Measurement of abnormal respiratory sounds during over-ground exercise

REASONS FOR PERFORMING STUDY: The presence of abnormal respiratory sounds is commonly associated with obstructions of the upper respiratory tract. In order to establish their clinical significance measurements are required of both normal and abnormal respiratory sounds produced by horses exercising over-ground. OBJECTIVES: To determine whether high quality recordings of respiratory sound can be made during over-ground exercise, and to develop a convenient measurement system that can be used to obtain respiratory sounds from horses exercising in field conditions. METHODS: A range of prototypes was evaluated against the requirements that the system must be easy to use under field conditions and produce high-quality recordings of respiratory sound. The chosen design incorporated a miniature microphone and an air-flow direction sensor mounted on a lightweight plastic face mask. The mask was attached to the horse's head using nylon straps secured by velcro fastenings. Sound and flow signals were recorded on a portable minidisc player carried by the jockey. RESULTS: The system fulfilled the design criteria. High quality recordings of respiratory sounds were obtained from Thoroughbred horse exercising on a training gallop under a variety of weather conditions. Intermittently occurring abnormal sounds were readily identified from the data. CONCLUSIONS: High quality measurements of respiratory sounds during over-ground exercise can be made relatively easily. POTENTIAL RELEVANCE: The system enables measurement of respiratory sounds outside a laboratory environment creating new opportunities for scientific research and clinical assessment. The study demonstrated that diagnostic systems based on respiratory sound analysis could potentially be manufactured at relatively low cost and be convenient and simple to use.