Effects of posture on the spread of spinal anaesthesia with isobaric 0.75% or 0.5% bupivacaine

Abstract

In a double-blind study the effects of posture on the the spread of 3 ml of isobanc bupivacaine 5 and 7 Smgml-1 were compared after intrathecal injection in 40 patients undergoing orthopaedic surgery. Three milhhtre of isobanc bupivacaine 7 5 mgml-1 administered with the patient in a sitting position during and for 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 the legs was good in all cases. Horizontal posture at the time of injection resulted in the longest mean duration of analgesia and motor block, although there was no statistically significant difference in mean rimes between the groups The longest mean duration of pin-prick analgesia (329 ± 23 min) was in the patients injected in the horizontal posture with bupivacaine 7.5 mgml-1. The course of anaesthesia and recovery were uneventful in all patients. © 1982 Macmillan Publishers Ltd.