Sedation and analgesia in patients with sepsis and hemodynamic instability may be challenging in the ICU. Opioids and propofol can further exacerbate tissue infusion in septic shock by reducing cardiac contractility, increasing vasodilation, and reducing respiratory drive. Ketamine is an NMDA receptor antagonist, which has no effect on respiratory drive and has diastolic airway smooth muscle and anti-inflammatory properties. Esketamine is a dextrorotatory cleavage twice as potent and reduces the incidence of dose-dependent side effects of ketamine. Although it has been successfully used in burn patients undergoing multiple operations and anesthesia-related maintenance analgesia, it has not been reported in ICU septic shock patients undergoing mechanical ventilation. The purpose of this study was to explore the use of esketamine in mechanically ventilated ICU septic shock patients in a single-center randomized controlled trial.