2018 Volume 77 Issue 2 Pages 93-97
Objectives: Dexmedetomidine, a highly selective α2-adrenergic receptor agonist, is often used for sedation during the perioperative period. Dexmedetomidine has complex effects on the cardiovascular system. The loading dose of dexmedetomidine increases the arterial pressure and decreases the heart rate, implying changes in arterialcardiac baroreflex. Many previous studies have reported various effects of dexmedetomidine on the cardiac responses to changes in arterial pressure. However, the effect of the loading dose of dexmedetomidine on the arterial-cardiac baroreflex has not been studied. Therefore, we investigated the effect of the loading dose of dexmedetomidine on the arterial-cardiac baroreflex. Methods: Twelve healthy men received loading dose dexmedetomidine (6 μg/kg/h for 10 minutes). Before and during dexmedetomidine infusion, beat-to-beat of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and R-R intervals were recorded. Arterial-cardiac baroreflex function was assessed by sequence analysis between beat-to-beat changes in the SAP and R-R interval. Results: During the infusion of a loading dose of dexmedetomidine, SAP and DAP increased significantly, and heart rate decreased significantly. All indices of arterial-cardiac baroreflex function increased significantly (total-slope: 20.3 ± 14.6 → 29.4 ± 17.4 ms/mmHg; up-slope: 19.9 ± 13.0 → 28.0 ± 14.3 ms/mmHg; down-slope: 20.0 ± 15.8 → 30.3 ± 19.9 ms/mmHg). Conclusions: The present results indicate that the loading dose of dexmedetomidine augments the arterialcardiac baroreflex, which may contribute to stabilization of haemodynamics, even in situations in which arterial blood pressure changes rapidly in response to perioperative stimuli.