Differences in Plasma Concentration of RAAS-axis Hormones in Patients Undergoing Cardiac Surgery With or Without Cardiopulmonary Bypass

In patients undergoing cardiac surgery, the occurrence of vasoplegia or vasoplegic shock is a common and sometimes very severe complication. Although there are multiple factors that may affect the incidence and severity of vasoplegia, it remains unclear which role the use of cardiopulmonary bypass may play in the pathogenesis of this complication. The heart normally pumps blood through the lungs where the blood primarily gets oxygenated. However, it is also known that pulmonary blood flow is also essential for the activation of various hormones, some of which are central to the regulation of vascular tension and blood pressure. If the pulmonary circulation is bypassed, as is the case in on-pump cardiac surgery, it is likely that the resulting differential activity of hormones may cause or contribute to the incidence of vasoplegia. This study aims to show whether cardiopulmonary bypass leads to the differential regulation of hormones of the renin-angiotensin-aldosterone-system which could explain why some patients suffer from vasoplegia or vasoplegic shock following such procedures.