The effects on mucus transport of different grades of tracheal injury produced experimentally by an intubation tube were studied in 26 pigs. Two of them were not intubated and served as controls, while the rest were anaesthetized and either intubated or tracheostomized, or both, and ventilated for approximately 4.5 h. They were then killed and the trachea and larynx were immediately removed and placed in a specially designed chamber at 37 degrees C and 85% relative humidity. Cardio-green dye was deposited caudally in the trachea as a mucus marker. The mucus transport was observed macroscopically and the ultrastructure of the tracheal wall at the region of mucus arrest was studied by light microscopy and scanning and transmission electron microscopy. In non-intubated pigs the mucus was transported to the posterior larynx. The ciliated epithelium was usually intact along the pathway where cardio-green-stained mucus had travelled. In pigs which had been intubated and/or tracheostomized, mucus transport stopped completely at different levels of the trachea. The damage to the ciliated epithelium varied; in some animals there was almost none at all and in others there was a patchy loss of a large proportion of the cilia, or complete lack of cilia. Lesions which also included epithelial cells were often seen. Tracheal injury due either to a cuffed endotracheal tube or to a tracheostomy tube, with destruction of epithelium and cilia, causes a barrier to mucus transport, leading to arrest and accumulation of mucus further down in the airway. We were unable, however, to demonstrate a direct correlation between grade of damage and tendency to mucus arrest.
Computerized and graphic three-dimensional reconstruction of a human endolymphatic duct and sac (ES) showed the ES to be a fusiform and flattened structure with marked tubularity, especially in the extraosseous region. The specimen was 18.2 mm long. It measured 60 X 200 microns at the isthmus portion of the endolymphatic duct and 200 X 7000 microns at the broadest part of the ES. The volume of the endolymphatic duct was 0.03 mm3 and of the ES, 1.85 mm3. The extraosseous ES volume represented more than two thirds of the total ES volume.
\s=b\ Twenty-nine specimens of the extraosseous portion of the human endolymphatic sac (ES) were serially sectioned longitudinally. The length and width of the extraosseous ES were measured and the surface area was calculated. As the specimens included the sigmoid sinus (SS), the relationship between the ES and the SS was analyzed. The extraosseous ES varied considerably in size. The lumen either consisted of a single tube or was subdivided into several tubules. The distal part of the ES overlapped the SS in one third of the specimens. The results indicate that a minute extraosseous ES could explain the sometimes difficult task of localizing this structure at ES surgery. The great variability in size might perhaps also explain the varying results of this surgery.(Arch Otolaryngol Head Neck Surg
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