RANDOMIZED TRIAL OF BOLUS PHENYLEPHRINE OR EPHEDRINE FOR MAINTENANCE OF ARTERIAL-PRESSURE DURING SPINAL-ANESTHESIA FOR CESAREAN-SECTION

Thirty-eight healthy women undergoing elective Caesarean section under spinal anaesthesia at term were allocated randomly to receive boluses of either phenylephrine 100 mu g or ephedrine 5 mg for maintenance of maternal arterial pressure. The indication for administration of vaso pressor was a reduction in systolic pressure to less than or equal to 90% of baseline values. Maternal arterial pressure (BP) and heart rate (HR) were measured every minute by automated oscillometry. Cardiac ou tput (CO) was measured by cross-sectional and Doppler echocardiography before and after preloading with 1500 ml Ringer lactate solution and then every 2 min after administration of bupivacaine. Umbilical artery pulsatility index (PI) was measured using Doppler before and after sp inal anaesthesia. The median (range) number of boluses of phenylephrin e and ephedrine was similar; 6 (1-10) vs 4 (1-8) respectively. Materna l systolic BP and CO changes were similar in both groups, but the mean [95% CI] maximum percentage change in maternal HR was larger in the p henylephrine group (-28.5 [-24.2, -32.9]%) than in the ephedrine group (-14.4 [-10.6, -18.2]%). As a consequence atropine was required in 11 /19 women in the phenylephrine group compared with 2/19 in the ephedri ne group (P < 0.01). Mean umbilical artery pH [95% CI] was higher in t he phenylephrine group (7.29 [7.28-7.30]) than in the ephedrine group (7.27 [7.25-7.28]). The results of the present study support the use o f phenylephrine for maintenance of maternal arterial pressure during s pinal anaesthesia for elective Caesarean section.