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

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'_O peak) and other gas exchange parameters when compared to a regular CPET.

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.

At peak exercise, the mean difference (95% confidence interval) between CPET with and without extra CLE set-up for V'_O 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'_O 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.

Parameters of gas exchange, including V'_O 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.