CARDIOPULMONARY EXERCISE TESTING FOLLOWING HAY EXPOSURE CHALLENGE IN FARMERS LUNG

In patients experiencing an acute episode of hypersensitivity pneumoni tis (HP), the alveoli and interstitium show a marked inflammation, The effects of this infiltration with effector cells on gas exchange and the cardiopulmonary system are not well characterized, and there are n o data regarding cardiopulmonary exercise testing during hypersensitiv ity pneumonitis, The aim of this study was to gain new insights into t he pathophysiology of acute farmer's lung using cardiopulmonary exerci se testing, Cardiopulmonary exercise testing was performed in patients who had farmer's lung (n=21) before and 4 h after a standardized expo sure with mouldy hay, Farmers who were asymptomatic for this condition (n=15) served as controls. At baseline, patients who had farmer's lun g had a decreased breathing reserve and a greater alveolar to arterial oxygen difference, Following exposure, all of these patients develope d hypersensitivity pneumonitis, Compared to the asymptomatic farmers, they showed an increase of alveolar to arterial oxygen difference and functional dead space ventilation during exercise and a reduction of t he breathing reserve, In addition, 40% of the asymptomatic farmers dem onstrated a pathological increase of the alveolar to arterial oxygen d ifference during exercise following exposure. In conclusion, our data signify that acute hypersensitivity pneumonitis induces significant ch anges in pulmonary gas exchange during exercise, Cardiopulmonary exerc ise testing may help to identify individuals with possible subclinical farmer's lung disease.