Intravenous regional anesthesia

Intravenous regional anesthesia (IVRA) or Bier's block anesthesia is an anesthetic technique on the body's extremities where a local anesthetic is injected intravenously and isolated from circulation in a target area. The technique usually involves exsanguination of the target region, which forces blood out of the extremity, followed by the application of pneumatic tourniquets to safely stop blood flow. The anesthetic agent is intravenously introduced into the limb and allowed to diffuse into the surrounding tissue while tourniquets retain the agent within the desired area. The use of tourniquets and injected anesthesia to induce localized anesthesia was first introduced by August Bier in 1908. He used an Esmarch bandage to exsanguinate the arm and injected procaine between two tourniquets to rapidly induce anesthetic and analgesic effects in the site. Though it proved effective, IVRA remained relatively unpopular until C. McK. Holmes reintroduced it in 1963. Today, the technique is common due to its economy, rapid recovery, reliability, and simplicity. Protocols vary depending on local standard procedures and the extremity being operated on. A vast majority of practitioners begin by exsanguinating the limb as Bier did with an elastic bandage (Esmarch bandage), squeezing blood proximally toward the heart, then pneumatic tourniquets are applied to the limb and inflated 30mmHg above arterial pressure to occlude all blood vessels and then the elastic bandage is removed. A high dose of local anesthetic, typically lidocaine or prilocaine without adrenaline, is slowly injected as distally as possible into the exsanguinated limb. The veins are filled with the anesthetic, with the anesthetic setting into local tissue after approximately 6–8 minutes, after which the surgery, reduction, or manipulation of the region may begin. It is important that the region is isolated from active blood flow at this time. Analgesic effect typically remains for up to two hours depending on the dosage and type of anesthetic agent being used.