Maximum Safe Dose of Liposuction
Safety is the state of being free from danger and exempt from harm. The foremost ethical principle of medicine is “First, do no harm.” In cosmetic surgery this principle is paraphrased by the statement, “Excessive liposuction is unsafe and therefore unethical.”
The safety of liposuction can be described as a function of the following independent parameters:
- Proper judgment in patient selection
- Duration and intensity of exposure to systemic and local anesthesia
- Amount of surgical trauma per month
- Effectiveness of postliposuction care
The safety of removing a huge volume of fat or undermining a large portion of the cutaneous surface during a single liposuction procedure has not been well studied. Clearly, however, removing 1 L of fat is relatively safe compared with removing 10 L of fat. Also, liposuction of 5% of the body surface area (BSA) is safer than liposuction of 40% BSA. Unnecessary exposure of patients to excessive surgery and excessive anesthesia is unethical, but it seems impossible to define precisely the boundary between safe liposuction and excessive liposuction.
This chapter focuses on the problem of determining a useful clinical definition of “excessive liposuction trauma.”
The following concepts from earlier chapters are discussed further here to help define volume (dose) limits of liposuction and prevent trauma-associated complications.
The concept of toxicity is associated with the dose-response phenomenon (see Chapter 6). The effects of most toxic chemicals can be described by a dose-response function. Increasing doses of a toxin can be expected to produce increasing risks of a toxic response.
Alcohol-induced intoxication is a universal example of a dose-response function. Most individuals can drink a small amount of alcohol without any detectable effect. With increasing doses of alcohol, the drinker passes through a series of thresholds that manifest additional symptoms. For example, beyond a no-effect or subthreshold range, increasing acute doses of alcohol first produce a mild subjective effect, then mild intoxication (inebriation), followed by moderate intoxication (drunkenness) and dangerous intoxication (debilitation, unconsciousness, coma, death). The subthreshold level for alcohol varies among individuals, and no distinct threshold for blood alcohol concentration defines alcohol intoxication.
Although trauma is not a chemical, a dose-response function defines the risk of increasing degrees of trauma. Burns can be quantified in terms of not only the depth of skin necrosis but also the BSA. The probability of death increases with increasing BSA affected by a full-thickness burn.
The same type of dose-response function can be applied to liposuction trauma. The risk of death increases with increasing trauma affecting the body’s subcutaneous tissue as a result of liposuction. In a manner similar to the effects of imbibing alcohol, small amounts of liposuction will rarely produce any serious adverse effects. With increasing amounts of liposuction the patient can be expected to cross over a series of toxic (traumatic) thresholds. The ultimate thresholds for excessive liposuction trauma are unconsciousness, coma, and death.
Liposuction surgery is analogous to cancer chemotherapy. With chemotherapeutic drugs, the goal is to maximize beneficial results and minimize toxic side effects. Although it might be more convenient for the patient and the oncologist to give one large dose of chemotherapy, it is usually safer and more effective to give anticancer drugs in divided doses over weeks to months. Similarly, although one large liposuction procedure might seem more convenient it is usually safer and more effective to do serial liposuction procedures, spaced at least a month apart.
Volume Versus Safety
The motivation for developing tumescent liposuction totally by local anesthesia was to improve patient safety and comfort. However, some surgeons and anesthesiologists saw the tumescent technique as an opportunity to maximize the volume of fat removed during a single surgery.
Liposuction of 6 L or more of fat in a single liposuction procedure is unnecessarily aggressive and potentially life threatening. Some publications have advocated “megaliposuction” but do not provide detailed information about complications or ultimate aesthetic results. Such articles typically state that no serious complications occurred, without bothering to define “serious complication.” Some consider death to be the only serious complication.
Although megaliposuction procedures are essentially experimental with unproven benefit, participation by investigational review boards or research committees on human subjects has been minimal. Hospitals, licensed surgical facilities, and academic institutions have permitted excessive liposuction with virtually no objection from credentialing committees. Among some surgeons, excessive liposuction has become a de facto standard of care.
