Vasopressin deficiency contributes to the vasodilation of septic shock
Landry, D.W.; Levin, H.R.; Gallant, E.M.; Ashton, R.C.; Seo, S.; D'Alessandro, D.; Oz, M.C.; Oliver, J.A.
Circulation 95(5): 1122-1125
1997
ISSN/ISBN: 0009-7322 PMID: 9054839 Document Number: 1310
Background. The hypotension of septic shock is due to systemic vasodilation. On the basis of a clinical observation, we investigated the possibility that a deficiency in vasopressin contributes to the vasodilation of septic shock. Methods and Results. In 19 patients with vasodilatory septic shock (systolic arterial pressure (SAP) of 92+-2 mm Hg (mean+-SE), cardiac output (CO) of 6.8+-0.7 L/min) who were receiving catecholamines, plasma vasopressin averaged 3.1 +- 1.0 pg/mL. In 12 patients with cardiogenic shock (SAP, 99+-7 mm Hg; CO, 3.5+-0.9 L/min) who were also receiving catecholamines, it averaged 22.7+-2.2 pg/mL (P lt .001). A constant infusion of exogenous vasopressin to 2 patients with septic shock resulted in the expected plasma concentration, indicating that catabolism of vasopressin is not increased in this condition. Although vasopressin is a weak pressor in normal subjects, its administration at 0.04 U/min to 10 patients with septic shock who were receiving catecholamines increased arterial pressure (systolic/diastolic) from 92/52 to 146/66 mm Hg (P lt .001/P lt .05) due to peripheral vasoconstriction (systemic vascular resistance increased from 644 to 1187 dyne cntdot s/cm-5; P lt .001). Furthermore, in 6 patients with septic shock who were receiving vasopressin as the sole pressor, vasopressin withdrawal resulted in hypotension (SAP, 83+-3 mm Hg), and vasopressin administration at 0.01 U/min, which resulted in a plasma concentration ( apprxeq 30 pg/mL) expected for the level of hypotension, increased SAP from 83 to 115 mm Hg (P lt .01). Conclusions. Vasopressin plasma levels are inappropriately low in vasodilatory shock, most likely because of impaired baroreflex-mediated secretion. The deficiency in vasopressin contributes to the hypotension of vasodilatory septic shock.
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