(1626) Effect of Ketamine on Vasopressor Requirements in the Setting of Septic Shock

Introduction: In the setting of shock, ketamine may decrease vasopressor requirements through a purported pharmacodynamic effect of catecholamine reuptake inhibition, though some literature suggests negative hemodynamic effects of ketamine in catecholamine depleted states. Several studies associate ketamine with a decrease in vasopressor requirements when compared to other sedatives such as propofol, midazolam, or fentanyl. Patients represented in the available literature had a relatively lower acuity of illness and lower initial vasopressor requirements compared to severely ill patients that may be encountered in clinical practice. The effect of ketamine on vasopressor requirements in patients with relatively high vasopressor requirements the setting of septic shock is not well defined.

Methods: This study was a retrospective chart review of patients admitted to the Medical Intensive Care Unit (ICU) or Trauma/Surgical ICU at a single quaternary referral center from January 1, 2020 to October 31, 2023. Adult patients with suspected septic shock who underwent invasive mechanical ventilation, received ketamine continuous infusion for at least 8 hours, and had requirements of at least 0.15 mcg/kg/min norepinephrine equivalents (NEE) at time of ketamine initiation were included. This study's primary objective was to evaluate the change in vasopressor requirements 8 hours after the initiation of ketamine continuous infusion.

Results: Of the 61 patients included, the median baseline total NEE was 0.27 mcg/kg/min (IQR: 0.20 - 0.38). The median total NEE 8 hours after the initiation of ketamine was 0.21 mcg/kg/min (IQR: 0.14 - 0.38). The median change in vasopressor requirement was –0.04 mcg/kg/min (IQR: -0.12 - 0.04; p = 0.064). Two patients experienced a new onset arrhythmia requiring intervention.

Conclusions: Ketamine did not significantly impact vasopressor requirements in a population of patients with suspected septic shock with relatively high vasopressor requirements at time of ketamine continuous infusion initiation. These findings suggest ketamine may be a safe adjunctive sedative for patients in septic shock requiring sedation.