High dose spinal anaesthesia with glucose free 0.5% bupivacaine 25 and 30 mg

The purpose of this study was to investigate if a more intense and/or prolonged blockade could be obtained safely when a high-dose intrathecal plain bupivacaine was given. Thirty patients for elective surgery were included. Two groups of 15 patients, received 25 or 30 mg 0.5% bupivacaine (plain). The sensory and motor blockade was determined. Heart rate and respiratory frequency was monitored continuously, arterial blood pressure every 5 minutes. Peak expiratory flow (PEF) was performed before, and 45 min after the spinal injection. In group 25 mg the maximal spread of analgesia was to T3.7 +/- 0.9 (mean +/- s.e.mean) after 45 minutes, in group 30 mg T3.1 +/- 0.4 also after 45 min (NS). The maximal extent of analgesia was retained for a significantly longer period and the initial decline in extent of analgesia was significantly slower in the 30 mg group. No significant difference as to duration of motor blockade was found. Peak expiratory flow diminished significantly 45 min after the spinal injection in both groups, but no significant difference was found between the groups. The total duration of analgesia did not differ significantly between the groups. A significantly longer duration of maximal cephalad spread, and a slower initial regression, was found in the 30 mg group. No severe uncontrolled haemodynamic or respiratory side effects occurred.