Continuous subarachnoid infusion of local anaesthetic

We observed the sensory, motor and cardiovascular changes occurring during subarachnoid infusion of bupivacaine 0.125% at 15 ml.h-1 in six patients. After 1 h, motor block and lower sensory levels were consistent and predictable but upper sensory levels were variable. There was a moderate decrease in systolic blood pressure. Regular assessments of motor block are more likely to detect accidental subarachnoid infusion than assessments of upper sensory level or measurements of blood pressure.