THE EFFECT OF PLAIN 0.5-PERCENT 2-CHLOROPROCAINE ON VENOUS ENDOTHELIUM AFTER INTRAVENOUS REGIONAL ANESTHESIA IN THE RABBIT

The possible venous endothelial toxicity of 0.5% 2-chloroprocaine with out additives in intravenous regional anaesthesia (IVRA) was evaluated in rabbits. After exsanguination of a hind limb with an Esmarch's ban dage a neonatal blood pressure cuff around the thigh was inflated (250 mmHg). For IVRA 4 ml of either plain 0.5% 2-chloroprocaine (pH 3.7), 0.9% NaCl (pH 6.0) or acidified NaCl (pH 3.7) was injected i.v. to the exsanguinated limb in a randomized, double-blind fashion. Each group comprised ii rabbits. Eleven rabbits received 4 ml of 0.5 M or 1.0 M K Cl, for the production of positive controls. Two hours after injection of the test solution the tourniquet was deflated and venous biopsies were taken one and 24 hours later for histological and immunocytochemi cal examination. Five to eight 24-hour samples from each group were al so processed for electron microscopy. A macroscopic thrombus formation was observed in four rabbits after KCl and in two after acidified NaC l administration. No inflammatory changes were observed at. histologic and immunocytochemical examination of any of the Vein samples. Electr on microscopy revealed that KCl had caused severe damage to the venous endothelium of four out of five samples and acidified NaCl had caused moderate damage to the endothelium of two out of seven samples. 2-chl oroprocaine had caused moderate damage in four and severe damage in tw o of the vein samples; two samples were normal. No thrombus formation occurred. It is concluded that additive-free 2-chloroprocaine caused d amage to the venous endothelium in rabbits when used for IVRA.