Effects of Dexmedetomidine on Minimum Alveolar Concentration of Sevoflurane for Blunting Sympathetic Response to...

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.

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.

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.

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.

The Chinese Clinical Trials Registry, ChiCTR2300071257.