Hemodynamic comparison of direct vision versus blind oral endotracheal intubation

Abstract

Study Objective: To determine the hemodynamic response to airway manipulation and endotracheal intubation by comparing the direct oral method of the Macintosh laryngoscope to the blind oral method of the Augustine guide. Design: Prospective, comparative, randomized study. Setting: University medical center. Patients: 24 ASA physical status I and II, nonpregnant female patients aged 18 years or older, undergoing outpatient gynecologic surgery with general anesthesia. Interventions: Patients were preoxygenated and received alfentanil 10 mcg/kg five minutes prior to anesthesia induction with thiopental sodium 5 mg/kg and succinylcholine 1 mg/kg. Under random assignment, patients (n = 12 in each group) were intubated with the Macintosh laryngoscope or the Augustine guide. After intubation, 50% nitrous oxide and 50% oxygen and 1.5% inspired concentration of isoflurane were administered. Measurements and Main Results: Oxygen saturation, heart rate (HR), and mean arterial pressure (MAP) were measured at baseline and at minutes 1 to 6 postinduction (time zero). Intubation time was defined as the interval between removal of the face mask from the patient's face and reconnection of the circle system airway connector after successful endotracheal intubation. The number of attempts and time to successful endotracheal intubation were noted. There was no difference between groups in age, weight, height, Mallampati airway class, oxygen saturation (at least 98%), or MAP. There was a significant difference ( p < 0.01) between groups (percent change from baseline) in HR from minutes 1 to 4 postinduction. Time to successful endotracheal intubation was significantly longer ( p < 0.05, mean ± SEM) with the Augustine guide (91.0 ± 15.9 seconds) than with the Macintosh laryngoscope (24.0 ± 1.73 seconds). Conclusions: The Augustine guide, a new technique for orally intubating patients blindly and when head and neck manipulations are contraindicated, had less of an effect on HR compared with the Macintosh laryngoscope. Minimal lifting of the tongue and mandible required with the Augustine guide could account for the decreased HR response. The Augustine guide appears to be a promising new addition to the airway armamentarium and deserves further testing.