Effects of Dexmedetomidine on Minimum Alveolar Concentration of Sevoflurane for Blunting Sympathetic Response to Pneumoperitoneum: A Randomized Trial

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Purpose: Laparoscopic procedures require abdominal inflation (pneumoperitoneum), which triggers strong stress responses that typically need high concentrations of sevoflurane to manage. Despite dexmedetomidine’s known anesthetic-sparing properties, its specific effects on sevoflurane minimum alveolar concentration for blunting sympathetic response (MAC BAR ) during pneumoperitoneum remain incompletely characterized. This study evaluates dexmedetomidine’s impact on sevoflurane requirements for blocking sympathetic responses during laparoscopic pneumoperitoneum. Patients and Methods: This prospective, randomized, double-blind, placebo-controlled trial enrolled 90 adults (aged 18– 45 years) classified as American Society of Anesthesiologists physical status I–II scheduled for elective laparoscopic cholecystectomy. Participants received either saline, low-dose dexmedetomidine (target 0.3 ng/mL), or high-dose dexmedetomidine (target 0.6 ng/mL). We determined sevoflurane MAC BAR using Dixon’s up-and-down method, defined as the concentration preventing ≥ 20% increase in heart rate or mean arterial pressure following pneumoperitoneum. Secondary outcomes included hemodynamic responses, emergence time, adverse events, and plasma catecholamine levels. Results: Dexmedetomidine significantly reduced sevoflurane MAC BAR compared to control (4.70% ± 0.18%; 95% confidence interval [CI], 4.61– 4.80): to 2.90% ± 0.19% (95% CI, 2.80– 3.00) in the low-dose group and to 1.90% ± 0.16% (95% CI, 1.82– 1.98) in the high-dose group (both p < 0.001). Patients receiving dexmedetomidine had significantly lower plasma epinephrine and norepinephrine levels following pneumoperitoneum compared to control (p < 0.001), with better hemodynamic stability. Emergence times and adverse event rates remained comparable between groups. Conclusion: Dexmedetomidine produces dose-dependent reductions in sevoflurane requirements for controlling sympathetic responses during pneumoperitoneum while maintaining hemodynamic stability, making it a valuable adjunct for anesthesia in laparoscopic surgery. Registration: The Chinese Clinical Trials Registry, ChiCTR2300071257.