Tumescent anesthesia is a technique commonly used in cosmetic and dermatologic procedures. It involves subcutaneous infiltration of large volumes of tumescent fluid containing lidocaine (0.05% or 0.1%), saline, and epinephrine (1:1,000,000) to produce anesthesia, swelling, and firmness of targeted areas. Maximum safe dosage is estimated to be 35-55mg/kg of lidocaine. This technique is most often used in conjunction with IV sedation. Its anesthetic effects can last up to 18 hours.
This technique is not without risk of complications. Lidocaine toxicity is a concern given the large amounts used in this technique. Epinephrine induced vasoconstriction reduces the rate of systemic absorption of lidocaine and peak plasma levels do not occur until 12-14 hours following injection; therefore, signs of lidocaine toxicity may not appear until well into the postoperative period. Lidocaine is metabolized via hepatic CYP3A4. Use of lidocaine along with medications that inhibit or are metabolized via CYP3A4 can lead to toxic plasma levels. Another concern, especially for liposuction procedures where larger volumes of tumescent fluid are injected, is volume overload, which can lead to significant pulmonary edema and fluid overload.