Bier Block Limitations
Basic, Clinical Sciences: Anesthesia Procedures, Methods, and Techniques
Bier block, also known as “Intravenous Regional Anesthesia” or “IVRA” was invented by August Bier in 1908 and has been most commonly used for short duration procedures of the upper extremity distal to the elbow. A Bier block is performed by inserting a small gauge IV as distal in the operative extremity as possible. Next, the arm is elevated and exsanguinated with an Esmarch. A proximal tourniquet is then applied to the upper extremity and inflated ideally to 50-100mmHg above the patient’s systolic BP although it is more common to simply inflate to 250mmHg. A distal tourniquet can also be placed for longer duration procedures. Relatively high doses of local anesthetic are then injected through the IV catheter. Lidocaine is most commonly used; 15-20mL of 2% lidocaine is a fairly standard dose. The IV catheter is then removed and blockade of distal nerves is achieved via diffusion of local anesthetic across the vascular bed. Other minor mechanisms of anesthesia include diffusion of local anesthetic into local tissues, tissue acidosis, hypothermia and ischemia.