Intravenous Regional Anesthesia

Intravenous regional anesthesia involves the intravenous administration of a local anesthetic into a tourniquet-occluded limb (i.e., Bier block). The local anesthetic diffuses from the peripheral vascular bed to nonvascular tissue such as axons and nerve endings. Both the safety and efficacy of this regional anesthetic procedure depend on the interruption of blood flow to the involved limb and gradual release of the occluding tourniquet. Intravenous regional anesthesia has been used primarily for surgical procedures on the upper limbs. Shorter procedures on the foot can also be successfully performed under intravenous regional anesthesia. If a lower leg tourniquet is used, it should be applied well below the fibular neck to avoid pressure over the superficial peroneal nerve; in general, use of an upper leg tourniquet is preferred over lower leg tourniquets.

Lidocaine has been the drug used most frequently for intravenous regional anesthesia, but prilocaine, mepivacaine, chloroprocaine, procaine, bupivacaine, and etidocaine have also been used successfully. One might suppose a safety advantage with the aminoester-linked compounds because of their hydrolysis in blood; however, thrombophlebitis has been reported in several patients in whom chloroprocaine was used.^[74] Cardiovascular collapse has been reported after the use of bupivacaine for intravenous regional anesthesia, and this use of bupivacaine is therefore discouraged.^[75]

In general, approximately 3 mg/kg (40 mL of a 0.5% solution) of preservative-free lidocaine without epinephrine is used for upper extremity procedures. For surgical procedures on the lower limbs, 50 to 100 mL of 0.25% lidocaine has been used.