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

We compared the quantitative leakage between forearm and conventional IV regional anesthesia (IVRA). Forearm NRA remains unpopular because of the theoretical risk of local anesthetic leakage through the interosseous vessels. NRA was simulated on the forearm or arm during two separate, randomized sessions using a double tourniquet in 14 volunteers. A radiolabeled substance, DISIDA (99(m) Tc-disofenin) with a structure similar to lidocaine, was injected instead of local anesthetic. Volumes of 0.4 mL/kg (maximum 25 mt), were used far forearm IVRA and 0.6 mL/kg (maximum 45 mt) for conventional IVRA. A gamma camera recorded radioactivity levels in the limb distal to the tourniquet every 30 s while the tourniquet was inflated (25 min) and for 20 min postdeflation. The leakage of radiolabeled substance during inflation was similar in both groups, 6% +/- 12% (mean +/- SD) from the forearm and 10% +/- 20% from the upper arm. After deflation, mean loss of radioactivity was 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 forearm IVRA results in tourniquet leakage comparable to conventional IVRA and is potentially safer because the required dose of local anesthetic is smaller. Implications: Using a tourniquet on the forearm for IV regional anesthesia does not increase the risk of drug leakage. This is potentially a safer technique compared with conventional IV regional anesthesia because a much smaller dose of local anesthetic is required.