The effects of two endotracheal tube cuff inflation pressures on liquid aspiration and tracheal wall damage in horses.

This research investigates the impacts of different inflation pressures in endotracheal tube cuffs on horses, particularly focusing on the potential for liquid aspiration and damage to the tracheal wall. The study found that both higher and lower pressure cuffs were efficient in preventing leakage, but higher pressure cuffs were associated with increased tracheal wall damage.

Methodology

• The study was a prospective, randomized experimental study involving ten healthy horses, with each weighing between 480 and 590 kg.
• Each horse was anesthetized, intubated through the mouth into the trachea, laid on its back, and maintained on isoflurane (an anesthetic) in oxygen with controlled ventilation for about 160 to 190 minutes.
• Randomly, the horses were assigned an endotracheal cuff pressure of 80-100 cm H2O or 120 cm H2O. The pressure in the cuff was continuously monitored and kept constant.
• At the site above the cuff, a solution of methylene blue in saline was instilled. This dye aids in visual detection of leaks or seepages.
• Following euthanasia, the horse’s trachea was opened below the tube’s tip to inspect for any dye that may have leaked past the cuff. The cervical trachea was then removed and opened lengthwise for both gross and microscopic examination.

Results

• No blue staining was found below the cuff in any of the horses, indicating that no leakage had occurred in any of the subjects.
• The visual inspection showed reddened and bloody lesions where the cuff had contacted the tracheal mucosa.
• The histologic examinations noted changes including thinning or abrasion of the epithelium, infiltration of neutrophils into the submucosa, and submucosal hemorrhages.
• These lesions were absent or less prominent in the group with the lower cuff inflation pressure compared to the group with the high cuff pressure.

Conclusions

• Both high and low endotracheal tube cuff pressures proved efficient in preventing leakage.
• However, the group with the higher cuff pressure suffered more severe and frequent tracheal wall damage.
• The damage to the tracheal mucosa from cuff inflation was found to be pressure-dependent.
• Based on these results, the study suggests that careful monitoring of cuff pressure during intubation procedures is recommended to minimize potential tracheal wall damage.