrine disorder, or psychiatric problem, a preoperative clearance letter should be obtained from the patient’s cardiologist, rheumatologist, endocrinologist, or psychiatrist, respectively. If the patient has a history of excessive surgical bleeding or an unusual family history of thrombosis, a hematologist should provide preoperative clearance.
If a patient has a significant medical problem, the surgeon should not do liposuction without the advice of the physician most familiar with the patient’s condition. If the patient is ASA class I or II, preoperative clearance is often not necessary.
The cosmetic surgeon must realize that some patients’ desire for a cosmetic procedure can overwhelm rationality. Some patients desperate to have liposuction might lie and may be incapable of informed consent. This is sufficient reason for seeking the advice of a physician more familiar with the patient’s medical history.
Concomitant Gynecologic Surgery
Abdominal liposuction is contraindicated with concomitant gynecologic surgery. Both abdominal liposuction and abdominoplasty after an intraabdominal gynecologic procedure appear to be associated with an exceptionally high incidence of serious perioperative complications. After dehiscence of sutured muscle wall incisions, thromboembolism, perforated abdominal viscus, and herniation of intestines are rare when gynecologic or cosmetic surgical procedures are done alone. The risk of these complications increases dramatically, however, when two such procedures are performed on the same day.
Obesity is not an indication for liposuction. No wellrecognized, scientifically documented proof indicates that liposuction has any therapeutic benefit for obesity. On the other hand, an obese patient might be very pleased with the results of localized liposuction. Thus liposuction in an obese patient is not absolutely contraindicated provided that the liposuction is done safely, with every effort to minimize the surgical risks associated with obesity.
Since obesity presents an increased risk for surgical complications, an ethical surgeon does not regard an obese patient’s request for liposuction as an indication to do largevolume liposuction.
Patients who exceed their ideal body weight by 30% are obese and at increased risk for perioperative surgical complications, especially respiratory sequelae. Because of the increased risk of postoperative complications, the amount of liposuction performed on any given day should be limited. In other words, obesity is an indication for serial or iterative liposuction procedures rather than one excessively aggressive liposuction procedure accomplished on a single day. The dilemma of choosing megaliposuction or multiple exposures to systemic anesthesia is avoided by doing liposuction totally by local anesthesia.
Morbid Obesity. Morbid obesity is a relatively strong contraindication for liposuction. Because of the increased risk of liposuction-related surgical complications, I will not treat patients with morbid obesity. The incidence of complications is higher because of the increased amount of surgical trauma, which predisposes to seromas, dermal necrosis, and infection. Postoperative hygiene, including drainage and compression, is usually inadequate. Cosmetic results are often disappointing. Little, if any, evidence indicates that liposuction for morbid obesity has any clinically significant therapeutic or lasting cosmetic benefit.
Prior Obesity. Liposuction of a previously obese patient can be more difficult. If two patients currently weigh exactly the same, but one patient was previously much more obese, liposuction of the previously obese patient is typically more difficult. A patient who previously weighed 11 kg (25 pounds) more than at present will have a relatively high proportion of fibrous tissue in subcutaneous fat.
With weight loss, individual adipocytes tend to diminish in volume but not in number. The relative proportion of the collagenous component of adipose tissue is increased in such patients. Liposuction of fat with a disproportionately large amount of fibrous tissue requires a greater effort.
The ultimate aesthetic results of liposuction in a previously obese patient tend to be less impressive than liposuction in a patient who is at maximum weight.
Insulin-dependent diabetic patients should not be considered for liposuction without significant caution. The risk of complications from anesthesia and surgery is approximately 10 times higher in diabetic patients, who also have a greater risk of dying in the perioperative period than healthy patients.4
Before deciding to do liposuction on an insulin-dependent diabetic patient, the surgeon should discuss the proposed surgery with the patient’s endocrinologist. Because diabetic patients are at greater risk for infection, especially nosocomial infections, the risk of doing the liposuction in a hospital must be considered. Diabetes mellitus is a predisposing factor for necrotizing fasciitis.
Preoperative laboratory tests should include a determination of hemoglobin Alc, a glycosylated hemoglobin that correlates with long-term diabetic control.
Liposuction on an immunocompromised patient may be associated with a significant risk of perioperative infections. Despite an intense desire to have liposuction, immunocompromised patients may not be good candidates for liposuction.
