Postoperative Sudden Hypotension Due to Relative Adrenal Insufficiency.

Systemic blood pressure is regulated by three mechanisms: the sympathetic nervous system, the renin-angiotensin system, and the arginine-vasopressin system. Hypotension is a condition that can occur at any stage of management of general anaesthesia, including induction, extubation, and maintenance. Many of the medications used for anaesthesia produce a mild to moderate decrease in systemic vascular resistance (SVR) with a subsequent decrease in arterial blood pressure. Profound and sustained hypotension, however, can have a global impact, resulting in a failure to adequately perfuse systemic capillary networks. The following report describes the case of a 69-year-old man undergoing surgery for total hip replacement who had hypotension that was refractory to fluid administration and inotropic agents at the end of the surgery. In this case study, the role of methylprednisolone therapy in catecholamine-resistant hypotension is also discussed.