Prospective Study of Lidocaine, Bupivacaine and Epinephrine Levels and Blood Loss in Patients Undergoing Liposuction and Abdominoplasty
Goals/Purpose:
Bupivacaine levels have not been studied in cosmetic surgery patients to establish safety. Blood loss from liposuction has been underestimated using the small blood volumes present in the aspirate. There is little information available regarding safety for combined procedures. The proportion of wetting solution removed by liposuction has not been reliably ascertained. Few studies have examined epinephrine levels after liposuction and/or abdominoplasty and none in conjunction with bupivacaine.1 This study was undertaken to investigate these important safety issues.
Methods/Technique:
A prospective study was undertaken among 322 consecutive patients presenting for superwet ultrasonic liposuction (n = 229) and/or abdominoplasty (n = 93), and other combined procedures, using infusions containing 0.05% lidocaine (liposuction) and/or 0.025% bupivacaine (abdominoplasty) with 1:500,000 epinephrine. Plasma levels of lidocaine, bupivacaine, and epinephrine were studied in a subset of 76 consecutive patients, including hourly intraoperative samples in 37 consecutive patients. In 95 patients (29.5%) who had combined procedures (e.g., simultaneous cosmetic breast surgery or a face lift), bupivacaine was also injected as a component of the local anesthetic (Fig.1). All patients were treated by the same surgeon (E.S.) as outpatients in a licensed ambulatory surgery center under an unconscious intravenous anesthetic administered by an anesthesiologist or certified nurse anesthetist. Sequential compression devices were used.
Results/Complications:
There were no pulmonary emboli and no deaths. There were two hospital admissions, one for treatment of a deep venous thrombosis and another for treatment of an infection. Among abdominoplasty patients, there were three cases of delayed wound healing (two needing revision), two seromas treated with aspiration, and no hematomas. No patient showed signs of fluid overload and none required fluid resuscitation beyond maintenance.
Mean heart rates and blood pressures did not fluctuate significantly during surgery. In the postanesthesia care unit, no patient developed symptoms or signs of local anesthetic or epinephrine toxicity.
The maximum lidocaine level dose was 3242.5 mg and level was 2.10 μg/ml. The maximum bupivacaine dose was 549.9 mg and level 0.81 μg/ml. No clinical toxicity was encountered. Estimated blood loss from liposuction was 217.5 cc + 187 cc/liter of aspirate (r = 0.65, Fig. 2). Abdominoplasty added 290 cc of blood loss, on average (Fig. 3). The mean proportion of wetting solution removed by liposuction was 9.8%, determined by the ratio of infranatant/plasma glucose (“glucose ratio”). The mean proportion of wetting solution in the aspirate was 10.4% (Fig. 4). The mean hematocrit (“lipocrit”) of the infranatant fluid was 1.76%.
The maximum bupivacaine level of 0.81 μg/ml, recorded the day after surgery, was well under the toxic threshold of 3 µg/ml, suggests a comfortable margin of safety despite the use of doses exceeding traditional recommendations (analogous to lidocaine). The finding of undetectable intraoperative plasma levels of bupivacaine in abdominoplasty patients, who typically received 250 mg (0.025%) of bupivacaine with their wetting solution, reveals profoundly delayed absorption of this anesthetic agent when it is administered in this very dilute form in the presence of 1:500,000 epinephrine. A more concentrated epinephrine solution may provide a greater anesthetic dampening effect, evidenced by the very gradual increase in bupivacaine levels.
Although there is minimal visible blood loss during liposuction, there is substantial extravascular (“third space”) blood loss into the interstitial tissues, accounting for 98% of the blood loss from liposuction (Fig. 5).
Knowledge of the expected blood loss from liposuction (Fig. 2) and combination procedures (Fig. 3), commonly performed today, is useful for the surgeon planning a combined procedure, so as to lessen postoperative anemia, a common cause of morbidity. Fat volumes under 5000 cc (maximum 4700 cc in this study) may be safely aspirated in combination with abdominoplasty and other cosmetic procedures.
Conclusion:
Bupivacaine may be safely used in cosmetic surgery in doses up to 550 mg delivered in dilute form into the subcutaneous tissues, and in combination with lidocaine. A concentration of 1:500,000 epinephrine is safe and effective when administered as part of a wetting solution that is limited to less than 5 liters. Estimated blood loss is higher than previous estimates based on lipocrits and is related to aspirate volume. Combination procedures are safe. Effective local anesthesia combined with unconscious intravenous sedation increases safety and improves recovery.
References:
- Burk RW, Guzman-Stein G, Vasconez LO. Lidocaine and epinephrine levels in tumescent technique liposuction. Plast Reconstr Surg. 1996;97:1379-1384.
Fig. 1. Local anesthetic and epinephrine concentrations.
Fig. 2. Estimated blood loss versus liposuction aspirate volumes for patients treated with liposuction only. A blood loss of 1153 cc is expected for a patient with 5 liters of aspirate. Infusion alone appears to cause a 217.5 cc blood loss.
Fig. 3. Estimated additional blood loss from specific combination procedures performed with liposuction, controlled for aspirate volume.
Fig. 4. Mean contents of liposuction aspirate.
Fig. 5. Fluid shifts and changes in blood volume after liposuction. ISF, interstitial fluid. IVF, intravascular fluid.