Hypotension After Spinal Anesthesia

The purpose of this study is to determine the 50% and 90% effective doses (ED50 and ED90) of prophylactic phenylephrine infusion for preventing spinal anesthesia-induced hypotension during elective cesarean delivery, in the supine position and in the left-lateral-tilt 15° position, respectively. Two hundred parturients with singleton term pregnancies will be randomized 1:1 to the supine group or the left-tilt 15° group, and within each position 1:1:1:1 to one of four fixed phenylephrine infusion rates (0.2, 0.4, 0.6, or 0.8 μg/kg/min; 25 per group), with the rate allocation masked by concentration blinding (identical pump rate, different solution concentrations). Spinal anesthesia consists of hyperbaric bupivacaine 12 mg plus morphine 0.15 mg. The primary outcome is the incidence of hypotension (systolic blood pressure \< 80% of baseline or \< 90 mmHg) from completion of the intrathecal injection to delivery. ED50 and ED90 will be estimated by probit regression within each position.

To assess the hemodynamic difference after spinal anesthesia with hyperbaric bupivacaine and isobaric bupivacaine in elective cesarean section

The aim of this double-blind randomised study will be to compare a fixed-rate prophylactic metaraminol infusion to a fixed-rate prophylactic norepinephrine infusion during elective cesarean section under combined spinal-epidural anaesthesia.

Methodologies and approaches have been implemented with differing degrees of success to prevent neuraxial hypotension. Currently utilized approaches to prevent hypotension during spinal anesthetic administration consist of physical precautions such as leg restraints and compression hosiery, as well as sympathomimetic medications Through a competitive inhibition of noradrenaline uptake, heptaminol hydrochloride prevented orthostatic hypotension and increased the plasma concentration of noradrenaline. This inhibitory effect might account for a portion of the antihypotensive effect After thorough research of the literature, studies evaluating the role of preoperative oral heptaminol hydrochloride in preventing hypotension after spinal anesthesia in lower limb surgeries with tourniquets are lacking.