Breathless challenges – understanding airflow limitation in exercise intolerance

Cardiopulmonary exercise testing (CPET) is crucial for evaluating ventilatory limitation during exercise in patients with exertional dyspnoea and detecting expiratory flow limitation (EFL), even in patients without obstructive lung diseases. This study aims to comprehend the mechanisms and severity of exertional dyspnoea by identifying EFL in patients with normal lung function at rest by performing CPET and using Impulse Oscillometer (IOS) to localize the airway obstruction. A prospective study was conducted in a Pulmonology outpatient clinic with adults with dyspnoea not explained by lung function. CPET was performed on a cycle ergometer according to American Thoracic Society guidelines, with determination of flow-volume loop. IOS manoeuvres were performed at rest and post-exercise. Descriptive analysis was conducted on demographic data, exercise test results, and IOS findings. Eleven patients were included (8 females), with a mean age of 53.4±12.4 years, 54.5% were non-smokers, the mean BMI was 27±4.4 kg/m². The modified Borg dyspnoea scale (mBDS) at peak exercise was on average 5.5±2.2. Four patients (36.4%) exhibited EFL: in these, 3 were females, 50% non-smokers, 2 overweight or obese, and the mean mBDS was 7.3±2.1. Three patients with EFL exhibited an increase in R5 and R20, and 2 patients showed an increase in X5 after exercise. Patients without EFL showed a negative variation in R20 and X5, whereas only 2 of them showed an increase in R5 after exercise. <bold>Conclusions:</bold> The prevalence of EFL was high, having more severe dyspnoea and IOS indicating a post-exercise positive variation in R5 and R20 in most patients. Limited sample size warrants further research for validation and deeper understanding.