Vasopressin.

Vasopressin is a hormone that is essential for both osmotic and cardiovascular homeostasis. A deficiency of vasopressin exists in some shock states and replacement of physiological levels of vasopressin can restore vascular tone. Vasopressin is therefore emerging as a rational therapy for vasodilatory shock. In this article we review the rationale and summarize the evidence for using vasopressin in vasodilatory shock states, such as septic shock. We then highlight the areas of uncertainty in using vasopressin for septic shock and summarize the reasons for clinical equipoise. We close by suggesting that further randomized controlled trials of vasopressin in septic shock are required before vasopressin is used routinely for management of septic shock.