RESUMEN
BACKGROUND: A rapid increase in desflurane concentration has been demonstrated to induce transient sympathetic hyperactivity and lead to increases in blood pressure and heart rate (HR). Additionally, the use of dexmedetomidine as an anesthetic adjunct has been reported to attenuate intraoperative sympathetic responses. We examined the hemodynamic effects of dexmedetomidine infusion before anesthetic induction on desflurane-induced cardiovascular changes. METHODS: Patients were randomly divided into three groups. They received either normal saline (NS) (group 1, only NS) or dexmedetomidine solution diluted in 50 ml NS (group 2, 0.5 µg/kg; group 3, 1.0 µg/kg) for 10 minutes with a syringe pump before anesthetic induction. Desflurane was administered at a vaporizer dial setting of 8% for 5 minutes by manual ventilation. RESULTS: In group 1, the HR significantly increased above the baseline during the entire 5 minutes after desflurane inhalation and the mean blood pressure (MBP) significantly increased above the baseline at 1, 2, and 3 minutes after desflurane inhalation. However, in groups 2 and 3, the increases in HR and MBP induced by desflurane inhalation were significantly suppressed. The HR and MBP in group 2 remained closer to the baseline than in group 3. CONCLUSIONS: A loading infusion of dexmedetomidine for 10 minutes before induction of general anesthesia effectively attenuates the transient cardiovascular stimulation induced by desflurane inhalation, without significant hemodynamic side effects. The HR and MBP remained closer to the baseline after administration of 0.5 µg/kg dexmedetomidine than after administration of a dose of 1.0 µg/kg.