Abstract

Three ml of glucose-free 0.5% and 0.75% bupivacaine and hyperbaric (8% glucose) 0.5% bupivacaine and 0.5% tetracaine administered intrathecally were compared in a double-blind study in 80 surgical patients. Following the injections the patient remained in a sitting position for 2 minutes before being turned supine. A T10 level of analgesia was achieved in 15 minutes for all solutions studied, while 20 to 30 minutes were required for maximum cephalad spread of analgesia (T7-T9). Motor blockade of the lower limbs developed quickly and reached its maximum in approximately 10 minutes for all solutions. Duration of motor blockade was significantly longer with 0.75% bupivacaine; whereas hyperbaric 0.5% bupivacaine provided the shortest duration of motor blockade. The longest duration of analgesia at L5 (approximately 4.5 hours) and of complete motor blockade of the lower limbs (approximately 3.5 hours) was recorded in the patients given 0.75% bupivacaine. Three cases of postspinal headache were observed.