Not all persons are good candidates for liposuction surgery, but the basis for this decision must be based on fact rather than prejudice. The wisdom of performing cosmetic surgery in immunosuppressed patients is open to question. Certainly, no convincing evidence indicates that liposuction does not represent a significant risk for postliposuction infections (see Chapter 12).
Considerable evidence suggests that anesthetic agents adversely affect immune competency. The decision to do any type of surgery must be based on clinical outcomes, with a rational assessment of the relative risks and benefits of the proposed surgery. Although the relative risk of perioperative liposuction infection in a person with human immunodeficiency virus (HIV) infection is not known, the risk cannot be ignored. Until such risks are known, it is reasonable to error on the side of caution.5
Some facts are known. All general anesthetic agents, both inhalational and intravenous, depress immune function.6 Narcotics such as morphine7 and fentanyl18 have immunosuppressive effects. Intravenous anesthetic agents, including propofol, methohexital, and thiopental, also depress immune function.9
Protease inhibitor drugs are relatively contraindicated for large doses of lidocaine associated with tumescent liposuction because of the potential for inhibiting cytochrome P450 3A4 and interfering with lidocaine metabolism.
All potential liposuction patients should be tested for HIV infection to provide patients with a complete assessment of their risk for perioperative complications. Again, good candidates for liposuction should be healthy ASA class I or II anesthesia-risk patients. Some surgery centers have written policies stating that all cosmetic surgery patients must be either ASA class I or II. Patients with HIV infection are typically considered ASA III and are not regarded as ideal candidates for cosmetic procedures.
Hepatitis C virus (HCV) infection is a potentially fatal disease that infects approximately 1% of the population. HCV has several modes of transmission, some of which are not precisely known. The most common form is parenteral exposure or intimate contact with infected body fluids.
Greater than 80% of HCV infections result in chronic viremia. Among all infected patients, 70% to 85% will develop chronic hepatitis. Among patients with hepatitis, 20% to 40% will have cirrhosis. Among patients with cirrhosis, 10% will develop hepatocellular carcinoma.10 Surgeons and surgical operating room staff are among the risk groups for occupational exposure.11-13
The effect of HCV on the metabolism with high dosages of tumescent lidocaine is not known. The effect of lidocaine on the risk of developing chronic hepatitis and cirrhosis also is unknown. Therefore the risks of tumescent liposuction in the setting of HCV infection are not known.
All potential liposuction patients should be tested for evidence of HCV. Some surgeons may classify patients with HCV infection as ASA II or III.
Hypertension, a common condition among overweight patients, must be well controlled before considering liposuction. When significant hypertension is detected at the preoperative examination, the patient should be referred to a primary care physician for appropriate treatment far in advance of surgery. Excessive hypertension on the day of liposuction may respond within 30 minutes to clonidine, 0.1 mg by mouth. If hypertension persists, this is a strong indication to cancel the surgery.
In general, patients should not discontinue antihypertension medications on the day of surgery. Calcium channel blockers and beta blockers, both commonly used to treat hypertension, may interact to some extent with lidocaine and epinephrine. Among patients taking these drugs, the total dosage of lidocaine should be limited to less than 45 mg/kg for liposuction totally by local anesthesia. No drug interactions appear to occur between tumescent epinephrine and beta blockers taken to treat hypertension or prevent migraine headaches (see Chapters 18 and 24).
Hypertensive patients who are subjected to systemic anesthesia are at particular risk for perioperative complications.
Age is considered a minimal risk factor for liposuctionassociated perioperative complications. Advanced age should not be a major factor in the decision to do liposuction. Older patients tend to have fat that is less fibrous and therefore much easier to aspirate. The expectations of older patients tend to be more realistic and less demanding.
Among the most satisfied patients a liposuction surgeon will encounter is the older woman with abdominal subcutaneous obesity that adversely affects physical activity and self-image. Tumescent liposuction of the abdomen in a woman in her 60s or 70s tends to produce dramatic results with relatively rapid and comfortable recovery.
On the other hand, liposuction of very young patients should be approached with considerable caution. A teenager should not have liposuction simply at the parents’ request. The admonition that liposuction should not be used to treat obesity is particularly appropriate for teenagers, who must realize that surgery is not the answer to unhealthy dietary habits.
Smoking is a relative contraindication for any cosmetic surgical procedure. Patients who smoke should be encouraged to abstain for at least 8 weeks before surgery. Because most patients are unable to quit smoking, surgeons should limit the amount of liposuction performed at any given time.
