Background: Arterial hypotension is a frequent complication following spinal anesthesia for cesarean sections. A fast treatment is necessary to maintain the well-being of the mother and to avoid deficiencies in the intrauterine supply to the child.
Objective: The aim of this analysis was to evaluate the effects of the most frequently used vasoactive substances for treatment of hypotension in patients undergoing cesarean sections in Germany, i.e. ephedrine (E), phenylephrine (P) and Akrinor (A, cafedrine/theodrenaline), a 20:1 combination of cafedrine and theodrenaline.
Methods: A retrospective single center analysis of 772 patients (16-50 years old) with arterial hypotension following spinal anesthesia for cesarean section and requiring treatment with vasoactive substances (July 2012-April 2017) was carried out. In the three observation periods the respective current clinical standard treatment of E, P or A was applied. The primary end-points were changes in maternal hemodynamics, pH and base excess (BE) in the child and the resulting blood pressure values. The statistical analysis plan of the study was registered in the German registry for clinical trials (DRKS-ID: DRKS00012520).
Results: The initial blood pressure before the intervention was comparable in all three groups, with no clinically relevant differences between the individual groups. In the course of anesthesia the largest blood pressure decrease as well as the largest resulting increase after the intervention were found in group A. In group P there was an increased need for an alternative catecholamine in comparison to the other two groups (P : 13 patients, 3.7%, E: 5 patients, 3.3% and A: 0 patients (0%), p 0.007). Differences were detected in the BE of the child (mean E: -1.36, P : -2.03, A: -2.57, p 0.0001) and the incidence of bradycardia requiring drug intervention (E: 0.7%, P : 5.4%, A: 1.9%, p = 0.007). No significant differences were found for the arterial pH of the child and APGAR scores.
Conclusion: The differences of the individual vasoactive substances seemed to be much smaller than one would expect based on the results of randomized clinical trials. The incidence and extent of bradycardia and neonatal acidosis were much lower than previously reported. The determined differences seemed to have no major clinical relevance. Although the A group required less bolus administrations and seemed to be the most potent substance, the results imply that the assessment of the effects of vasoactive substances should not be carried out without consideration of the accompanying measures.
Keywords: Cesarean section; Hypotension; Obstetrics; Spinal anesthesia; Vasopressors.