Reliability of maximum oxygen uptake in cardiopulmonary exercise testing with continuous laryngoscopy.

AIMS: A cardiopulmonary exercise test (CPET) is the gold standard to evaluate symptom-limiting exercise intolerance, while continuous laryngoscopy performed during exercise (CLE) is required to diagnose exercise-induced laryngeal obstruction. Combining CPET with CLE would save time and resources; however, the CPET data may be distorted by the extra equipment. We therefore aimed to study whether CPET with CLE influences peak oxygen uptake (V'O2 peak) and other gas exchange parameters when compared to a regular CPET. METHODS: Forty healthy athletes without exercise-related breathing problems, 15-35 years of age, performed CPET to peak exercise with and without an added CLE set-up, in randomised order 2-4 days apart, applying an identical computerised treadmill protocol. RESULTS: At peak exercise, the mean difference (95% confidence interval) between CPET with and without extra CLE set-up for V'O2 peak, respiratory exchange ratio (RER), minute ventilation (V'E) and heart rate (HR) was 0.2 (-0.4 to 0.8) mL·kg-1·min-1, 0.01(-0.007 to 0.027) units, 2.6 (-1.3 to 6.5) L·min-1 and 1.4 (-0.8 to 3.5) beats·min-1, respectively. Agreement (95% limits of agreement) for V'O2 peak, RER and V'E was 0.2 (±3.7) mL·kg-1·min-1, 0.01 (±0.10) units and 2.6 (±24.0) L·min-1, respectively. No systematic or proportional bias was found except for the completed distance, which was 49 m (95% CI 16 to 82 m) longer during CPET. CONCLUSION: Parameters of gas exchange, including V'O2 peak and RER, obtained from a maximal CPET performed with the extra CLE set-up can be used interchangeably with data obtained from standard CPET, thus preventing unnecessary additional testing.

Exercise Induced Laryngeal Obstruction in Humans and Equines. A Comparative Review.

Dynamic obstructions of the larynx are a set of disorders that occur during exercise in equines and humans. There are a number of similarities in presentation, diagnosis, pathophysiology and treatment. Both equines and humans present with exercise intolerance secondary to dyspnea. During laryngoscopy at rest, the larynx appears to function normally. Abnormalities are only revealed during laryngoscopy at exercise, seemingly triggered by increased ventilatory demands, and quickly resolve after cessation of exercise. Lower airway disease (asthma being the most prevalent condition), cardiac disease and lack of fitness are the major differentials in both species. Laryngoscopic examination during exercise should be performed from rest to peak exertion to allow for a comprehensive diagnosis, including where the airway collapse begins, and thereafter how it progresses. Dynamic disorders with most visual similarity between humans and equines are: aryepiglottic fold collapse (both species); equine dynamic laryngeal collapse (DLC) relative to some forms of human combined supraglottic/glottic collapse; and epiglottic retroversion (both species). Quantitative grading techniques, such as airway pressure measurement, that have proven effective in veterinary research are currently being piloted in human studies. Conditions that appear visually similar are treated in comparable ways. The similarities of anatomy and certain types of dynamic collapse would suggest that the equine larynx provides a good model for human upper respiratory tract obstruction during exercise. Thus, close collaboration between veterinarians and medical personal may lead to further advancements in understanding pathophysiologic processes, and enhance the development of improved diagnostic tests and treatments that will benefit both species.