Dexmedetomidine Dosing in Critically Ill Patients With Obesity

Introduction: Dexmedetomidine, a selective α-2-adrenergic agonist, is a recommended sedative agent with minimal risk of respiratory depression, recommended by the Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption in Adult Patients in the ICU. However, there is limited guidance on optimal dosing in patients with obesity, a population known to exhibit altered pharmacokinetics that can impact drug efficacy and safety.


Methods: This single-center, retrospective, descriptive quality improvement study evaluated dexmedetomidine prescribing practices and adverse drug events (ADEs) in critically ill obese adults at Northwestern Memorial Hospital (NMH) between September 1, 2023, and August 31, 2024. NMH is an 894-bed academic medical center with a 40-bed medical ICU and 16-bed surgical ICU. This study included adult medical and surgical ICU patients with a BMI ≥ 30 kg/m², total body weight ≥ 120% of ideal body weight, and who received dexmedetomidine for ≥ 24 hours. Patients were excluded if concomitantly on extracorporeal membrane oxygenation support or targeted temperature management.


Results: Fifty patients met inclusion criteria with a mean total body weight of 115.63 ± 37.89 kg. Dosing was almost universally based on total body weight (96%), regardless of BMI. Most patients (72%) fell within class I–II obesity (BMI 30–39 kg/m²), while 28% had class III obesity (BMI ≥ 40 kg/m²). The most frequent ADEs within 48 hours of dexmedetomidine initiation were hypotension (60%), bradycardia (32%), and fever (16%). Sedation efficacy, defined as the percentage of measured Richmond Agitation-Sedation Scale (RASS) levels within the appropriate 0 to –2 range during the first 48 hours, averaged at 53.2% (SD ±25.9%). Twenty-eight patients (56%) required additional rescue sedation within 48 hours of dexmedetomidine initiation.


Conclusions: These findings suggest that dexmedetomidine is most commonly dosed based on total body weight in obese ICU patients at this institution, which may contribute to increased rates of hemodynamic adverse events. Future studies should compare adverse event rates with dexmedetomidine between prespecified obesity classes to help elucidate whether adjusted or ideal body weight may offer a safer dosing weight in obese populations.