RESUMO
Background Maternal hypotension occurs in up to 80% of parturients during cesarean section (CS) under spinal anesthesia. Phenylephrine, a direct-acting α-1 agonist, has been widely recommended for the prevention of hypotension. We evaluated the efficacy and safety of phenylephrine infusion to prevent hypotension in obese and non-obese patients during cesarean section. Methods One hundred forty-one patients were included in this single-arm study. Patients received prophylactic phenylephrine infusion at a rate of 50 µg/min-1 immediately after spinal local anesthetic injection until delivery. Hypotension was defined as a systolic blood pressure <100 mmHg or <20% of baseline. The primary outcome was the incidence of hypotension. Results The incidence of hypotension was 17%. The median and interquartile range (IQR) of the number of hypotensive episodes was 0 (0-0). It was observed that 79.1% of the patients had hypotension in the first six minutes. Reactive hypertension and bradycardia occurred in 20.5 and 12.7% of the patients, respectively. In addition, there was a higher incidence of bradycardia in pregnant women with a body index mass of < 30 kg/m-2. Patients with baseline systolic blood pressure <120 mmHg had a threefold increased risk of hypotension. The incidence of nausea and vomiting was 13.4 and 2.8%, respectively. The incidence of an Apgar score <7 at the first minute was 2.8%, and no neonates presented an Apgar score <7 at the fifth minute. A pH of <7.2 occurred in 6.3% of the neonates. All neonates had no sequelae and were discharged together with their mothers. Conclusion The prophylactic infusion of phenylephrine 50 µg/min-1 is safe and demonstrates efficacy in reducing maternal hypotension providing adequate maternal hemodynamic stability during CS under spinal anesthesia.
