SPINAL ANAESTHESIA WITH HYPERBARIC BUPIVACAINE: EFFECTS OF CONCENTRATION AND VOLUME WHEN ADMINISTERED IN THE SITTING POSITION

In a double blind study, solutions of 0.5% or 0.75% bupivacainecontaining 8% dextrose were compared with regard to the effectof varying concentration and volume when administered intrathecallyto patients in the sitting position. Ten patients received 3or 4 ml of 0.5% bupivacaine or 2 or 3 mi of 0.75% bupivacaine.Nine patients received 0.5% bupivacaine 2 ml and another ninereceived 0.75% bupivacaine 1.3ml. The use of the 10-mg doseof both solutions was abandoned after nine patients in eachgroup becafse of insufficient cephalad spread. With both solutions,the smallest volumes (bupivacaine 10 mg) had significantly shorterdurations of action than both the larger ones (15–20/22.5mg), between which there were no significant differences.