A procedure cannot be considered “safe and effective” simply because it has been performed a certain number of times without serious complications. The safety and efficacy of a therapeutic procedure can only be defined relative to alternative procedures.
Anecdotal evidence alone is inadequate to establish safety of a procedure. Studies must provide reproducible results that demonstrate superior safety compared with alternative procedures. Surgeons who advocate huge-volume liposuction must provide convincing evidence that one massive liposuction surgery is as safe and effective as two more sequential liposuctions.
Ethical cosmetic surgery demands proof of any elective procedure’s safety and efficacy. The argument that “no published data refute the presumption of safety” is insufficient. Ethical cosmetic surgery demands a radical empiricism in which every dogma or underlying assumption is regarded as a hypothesis that must be verified. The dogma that liposuction by general anesthesia is safe or the assumption that hugevolume liposuction is effective and provides long-lasting results must be verified.
Academic surgeons and anesthesiologists who do liposuction by systemic anesthesia believe the safety of liposuction by systemic anesthesia is not open to question. Therefore it is unnecessary to conduct research that documents the safety of liposuction by systemic anesthesia. These surgeons and anesthesiologists respond to an assertion that “virtually all liposuction deaths are associated with systemic anesthesia” by declaring they are unaware of any published report documenting such an association.
Every toxin has a “safe” range of small dosages within which the risk of toxicity is insignificant. Similarly, each has a “toxic” range of relatively large dosages within which every dose has a significant risk of toxicity. Between these low and high dosage ranges is a threshold range of dosages within which the exact risk of toxicity is not immediately apparent (Figure 15-1).
Lethal Dose. The concept of measuring the average lethal dose (LD) of a substance is familiar to physicians. A common means of expressing this probability function is that a given dose LDp will produce a lethal effect in p percent of the test animals. Thus the LD50 for lidocaine in mice is the dose that would be expected to kill 50% of the test animals.
What is the LD1 (or LD50, LD0.1, LD1/10,000) of liposuction, or what is the dose of liposuction that will, on average, cause death in 1% of patients?
The BSA affected by a burn can be used to predict the probability of death. By analogy, the proportion of the subcutaneous surface that is traumatized by liposuction should help predict the risk of death from liposuction. As noted, the greater the number of areas treated by liposuction at any one time, the greater is the risk of iatrogenic surgical death.
For liposuction, the estimate of LDp depends on the health of the targeted population. Because the risk of perioperative complications increases with increasing degrees of obesity, obese people are relatively poor candidates for a megaliposuction.
High-to-low Extrapolation. Experimental toxicology using high doses of a toxin requires relatively few animals to estimate LD50. As the dose of a toxin is decreased, however, the probability of death also decreases. Therefore the number of experimental animals required to detect a true toxic effect increases.
The process by which “toxicity at high doses is used to estimate the toxicity at much lower doses” is known as high-to-low extrapolation. The task of defining an estimate for a clinically safe amount of liposuction trauma is a high-to-low extrapolation problem.
Excessive liposuction is defined as a volume of liposuction that is unnecessarily or unreasonably dangerous. This definition is intentionally nonspecific and vague. Excessive liposuction is defined subjectively according to each clinical situation.
The designation of excessive liposuction depends on the patient’s size and health. Excessive liposuction may be less than 1 L if the patient is a 50-kg (110-pound), muscular, lean female athlete with little adipose tissue. On the other hand, removing 4 L of supranatant fat in one procedure might not be excessive in an otherwise healthy 100-kg (220-pound) female patient.
The body cannot tolerate an unlimited amount of trauma. Increasing degrees of liposuction-associated trauma produce progressive capillary endothelial damage and platelet activation. Beyond a certain threshold of liposuction trauma the risk of hypercoagulability, such as disseminated intravascular coagulation (DIC), or thromboembolism may be significant. The greater the area of the body’s subcutaneous surface that is traumatized by liposuction, the greater the degree of systemic inflammatory response. This results in decreased levels of free protein S, which is associated with increased risks of thromboembolism. Excessive liposuction is associated with excessive morbidity, prolonged postoperative recovery, and greater risk of disappointing cosmetic results.
