The intraoperative 15° left-tilt position during cesarean delivery has more recently been questioned regarding its effect on fetal acid-base balance and is a frequent source of complaints by surgeons. We hypothesized that a 30° left-tilt position during surgical preparation could improve the acid-base balance of the fetus compared with the 15° left-tilt or supine position during surgical preparation.
Women undergoing elective cesarean delivery under combined spinal epidural anesthesia were randomized to a supine position, 15° left-lateral tilt position or 30° left-lateral tilt position; the position was changed to supine before the incision. Anesthetic management was standardized and included fluid loading with 10 mL/kg of normal saline followed by colloid loading. Hypotension (systolic blood pressure [SBP] reduction >20% baseline value or SBP <90 mm Hg) was treated with boluses of phenylephrine or ephedrine according to maternal heart rate. The primary outcome was umbilical arterial blood pH and the secondary outcomes included maternal SBP within 15 minutes after induction of anesthesia, the amount of vasoactive drug administered before end of the surgery, and the incidence of hypotension during cesarean delivery.
Seventy-five patients were included. After testing by analysis of variance, there was no significant difference in the umbilical arterial pH among the 3 groups (supine group: 7.31 ± 0.03 vs 15° group: 7.30 ± 0.04 vs 30° group: 7.31 ± 0.02, P = .28). The 30° group required significantly less phenylephrine (P = .007) and ephedrine (P = .005) before the end of surgery than the supine group; however, the only benefit observed in the 15° group was that the mean SBP at 3 minutes after spinal injection was significantly improved compared with the supine group.
Compared with the supine position, the 30° left-tilt position during surgical preparation did not significantly improve the fetal acid-base status, but it significantly reduced the use of phenylephrine and ephedrine and reduced the incidence of hypotension; however, these benefits were not observed in the 15° left-tilt group.