Recent advances in perioperative anesthetic management update on the role of vasopressin and its effects on outcomes.

The vasoconstrictive and antidiuretic physiologic properties of vasopressin (antidiuretic hormone) have long been known. Until recently however, vasopressin was mostly used for diabetes insipidus and noctournal enuresis. This review summarizes the growing body of evidence regarding the perioperative use of vasopressin and its analogues in the management of certain forms of cardiovascular collapse. Physiologically, vasopressin is involved in regulating osmotic, volemic, and cardiovascular homeostasis. It acts via several specific vasopressin receptors that are variably distributed in the heart, kidneys and vasculature etc. Under normal conditions, its antidiuretic effect predominates and vasopressin only induces vasoconstriction at high concentrations. Regarding catecholamine-resistant vasodilatory shock, current evidence suggests that with adequate volume resuscitation, exogenous vasopressin in low "physiologic" doses (0.01-0.04 units/min) safely supports mean arterial pressure without adversely affecting myocardial function and splanchnic circulation. One possible explanation is that metabolic acidosis impairs the function of alpha-adrenergic (but not vasopressin) receptors, thus diminishing the response to catecholamines. Although there is yet no clear cut mortality benefit, vasopressin is now recommended as a second-line agent in septic shock for its catecholamine-sparing effect and as an alternative to epinephrine in cardiopulmonary resuscitation. It has also demonstrated efficacy in ameliorating vasoplegia after cardiopulmonary bypass as well as perioperative hypotension in patients on renin-angiotensin system antagionists preoperatively. In summary, accumulating clinical experience and formal studies indicate that vasopressin has a role in restoring vascular tone in refractory vasodilatory shock states with minimal adverse effects provided that euvolemia is assured.