The effect of an intermediate dose of labetalol on heart rate and blood pressure responses to laryngoscopy and intubation

Abstract

Study Objective: To evaluate the efficacy of an intermediate dose of labetalol (0.4 mg/kg) for attenuation of heart rate (HR) and blood pressure (BP) responses to laryngoscopy and intubation. Design: Randomized, double-blind, placebo-controlled study. Setting: Inpatient gynecology service at a university medical center. Patients: Two groups of 18 patients each undergoing elective surgery under general anesthesia. Interventions: Patients received either 0.4 mglkg of labetalol or an equal volume of normal saline 5 minutes prior to laryngoscopy and intubation. Measurements and Main Results: HR and BP were measured upon arrival in the operating room (OR) (baseline) and at 1 minute intervals thereafter for 4 minutes prior to intubation and through 10 minutes following intubation. The labetalol group had a significantly lower HR from induction through 1 minute following intubation. Intragroup differences in HR were greatest immediately following laryngoscopy and intubation (33% increase above baseline for the placebo group vs 1% for the labetalol group, p < 0.05). At the same time, a significant increase in mean arterial pressure (MAP) from baseline was noted in both groups (29% for the placebo group vs 23% for the labetalol group), but the difference between the groups was not significant. Conclusions: An intermediate dose of labetalol blunted the HR response to laryngoscopy and intubation during rapid-sequence induction in healthy patients but had a minimal effect on BP.