Evaluation of two Different Doses of Dexmedetomidine Infusion on Oxygenation, Lung Mechanics in Morbid Obese Patients: A Prospective Study

Background: Dexmedetomidine, a selective alpha-2 adrenoceptor agonist, is increasingly used in anesthesia for its sedative and analgesic effects without respiratory depression. In morbidly obese patients, respiratory management is challenging due to reduced lung compliance and oxygenation. This study evaluates the effect of two different doses of dexmedetomidine infusion on oxygenation and lung mechanics in morbidly obese patients undergoing surgery. Materials and Methods: A prospective study was conducted on 60 morbidly obese patients (BMI ≥ 40 kg/m²) scheduled for elective surgery under general anesthesia. Patients were randomized into two groups: Group A received a dexmedetomidine infusion of 0.4 µg/kg/hr, and Group B received 0.7 µg/kg/hr after an initial loading dose of 1 µg/kg over 10 minutes. Oxygenation parameters (PaO₂, SpO₂) and lung mechanics (peak inspiratory pressure, compliance) were recorded at baseline, after induction, and hourly during surgery. Statistical analysis was performed using a two-way ANOVA, with significance set at p < 0.05. Results: Group B showed a statistically significant improvement in PaO₂ levels compared to Group A, with mean values of 95 ± 10 mmHg versus 88 ± 12 mmHg (p = 0.03). Peak inspiratory pressure was lower in Group B (22 ± 3 cm H₂O) than in Group A (25 ± 4 cm H₂O), indicating better lung compliance (p = 0.02). No significant difference in heart rate or mean arterial pressure was observed between the two groups. Conclusion: A higher dose of dexmedetomidine infusion (0.7 µg/kg/hr) improved oxygenation and lung mechanics in morbidly obese patients without adverse cardiovascular effects. This dose may offer a safer anesthetic regimen for this patient population, enhancing respiratory outcomes during surgery.