Patients with significant atherosclerotic coronary artery disease are questionable candidates for liposuction surgery. Exposing such patients to the stress of surgical trauma should be contemplated with great caution. These patients require preoperative clearance from a cardiologist. Epinephrine, and therefore tumescent liposuction, is relatively contraindicated in patients with a history of angina or atherosclerosis.
Mitral valve prolapse (MVP) is usually asymptomatic. Patients who have required medical management of symptomatic MVP because of palpitations, arrhythmias (dysrhythmias), or atypical chest pain may benefit from a preoperative cardiology consultation.
The cosmetic surgeon must not do liposuction on a patient with a psychiatric problem that prevents reasonable, informed decision making. Liposuction is usually safe in a patient with mild situational depression. For a prospective liposuction patient who is seeing a psychiatrist, either regularly or intermittently, requesting that the psychiatrist provide a preoperative evaluation and letter of approval before scheduling liposuction might be appropriate.
Some antidepressant drugs, including selective serotonin reuptake inhibitors and tricyclic antidepressants, are among those drugs that may interfere with hepatic metabolism of lidocaine. If clinically feasible, these antidepressants may be discontinued at least 7 days before surgery. If they cannot be discontinued, the total dosage of lidocaine should be limited to less than 35 to 45 mg/kg.
Hypothyroidism and Hyperthyroidism
Liposuction patients with thyroid disease should be well controlled, with serum thyroid hormone levels within normal limits. If a patient is taking thyroid supplementation, the preoperative laboratory evaluation should include a determination of thyroid hormone to rule out the possibility of overmedication and iatrogenic hyperthyroidism.
Hyperthyroidism increases the risk of cardiac dysrhythmias. Some prospective liposuction patients who are somewhat obese will take excessive doses of thyroid supplementation under the assumption that hyperthyroidism will facilitate weight loss.
Patients who have a personal or a family history of unusual thromboembolic events should be evaluated for thrombophilia (see Chapter 10). Unusual venous thromboses include those occurring at a young age; multiple episodes of venous thrombosis or embolism; thrombosis in an unusual anatomic location, such as mesenteric, axillary, or cavernous sinus thrombosis; and spontaneous thrombosis without any known predisposing factors.
Prospective patients who have a personal history of malignant hyperthermia are questionable candidates for liposuction. Prospective patients who have a family history of this condition may be at risk for developing malignant hyperthermia as a reaction to systemic anesthetics. Because significant trauma or excessive physical exercise can precipitate malignant hyperthermia, even liposuction by local anesthesia may be dangerous.
One of the most important qualifications for a cosmetic surgeon is the knowledge of when and how to say “no” to inappropriate patients, including the following:
- Patients who have unrealistic expectations
- Patients who are unreasonably demanding, inconsiderate, or disrespectful of the office staff
- Patients who demand a guarantee of flawless results
- Patients who lie or “neglect” to give complete information about their health or previous surgeries
Poor interpersonal communication between patient and surgeon or a language barrier that cannot be remedied by an interpreter is a contraindication for liposuction.
Patients with a history of serious psychologic problems must have preoperative clearance from a psychiatrist. For medicolegal and ethical reasons, the surgeon should require documentation from the psychiatrist, in the form of a typewritten letter on professional letterhead stationery, which is placed in the patient’s chart.
“Red Flag” Patients. Certain categories or stereotyped groups of patients are known to be excessively demanding or unrealistic in their expectations. Patients in these categories are more likely to be impossible to please. This “red flag” status does not automatically exclude these patients from cosmetic surgery, but they should be approached with caution.
The patient who must have liposuction as soon as possible and who demands that the surgeon and nursing staff rearrange their schedules is the most likely patient to cancel surgery at the last minute. Self-important patients who boast of their own fame or wealth may be unusually troublesome. Patients who are “addicted” to cosmetic surgery are often unrealistic. Patients who are disheveled or appear unconcerned about their appearance may be unsuitable for cosmetic surgery.
Patients whose aesthetic judgment differs greatly from that of the surgeon are likely to be difficult to please. For example, the surgeon must be especially alert and judicious when considering the female with large hips who only wants liposuction of her relatively small abdomen.
