Perioperative noninvasive cardiac output monitoring in parturients with singleton and twin pregnancies undergoing cesarean section under spinal anesthesia with prophylactic phenylephrine drip: a prospective observational cohort study

Purpose: Spinal anesthesia is considered the gold standard anesthetic technique for cesarean deliveries (CDs) but is associated with a high rate of hypotension. The recent international consensus recommends continuous prophylactic phenylephrine infusion (PPI) administered throughout CD to prevent hypotension. However, little information is available on the hemodynamic profiles of women with twin pregnancies as compared to singleton pregnancies perioperatively. Therefore, in this study, we aim to compare maternal hemodynamic changes both intraoperatively and postoperatively with the use of the NICAS bioimpendence monitor in healthy singleton versus twin parturients undergoing CD deliveries with spinal anesthesia with PPI. Materials and methods: After IRB approval and signed informed consent, healthy term women with either twin or singleton pregnancies undergoing spinal anesthesia for uncomplicated CD were enrolled. The following data were collected–cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), and total peripheral resistance (TPR). Measurements were measured at five time points: (1) before arrival in OR, (2) after spinal anesthesia with PPI, (3) after beginning of oxytocin infusion, (4) in post anesthesia care room, (5) 24 hours postoperatively, and (6) 48 hours postoperatively. All parturients received standardized spinal solution consisting of 12 mg hyperbaric bupivacaine, 20 µg fentanyl and 100-µg preservative-free morphine. PPI administered was titrated to preserve blood pressure to 20% of baseline blood pressure and stopped at the end of surgery. Oxytocin was administered as a continuous infusion (20-units/1000 cm³ Ringer’s lactate) at a rate of 100 cm³/h. Results: One hundred and thirty seven parturients with singleton pregnancies and 27 parturients with twin pregnancies completed the study. There were no significant differences between groups in age or BMI. Intraoperatively, there was no difference in any hemodynamic parameter. However, postoperatively at all three times women with twin pregnancies had higher MAP, lower CO and higher TPR compared with parturients with singleton pregnancies. Conclusions: There were significant hemodynamic changes postoperatively but not intraoperatively in parturients with twin pregnancies compared to women with singleton pregnancies. These changes need to be further investigated.