Reversal by Vasopressin of Intractable Hypotension in the Late Phase of Hemorrhagic Shock

Abstract

Background —Hypovolemic shock of marked severity and duration may progress to cardiovascular collapse unresponsive to volume replacement and drug intervention. On the basis of clinical observations, we investigated the action of vasopressin in an animal model of this condition. Methods and Results —In 7 dogs, prolonged hemorrhagic shock (mean arterial pressure [MAP] of ≈40 mm Hg) was induced by exsanguination into a reservoir. After ≈30 minutes, progressive reinfusion was needed to maintain MAP at ≈40 mm Hg, and by ≈1 hour, despite complete restoration of blood volume, the administration of norepinephrine ≈3 μg · kg −1 · min −1 was required to maintain this pressure. At this moment, administration of vasopressin 1 to 4 mU · kg −1 · min −1 increased MAP from 39±6 to 128±9 mm Hg ( P <0.001), primarily because of peripheral vasoconstriction. In 3 dogs subjected to similar prolonged hemorrhagic shock, angiotensin II 180 ng · kg −1 · min −1 had only a marginal effect on MAP (45±12 to 49±15 mm Hg). Plasma vasopressin was markedly elevated during acute hemorrhage but fell from 319±66 to 29±9 pg/mL before administration of vasopressin ( P <0.01). Conclusions —Vasopressin is a uniquely effective pressor in the irreversible phase of hemorrhagic shock unresponsive to volume replacement and catecholamine vasopressors. Vasopressin deficiency may contribute to the pathogenesis of this condition.