Some surgeons regard out-of-town cosmetic surgery patients as “high risk” if they are unwilling to stay long for postoperative care.14 This is reasonable for many cosmetic surgery procedures. In the case of tumescent liposuction, however, with a postoperative care technique that incorporates open drainage and bimodal compression, the patient rarely needs to remain in town more than 24 hours after surgery. Thus the out-of-town liposuction patient who desires an uneventful recovery and a quick return home is not being unrealistic.
Unrealistic Expectations. The surgeon should not do liposuction on a patient with unrealistic expectations, such as the following examples:
- A 60-kg (132-pound) woman who expects that liposuction of the lateral thighs and abdomen will allow her to fit into clothes she wore when she weighed 50 kg (110 pounds)
- A woman who expects liposuction to cure her adulterous husband of his wandering ways
- A patient who expects liposuction to achieve perfect results
Patients should be told that they are good candidates for liposuction only if they would be satisfied with a 50% improvement. Most patients will achieve much more improvement, but any patient who would not be satisfied with 50% might have unrealistic expectations.
The unrealistic patient who cannot take “no” for an answer is especially troublesome. The patient may return for repeat consultations and attempts to convince the surgeon to do a procedure that is contrary to good judgment. A signed informed-consent form with explicit disclaimers and warnings will not prevent an unrealistic preoperative patient from becoming an unhappy and litigious postoperative patient.
How to Say “No.” The liposuction surgeon must minimize the incidence of dissatisfied patients or patients who are impossible to please. To minimize the risk of gratuitous malpractice litigation, a liposuction surgeon must be skilled at saying “no” to difficult or inappropriate patients.
A surgeon must always be willing to correct a mistaken or inappropriate decision to do liposuction. After having consented to do liposuction on a particular patient, if compelling new evidence of the patient’s inappropriate behavior becomes apparent, the surgeon should reverse the decision to do the surgery.
A liposuction surgeon must know how to be diplomatic when rejecting an inappropriate patient. The surgeon must be assertive but polite and considerate. The following statement has proved effective in this regard: “I do not believe I have the skill to achieve the results that you desire, and therefore it would be unethical and inappropriate for me to attempt to do your liposuction surgery.” No patient can reasonably expect or demand that a surgeon do something that is unethical.
Physics of a Liposuction Aspirator
The basic laws of physics state that the effect of a negative pressure applied to a liposuction cannula is independent of whether the negative pressure is created manually by pulling on a syringe or mechanically by using an electric motor. At equal magnitudes of negative pressure, a syringe or an electric aspirator produces equal effects on adipose tissue. In terms of tissue trauma, no difference exists between a syringe or aspirator.
Advantages of syringe liposuction include low initial costs, light weight, and ease of transport. Syringe-assisted liposuction using microcannulas, however, especially the smaller microcannulas, can be extremely tedious.
Using a syringe for liposuction may limit the surgeon’s liposuction technique. For example, achieving optimally smooth results, especially on the inner thighs, requires frequently switching liposuction adit (incision) sites and doing only a small amount of liposuction through any one adit before changing to another. This repeatedly causes a loss of negative pressure within the syringe and requires extra time and effort to reestablish the syringe vacuum.
Modern electric liposuction aspirators are more time efficient. Also, by eliminating the need to repeatedly reestablish a vacuum in the syringe, these aspirators may limit the surgeon’s exposure to the risk of repetitive-motion injury.
Misconceptions about the physical principles that govern the function of an electric vacuum-pump aspirator are the source of many paradoxes. For years it was assumed that the most powerful electric vacuum pump was a necessary component for the most effective liposuction aspirator. In fact, this is not the case.
A liposuction aspirator consists of two components: an electric vacuum pump and a liposuction canister (or vacuum reservoir). A vacuum pump is simply an air pump; by pumping the air out of a canister, an air pump creates a vacuum. As a component of a liposuction aspirator, the vacuum canister has two distinct functions: (1) to collect the aspirated fat and (2) to act as a reservoir for storing the potential kinetic energy of the vacuum.
It is an apparent paradox that the liposuction aspirator with “the most powerful electric vacuum pump” is not necessarily the optimal “liposuction aspirator.” The statement that “two electric vacuum pumps of different power can produce equally efficient liposuction aspirators” at first seems self-contradictory (see following discussion). With an appreciation of the physics of a vacuum and the functional difference between a liposuction aspirator and its component vacuum pump, the paradox becomes a statement of common sense.
