Mechanical properties of the isolated equine trachea.

The research paper presents a study on the mechanical properties of the trachea in horses. It investigates how the trachea reacts to different pressure levels, typically experienced by the animal, using post-mortem samples from healthy horses.

Research Methodology

• The researchers studied the in vitro mechanical properties of the equine trachea.
• They achieved this by determining the pressure-volume relationship in tracheal segments taken from the thoracic and extra-thoracic regions, post-mortem from 29 horses aged between one to 15 years old and weighing 352 to 651 kg.

Data Collection and Measurement

• Alongside the pressure-volume measurements, the researchers also measured the cross-sectional lumen area (X-SA) at the mid-point of the segment. This was done using a slit-lamp transillumination technique and a photographic measurement by endoscopy.
• The tracheal specific compliance (Cs), as well as the relative changes in X-SA and in the sagittal and transverse diameters, were calculated for intraluminal pressures ranging from 5 to – 5 kPa.

Research Findings

• The research found that the extrathoracic tracheal Cs was 0.060 +/- 0.002 kPa-1, and at an intraluminal pressure of – 5 kPa, X-SA was reduced to about 73 per cent of its resting value.
• Compared to the extrathoracic tracheal segments, the intrathoracic segments were more compliant, and their X-SA was more reduced at similar compressive pressure.
• This data indicates that the trachea of the horse possesses high compliance.

Implications of the Research

• The results of the study suggest that an increase in pulmonary resistance observed during strenuous exercise in horses may be partly due to a partial collapse of the trachea.
• This finding could have implications for the care and treatment of equine respiratory disorders, and for understanding the biological limitations on the performance of racehorses and other working horses.