(1008) Impact of Obesity on ICU Patients' Hemodynamics Receiving Dexmedetomidine on Mechanical Ventilation

Introduction: Dexmedetomidine (DEX) is a commonly used sedative in the intensive care unit (ICU) as a weight-based infusion; however, there is no guidance for dose adjustments in obesity. Most studies were conducted on patients in the operating room and found decreased drug clearance and increased concentration in patients with obesity, which may potentially increase risk of adverse effects. The purpose of this study is to compare rates of hypotension and bradycardia in patients with and without obesity (BMI ≥ 30 kg/m2) receiving DEX dosed on actual body weight.

Methods: This IRB-approved, retrospective cohort study included adult patients receiving DEX for at least 4 hours and requiring mechanical ventilation (MV) in the ICU from June 1, 2017 to June 1, 2022. Patients were excluded if systolic blood pressure (SBP) < 90 mmHg, mean arterial pressure (MAP) < 65 mmHg, heart rate (HR) < 50 bpm, or required vasopressors prior to DEX initiation; DEX used for procedural sedation or general anesthesia; received bolus dose of DEX; admitted to cardiac service; or had history of heart block or a pacemaker. The primary outcome was development of hemodynamic instability (SBP < 90 mmHg, MAP < 65 mmHg, HR < 50 bpm) or intervention (atropine, vasopressors, or ≥ 500 mL fluid bolus) within the first 24 hours of DEX administration. Chi-square or Mann-Whitney U test was utilized for statistical analysis.

Results: 121 patients were included: 69 with a BMI ≥ 30 and 52 with a BMI < 30. Most patients were white males in their fifth decade of life. More patients in the BMI ≥ 30 group had a history of hypertension, diabetes, heart failure; and covid during admission. There was no difference in hemodynamic instability between patients with BMI ≥ 30 (54%) and < 30 (62%), p < 0.767. The total dose of DEX administered over the first 24 hours was higher in BMI ≥ 30 with median dose of 1223 mcg vs 796 mcg, p < 0.004. There was no difference in ICU length of stay or in-hospital mortality, though hospital length of stay was longer in the BMI ≥ 30 group (21 vs 17 days, p < 0.014).

Conclusions: There was no difference in hemodynamic instability between patients with and without obesity. Larger, multi-center studies are warranted to assess safety of dexmedetomidine based on actual body weight for patients with BMI ≥ 30 kg/m2.