Effect of Aspiration of Cerebro‐Spinal Fluid on Spinal Anaesthesia with Isobaric 0.5% Bupivacaine

The effect of changing the volume of cerebro-spinal fluid (CSF) before spinal anaesthesia with 3 ml of isobaric 0.5% bupivacaine was investigated in 60 elderly (58-77 years) orthopaedic or urological patients. The patients were randomly allocated to three groups. They received the spinal anaesthetic either with or without the aspiration of 3 ml of CSF. In the third group a mixture of 3 ml of aspirated CSF and 3 ml of 0.5% isobaric bupivacaine was given. Pin-prick analgesia and motor block were tested during the induction and recovery. The only statistically significant difference between the groups was in the time-lag from administration to maximum spread of pin-prick analgesia, which was shortest in the group without aspiration (mean 19.5 min, other groups 29-30 min). The mean maximum level of analgesia was T6-T7 in each group. The anaesthesia was satisfactory in most cases. One death occurred because of a massive pulmonary embolism. The clinical significance of aspirating CSF before attempting spinal anaesthesia with 3 ml of 0.5% isobaric bupivacaine was found to be small.