2014 Papers - Sarkar


Vasopressin Decreases Pulmonary-to-Systemic Vascular Resistance Ratio in a Porcine Model of Severe Hemorrhagic Shock

Joy Sarkar Surgical Residency Program, Tripler Army Medical Center


Background: Vasopressors are gaining renewed interest as treatment adjuncts in hemorrhagic shock. The ideal vasoconstrictor will increase systemic blood pressure without increasing pulmonary vascular resistance, which hinders pulmonary perfusion and exacerbates hypoxemia. However, the selectivity of pressors for pulmonary vs systemic vasoconstriction during hemorrhage has not been characterized. The purpose of this study is to test the hypothesis that vasopressin has distinct effects on pulmonary vs. systemic hemodynamics, unlike the catecholamine vasopressors norepinephrine (NE) and phenylephrine (PE).

Methods: Anesthetized and ventilated pigs were assigned to resuscitation with saline only (n = 7), or saline with either VP (n = 6), NE (n = 6), or PE (n = 6). Animals were hemorrhaged to a target volume of 30 mL/kg, and mean arterial pressure of 35 mmHg. One hour after the start of hemorrhage, animals were resuscitated with saline up to one shed blood volume, followed by either additional saline or a vasopressor. Hemodynamics and oxygenation were measured hourly for 4 hours after the start of hemorrhage.

Results: VP increased SVR while sparing the pulmonary vasculature, leading to a 45% decrease in the PVR/SVR ratio compared to treatment with PE. Conversely, NE induced pulmonary hypertension and led to an increased PVR/SVR ratio, associated with decreased oxygen saturation. PE and crystalloid had no significant effect on the PVR/SVR ratio.

Conclusion: Vasopressin can effectively maintain blood oxygenation by sparing the pulmonary vasculature while raising arterial blood pressure via systemic vasoconstriction, which has been demonstrated in other studies to decrease splanchnic non-compressible bleeding. Our results demonstrate that vasopressin administered during early hemorrhagic shock can be useful as early supportive therapy. The ability of VP to maintain blood oxygenation indicates that VP may reduce hypoxemia and oxygen debt accumulation if used early in the management of hemorrhagic shock.