DEXMEDETOMIDINE, AN ALPHA-2-ADRENOCEPTOR AGONIST, REDUCES ANESTHETIC REQUIREMENTS FOR PATIENTS UNDERGOING MINOR GYNECOLOGIC SURGERY

The effects of dexmedetomidine, an α2-adrenoceptor agonist, on vigilance, thiopental anesthetic requirements, and the hemodynamic, catecholamine, and hormonal responses to surgery were investigated in healthy (ASA physical status 1) women scheduled for dilatation and curettage (D and C) of the uterus. Fifteen minutes before induction they received single iv doses of either dexmedetomidine (0.5 μg/kg; n = 19) or saline (n = 20) in a double-blind fashion. Anesthesia was induced with thiopental and maintained with N2O/O2 (70/30%) and thiopental. Dexmedetomidine was well tolerated and no serious drug-related subjective side-effects or adverse events were observed. The most prominent subjective effects were fatigue and decreased salivation. The total amount of thiopental needed to perform D and C of the uterus was reduced approximately 30% (from 456 ± 141 mg [mean ± SD] after saline to 316 ± 79 mg after dexmedetomidine). This was mostly due to a smaller induction dose in the group receiving dexmedetomidine. Dexmedetomidine appeared to improve the recovery from anesthesia as measured by visual analogue scales (VAS) on fatigue and nausea. The plasma concentration of norepinephrine was decreased by 56% after dexmedetomidine implying decreased sympathetic nervous activity. Systolic and diastolic blood pressure were moderately reduced after dexmedetomidine administration. The authors conclude that dexmedetomidine preanesthetic medication decreases thiopental anesthetic requirements and improves the recuperation from anesthesia with no serious hemodynamic or other effects. Further studies in patients undergoing more stressful surgery are indicated.