PURPOSE: To study morphological findings in the tracheal epithelium of dogs exposed to the inhalation of poorly conditioned gases under use of an endotracheal tube (ET) or laryngeal mask airway (LMA). METHODS: Twelve dogs randomly were allocated to two groups: ET group (n-6) and LMA group (n-6), anaesthetized and mechanically ventilated, without CO2 reabsorption. Haemodynamic and ventilatory parameters, tympanic temperature, temperature, relative and absolute humidity of the ambient and inhaled gases were analyzed during three hours. The animals were submitted to euthanasia and biopsies were carried out along the tracheal segment to morphological study. Three healthy dogs were used to morphological control. RESULTS: Inhaled gas temperature was maintained between 24ºC and 26ºC, relative humidity between 10% and 12%, and absolute humidity between 2 - 3 mg H2O.L-1 with no significant differences between groups. In both groups, histological analysis showed epithelial inflammation and congestion in the corion and scanning electron microscopy showed ciliary grouping and disorganization. Transmission electron microscopy showed higher alterations in ET group than LMA group as widening of cell junctions, ciliary disorientation, cytoplasmic vacuolization, nuclear abnormalities, picnosis and chromatin condensation. CONCLUSION: LMA determined less pronounced changes in the tracheal epithelium in dogs exposed to the inhalation of poorly conditioned gases.
Larynx; Trachea; Laryngeal Masks; Intubation; Intratracheal; Morphology; Dogs
