Safety and Efficacy of Esketamine Combined With Dexmedetomidine for Sedation of Mechanically Ventilated Patients

This study looks at whether combining two sedation medications — esketamine and dexmedetomidine — is safe and effective for patients on breathing machines in the ICU. The goal is to find a sedation approach that is better tolerated and leads to better recovery. You may be eligible if... - You are between 18 and 70 years old - You are on a mechanical ventilator (breathing machine) in an ICU with a tube through your mouth - You are expected to need the ventilator for more than 24 hours You may NOT be eligible if... - You have a known allergy to esketamine, dexmedetomidine, remifentanil, or propofol - You are pregnant or breastfeeding - Your BMI is over 35 kg/m² - You have severe burns or trauma (Injury Severity Score ≥25) - You drink heavily (60g+ pure alcohol/day for men, 40g+ for women) - You have terminal illness (e.g., widespread metastatic cancer) - You take sedatives, opioids, or anti-anxiety drugs long-term - You have severe neurological conditions (stroke, epilepsy, coma) - You have severe liver or kidney disease - You have been on the ventilator for more than 24 hours before enrollment Talk to your doctor to see if this trial is right for you.