Oxford positioning technique improves haemodynamic stability and predictability of block height of spinal anaesthesia for elective caesarean section

Abstract

A novel positioning technique was tested to see whether the unpredictability of block height and haemodynamic instability during spinal anaesthesia for caesarean section could be reduced. In this 'Oxford' position, the woman is placed left lateral with an inflated bag under the shoulder and pillows supporting the head. Following spinal injection the woman is turned to an identical right lateral position. This is maintained until just before incision to minimise aorto-caval compression, when she is placed in the wedged supine position. Sixty women undergoing elective caesarean section were randomised to receive spinal anaesthesia using hyperbaric bupivacaine in either the Oxford (group O), or the sitting position followed immediately by the wedged supine position (group S). Ephedrine 6 mg was given every minute that systolic blood pressure was less than 80% of baseline. In group S, 9/30 women lost pinprick sensation up to T4 at 5 minutes compared with 2/30 in group O (chi2 test, P = 0.04). Block height was more variable in group S than in group O (f test, P = 0.001). Blood pressure decreased by a greater amount initially: group S women required more ephedrine (15.5 +/- 12.9 versus 9.2 +/- 7.7 mg, t test, P = 0.03). Block height with spinal anaesthesia for caesarean section is more predictable and haemodynamically stable if the Oxford position is used whilst anaesthesia develops.