When One Liter Does Not Equal 1000 Milliliters: Implications for the Tumescent Technique

Abstract

Tumescent anesthesia has revolutionized the practice of liposuction. Inherent to the tumescent technique is the use of large volumes of dilute solutions of lidocaine with epinephrine instilled into subcutaneous fat deposits. Precise formulation of the tumescent anesthesia is essential to liposuction technique. To determine the actual volumes of fluids contained in intravenous (IV) 1 L bags of saline used for tumescent anesthesia, to calculate volumes supplied in 50 cc stock solutions of 1% lidocaine, and to measure the amount of fluid retained by peristalic pump tubing used for infiltration. The amount of saline contained in fifteen 1 L saline bags from three different manufacturers was calculated using graduated cylinder methodology. The volume of tumescent anesthesia retained by peristaltic pump tubing was calculated by expelling the contents of the filler tubing and measuring it. The actual amount of 1% lidocaine contained within fifteen 50 ml "stock" 1% lidocaine bottles from different manufacturers and with different lot numbers was calculated by transferring the contents into graduated cylinders. One liter IV bags of physiologic saline contained an average volume of 1051 ml (range 1033-1069 ml). The 50 ml bottles of 1% lidocaine with epinephrine contain an average of 54 ml of anesthetic (range 52.5-55 ml). Infusion tubing for use with peristaltic pumps may retain 46-146 ml of tumescent anesthesia. One liter IV bags of normal saline contain more than 1 L, having an average volume of 1051 ml. Common methods of preparation of 0.05% lidocaine with 1:1,000,000 epinephrine and sodium bicarbonate can increase the total amount of fluid in the tumescent anesthesia to 1112 ml for 0.05% solutions and preparation of a 0.1% solution contains an average volume of 1162 ml. The fluid contained in each bag may be increased over labeling by as much as 11-16%. Final concentrations of lidocaine in tumescent anesthesia may be reduced due to extra fluids. A 0.05% lidocaine solution may have a final lidocaine concentration of 0.045% and a 0.1% lidocaine solution may have an actual concentration of 0.086%. Lidocaine concentrations may be reduced by as much as 10-14%. Extra anesthesia fluid is also contained within stock 50 ml bottles of 1% lidocaine. Dermatologic surgeons should be aware of extra fluid possibly contained within tumescent anesthetic preparation, be aware of the extra anesthesia supplied in standard 1% lidocaine bottles, and possible decreased concentration of lidocaine within the final tumescent anesthesia.