EFFECTS OF POSTURE ON THE SPREAD OF SPINAL ANAESTHESIA WITH ISOBARIC 0.75% OR 0.5% BUPIVACAINE

In a double-blind study the effects of posture on the the spreadof 3 ml of isobanc bupivacaine 5 and 7 Smgml^–1 were comparedafter intrathecal injection in 40 patients undergoing orthopaedicsurgery. Three milhhtre of isobanc bupivacaine 7 5 mgml^–1administered with the patient in a sitting position during andfor 2.5 mm after injection produced the highest spread of analgesia(T4) Horizontal posture, and the smaller dose in both positions,resulted in spread of analgesia to T7-8. Motor block in thelegs was good in all cases. Horizontal posture at the time ofinjection resulted in the longest mean duration of analgesiaand motor block, although there was no statistically significantdifference in mean rimes between the groups The longest meanduration of pin-prick analgesia (329 ± 23 min) was inthe patients injected in the horizontal posture with bupivacaine7.5 mgml^–1. The course of anaesthesia and recovery wereuneventful in all patients.