Individual predictability of repeated spinal anaesthesia with plain 0.5% bupivacaine

To evaluate the individual predictability of spinal anaesthesia, 10 patients (3 women and 7 men) scheduled for control cystoscopy were studied twice within 9 months. Lumbar puncture was performed in the midline at the L2/3 interspace with the patient in the sitting position using plain 0.5% bupivacaine at 37 degrees C. A non-parametric Spearman test showed that, on the basis of the first block, the predictability of the cephalad analgesic spread of the second anaesthesia was high up to 60 min after injection. Thereafter the predictability decreased. The predictability of the motor blockade was generally low. Six patients obtained complete motor blockade twice; the remaining four, once.