Effect of Body Weight on Hemodynamic Response in Patients Receiving Fixed-Dose Vasopressin for Septic Shock

Background: Fixed-dose vasopressin is an adjunctive therapy to norepinephrine (NE) to raise mean arterial pressure (MAP) and decrease NE requirements in patients with septic shock. It is unknown if weight affects hemodynamic response to vasopressin or if a weight-based vasopressin strategy is superior to fixed dosing. Objective: The primary objective was to evaluate effect of body weight on response to vasopressin as measured by change in MAP 1 hour post–vasopressin initiation. Methods: A single-center, retrospective study was performed in patients with septic shock. Baseline characteristics, catecholamine and vasopressin requirement, response to therapy, and adverse events were collected. Results: Forty patients were included who received a fixed-dose vasopressin in addition to catecholamine infusions. No correlation was found in the primary outcome of change in MAP at 1 hour after vasopressin initiation compared with vasopressin dose relative to patient weight or body mass index (BMI). Change in MAP at 6 and 12 hours was not significant. In the obese population (n = 9), there was a significant negative correlation between BMI and change in MAP at 6 hours (correlation coefficient r = −0.951; P = 0.0009). Linear regression analysis confirmed that vasopressin dose relative toweight was independently associated with change in MAP at 1, 6, and 12 hours, whereas changes in NE dosing were not. Conclusion: Increasing weight-based dosing of vasopressin did not correlate with change in MAP when used with catecholamine vasopressors in septic shock. However, fixed-dose vasopressin may not be sufficient in obese septic shock patients with a BMI ≥30 kg/m².