What is the most common cause of hypotension in the immediate post-operative period after CABG?

In the immediate post-operative period following coronary artery bypass grafting (CABG), the most common cause of hypotension is frequently related to decreased systemic vascular resistance (SVR). Following surgery, factors such as vasodilation due to anesthesia and the effects of surgical manipulation can lead to decreased vascular tone. In this context, when the SVR decreases, the body is unable to adequately maintain blood pressure, resulting in hypotension.

Decreased circulating volume, while a possible contributor, is not typically the primary cause of hypotension immediately after CABG, as patients are usually well-hydrated during the procedure. Left ventricular failure, although a critical concern, often necessitates intervention rather than being a common cause of hypotension on its own, as the heart may be able to compensate adequately in the early hours after surgery. The need for inotropic support typically arises in response to hypotension rather than being a fundamental cause. Therefore, recognizing the relationship between systemic vascular resistance and blood pressure regulation is vital in understanding post-operative management in CABG patients.