Lack of an Effect of Body Mass on the Hemodynamic Response to Arginine Vasopressin During Septic Shock

Study Objective. To determine whether body mass alters the effectiveness of a fixed‐dose infusion of arginine vasopressin. Design. Retrospective medical record review. Setting. All intensive care units of a tertiary medical center. Patients. Sixty‐six mechanically ventilated patients who received a fixed‐dose intravenous infusion of arginine vasopressin at 0.04 U/minute as the sole agent for hemodynamic support during septic shock. Measurements and Main Results. Patients were divided into four groups on the basis of body mass index. Effectiveness was measured as hemodynamic stability, which was defined as the proportion of patients achieving a mean arterial pressure (MAP) of 65 mm Hg or higher, the magnitude of the change in MAP at 1 hour, and the need for additional rescue vasopressors. Secondary outcomes included mortality and length of stay. Baseline characteristics of all four groups were comparable for age, sex, and severity of illness determined by using Acute Physiology and Chronic Health Evaluation II (APACHE II), Simplified Acute Physiology II (SAPS II), and Sequential Organ Failure Assessment (SOFA) scores. The only significant differences in baseline characteristics among the groups were in their central venous pressures. The four groups similarly achieved hemodynamic stability at 1 hour after the administration of arginine vasopressin (p=0.41). We observed no significant differences among groups in the magnitude of MAP change (p=0.62), need for rescue catecholamine vasopressors (p=0.17), 28‐day mortality rates (p=0.31), or length of stay in the intensive care unit (p=0.43). Conclusion. Body mass index did not alter the effects of arginine vasopressin on hemodynamic stability or changes in MAP when the drug was administered as a fixed‐dose infusion of 0.04 U/minute. Our results do not support weight‐based dosing of vasopressin, unlike the dosing for catecholamine vasopressors.