Evaluation of Masks for Field Testing of Exercising Horses

Abstract

IntroductionThe ability to accurately assess equine oxygen consumption (VO2) under field conditions has been limited by the need for unrestricted gas exchange.MethodsTwo variations of a mask and an associated electronics control module (ECM) were designed to enable breath‐by‐breath measurement of airflows with two 8.0 cm diameter pneumotachometers located 7.5 cm in front of each narus and connected to differential pressure transducers mounted on the outside of the mask. The ECM was comprised of electronics for signal filtering to the flow transducers, an oxygen sensing cell, and an analog‐to‐digital converter all powered by a lithium‐ion battery. The battery also powered a pump connected to gas sampling ports between the nares and pneumotachometers. Airflow and oxygen content of inspired and expired gases were recorded through the ECM and electronically transferred to a notebook. VO2 was determined from these recordings by an operator using a customized software analysis program. One mask encased the lower head (E). The other left the jaw free so horse could wear a bit and be ridden (R). Multiple treadmill exercise tests were undertaken by 6 horses to measure VO2max and blood gases. Each mask was worn twice and results compared to those from an open flow‐through system (O) by 2‐way RMANOVA (P<0.05). Utility of the system was evaluated using the intraclass correlation coefficient of 4 independent raters.ResultsBlood gases and VO2max (152.0 ± 4.0 (mean ± SEM; O), 147.7 ± 4.3 (E), 150.7 ± 3.3 (R) ml/(kg.min) were not different between masks. VO2 measures were reproducible for each mask. Agreement between the 4 raters was excellent (intraclass correlation coefficient = 0.99).ConclusionsMasks capable of measuring VO2 during field exercise were developed, tested and found accurate by multiple users.Ethical Animal ResearchStudies performed were approved by the Institution's Animal Care and Use Committee (protocol #3807). Sources of funding: Institutional sources. Competing interests: Washington State University has filed notice of its intent to apply for a patent for facemask used in this study.