Use of the impulse oscillometry system for testing pulmonary function during methacholine bronchoprovocation in...

Area of Science:

• Equine respiratory physiology
• Pulmonary function testing
• Veterinary diagnostics

Background:

• Conventional reference techniques (CRT) for pulmonary function testing in horses can be invasive.
• Impulse oscillometry system (IOS) offers a potentially less invasive alternative.
• Evaluating the sensitivity of IOS compared to CRT is crucial for accurate diagnosis.

Purpose of the Study:

• To compare the sensitivity of impulse oscillometry system (IOS) with the conventional reference technique (CRT) for pulmonary function testing in horses.
• To assess the utility of IOS in detecting changes in horses with recurrent airway obstruction.

Main Methods:

• Ten horses (4 healthy, 6 with recurrent airway obstruction) underwent a methacholine bronchoprovocation test.
• Pulmonary function was assessed using IOS (measuring respiratory system resistance and reactance) and CRT (measuring total pulmonary resistance and dynamic lung compliance).
• Sensitivity was determined by threshold concentration (TC(2SD)) and sensitivity index (SI) at various frequencies.

Main Results:

• IOS parameters, specifically respiratory system reactance at 5 Hz (X(5Hz)) and resistance at 5 Hz (R(5Hz)), were significantly more sensitive than CRT parameters.
• Bronchoconstriction increased R(rs) and decreased X(rs) in all horses.
• Threshold concentrations for X(rs) were lower in horses with recurrent airway obstruction, indicating greater sensitivity.

Conclusions:

• IOS parameters demonstrate significantly higher sensitivity for pulmonary function testing in horses compared to CRT.
• IOS is a practical, noninvasive tool for assessing pulmonary function.
• IOS may be valuable for identifying subclinical respiratory changes in horses.