Neurologic effects of subarachnoid administration of 2-chloroprocaine-CE, bupivacaine, and low pH normal saline in dogs.

The purpose of this study was to evaluate the neurologic consequences of deliberate subarachnoid injection of large volumes of 2-chloroprocaine-CE in experimental animals. The possible role of low pH as well as total volume as potential factors in causing neurotoxicity was evaluated. The 65 dogs in the study received injections in the subarachnoid space as follows: 6 to 8 ml of bupivacaine (N = 15), 2-chloroprocaine-CE (N = 20), low pH normal saline (pH 3.0) (N = 20), or normal saline (N = 10). Of the 20 animals that received subarachnoid injection of 2-chloroprocaine-CE seven (35%) developed hind-limb paralysis. None of the animals that received bupivacaine, normal saline, or normal saline titrated to a pH 3.0 developed hind-limb paralysis. Of the 15 spinal cords of the animals that received 2-chloroprocaine-CE, 13 showed subpial necrosis; the nerve roots and subarachnoid vessels were normal. The spinal cords of the animals that received bupivacaine, low pH normal saline (pH 3.0), or normal saline did not show abnormal findings.