Influence of breathing pattern and lung inflation on impulse oscillometry measurements in horses.

The research article is about investigating if changes in breathing patterns and lung inflation can influence respiratory function measurements done by an impulse oscillometry system (IOS) in horses.

Objective of the Study

• The paper aimed to understand if variations in ventilation patterns could impact respiratory function measurements carried out by using the impulse oscillometry system (IOS) in horses.

Methodology

• The research was divided into two parts: an in vitro study conducted on six isolated equine lungs, and an in vivo study executed on five healthy mature horses. Lung inflation levels were manipulated by modifying depressurisation inside an artificial thorax and different ventilation patterns were imposed.
• In the in vivo study, temporary changes in the breathing pattern were measured both with IOS and a Current Reference Technique (CRT) in five healthy adult horses after they were given an intravenous injection of a drug called lobeline hydrochloride.

Key Findings

• The studies indicated that the respiratory rate (RR) and tidal volume (V(T)) had little or no impact on IOS parameters. The influence of lung inflation was most marked for resistance at 5 Hz (R(5 Hz)), but was limited for the considered physiological range.
• In the in vivo study, statistical models showed that the maximum changes in pleural pressure (Max Delta Ppl) and peak flows were the main determinants of the variability of the resistance (R(rs)) and the reactance (X(rs)) of the respiratory system.
• The significant increase of Max Delta Ppl and peak flows during hyperpnoea led to a marked increase in R(rs) at 5 and 10 Hz and a decrease in X(rs) at all frequencies.

Conclusion

• The researchers concluded that while the IOS parameters are not affected by tachypnoea (rapid breathing), they do reflect changes in the respiratory mechanics caused by hyperpnoeic breathing (deep or heavy breathing).