Maternal position during induction of spinal anaesthesia for caesarean section. A comparison of right lateral and sitting positions.

Forty women presenting for elective Caesarean section under spinal anaesthesia were randomly assigned to have anaesthesia induced in either the sitting or right lateral positions; 2.5 ml 0.5% hyperbaric bupivacaine was injected over 10 s before the mother was placed in a supine position with a 20 degree lateral tilt. The onset time and height of the subsequent analgesic and anaesthetic block was measured. It took longer to site spinal needles in the lateral position (240 vs 115 s, p < 0.001). There was a faster onset of sensory block to the sixth thoracic dermatomal level (8 vs 10 min, p < 0.001), in the lateral group, although onset time to T4 was comparable. There was no difference in maximum block height or degree of motor block. Mothers in the lateral group required more ephedrine in the first 10 m after siting the spinal (13.5 vs 10.5 mg, p < 0.05).