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

Objective 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 exercised induced laryngeal obstruction (EILO). 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 if CPET with CLE influences peak oxygen uptake (VO₂peak) 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 2–3 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 VO₂peak, respiratory exchange ratio (RER), minute ventilation (VE) 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/minute, respectively. Agreement (95% limits of agreement) for VO₂peak, RER and VE 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 (95% CI 16 to 82) meters longer during CPET.

Conclusions Parameters of gas exchange including VO₂peak 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.