Primer on aneshesia for liposuction

There are several techniques used to perform liposuction. See table.1


The wet technique was introduced in the 1980s, and the superwet technique was introduced in 1980 and advocated by fodor. With this technique, infiltration was injected in equal volume to aspirated liposuction. In the same year, the tumescent technique, introduced by Klein, was described and the injectate volume was now 2 to 3.1 to 12 part aspirated and required only local anesthesia.3 Some have liberalized the tumescent technique using ratios from 3-7:1.6 Blood loss was minimal with the tumescent technique and deemed safe.4 While these techniques have been accepted by surgeons, there is still controversy regarding the resuscitation of these patients, typified by the stances of Klein and Pitman. Klein considers (for the tumescent technique) the fluid injected into the tissues sufficient for volume resuscitation hypothesizing that this fluid makes its way into the intravascular space.5 In fact, this process is known as hypodermoclysis. Hypodermoclysis is the mechanism described by which SQ fluid migrates to the intravascular space. This process is estimated to take around 2 ½ hours for 1 liter of fluid infiltrated into medial thigh.11 Unfortunately, this data is from only one study and therefore, the true rate may be quite different. Authors have tried to quantify how much of the infiltrate is removed in the aspirate and have estimated that only 2212 to 29%13 of the aspirated fluid contains the original fluid infiltrated. This view contrasts with Pitman, who advocates a 2:1 ratio (IV + injected SQ:aspirate).7 Neither author reports complications from fluid overload, and there is only one reported case of fluid overload.8 Other reports of death have been documented.9-10
A prospective observational trial of 53 patients who underwent USG liposuction using a superwet technique, where the ratio was 1:1 (infiltrate:aspirate) was used.1 Fluid was replaced per preoperative deficits, and then given to maintain VS and UO WNL, and finally per protocol of 1:1 ratio of infused crystalloid:aspirate after >4L of aspirate. Infiltrate solution contained 0.03% lidocaine plus 0.01% epinephrine (1:1,000,000), and given to maximum of 4,000 mL (lidocaine 1200 mg=17 mg/kg assuming 70kg). In this study the average aspirated volume was ~4.5 L (range 300 mL to 15.5 L). The average UO for both small volume (<4l)>4L) aspirate liposuction was > 1.5cc/kg/hr. There were 3 episodes of transient hypotension responsive to fluid in the PACU and 3 more on the floor. See table 2.

average volume used on per kg per hour basis.
The authors for this study used a reference for fluid replacement of 5 to 6 cc/kg/hr based on the stoelting and miller textbooks of anesthesia stating this type of surgery represented moderate trauma. Based on this study the authors gave the following recommendations based on the fact that the large volume patients seemed to be slightly over resuscitated by virtue of the UO all greater than 1 cc/kg/hr in OR and PACU.
1. Pre op deficits as needed.
2. IVF per VS and UO
3. infiltrate solution
4. 0.25 mL per mL infiltrated after 4 L aspirated.

This same group followed up their first study with a review of 89 patients14 using their own recommendations for IVF therapy from the previous study in an attempt to avoid the slight over resuscitation that occurred. They did modify the regimen only slightly by not starting to give IVF 0.25 mL/mL aspirated until after 5 L of aspirate. Of these 89 pts only 21 underwent large volume liposuction (>5 L aspiration). This group used a super wet technique with a similar lidocaine + epinephrine mixture as detailed in their first study, but this was given up to a total of 5 L of infiltrate after which lidocaine was removed from the LR. See table for volume resuscitation:
The average intraop fluid ratio (total volume in/total volume aspirated) was 1.8 for the small volume group (<5l)>5L). UO ave was 1.5 cc/kg/hr and 1.7 cc/kg/hr for the small and large volume groups respectively. In the PACU, UO was 1.6 and 1.7 for the small and large volume groups respectively, while fluid given was 3.8 and 4.4 mL/kg/hr for the small and large volume groups respectively. On the floor, fluid was required for 10 hrs and 16 hrs for the small and large volume groups respectively, while fluid given was 1.6 and 1.3 mL/kg/hr for the small and large volume groups respectively. UO was 2.9 and 2.5 mL/kg/hr for the small and large volume groups respectively.
They did not have any major complications in this study, and no transfusion was given. This group reports that they have never had pulmonary edema as a complication in over 700 patients, but are still yet wary of this complication.
The graphs below depict comparison from the first cohort on 1st protocol (1 mL IVF given for each mL of aspiration after 4000 mL) compared to the current protocol. The original protocol is blue and revised protocol in purple.
the original protocol is represented by the yellow, and revised by the light blue. The authors note that in the second graph, UO peaked in the RR in the original protocol, which could represent a more sudden and abrupt IV volume shift as compared to the more delayed and gradual shift as occurred with the current protocol. They also note that UO was still high representing a slight over resuscitation which might be modified by not replacing aspirate with IVF therapy at all.
Although this group does not report morbidity from high volumes of fluid, the tumescent technique has potential for harm. Gilliland reports a case of pulmonary edema in a 55 year old ASA 1 male who returned for a 3rd liposuction surgery.8 He received a 7900 mL SQ and 2200 mL IV. He develop hypoxemia in the PACU and required 2 doses of lasix after which he urinated approximately 5 L over the ensuing several hours improving saturations from the 80s to 100. Pitman submitted a response to this case report stating that he believes the imminent cause of this patient’s pulmonary edema to be the 2200 mL of IV fluid.15 He then describes a formula that has been shown to be safe for tumescent liposuction of up to 6 L. He suggests limiting IVF intraop to KVO max 100 to 300 cc. He uses 0.5% lidocaine + 1:1,000,000 epinephrine for the injectate solution and typically gives up to 40 mg/kg. see fig from pitman.

