The prophylactic granisetron does not prevent postdelivery nausea and vomiting during elective cesarean delivery under spinal anesthesia

BACKGROUND: Intraoperative nausea and vomiting (IONV) during cesarean delivery (CD) under regional anesthesia has multiple etiologies, and the role of prophylactic antiemetics for prevention of IONV remains controversial. In this trial we sought to determine the efficacy of granisetron for prevention of IONV during elective CD under spinal anesthesia with strict control of the causative factors. METHODS: The study was conducted as a randomized, double-blind, placebo-controlled trial in 176 parturients. After administration of 10 mL/kg of lactated Ringer's solution, spinal anesthesia was administered with 0.75% hyperbaric bupivacaine 15 mg, fentanyl 10 μg, and morphine 100 μg. Systolic blood pressure was maintained at 100% of baseline with aliquots of phenylephrine. Oxytocin 0.5 IU was administered IV upon delivery followed by a maintenance infusion. The patients received either granisetron 1 mg or normal saline IV immediately after cord clamping. In case of persistent IONV, rescue dimenhydrinate 50 mg IV was administered. The primary outcome was the presence of postdelivery IONV. Secondary outcomes included the need for rescue antiemetic, hypotension, pain, and adverse effects. RESULTS: The incidence of postdelivery IONV was 20.4% in the granisetron group and 17.0% in the control group (P = 0.56, NS). The incidence of intraoperative hypotension, pre- (9.6%) and postdelivery (6.2%), was similar in both groups. The incidence of postdelivery pain (2.2% vs 4.5%, P = 0.68) and the requirement for rescue antiemetic (8% vs 6.8%, P = 0.77) were similar in the granisetron and control groups. CONCLUSIONS: Despite strict control of the causative factors, IONV still affects 18% of patients undergoing elective CD, and prophylactic granisetron 1 mg is ineffective under the studied circumstances.