Intravenous regional anesthesia (IVRA)

Intravenous regional anesthesia (IVRA)

Also called a Bier² block, this is perhaps the simplest, safest, most foolproof regional anesthetic technique. We replace the blood in the venous system of an extremity with local anesthetic (large volume, low concentration, i.e., 0.5% lido-caine WITHOUT epinephrine) by first exsanguinating the extremity (usually arm), applying a tourniquet, then infusing the local anesthetic distal to the tourniquet. We obtain excellent anesthesia within minutes. It will last until the tourniquet is deflated. The local anesthetic will flow retrograde through the venous system into the vasa nervorum that bathes each nerve fiber. Unfortunately, not infrequently the patient will be troubled by tourniquet pain. Therefore, this technique is best suited for operations lasting less than an hour. The technique is safe as long as the tourniquet holds tight, preventing the local anesthetic from gaining access to the circulation and causing systemic toxicity. If the local anesthetic has been in the extremity for at least 20–30 minutes when the operation is complete, the tourniquet can be safely deflated without toxic effects.