Prophylactic, Manually Titrable Variable Rate Norepinephrine Infusion for Prevention of Hypotension during Spinal Anesthesia for Cesarean Section: A Randomized, Double Blind, Controlled Study

Abstract

Background and Aims: Norepinephrine is recently being investigated for mitigation of spinal-induced hypotension. Our study aimed at evaluating the role of manually titrated infusion of norepinephrine in preventing hypotension in patients undergoing lower segment cesarean section (LSCS) under subarachnoid block (SAB). Subjects and Methods: This prospective, randomized, double-blind, placebo-controlled trial was conducted in 140 parturients undergoing LSCS under SAB. Patients were randomly allocated to two groups: group A received an infusion of 5 µg/mL norepinephrine started at 30 mL/h (2.5 µg/min) immediately after SAB and manually adjusted within the range 0–60 mL/h (0–5 µg/min), according to the values of systolic blood pressure (SBP) until delivery; in group B, no prophylactic vasopressor was given, and bolus 1 mL norepinephrine (5 µg) was given whenever the SBP decreased to <80% of the baseline value. Groups were compared with regard to the incidence of hypotension, hemodynamic parameters, and norepinephrine consumption. Categorical data were presented as number and compared using the Chi-square test. Continuous variables were presented as mean ± standard deviation (SD) and compared using t-test. P <0.05 was considered statistically significant. Results: Cumulative episodes of hypotension were significantly lesser in group A (eight) than group B (29) (P < 0.001). Mean time of onset of hypotension was significantly higher in group A (19.75 ± 8.24 min) compared to group B (4.36 ± 0.77 min) (P < 0.001). Mean SBP, diastolic blood pressure (DBP), and mean arterial pressure (MAP) were significantly higher in group A compared to group B intraoperatively (P < 0.001). Mean heart rate (HR) was significantly lower in group A compared to group B (P < 0.05). Neonatal outcomes were comparable between both the groups. Conclusions: In patients undergoing SAB for LSCS, a manually titrated infusion of 5 µg/mL of norepinephrine was effective for maintaining BP and decreasing the incidence of hypotension, with no detectable detrimental effect on neonatal outcome.