Intramuscularly Administered Dexmedetomidine Attenuates Hemodynamic and Stress Hormone Responses to Gynecologic Laparoscopy

The hemodynamic and endocrine effects of three different doses of dexmedetomidine (0.6, 1.2, and 2.4 micrograms/kg), oxycodone (0.13 mg/kg), and saline solution, injected intramuscularly 45-60 min before induction of general anesthesia, were compared in a double-blind, randomized study involving 100 women undergoing gynecologic diagnostic laparoscopy. Anesthesia was induced with thiopental (4.5 mg/kg) and maintained with 0.3% end-tidal isoflurane and 70% nitrous oxide in oxygen. Arterial blood pressure and heart rate increased after endotracheal intubation and during laparoscopy in all groups, but the maximal mean arterial pressure after tracheal intubation was lower in the dexmedetomidine 2.4-micrograms/kg group (104 mm Hg [SD 19]) than in the saline solution group (130 mm Hg [SD 12]). Dexmedetomidine (2.4 and 1.2 micrograms/kg) attenuated the maximal heart rate after intubation (84 [SD 11] and 101 beats/min [SD 15], respectively) compared with saline solution (116 beats/min [SD 19]). On the other hand, 40% of the patients in the dexmedetomidine 2.4-micrograms/kg group received atropine in the postanesthesia care unit for bradycardia (heart rate < or = 40 beats/min). Preoperative anxiety and sedation before and after preanesthetic medication were evaluated by the patients with the aid of a profile of mood-state questionnaire; only dexmedetomidine 2.4 micrograms/kg produced significant anxiolysis and sedation. Plasma concentrations of norepinephrine, epinephrine, 3,4-dihydroxyphenylglycol, cortisol, and beta-endorphin increased less in the dexmedetomidine 2.4-micrograms/kg group in response to tracheal intubation and surgery than in the saline solution group.