Catecholamine-resistant hypotension following induction for spinal exploration.

Systemic blood pressure is regulated by 3 mechanisms: the sympathetic nervous system, the renin-angiotensin system, and the arginine-vasopressin system. The use of angiotensin II receptor blockers and angiotensin-converting enzyme inhibitors has become prevalent in the medical treatment of hypertension. These classes of medications inhibit the renin-angiotensin-aldosterone system, specifically the action of angiotensin II, a potent vasoconstrictor. This article describes the case of a 67-year-old man undergoing surgery for a spinal exploration who had hypotension following induction that was refractory to fluid administration and agents with mixed alpha-beta agonistic activity but responded to a vasopressin and phenylephrine infusion. Following the case study is a discussion of the impact that angiotensin II inhibitors may have on a patient undergoing general anesthesia and the role of vasopressin in reversing catecholamine-resistant hypotension.