At the conclusion of surgery the aspirate is measure and compared to the total injectate seeking a 2:1 ratio for injectate (infiltrate):aspirate. If this ratio is <2:1,>2:1, then no IVF are given. He states that he has experienced no adverse events in over 1000 patients using this formula. Pitman also states that for his procedures using the tumescent technique, he has calculated blood loss at 7.8% of aspirate volume (78cc blood per 1000cc aspirated).
Grazer has written about the dangers associated with the tumescent technique and reports that most morbidity and mortality is associated with poorly trained physicians performing very large aspiration (~10L) in office type settings. Furthermore, large amounts of lidocaine (40 to 70 mg/kg) are being used in these procedures resulting in toxicity of both lidocaine and epinephrine. He also emphasized pulmonary edema as a problem. In another review, Grazer discussed lidocaine toxicity. He points out that therapeutic plasma lidocaine levels are between 1.5 mcg/mL and 5 mcg/mL total lidocaine, and this is different from reported levels that only measure active drug (unbound) which is 0.5 to 1.5 mcg/mL. Lidocaine is only active when unbound, and 60 to 70% is bound in healthy individuals: to alpha 1 glycoprotein (50%), albumin 25%, and other miscellaneous proteins (25%). Grazer notes that patients undergoing liposuction have increased FFA levels which displace lidocaine from its binding sites on proteins, which will increase the unbound active fraction, increasing the potential for toxicity. They also note that with lidocaine dosages in the tumescent technique, they have measured total lidocaine plasma levels at <1 mcg/mL when up to 35 mg/kg were used. Other factors to consider are metabolites of lidocaine which include MEGX and GX, where MEGX is the active metabolite and is not measured in serum assays. The author concludes by making the following recommendations regarding the tumescent technique. 1) Limit the volume of fluid injected to 3 to 5 L, 2) limit total lidocaine dose to 35 mg/kg.. 3) The volume of injectate should be modified down in patients with one comorbid condition, or may be modified up in the occasional healthy patient. 4) Pts taking dietary medications should be cleared by a medical specialist.
Grazer, in another paper,16 states that the most common cause of mortality from liposuction is PE, thus spawning the practice of giving 5% etOH in D5W although this is only supported by anecdotal evidence.

In summary, the approach to a patient who is to undergo liposuction under anesthesia care requires consideration of more than the standard preoperative history and physical, intraoperative monitoring and post operative care. There should be awareness of the liposuction technique used (superwet, tumescent) and more importantly an understanding of the injectate to aspirate ratio to expect during the procedure since this is critical in determining the volume status of your patient. A clear awareness of expected and actual aspirate volumes is necessary as well to determine fluid requirements and foresee potential risks to the patient. Also, a general understanding of L.A. toxicity is necessary as well as the amount of lidocaine your patient receives on a per kg basis. In addition the amount of epinephrine is important since this is almost universally used in wetting solutions. Finally, some surgeons may ask for a 5% alcohol in dextrose solution be used. Extensive searches in pub med and on the web by myself have proven futile in turning up any articles dedicated to the use of this technique in liposuction. Only peripheral mention of this technique is made in several articles which discuss liposuction and it is noted in each of the articles that there is no evidence to suggest that it is beneficial. Nevertheless, if the surgeon requests this infusion, (in hopes to reduce the risk of fat embolism or pulmonary embolism), it


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