What effect does a Bier block have on blood flow in the injected extremity?

A Bier block, also known as intravenous regional anesthesia, is a technique used primarily for surgeries of the arm or hand. It involves the injection of a local anesthetic into a vein after a tourniquet has been applied to prevent the anesthetic from spreading to the systemic circulation. This creates a localized anesthetic effect in the extremity while the circulation is temporarily restricted.

When the tourniquet is applied, it significantly reduces blood flow to the injected extremity. As a result, the injected anesthetic remains confined to the area, allowing for effective numbness during a procedure. The temporary restriction of blood flow caused by the tourniquet means that the blood vessels are essentially occluded, leading to a decrease in blood flow within the targeted limb.

It is essential to monitor the duration for which the tourniquet is applied, as prolonged occlusion can lead to complications. In summary, the correct response is that a Bier block decreases blood flow temporarily due to the application of the tourniquet, which allows for concentrated anesthetic effect while minimizing systemic absorption.