Intravenous Regional Block
A Bier block utilizing local anes-thetic solution with or without adjuvants can be used to interrupt sympathetic innervation to an extremity. A total volume of 50 mL of 0.5% lidocaine is typically injected, either alone or in combination with clonidine (150 mcg) and in some cases ketoro-lac (15–30 mg). A tourniquet is placed proximally on the extremity, which is then elevated and exsan-guinated using an Esmarch bandage. The tourniquet is inflated to a pressure that is two times the systolic blood pressure, the Esmarch bandage is removed, and the limb is checked to be certain the pulse is absent and there is no evidence of blood flow. The solution is then injected and usually left in place for at least 30 min, after which the tourniquet is released incrementally and the patient is observed for any signs or symptoms of local anesthetic toxic-ity. Premature release of the tourniquet may result in seizure, hypotension, arrhythmia, edema, diarrhea, and nausea. Intravenous regional sympathetic block is a safe alternative to standard sympathetic blocks in patients with hemostatic defects.