No absolute threshold or cutoff line exists above which all volumes are considered excessive. I believe, however, that it is usually unwise to remove more than 4 L of supranatant fat under any circumstances. It is safer to divide the case into two separate procedures, which can be accomplished several weeks apart.
When total aspirate volume exceeds 5000 ml, “the operation becomes more physically disruptive, and patients should be kept overnight in the hospital.”1 A dangerous procedure performed in the hospital is still dangerous. Performing excessive liposuction in a hospital cannot compensate for a poor clinical decision. Unnecessarily dangerous liposuction procedures in the hospital might explain why 70% of liposuction-related malpractice cases have been done in hospitals.2
I rarely remove more than 3 L of supranatant fat. The most supranatant fat I have ever removed was 4.2 L. I have removed 4.0 L or more of supranatant fat on only five occasions. When the surgeon has underestimated the actual aspirated volume, the 4-L limit allows for a small margin of safety.
Liposuction can also be excessive when patients undergo concomitant, unrelated surgical procedures. Subjecting a patient to multiple cosmetic procedures is rarely a problem when local anesthesia is used. An awake patient usually complains and declines further surgery long before the surgery becomes excessive.
The risk of perioperative complications increases with increasing duration and intensity of the surgical insult. Conservative surgeons do not advise patients to undergo two simultaneous, unrelated therapeutic surgeries. Elective hysterectomy is rarely contemplated in conjunction with some other elective therapeutic procedure, such as gallbladder surgery, joint replacement, herniorrhaphy, or laminectomy. In contrast, well-trained surgeons and concurring anesthesiologists often advocate multiple concurrent cosmetic surgical procedures, such as liposuction, facelift, and breast augmentation. The rationale for such unnecessarily excessive cosmetic surgery is obscure.
In the early era of dry and wet techniques for liposuction, the volume of aspirated material (blood plus fat) was directly correlated with the volume of surgical blood loss and the necessity for postoperative blood transfusions.
Among surgeons not using the tumescent technique, a standard rule was that 1.5 to 2.0 L of aspirate was the threshold for requiring an autologous blood transfusion.3 Without tumescent vasoconstriction, each liter of liposuction aspirate contained 15% to 50% whole blood. With such a conspicuously bloody visual reminder, the volume of liposuction aspirate became indelibly associated with the estimated risk of liposuction surgery.
Even after the tumescent technique had eliminated surgical blood loss as the limiting variable for liposuction, surgical tradition has continued to regard the total volume aspirated as the standard measure of liposuction trauma.
Total aspirate volume is an inaccurate measure of surgical trauma for several reasons. First, the total aspirate volume is not an accurate predictor of the risk of serious complications. It does not account for the size of the patient, and the risks associated with a given total aspirate depend on the patient’s size. The removal of a 4-L total aspirate volume for a 50-kg woman is not the same as removing it from a 100-kg woman. Furthermore, total aspirate volume is no longer closely correlated with blood loss; the tumescent technique has essentially eliminated acute surgical hemorrhage as a common risk of liposuction.
Second, the significance of the total aspirate volume is diminished because it is the sum of both the supranatant fat floating in the collection cannister on top and the infranatant blood-tinged anesthetic solution layered below the fat. The volume of the aspirated infranatant blood-tinged anesthetic solution does not reflect the degree of liposuction trauma, and the volume of the infranatant fluid varies widely from patient to patient and from surgeon to surgeon. This large random variation confounds the precision of any prediction based on total aspirate volume. The supranatant fat volume (S) is the more relevant variable. The infranatant fat volume (I) is an irrelevant, or confounding, variable. The total aspirate volume (T) where T = S + I, is the sum of two independent variables. From a biostatistical perspective, S is a much more efficient estimate of liposuction risk than T.
