Laryngeal mask versus endotracheal tube in a ferret model

Abstract

Acquired subglottic stenosis in infants is a difficult iatrogenic problem with notable morbidity, primarily caused by prolonged endotracheal intubation. The laryngeal mask airway (LMA) is a recently developed, alternative airway device that does not contact the subglottis. To explore the possibility of preventing subglottic stenosis, we compared the endotracheal tube (ETT) and the LMA in terms of the incidence and severity of glottic and subglottic injury resulting from prolonged intubation in the adult ferret model of the infant airway. Ten adult ferrets were randomly intubated under inhalational anesthesia with either a 4.0 cuffless ETT or a size 1 LMA for a 24- to 48-hour period. Rigid laryngeal endoscopy was used to detect pharyngeal or glottic injury during the period of intubation and on a routine basis for 3 months after extubation. All 5 ferrets in the ETT group developed endoscopically evident glottic and subglottic injury; 2 of the 5 developed a symptomatic, mature subglottic stenosis. The 5 ferrets in the LMA group had endoscopically normal larynges. However, all ferrets in the LMA group developed significant tongue edema and cyanosis during the first 24 hours of intubation, and 3 of the 5 died of respiratory failure due to airway obstruction. In the 2 LMA survivors, evidence of oropharyngeal injury persisted until 6 weeks after extubation. We conclude that the LMA does not cause subglottic injury in this model. However, its prolonged use results in significant pharyngeal morbidity that raises serious doubt as to its potential routine use in infants requiring prolonged ventilatory support.