Plain bupivacaine 0.5%: a preliminary evaluation as a spinal anaesthetic agent.

Three hundred and forty consecutive patients received successful spinal anaesthesia with 0.5% plain bupivacaine. A small randomised study of 40 of these cases showed little difference between 3.5 and 3 ml; however, analysis of its use in 200 patients receiving 3.5 ml (mean block T10.5 +/- 1 segment) and 100 receiving 3 ml (T10 +/- 0.5 segment) confirmed the impression that the smaller volume produced a more limited range of segmental block, which was desirable notably in the over-70-year age group. The main complications were hypotension (14.1%) and headache (1.5%).