Objectives: (1) To develop a practical animal model of endolaryngeal damage secondary to prolonged endotracheal intubation. (2) To demonstrate the contribution of chronic hypoxia to laryngeal injury in the context of this model.
Methods: Four Sus scrofa piglets were anaesthetized and intubated for 24h. Two animals were maintained in a state of constant hypoxia (pO(2)<60 mmHg) while two others were ventilated with 100% oxygen. Prior to sacrifice, fluorescein dye was infused intravenously to highlight areas of hypoperfusion. The larynx and trachea were then harvested for gross and histological examination.
Results: All four specimens demonstrated areas of edema, erythema, and ulceration on gross examination. Areas of significant histological inflammation, ulceration, and necrosis involved tube-mucosa contact, in particular, the arytenoids, the interarytenoid area, and the subglottis.
Conclusions: This animal model represents a practical and novel means for the investigation and treatment of laryngeal injury secondary to prolonged endotracheal intubation. Significant injury to the endolarynx was evident after only 24h of intubation and the injury involved similar areas within the larynx as described in human studies. Although clinical experience suggests that chronic hypoxia is a risk factor for endolaryngeal injury, this model did not provide experimental evidence to support this observation, most likely due to the small study size.