Different Noradrenaline Protocols in Post Spinal Hypotension in CS

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.

Inclusion criteria

• ASA 2
• 38 +4 gestational age parturient

Exclusion criteria

• ASA 3-6
• Parturients with any kind of contraindication to spinal anesthesia
• Hypertensive parturients (basal systolic blood pressure above 140 mmHg)
• Parturients having basal systolic blood pressure below 100 mmHg
• Parturients having peripartum hemorrhage
• Parturients having body mass index above 40
• Parturients with a known allergic reaction to one of the study drugs
• Parturients not willing to be included into the study