Different Noradrenaline Protocols in Post Spinal Hypotension in CS

Overview

The incidence of hypotension after spinal anesthesia is approximately 60% in parturients undergoing cesarean section. As a consequence of hypotension, nausea-vomiting, dyspnea and neurological deterioration in patients and low Apgar scores in newborns may occur. Therefore, there is an increasing interest to prevent maternal post spinal hypotension by using several drugs including noradrenaline given in different protocols to the patients undergoing spinal anesthesia for cesarean section. However, there is no conclusive answer to the question of which dosage is the best to prevent the maternal post spinal hypotension in literature. In this prospective randomized study, we aimed to compare different noradrenaline protocols for preventing maternal post spinal hypotension during elective cesarean delivery.

One of the most important and frequent adverse effects of spinal anesthesia is post procedure hypotension. The emerging hypotension does not affect only the pregnant, it also does harm to the newborn. Therefore, an anesthesiologist should avoid and take precautions to prevent maternal post spinal hypotension. There is a growing body of evidence about noradrenalin application in the management of hemodynamic optimization of patients undergoing cesarean section with spinal anesthesia. However, there is no conclusive decision about the dosage and application protocol of noradrenaline in this patient population. In a study comparing the incidence of post spinal maternal hypotension given noradrenaline versus phenylephrine, the authors reported that both of drugs effectively controlled maternal blood pressure. The incidence of maternal hypotension was 30% and 32% (p= 0.8) in noradrenaline and phenylephrine study arms, respectively. Therefore, one can speculate that the incidence of maternal post spinal hypotension remains high even in patients receiving noradrenaline or phenylephrine. In the noradrenaline arm, only noradrenaline infusion with a dosage of 0.05 microgram/kg/minute without any bolus was applied to the patients. In another study, the effects of different noradrenaline infusion dosages with 5 microgram bolus dosage on maternal post spinal hypotension were investigated. The frequencies of maternal hypotension were 42.1%, 24.7% and 26% in patients receiving 0.025, 0.05 and 0.075 microgram/kg/minute with a bolus 5 microgram noradrenaline, respectively. As a conclusion of this study, addition of a bolus dose of 5 microgram noradrenaline may lower the incidence of post spinal hypotension. However, as in the previous study, approximately one fourth of patients still may have a post spinal hypotension episode. Regarding these results, the present study is planned to answer the question of which approach including increasing infusion or bolus dosage of noradrenaline is superior to ameliorate the incidence of hypotension in this population. In conclusion, the aim of this study is to compare three different noradrenaline protocols including different bolus and infusion dosages to decrease the rate of hypotension in patients undergoing cesarean section with spinal anesthesia.