Effects of Nicardipine on Changes of Blood Pressure and Heart Rate during Laryngeal Microscopic Surgery

Background: Laryngoscopy, tracheal intubation and the suspension laryngoscopy often provoke an undesirable increase in blood pressure and/or heart rate during laryngeal microscopic surgery. Thus, the anesthesiologist's objectives are to maintain sufficient anesthetic depth and to promote rapid awakening. Nicardipine, a direct arterial dilator, can be used to attenuate increasing blood pressure. We investigated the effects of nicardipine on changes of blood pressure and heart rate during laryngeal microscopic surgery. Methods: Eighty patients of ASA class 1 or 2 scheduled for laryngeal microscopic surgery were randomly allocated into 4 groups. For anesthetic induction, IV propofol 1.5 mg/kg, rocuronium 0.4 mg/kg, and glycopyrrolate 0.2 mg were administered followed by mask ventilation for 5 minutes with isoflurane. One minute before tracheal intubation and suspension laryngoscopy saline, nicardipine 10, 20, or 30/kg was injected in each group. Thereafter we measured blood pressure and heart rate one minute after each procedure. Results: Increases in blood pressure were blunted in the nicardipine 20 and 30/kg group. In the nicardipine 30/kg group, heart rates were significantly increased and facial flushing was observed in two patients. Conclusions: We suggest that nicardipine 20/kg can alleviate blood pressure increases with little effect on heart rate during laryngeal microscopic surgery. However, although nicardipine 30/kg could blunt blood pressure increases, it produces tachycardia and perhaps overdose.