Another misconception leads to an apparent paradox. For liposuction performed at higher elevations, a widely held belief is that optimal efficiency requires a vacuum pump of maximum power. To compensate for the decreased ambient atmospheric pressure, the assumption is that an extra-powerful vacuum pump is necessary. The fallacy of this assumption is revealed by an analysis of the physics of a liposuction aspirator. As presented in the following discussion, the magnitude of the negative pressure contained in the vacuum canister determines the effectiveness of a liposuction aspirator. Provided that a vacuum (air) pump exceeds a certain power threshold, any additional power is essentially superfluous.
Criteria for Optimal Aspirator
The usefulness of a liposuction aspirator depends more on its ability to aspirate water than its ability to pump air.
An excessively powerful pump is not only unnecessarily expensive, but also unnecessarily heavy and noisy. A smaller aspirator is easier to move from room to room and requires less storage space when not in use. An unnecessarily heavy pump presents a greater risk of a back injury to the surgeon or staff members who might have to move or lift the machine. A lightweight pump minimizes the risk of an occupational back injury and employee disability. Finally, an aspirator with one vacuum pump not only weighs less but is also easier to soundproof than an aspirator with three vacuum pumps.
As discussed next, any vacuum pump that exceeds a minimum threshold of power will allow liposuction at virtually the same rate as more powerful pumps. Excessive power beyond this threshold may be detrimental as well as wasteful. Suppose two aspirators aspirate 1 L of water at identical rates. The most advantageous aspirator is the quietest (least annoying and least likely to interfere with verbal communication), the most lightweight (least likely to cause back injury), and the least expensive. Thus a less powerful and less expensive aspirator may be more practical and desirable.
The Nature of a Vacuum
The power rating of a vacuum pump and the effectiveness of a vacuum pump as a component of a liposuction aspirator are independent variables. The power of vacuum pumps is rated in terms of the volume of air evacuated per minute. The ability to move large volumes of air per minute has little effect on the volume of water or fat that the pump can aspirate per minute.
If the power of a pump exceeds a certain threshold, the power of a vacuum pump is not an important factor in determining the effectiveness of the pump used as a liposuction aspirator.
A vacuum is a space from which the air has been artificially withdrawn. A complete vacuum cannot be produced by mechanical pumps. At best, one can create only a partial vacuum, which is almost but not completely devoid of gaseous molecules.
A torricellian vacuum is the space left at the top of a barometer by the mercury falling. The height of this column of mercury is a measure of the local atmospheric pressure, and the pressure within the vacuum is the negative value of the local atmospheric pressure. The magnitude of the negative pressure of a torricellian vacuum can never exceed the magnitude of the atmospheric pressure.
Another means of creating a vacuum is by an air pump, or a vacuum pump, which pumps air out of a hollow rigid vessel (e.g., a liposuction canister) to create a space almost empty of air. Commercially available vacuum pumps are either of the rotary vane type or the piston type. A syringe can be made to function as a vacuum pump by forcefully retracting the syringe’s piston and creating a space that has negative pressure compared with that of the surrounding atmosphere. Relative to the outside atmospheric pressure at sea level, the relative pressure inside an evacuated vacuum canister is negative, measuring approximately –760 mm Hg, or about –30 inches of mercury.
Atmospheric Pressure. Expressed in terms of force per unit area, atmospheric pressure is the pressure exerted by the atmosphere on the earth’s surface. At sea level the atmospheric pressure is approximately 1 kg per square centimeter, or 14.7 pounds per square inch. The weight of the atmosphere can also be expressed in terms of millimeters of mercury (760 mm Hg) or inches of mercury (30 inches Hg) that the atmosphere can support.
Relative pressure is the measure of pressure relative to the atmospheric pressure. Any pressure greater than the atmosphere is considered positive, and any pressure less is negative.
Vacuum Applied to Fat. Liposuction is accomplished by applying the force provided by a vacuum within a canister directly to the subcutaneous fat. This force can never exceed the negative value of the atmospheric pressure. The vacuum within a canister created by a suction device (e.g., vacuum pump, syringe) forces small globules of gelatinous fat through the cannula apertures and into the vacant space within the liposuction cannula.
If a liposuction cannula does not move relative to the fat, no liposuction will occur. The to-and-fro, in-and-out motion of the cannula acts as a rasp that effectively tears off small fragments of fat. These fat fragments are then sucked into the cannula, flowing into the liposuction tubing and finally into the vacuum canister.
