A randomized, double-blinded comparative study of phenylephrine infusion and norepinephrine infusion for the prevention and treatment of spinal anesthesia-induced hypotension in elective and emergency cesarean deliveries

Abstract

Context and Aims: Among vasopressors used to treat postspinal hypotension (PSH) in cesarean sections (CS), phenylephrine (PE) is the preferred drug at present but reflex bradycardia and thus reduction in cardiac output still pose a concern. Norepinephrine (NE), with its better pharmacological properties, may be a better alternative to overcome this risk. Hence, we did this study intending to compare both the drugs. Materials and Methods: A double-blinded, randomized, controlled trial (RCT) was carried out on 70 patients, 35 in each group-group P (PE) and group N (NE) undergoing CS, to compare and evaluate the efficacy of both drugs for preventing and treating PSH. Patients in Group P and Group N were given intravenous infusion of PE at the rate of 50 μg/min and NE at the rate of 2.5 μg/min, respectively, after the intrathecal injection of bupivacaine. The number of intermittent bolus doses required, heart rate, and mean arterial pressure (MAP) at predefined intervals were noted. Results: The incidence of hypotension calculated from the number of bolus doses required was lower in Group N than in Group P for the initial 15 min (P < 0.05). The incidence of bradycardia and vomiting was higher in Group P but were not statistically significant, while the incidences of nausea (P = 0.004) and oxygen requirement (P = 0.03) were statistically significantly higher in Group P. Conclusion: This study suggests that NE infusion is superior to PE infusion when used in the potency ratio of 20:1, to prevent and treat PSH in CS, with a lesser number of side effects.

Keywords

• cesarean section
• norepinephrine
• phenylephrine
• postspinal hypotension
• spinal anesthesia
• vasopressors