Third, when ultrasonic liposuction is used, the supranatant fat becomes emulsified (dispersed in small droplets) and suspended within the infranatant anesthetic solution. For example, if a vibrating internal ultrasonic probe is placed into a beaker containing 500 ml of supranatant fat and 500 ml of infranatant solution, the resulting emulsion will appear as 900 ml of supranatant fat that persists for many hours. This phenomenon completely obscures the distinction between S and I.
True Threshold Is Indeterminate
A plausible estimate of the threshold for excessive liposuction trauma can be constructed by using a sophisticated, probabilistic, multivariate dose-response function. Elaborate criteria that define a safe dose of liposuction can be used in increasing degrees of complexity and theoretic precision.
Ultimately, however, such elaborate criteria are merely academic exercises. No amount of biostatistical erudition can ever accurately define a safe maximum dose of liposuction. Too many patient-dependent and surgeon-dependent variables exist. The vagaries of real-life cosmetic surgery result in an indeterminate threshold for safety.
Telephone Calls as Threshold. Some dermatologic surgeons consider a nighttime telephone call from a patient to be a significant postoperative complication. This call is a reasonable, prudent threshold for defining excessive liposuction trauma.
If the surgeon regularly receives after-hours telephone calls from postoperative patients because of discomfort, pain, nausea, vomiting, or anxiety, the amount of liposuction has probably been excessive. The probability that a patient will need to telephone later because of the effects of too much liposuction should ideally approach zero.
If a liposuction surgeon does not expect every patient to be ambulatory within 30 minutes of completion of the surgery, the liposuction and anesthetic technique probably are excessive. Liposuction is excessive if the following occur:
- Pain confines the patient to bed.
- Nausea prevents the patient from eating a normal meal soon after surgery.
- Discomfort prevents the patient from returning to desk-type work 1 or 2 days after surgery.
Patients should be well enough to manage their postoperative care. Every effort should be made to minimize the trauma of liposuction to the level where their telephone calls or unscheduled postoperative office visits are a rare occurrence.
Liposuction of more than 3 L of supranatant fat is probably excessive in most patients. I define the liposuction or more than 6 L of supranatant fat as megaliposuction, which is dangerous in all patients. A dose-response relationship exists between the volume or extent of liposuction and the incidence of postliposuction complications. Again, serial liposuction procedures are much safer than a single megaliposuction procedure.
The invention of tumescent liposuction was motivated by a need to increase the safety of liposuction, not the volume of liposuction. I believe megaliposuction is a misguided extension of the tumescent technique.
Because patients have died as a result of megaliposuction, it cannot be regarded as safe. The intense conviction that huge-volume liposuction is both safe and justifiable does not prove the conviction’s validity. A patient should not be given unsubstantiated assurance that megaliposuction is safe or is an effective treatment for morbid obesity. Massive liposuction of the abdomen, flanks, buttocks, arms, and lower extremity has been reported in association with bilateral lumbar artery laceration.4
It is reasonable for a surgeon to present a series of 10 cases of megaliposuction at a cosmetic surgery meeting and propose that the procedure might be a treatment for morbid obesity. It is misguided, however, for a surgeon in the audience to conclude that megaliposuction is now a legitimate treatment for morbid obesity. The first surgeon proposed a hypothesis. The second surgeon concluded, without adequate clinical evidence, that the hypothesis had been proved.
An anecdotal report cannot prove the relative safety of a procedure. A series of megaliposuction cases must be compared to a series of serial liposuction procedures, with both having removed comparable volumes of fat, before the relative safety can be determined.
Standard of Care
As with any experimental surgical procedure, megaliposuction should be confined to a clinical setting, where its indications, the completeness of informed consent, and the adequacy of postoperative care are subject to peer review. As an experimental procedure, every case of megaliposuction should have documentation of important preoperative, perioperative, and long-term postoperative data. The surgeon who advocates megaliposuction has a responsibility to provide evidence from the literature that documents the procedure’s safety.