Vacuum Canister Stores Potential Energy
To understand how liposuction works, one must recognize that the vacuum within the canister is directly responsible for the work of liposuction, not the vacuum pump. A container (within the earth’s atmosphere) that holds a vacuum is a reservoir for potential kinetic energy. The potential energy of a vacuum is converted to kinetic energy, which produces work when the vacuum sucks a fluid up a tube against a resisting force. The potential energy stored in the vacuum canister, not the power of the vacuum pump, determines the rate of liposuction and the relative proficiency of the aspirator.
The magnitude of the potential energy stored in a vacuum depends on the magnitude of the surrounding atmospheric pressure and the volume of the canister. At higher altitudes the pressure difference between the surrounding atmosphere and the inside of a vacuum canister is essentially independent of the size of the vacuum pump that created the vacuum. In other words, for liposuction at higher altitudes, no advantage exists to using an aspirator with an extra-powerful vacuum pump.
Unequal Vacuum Pumps Yield Equal Aspirators
Energy and work, which are equivalent, are defined as the product of force times distance. One joule of energy is equivalent to moving one kilogram of water against the force of gravity for a distance of one meter.
Power is defined as the amount of work that is done per unit of time. One joule per second is a measure of power (equivalent to one watt). The power of a vacuum pump is rated in terms of the volume of air at one atmosphere that can be moved in a unit of time. The power of a liposuction aspirator (vacuum pump plus collection canister containing a vacuum) can be measured in terms of the volume of water that can be moved in a unit of time.
The power produced by a vacuum pump when moving air does not necessarily correlate with the power produced by the pump when it is moving water. One aspirator may have a vacuum pump that is twice as powerful as the vacuum pump of another aspirator, but both aspirators require virtually the same amount of time to suction one liter of water.
The more powerful a vacuum pump, the more rapidly it can create a vacuum. Once the vacuum is established, however, the force necessary to maintain the vacuum does not require a pump of maximum power. Furthermore, the time required to raise one liter of water a distance of one meter is long compared with the short time required to evacuate air out of a liposuction canister. Thus, although two vacuum pumps may evacuate air at slightly different rates, once a vacuum is achieved within two canisters of equal volume, each will move water at equal rates (because equal amounts of potential energy are stored within the vacuum canisters).
Liposuction Canister: Reservoir of Potential Energy
The liposuction canister not only collects fat but also acts as a “vacuum reservoir” that stores the vacuum’s potential kinetic energy. The larger the canister, the greater is the amount of work that must be accomplished by the vacuum pump to evacuate the canister air and create a vacuum, and the greater is the potential energy.
The optimal volume of a canister is not excessively large and thus does not require too much time to achieve a vacuum. A canister must be large enough to accommodate a reasonable volume of fat. A canister that has a given wall thickness, however, cannot exceed a certain volume, beyond which the canister will implode. As the volume of a canister increases, the total force exerted on the canister by the atmosphere (the force per unit area of atmospheric pressure multiplied by the canister’s total surface area) also increases.
It is not necessary for the power of the vacuum pump to be excessive. Whether generated by a one-horsepower or 100-horsepower vacuum pump, a vacuum is a vacuum, and its magnitude cannot exceed the magnitude of the surrounding atmospheric pressure.
Real Power and “Pseudopower.” The real power of a liposuction aspirator is the speed with which it can move a given volume of water. When measured in terms of “the volume of air that can be pumped in one minute,” the power rating of a vacuum pump is irrelevant to microcannular liposuction and can be regarded as “pseudopower.”
If aspirator III consists of three pumps and can pump three times the volume of air per minute as an aspirator I with one pump, but both aspirators raise one liter of water a distance of one meter in essentially the same time, both aspirators deliver equal liposuction power. The power of an aspirator that contains one or more superfluous pumps is also “pseudopower.”
Analogy: Water Reservoir
A liposuction aspirator is analogous to water storage tower. When a water pump delivers water to a tank on the top of a high tower, work (force times distance) is converted into potential energy. This potential energy is converted to kinetic energy when the water is released from the reservoir and is allowed to flow downward under the force of gravity. The volume (or mass) of water stored in the reservoir determines the magnitude of the potential energy within the reservoir.
A water reservoir and a vacuum reservoir have similar physical properties and functions. Both store kinetic energy. This analogy will help the liposuction surgeon better understand the requirements for an ideal liposuction pump. Although two air (vacuum) pumps may be different in terms of power (different rates of pumping air), they may be equivalent in their ability to maintain a vacuum reservoir and to suck fat.
