Cardio Vascular Assessment in Vasoplegia Following Cardiac Surgery

Severe vasodilatation during cardiac surgery has been known for many years. It is characterized by a low systemic vascular resistance, a high cardiac index, and a low blood pressure, which can be resistant to even high doses of vasoconstrictors. This condition is associated with a high mortality. After cardiac surgery, there can be cardiac dysfunction as well. However with a low systemic vascular resistance, the cardiac function curve would be shifted upwards and to the left, giving the impression of good contractility. The ejection fraction, which is the commonly used measurement of cardiac contractility, cannot therefore be relied upon for a correct assessment under these circumstances. This can affect fluid and inotrope management. Therefore a measurement which does not depend on the afterload, but measures pure myocardial contractility is required. Ventricular elastance is such a measure. A measurement of arterial elastance which reflects the flow characteristics and pulsatility of flow may be more appropriate than systemic vascular resistance to measure arterial tone. Ventricular-arterial coupling has to be maintained for optimum myocardial performance. The severe vasodilatation, the possible myocardial impairment and also its treatment with high doses of vasoconstrictors can affect the relationship between the ventricular and arterial systems. Therefore measurement of ventricular arterial coupling is also important. ISSN 2639-846X Review Article Citation: Indraratna K. Cardiovascular Assessment in Vasoplegia Following Cardiac Surgery. Anesth Pain Res. 2018; 2(2): 1-4. Keyword Arterial elastance, Ejection fraction, Vasoplegia, Ventricular arterial coupling, Ventricular elastance. Introduction Vasoplegic shock is associated with severe hypotension, and tissue hypoperfusion. Vasoplegic syndrome is a fairly frequent occurrence during cardio pulmonary bypass. The incidence ranges from 9% to 44% [1]. Vasoplegic shock is characterized by a low blood pressure, the requirement for vasopressors and fluids, a high cardiac output, and a low systemic vascular resistance [2-4]. This is similar to septic shock [5]. Severe vasodilatation with the above features is termed vasoplegia [6]. In this situation the inability to achieve adequate organ perfusion can lead to multiple organ failure and death. Pathophysiological alterations in the cardiovascular system in vasoplegia after cardiac surgery The main issues would be due to, • Vasodilatation because of vasoplegia • Myocardial depression may occur during cardiac surgery. Vasodilatation Extreme vasodilatation or vasoplegia causes persistent and severe hypotension. The causes for vasoplegia are • Activation of adenosine triphosphate sensitive potassium channels • Activation of inducible forms of nitric oxide synthase • Deficiency of vasopressin [3]. Fischer GW et al. [3] identified several aetiological factors, for the vasoplegic syndrome after cardio-pulmonary bypass. • Pre-operative use of angiotensin-converting enzyme inhibitors • Beta blockers • Higher euro score • Heart failure surgery • Decline in Mean Arterial Pressure after initiation of Cardiopulmonary bypass Because of the vasodilation, there is a reduction in the total peripheral vascular resistance. With vasoplegia, despite, adequate