Quantitative comparison of leakage under the tourniquet in forearm versus conventional intravenous regional anesthesia

We compared the quantitative leakage between forearm and conventional IV re gional anesthesia (IVRA). Forearm NRA remains unpopular because of the theo retical risk of local anesthetic leakage through the interosseous vessels. NRA was simulated on the forearm or arm during two separate, randomized ses sions using a double tourniquet in 14 volunteers. A radiolabeled substance, DISIDA (99(m) Tc-disofenin) with a structure similar to lidocaine, was inj ected instead of local anesthetic. Volumes of 0.4 mL/kg (maximum 25 mt), we re used far forearm IVRA and 0.6 mL/kg (maximum 45 mt) for conventional IVR A. A gamma camera recorded radioactivity levels in the limb distal to the t ourniquet every 30 s while the tourniquet was inflated (25 min) and for 20 min postdeflation. The leakage of radiolabeled substance during inflation w as similar in both groups, 6% +/- 12% (mean +/- SD) from the forearm and 10 % +/- 20% from the upper arm. After deflation, mean loss of radioactivity w as higher in conventional IVRA,70% +/- 7% vs 57% +/- 11% and 82% +/- 5% vs 69% +/- 11% at 3 and 20 min, respectively (P < 0.001). We conclude that for earm IVRA results in tourniquet leakage comparable to conventional IVRA and is potentially safer because the required dose of local anesthetic is smal ler. Implications: Using a tourniquet on the forearm for IV regional anesth esia does not increase the risk of drug leakage. This is potentially a safe r technique compared with conventional IV regional anesthesia because a muc h smaller dose of local anesthetic is required.