Consider a 25-m-tall water tower that is filled with water by an electric pump that pushes the water from ground level up to the storage tank. If the maximum amount of water that can be drained from the tower is 10 liters per minute (L/min), the electric pump that pumps water up to the storage tank at 20 L/min will be sufficient to keep the tank full at all times. A 100-L/min pump is not more useful in storing water than a 20-L/min pump. The more powerful water pump is noisier, more difficult to transport, and less economical.
Two simple experiments reveal the true nature and functional parameters that determine the efficiency of a liposuction aspirator. An understanding of these experiments will help optimize the efficiency of the surgeon’s own liposuction technique.
The first experiment compares the function of two liposuction aspirators. One is powered by a single vacuum pump and the other by a combination of three vacuum pumps. Although the triple-pump aspirator moves air more rapidly than the single-pump aspirator, the experiment shows that both aspirators move fluids at equal rates (Figure 28-9).
The second experiment measures the rate of fluid (water) aspiration as a function of negative pressure. Comparing the rate that water is aspirated as a function of negative pressure, only a 10% difference exists in flow rates between –29 and –20 inches Hg. In other words, reducing the magnitude of the negative pressure within the liposuction canister, from –29 to –20 inches Hg, does not substantially alter the rate of liposuction (Figure 28-10).
This fact is also apparent when using a syringe for liposuction. As the syringe fills with aspirated fat, the degree of vacuum decreases in intensity, but the rate of fat aspiration does not decrease significantly.
Reduced negative-pressure liposuction does not improve the results of liposuction, does not minimize trauma to residual subcutaneous adipose tissue, and does not reduce postliposuction recovery time. It may be less stressful to individual aspirated lipocytes, however, and may be preferable for fat transplantation.
Choices for Liposuction
Aspirator. When a small, quiet, inexpensive liposuction aspirator performs as well as a heavier, noisier, more expensive aspirator, little advantage exists in buying the larger machine.
Aspirator Tubing. Plastic tubing specifically designed to connect liposuction cannula handles to vacuum canisters of the liposuction aspirator is relatively lightweight, flexible, and easy to use. The wall thickness of disposable suction tubing does not collapse under the force of the vacuum provided by an electric liposuction pump. Current liposuction aspirator tubing is considerably lighter and smaller in diameter than the thick, heavy-duty plastic hose used in the early 1980s.
All liposuction equipment must be steam sterilized in an autoclave before reuse. To minimize the risk of liposuction-associated infections, current aspirator tubing is intended to be single use and disposable. Aspirator tubing is not designed to be autoclaved or reused.
Machine-Powered liposuction cannulas
Machine-powered (MP) liposuction cannulas have recently been introduced. Prototype MP cannulas use electric or pneumatic engines to provide a form of “automatic” liposuction. Although most MP cannulas are merely modifications of existing orthopedic surgical devices, a few have been designed specifically for liposuction. Rectilinear MP cannulas can be rapid (7000 cpm) vibratory devices or slower (200 to 6000 cpm) reciprocating devices. Rotary MP cannulas might use reciprocating motion or continuous spinning.
Potential problems include noise pollution, which can be physically uncomfortable, psychologically annoying, and perhaps dangerous by impairing communication among the surgeon, staff members, and patient. Prolonged exposure to high-frequency sound may injure the inner ear of the surgeon and staff. Prolonged exposure to vibratory mechanical forces may damage the muscles, nerves, joints, or tendons of the fingers and hands. Blood vessels, nerves, or other tissues of patients may be at increased risk of injury from MP liposuction cannulas.
The risks/benefits and dependability of MP cannulas are unknown. The expense of some devices might outweigh their relative benefits. Preferably, MP cannula devices will accommodate existing cannulas and not require the purchase of new ones.
At this time, liposuction experience with MP cannulas is limited, and important questions remain unanswered. Objective and unbiased studies will be important in defining their eventual role in liposuction surgery.
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Figure 28-1 A, Preoperative view of contour lines drawn before liposuction of hips, outer thighs, and buttocks. Small bilateral areas of solid color emphasize location and size of common concavities on lateral buttocks between hips and lateral thighs. Surgeon must avoid liposuction in such areas. B, Postoperative view reveals persistent bilateral concavities. Without proper preoperative documentation, patient might erroneously assume “defects” were result of liposuction.
