Heterogeneity of intrapleural pressures during exercise.

This study investigates the variation of intrapleural pressure in different areas of the thorax in exercising horses, specifically if the caudodorsal region experiences more pressure changes and if there are moving pressure waves in the thorax during exercise. The research used pressure-tip transducers in the thorax and oesophagus, with horses exercising on a treadmill and during swimming, and found no significant pressure variation nor consistent pressure waves during either exercise scenario.

Methodology

• The experiment monitored the pressures in different regions of the intrapleural space (the thin, fluid-filled space between the two pulmonary pleurae of each lung) in horses during exercise.
• Measurements were taken using percutaneous introducers and solid-state pressure-tip transducers planted along the dorsal aspect of the thorax, mid-thorax or oesophagus of three horses.
• These measurements were taken while the horses exercised on a treadmill at a speed of 13-14 m/s and during high-intensity swimming exercises where the heart rate reached 170-190 beats per minute.

Input Variables

• The different regions on the thorax where data was sampled include the dorsal, mid-thorax and oesophageal areas.
• The different exercises the horses performed were galloping on a treadmill and swimming. Two drastically different exercises were chosen to represent the variety of physical exertion.

Findings

• According to the study, there were no major systematic pressure variations in the caudodorsal region compared to the other regions during both the swimming and treadmill exercises.
• The research found that, during swimming, the peak expiratory pressures were higher compared to when the horses were galloping (68-79 torr vs. 26-32 torr).
• The horses breathed five times slower when swimming compared to when they were running on the treadmill (28 breaths per minute vs 120 breaths per minute).
• The study found that, while there were instances where individual catheter locations registered locomotor concussion during galloping, these occasions were variable and did not clearly indicate a systematic pressure wave passing through the lungs or intrapleural space.

Conclusion

• The research concluded that there were no significant pressure variations nor consistent pressure waves moving through the lungs or intrapleural space of exercising horses, either when running on a treadmill or during high intensity swimming.
• There is no evidence to suggest that the caudodorsal region of the intrapleural space in exercising horses experiences larger pressure fluctuations than other regions.