(1491) Evaluation of the Addition of Vasopressin to Norepinephrine in Time to Resolution of Septic Shock

Introduction: Standard of care for patients with fluid-refractory septic shock is to initiate norepinephrine; if MAP cannot be maintained on norepinephrine alone, vasopressin is recommended. Current literature is limited on the optimal time to initiate vasopressin, whether it be at a certain time mark from sepsis onset or at a specific dose of norepinephrine. The Surviving Sepsis Campaign guidelines suggest vasopressin initiation at norepinephrine 0.25-0.5 mcg/kg/min. The aim of this study is to investigate the efficacy of vasopressin in septic shock patients on norepinephrine.

Methods: This is a single-center retrospective cohort study that evaluated critically ill adults that received continuous infusions of norepinephrine and vasopressin for septic shock between January 2017 and May 2023. Patients that were post-cardiac arrest, diagnosed with COVID-19, or received other continuous infusion vasopressors or inotropes were excluded. Patients were categorized based on norepinephrine dose at time of vasopressin initiation: high (≥ 0.2 mcg/kg/min) or low ( < 0.2 mcg/kg/min). Primary outcome was time to shock resolution defined as vasopressor-free for 24 hours. Secondary outcomes included time to norepinephrine and vasopressin initiation, time on vasopressors, dose of norepinephrine, ICU mortality, ICU LOS, and incidence of tachyarrhythmia.

Results: One-hundred four patients were included in the analysis: 79 in high dose and 25 in low dose. Median time to shock resolution in patients initiated on vasopressin at norepinephrine ≥ 0.2 mcg/kg/min was 115.9 hours (IQR 79.4-199.6) and those at norepinephrine < 0.2 mcg/kg/min was 121.8 hours (IQR 76.9-280.0) (p = 0.520). Median dose of norepinephrine at vasopressin initiation was 0.3 mcg/kg/min (IQR 0.22-0.40) in high dose versus 0.1 mcg/kg/min (0.08-0.16) in low dose (p < 0.001). No significant difference was found in time to norepinephrine and vasopressin initiation, total time on vasopressors, ICU mortality, ICU LOS, and tachyarrhythmia.

Conclusions: In critically ill adult patients with septic shock on norepinephrine that require an additional vasopressor, there was no difference found in time to shock resolution in patients initiated on vasopressin at norepinephrine ≥ 0.2 mcg/kg/min compared to < 0.2 mcg/kg/min.