Figure 28-2 Hip and lateral thigh prepared for liposuction, after washing with surgical soap and placement of sterile drape. Preoperative topologic contour markings, including area of solid color that designates focal depression, have been partially washed off. Absorptive cotton gauze sponges are placed on drape and readily available for use during tumescent liposuction.
Figure 28-3 Close-up and full views of microcannula handle attached to 14-gauge microcannula. Handle attaches to microcannula hub by means of standard Luer-lock connector, which facilitates rapid exchange of microcannulas during surgery. Microcannula handle has air vent within thumb-rest depression; removing thumb from air vent immediately eliminates vacuum inside microcannula. Minuscule 20-gauge microcannula, attached directly to Fine-Touch Aspiration Tubing, is used for delicate liposuction of chin, cheeks, and jowls.
Figure 28-4 Sensory (left) hand grips, immobilizes, elevates, and presents targeted fat to microcannula. Tactile sensitivity of sensory hand is maximized by using volar aspects of thumb and flat volar surface of remaining four fingers to grip targeted fat. This allows surgeon to be constantly aware of location of microcannula tip. Sterile cotton gauze sponges can help surgeon grip slippery skin. Motor (right) hand controls motion of microcannula. When changing direction of microcannula, fulcrum of rotation should coincide precisely with adit.
Figure 28-5 Conceptual depiction of fat, represented by layers of gauze sponges, illustrates two techniques for immobilizing subcutaneous fat. Using sensory hand to reduce mobility of subcutaneous fat increases amount of fat that can be aspirated per in-and-out stroke of liposuction cannula. A, Compressing subcutaneous fat with palm of hand pushes cannula closer to muscle fascia. With this technique, surgeon has difficulty precisely localizing depth of cannula tip within fat. B, Squeezing and lifting subcutaneous fat between thumb and flat surface of fingers displaces fat away from muscle fascia. This technique allows liposuction within deepest plane of fat while increasing distance between cannula and muscle. Thus liposuction of deepest fat can be done with minimal risk of inadvertent injury to muscle. In addition, surgeon always knows precise location of cannula tip.
Figure 28-6 Tip of index finger on motor hand extends beyond microcannula hub and acts as cushion to prevent hub from repeatedly traumatizing skin. Each time cannula hub is allowed to bump skin surrounding adit, hub will injure dermal-epidermal junction and produce postinflammatory hyperpigmentation.
Figure 28-7 If liposuction is initiated too superficially, as shown here, deeper layers of fat probably will not be adequately liposuctioned. Despite thick layer of deep subcutaneous fat, surgeon’s hand will grip thin flap of skin and liposuctioned subcutaneous fat, which gives erroneous impression of more complete liposuction.
Figure 28-8 A, Tumescent fat showing subtotal liposuction with multiple crisscrossing tunnels resulting from deep and superficial microcannular liposuction. Superficial liposuction does not require injury to dermis or subdermal vascular plexus. Liposuction that leaves thin but smooth layer of intact fat immediately subjacent to dermis increases probability of optimal cosmetic results. B, After 24 hours of open drainage and bimodal compression, microcannular tunnels have collapsed, apposed surfaces are in direct contact, and risk of postoperative seromas is virtually eliminated. After liposuction, skin retraction results from normal elastic recoil of dermis and fibrous contraction of subcutaneous fat.
Figure 28-9 Small aspirator powered by single vacuum pump (□) is compared to larger aspirator powered by three vacuum pumps (●) by measuring time required to aspirate 1000 ml of water through tubes with following inside diameters: 14-gauge microcannula, 1.60 mm; 12-gauge microcannula, 2.16 mm; and male connector on microcannula handle, 2.77 mm. Although triple-pump aspirator moves air more rapidly than single-pump aspirator, experiment shows that both aspirators move fluids at nearly equal rates.
Figure 28-10 Rate of aspiration of water (ml/sec) at sea level as function of negative pressure (– inches Hg) is determined for four tubes with following inside diameters: 14-gauge microcannula, 1.60 mm; 12-gauge microcannula, 2.16 mm; male connector on microcannula handle, 2.77 mm; and aspiration hose/tube connector, 6.35 mm. Comparing rate that water is aspirated through 14-gauge and 12-gauge cannulas shows little difference in flow rates between –29 and –20 inches Hg.