Does body weight impact the efficacy of vasopressin therapy in the management of septic shock?

Background: Vasopressors used for the management of septic shock are often dosed according to body weight. Use of vasopressin for physiologic replacement in patients with septic shock is usually administered as a standard non-weight-based dose. We hypothesized that the efficacy of vasopressin may be influenced by body weight. Purpose: The primary objective was to determine if the effects of vasopressin on other vasopressor dosing requirements is related to body weight. Secondary objectives included evaluation of blood pressure and heart rate after the start of vasopressin infusion. Methods: A retrospective, cohort study in a large academic health center was conducted. Sixty-four adult inpatients with septic shock (26 medical intensive care unit and 38 surgical intensive care unit) who required vasopressor administration including vasopressin therapy were included. Dosing requirements of vasopressors were captured 1 hour before and during the hour of vasopressin initiation and 2 and 4 hours later. Other information collected during the study period included blood pressure, mean arterial pressure, and heart rate. Results: Most of the patients (n = 61) received vasopressin at a dose of 0.04 U/min. Changes in vasopressor dosing were significantly correlated with weight-adjusted vasopressin at 2 hours (correlation coefficient = -0.36, P = .03) and 4 hours (correlation coefficient = -0.46, P < .001). Use of vasopressin was associated with significant increases in systolic blood pressure, diastolic blood pressure, and mean arterial pressure at each time point compared with baseline. Conclusions: Effects of vasopressin on catecholamine dosing requirements in the setting of septic shock may be influenced by body weight. Prospective studies are needed to examine weight-based dosing of vasopressin in this setting.