The safety and efficacy of megaliposuction have yet to be established. To my knowledge, no published controlled clinical studies support the assumption that huge-volume liposuction is effective and safe. In other words, no standard of care exists for megaliposuction. An anesthesiologist should not condone megaliposuction unless there is proof of its safety and efficacy. A hospital surgical credentials committee should determine whether megaliposuction is a safe and reasonable procedure. Liposuction privileges should not be construed as permission to do megaliposuction.
Financial Conflicts of Interest
The following situations make it difficult for a surgeon to avoid the appearance of a financial conflict of interest when recommending megaliposuction.
The procedure is dangerous, and no data have established the long-term safety and efficacy of megaliposuction.
Prospective megaliposuction patients are psychologically desperate and therefore vulnerable to unsubstantiated claims. Truly informed consent for megaliposuction is often nonexistent. If the liposuction surgeon is unaware of the dangers of a megaliposuction, the patient is unlikely to be given a reasonable or accurate view of its dangers. Similarly, obese patients who are desperate may be incapable of making an objective decision regarding huge-volume liposuction.
The same surgeon who assumes primary responsibility for informing prospective patients about the risks and benefits of the megaliposuction also profits by performing the surgery.
Safer alternatives to megaliposuction are available. For example, performing serial liposuctions on separate occasions is safer than one extensive and intensive traumatic procedure.
No longitudinal studies justify megaliposuction as an effective treatment for morbid obesity. Any claim of a therapeutic benefit must be supported by evidence that the result has a long-lasting effect. Megaliposuction has not been shown to produce a long-term decrease in body weight in a significant majority of patients.
Solution. To avoid the appearance of a financial conflict of interest, an ethical surgeon would require that potential megaliposuction patients have preoperative evaluation by another qualified physician consultant. This consultant should know about the health risks of obesity, the surgical risks associated with obesity, and the risks and benefits of megaliposuction. Finally, the consultant must give written recommendation for the surgery.
Codes of ethics require that a surgeon avoid performing a procedure that involves a financial conflict of interest. A surgeon’s financial interests should not outweigh concerns for patient safety.
It is safer to remove 3 L of supranatant fat in three separate surgeries than 9 L of fat on a single day. It is naive or self-serving to rationalize that “patients want to have their surgery accomplished during one procedure.”
Market forces are not an indication for agreeing to do the more dangerous of two possible cosmetic surgical procedures. A reasonable, ethical surgeon will inform any prospective patient that it is unsafe to do too much liposuction at one time.
I believe that aspirating 6 L or more of supranatant fat on a single day has a mortality rate that is approximately 100 to 1000 times greater than doing liposuction of less than 3 L of supranatant fat. Sequential liposuction procedures accomplished several weeks to months apart are safer than a single large, aggressive procedure. The ethics of doing huge-volume liposuction as a single procedure are questionable.
Most healthy patients are likely to survive an unnecessarily voluminous liposuction. The surgeon may eventually learn, however, that megaliposuction is associated with many complications and megalitigation.
- Pitman GH: Liposuction in the outpatient setting, Aesthetic Surg J 19:167, 1999.
- Coleman WP III, Hanke CW, Lillis P, et al: Does the location of the surgery or the specialty of the physician affect malpractice claims in liposuction? Dermatol Surg 25:343, 1999.
- Pitman GH: Liposuction and aesthetic surgery, St Louis, 1993, Quality Medical Publishing.
- Talmor M, Baire PS: Deaths related to liposuction, N Engl J Med 341:1001, 1999 (letter).
Figure 15-1 Threshold range between safe and toxic “doses” (volumes) of liposuction. Increasing doses of liposuction (excessive iatrogenic surgical trauma) carry significant risks of toxicity (severe postoperative complications). Below a “safe dose limit” of liposuction, risk of postoperative complications is minimal. Above some “toxic dose limit,” risk of severe postoperative complications is unacceptable.