Up-and-down determination of prophylactic norepinephrine boluses combined with crystalloid co-load for preventing post-spinal anesthesia hypotension during cesarean section.

Abstract

Background: The use of a fluid co-load has been shown to enhance hemodynamic stability and diminish the occurrence of hypotension after spinal anesthesia when paired with prophylactic norepinephrine. This research aimed to identify the effective dosages (ED₉₀ and ED₅₀) of prophylactic norepinephrine boluses, in conjunction with a crystalloid co-load, for the prevention of hypotension after spinal anesthesia in cesarean delivery patients.

Methods: Patients were administered crystalloid co-loads at a dosage of 10 mL/kg, in addition to preventive norepinephrine dosages direct following spinal anesthesia administration. The dosages of norepinephrine were established employing the up-and-down sequential allocation technique, starting with 8 µg and progressively rising by 1 µg increments. The primary objective was to detect the effective dosage (ED₉₀ and ED₅₀) of norepinephrine necessary to avoid hypotension following spinal anesthesia.

Results: The ED₉₀ for a single norepinephrine bolus, in combination with a crystalloid co-load, was calculated to be 5.35 µg (95% CI: 4.75 to 7.13). The ED₅₀ was determined to be 4.05 µg (95% CI: 3.68 to 4.46) using the up-and-down method and 3.926 µg (95% CI: 3.362 to 4.422) through the probit regression model.

Conclusion: A prophylactic norepinephrine bolus of 5.35 µg, administered with a crystalloid co-load, effectively prevents hypotension following the spinal anesthesia in cesarean delivery patients.