Effect of fluid preloading on cardiovascular variables after spinal anaesthesia with glucose-free 0.75% bupivacaine

We studied the effect on systemic arterial pressure of fluid preloading with 1 litre of crystalloid fluid before spinal anaesthesia in 40 patients undergoing minor lower abdominal or lower limb surgery. Fluid was given at a rate of either 1 ml min-1 (no preload group), or 1000 ml in the 15 min (preload group) immediately before induction of spinal anaesthesia with 3 ml of 0.75% glucose-free bupivacaine. There was no difference between the groups in the character of anaesthesia or motor block in the lower limbs. The cephalad spread of analgesia ranged from L1 to C8. Analgesia was insufficient for surgery without supplementary analgesia in three patients in each group. The group not given a fluid preload had significantly lower arterial pressures (P less than 0.05) when anaesthesia extended above the T5 dermatome. The mean time before the lowest arterial pressure was recorded was twice as long in the preloaded group as in the non-preloaded group. Glucose-free 0.75% bupivacaine did not give a reliable extent of anaesthesia for lower abdominal surgery.