Final answer:
During a Bier block, the anesthetic injected is usually lidocaine (Xylocaine) without epinephrine. Lidocaine acts by blocking sodium channels, thereby preventing nerve impulse transmission, which causes numbness and pain relief. The effects of this local anesthetic are temporary and reversible.
Step-by-step explanation:
The type of anesthetic injected during a Bier block is typically lidocaine (Xylocaine) without epinephrine. A Bier block, or intravenous regional anesthesia, involves injecting a local anesthetic into a vein of an extremity with a tourniquet applied to isolate the area. This technique numbs the specific region for surgical procedures without affecting the rest of the body. The use of epinephrine is generally avoided in this type of anesthesia because it can cause complications due to vasoconstriction when the tourniquet is released.
Local anesthetics like lidocaine work by blocking voltage-gated sodium channels within nerve cells, which prevents the initiation and transmission of nerve impulses. This action results in the temporary loss of sensation and muscle function in the targeted area, ultimately leading to numbness and pain relief during medical procedures. Once the anesthetic is metabolized and cleared from the tissue, normal nerve function resumes.