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Abstract

We thank colleagues Langesaeter and Rosseland for interest in our article “Maternal hemodynamics during cesarean delivery assessed by whole-body impedance cardiography”. They point out the possible role of oxytocin in hemodynamic changes at the moment of delivery. Transitory hypotonia and compensatory tachycardia are possible known side effects of fast intravenous bolus of oxytocin. Langesaeter and Rosseland find that a fall in systemic vascular resistance after delivery causes a compensatory rise in heart rate (HR) and cardiac output and is mainly due to the effect of oxytocin rather than volume load in the vasculature. Our parturients received intravenous 5 IU oxytocin bolus routinely after the closure of the umbilical cord. However, in our study increase in cardiac output index (CI) after delivery was due to a rise in stroke volume index (SI) and HR, not only in HR. When values before surgery and after delivery are compared, there is a more prominent change in SI compared to HR. According to the law of Frank-Starling, the healthy heart pumps all the blood that comes to it. We assume that the distinct increase in SI is due to increased preload to the heart leading to a rise in CI in our study. Therefore we find that the rise in CI after delivery cannot be explained only as a compensatory reaction against a fall in systemic vascular resistance index (SVRI). But obviously we cannot exclude the enhancing effect of oxytocin on decreasing SVRI after delivery.