ABSTRACT
We examined the response to the laryngeal mask (LM) compared to the endotracheal tube (ETT) in patients undergoing ambulatory anesthesia. The differences in management by the anesthesiologists for these two airways were also examined. Peripheral orthopedic procedures were studied in 44 outpatients randomized to receive a LM or ETT, and either spontaneous or controlled ventilation. Anesthesia was induced with propofol and succinylcholine intravenously (i.v.) and maintained with N2O and isoflurane. Anesthesiologists were allowed to determine ventilatory variables and anesthetic concentration. Hemodynamic and ventilatory measurements were made during the anesthesia. Barium sulfate was poured into the oropharynx after the airway was secure. Fiberoptic examination through the LM was performed at the beginning and at the end of the administration of each anesthetic. Radiographs were taken at the end of the anesthetic administration before LM or ETT removal to look for barium in the trachea. After airway removal, presence of blood on the airway, sore throat, coughing, nausea, vomiting, shivering, and amount of morphine demanded during recovery were noted. No barium in the trachea or bronchial tree was seen in any of the radiographs. The ETT was associated with greater hemodynamic response not only to airway placement (P < 0.05), but also to surgical incision (P < 0.05) and airway removal (P < 0.05). Spontaneous or controlled ventilation favored neither airway, although the ETT was associated with increased work of inspiration with controlled ventilation (P < 0.05). Anesthesiologists tended to elect smaller tidal volumes, faster ventilation rates, and lower anesthetic concentrations for patients with the LM (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
