(1486) Evaluating Septic Shock Duration After Vasopressin Initiation at Various Norepinephrine Equivalents

Introduction: Norepinephrine is the first-line vasopressor in septic shock and vasopressin is recommended as an adjunct. However, the optimal time to initiate vasopressin relative to norepinephrine is unclear. Some studies show benefits of early-use vasopressin, while others show no difference between early and late-use of vasopressin. Therefore, this study investigates whether the dose of norepinephrine equivalents (NE) at vasopressin initiation impacts the number of vasopressin-free days in septic shock patients.

Methods: This retrospective study included adults who received vasopressin for septic shock. Subjects were excluded if they expired within 48 hours of vasopressin initiation, were pregnant or incarcerated. Patients included were grouped based on NE at vasopressin initiation; low-dose ( < 10 µg/min), moderate-dose (10-19 µg/min), and high-dose (20-30 µg/min) NE. A one-way ANOVA was used to evaluate the primary outcome, vasopressor-free days between the groups. A Tukey post-hoc test was planned if a difference was identified. A priori power calculation found that a total of 114 subjects were required, 38 per group to achieve 80% power and two-sided alpha of 0.05.

Results: A total of 114 patients were included in this study. Majority of subjects were 65 years old men with a mean APACHE 2 score of 26. Past medical history of diabetes, duration of shock before vasopressin initiation, and norepinephrine equivalents prior to starting vasopressin were the only baseline characteristics statistically different between groups. There was no statistically significant difference in all three groups for the primary outcome, vasopressor-free days at 28 days, (p-value 0.3794). There was no difference in mortality within 28 days of vasopressin initiation, hospital/ICU length of stay, occurrence of AKI during vasopressin therapy and 24 hours after, and RRT starting during vasopressin use and 24 hours after.

Conclusions: There was no difference in vasopressor-free days at 28 days when patients were started at either the low, moderate, or high dose NE. Initiating vasopressin at various NE also did not affect mortality, hospital/ICU length of stay, occurrence of AKI or new RRT during vasopressin use and 24 hours after.