Effect of delayed supine positioning after induction of spinal anaesthesia for caesarean section

Abstract

Background: The study tested the hypothesis that the incidence of hypotension during spinal anaesthesia for caesarean section is less in parturients who remain in the sitting position for 3 min compared with parturients who are placed in the modified supine position immediately after induction of spinal anesthesia. Methods: Spinal anaesthesia was induced with the woman in the sitting position using 2.8ml hyperbaric bupivacaine 0.5% at the L3-4 or L2-3 interspace. Ninety-eight patients scheduled for elective caesarean section under spinal anaesthesia were randomised to assume the supine position on an operating table tilted 10° to the left (modified supine position) immediately after spinal injection (group 0, n=52) or to remain in the sitting position for 3 min before they also assumed the modified supine position (group 3, n=46). Isotonic saline 2-300ml was given intravenously over 15min before spinal injection followed by 15 ml/kg over 15-20min after induction of spinal anaesthesia. If the systolic blood pressure decreased to less than 70% of baseline or to less than 100mmHg or if there was any complaint of nausea, ephedrine was given in 5mg boluses intravenously every 2min. Results: The blood pressure decreased significantly in both groups following spinal injection (P<0.001). Blood pressure variations over time differed significantly between the two groups (P<0.05). However, the incidence of maternal hypotension before delivery was similar in the two groups. The difference was caused by the time to the blood pressure nadir being significantly shorter in group 0 compared with group 3 (9.1±4.5 min vs. 11.7±3.7min, P<0.01). Similar numbers of patients received rescue with ephedrine before delivery: 35 (67%) in group 0 vs. 26 (57%) in group 3 (NS). The mean total dose of ephedrine before delivery was 10.9mg in group 0 vs. 9.2mg in group 3 (NS). There were no differences in neonatal outcome between the two groups. Conclusion: At elective caesarean section, a 3-min delay before supine positioning does not influence the incidence of maternal hypotension after induction of spinal anaesthesia in the sitting position with 2.8ml of bupivacaine 0.5% with 8% dextrose. © Acta Anaesthesiologica Scandinavica.