Liposuction: LA solution

Liposuction can be performed under general anesthesia, deep or conscious sedation, or as a purely “tumescent technique.” The tumescent technique uses a “wetting solution” to control intra-operative and post-operative pain as well as bleeding specifically during liposuction procedures, facilitating the procedure. This wetting solution is often used during liposuction performed under general anesthesia or deep/conscious sedation.

This technique uses large volumes of either normal saline or lactated ringers with added epinephrine and lidocaine. The volume varies from 1-4 mL per 1 mL of lipid tissue to be removed. The epinephrine concentration is generally 1:1,000,000 and the lidocaine concentration varies from 0.025-0.12%.¹ Post-operatively, the effect of the local anesthetic provides anywhere from 8-24 hours of pain-control. The addition of vasoconstrictors reduces the blood circulation in the tissues, thus delaying the absorption of the local anesthetic. ²

There are two broad types of wetting solution – Klein’s solution and Hunstadt’s solution. Both include lidocaine and epinephrine. Klein’s solution is made with a base of normal saline and includes sodium bicarbonate. The sodium bicarbonate decreases the burning sensation associated with the injection. Additionally, it raises the pH of the solution leading to an increased proportion of non-ionized, lipid soluble lidocaine, which enables more rapid entry into nerve cells. Conversely, Hunstadt’s solution is made with a Lactated Ringers base and does not include sodium bicarbonate.³

Use of the wetting solutions necessitates several intra-operative considerations including careful fluid and temperature management and vigilance to epinephrine and local anesthetic toxicity. Due to the large volume of the injectate, there is a risk of hypervolemia or pulmonary edema, especially in the case of large volume liposuction (>5,000 mL), which requires a large volume of wetting solution. The fluid is slowly absorbed from the extravascular to intravascular space and should be included when considering intraoperative fluid administration. Patients are also at risk for hypothermia as the solution is typically not warmed.

The dose of epinephrine administered should not exceed 0.07 mg/kg to prevent cardiovascular effects. The dose of lidocaine in the infiltrate is typically 35-55 mg/kg, which is considerably more than the 4.5 mg/kg maximum recommended for regional techniques. Generally, this is well tolerated as it is cleared from a single compartment, leading to a delayed onset of effect. However, its absorption from subcutaneous tissue is variable and patients should be monitored for toxicity within the post-operative period.⁴