A randomized trial of phenylephrine infusion versus bolus dosing for nausea and vomiting during Cesarean delivery in obese women

Abstract

Purpose Hypotension is common after spinal anesthesia for cesarean delivery. It is associated with nausea, vomiting and fetal acidosis. Previous research on phenylephrine excluded obese subjects. We compared the incidence of intraoperative nausea and vomiting (IONV) in obese patients who received a prophylactic phenylephrine infusion versus those who received phenylephrine boluses for the treatment of spinal-induced hypotension. Methods In this multi-centre, double-blinded randomized controlled trial, 160 obese women undergoing elective cesarean delivery under spinal anesthesia were randomized to receive a prophylactic phenylephrine infusion initiated at 50 μg/min and titrated according to a predefined algorithm or 100 μg phenylephrine boluses to treat hypotension. Maternal systolic blood pressure was maintained within 20% of baseline. The primary study outcome was the incidence of IONV. Results IONV was significantly reduced in the infusion group compared to the bolus group, 46% vs 75%; relative risk 0.61 (95% CI 0.47 to 0.80); P < 0.001. This was associated with significantly reduced need for intraoperative rescue antiemetics, 26% vs 42%; relative risk 0.62 (95% CI 0.40 to 0.97); P = 0.04, but no difference in the incidence of vomiting. Postoperative vomiting at 2h was reduced in the infusion group, 11% vs 25%; relative risk 0.44 (95% CI 0.21 to 0.90); P = 0.02, however there were no differences in the incidence or severity of postoperative nausea, need for rescue antiemetics at 2h and 24h or the incidence of postoperative vomiting at 24h. The infusion group had a significantly lower incidence of hypotension but greater incidence of reactive hypertension. Conclusion In obese women undergoing cesarean delivery with spinal anesthesia, prophylactic phenylephrine infusion was associated with less intraoperative nausea, less need for rescue antiemetics and reduced early postoperative vomiting. Trial Registry Number NCT01481740 https://clinicaltrials.gov/ct2/show/NCT01481740?term=NCT01481740&rank=1

Effect of Glucose Containing Crystalloid Infusion on Maternal Hemodynamic Status After Spinal Anesthesia for Cesarean Section

“…Hypotension decreases cerebral blood flow and may lead to side effects such as nausea, vomiting, decreased consciousness, as well as respiratory and cardiac depression in the mother. Moreover, severe and sustained hypotension can reduce the uteroplacental blood flow and ultimately lead to fetal acidosis and depressed APGAR score ( 8 - 12 ).…”

The Effect of Phenylephrine Infusion on Maternal Hemodynamic Changes During Spinal Anesthesia for Cesarean Delivery

“…In our study, nausea and vomiting during surgery were less reported in the phenylephrine group than the control group, which is consistent with the results of other studies. For example, George et al (19) showed that intraoperative nausea and vomiting were significantly reduced in the prophylactic phenylephrine infusion group compared with the phenylephrine bolus (46% vs. 75%, respectively; relative risk = 0.61 (95% CI: 0.47 -0.80)), which was associated with the significantly reduced need for antiemetic drugs in this group. It was lower than the bolus group (26% vs. 42%; relative risk = 0.62 (95% CI 0.40 to 0.97) (19).…”

“…For example, George et al (19) showed that intraoperative nausea and vomiting were significantly reduced in the prophylactic phenylephrine infusion group compared with the phenylephrine bolus (46% vs. 75%, respectively; relative risk = 0.61 (95% CI: 0.47 -0.80)), which was associated with the significantly reduced need for antiemetic drugs in this group. It was lower than the bolus group (26% vs. 42%; relative risk = 0.62 (95% CI 0.40 to 0.97) (19). In a study by Atashkhoie et al (20) on 90 pregnant women under spinal anesthesia for elective cesarean delivery, nausea and vomiting in the phenylephrine and ephedrine infusion group (intervention group) was significantly lower than the placebo group.…”

In reply: Spinal anesthesia for Cesarean delivery in obese parturients: is this the best option?

“…1,2 We do agree that epidural anesthesia is indeed an option for cesarean delivery, though in our usual practice we generally prefer spinal anesthesia related to the overall better block quality and less need for supplementation or conversion to general anesthesia compared with epidural techniques. 3 We believe avoidance of general anesthesia is a primary goal in the obese population to avoid the potentially difficult airway.…”