Tumescent technique for local anesthesia

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Tumescent local anesthesia was originally used in liposuction but is also carried out for other plastic, cosmetic, dermatological procedures and for surgery of the venous system, often in outpatients. For this purpose, large amounts of fluids containing diluted lidocaine or prilocaine and epinephrine are infused subcutaneously. In this review of the literature, this technique is assessed in view of potential anesthesiological complications such as intoxication with lidocaine, prilocaine, overdosage of epinephrine or overload with fluids. While originally a lidocaine dosage of 35 mg/kg b.w. was considered to be safe, dosages were then increased to 55 mg/kg b. w. and even 90 mg/kg b. w. without data showing the safety of such high doses. Published data of plasma concentrations were obtained from small numbers of patients, showing that the concentrations were below 5 microg/ml which is considered the nontoxic range. The maximum levels were observed after 4 - 12 hours, if epinephrine was used. In a few patients, however, the values had not yet begun to decrease at the end of the 23 hours observation period. Replacing lidocaine by prilocaine shifts the problem of toxicity to that of the formation of methemoglobine, which can reach levels of more than 10 %. Data about effects of high-dose epinephrine in the literature are sparse, but tachycardia, arrhythmias and hypertension remain a major concern. Although fluids are applied subcutaneously, an overload with fluids may occur. Cases of lung edema have been reported, however, hypovolemia caused by a loss of fluid into the third space cannot be excluded. Because of these possible complications, tumescent local anesthesia should be employed in outpatients with great care. Patients should be monitored during the procedure and for a sufficient period of time thereafter by adequately trained staff. Patients with cardiac or pulmonary risk factors should not undergo tumescent local anesthesia.