Relationship between pulmonary function tests and exercise performance in patients with alveolar proteinosis

BACKGROUND : Pulmonary alveolar proteinosis (PAP) is a rare lung disease affecting the interstitium with an abnormal accumulation of surfactant within the alveoli that may affect gas exchange and can lead to dispneea and exercise limitation. AIM: The aim of this study was to analyse the relation bewteen exercise capacity and pulmonary lung function in a series of patients diagnosed with alveolar proteinosis. SUBJECTS AND METHOD : retrospective analysis of 7 consecutives cases of PAP diagnosed in our clinic. All patients performed, at the time of diagnostic, body pletismography: Total Lung Capacity (TLC), carbon monoxide diffusion capacity (DLCO), 6 minutes walking test (6MWT). RESULTS: 7 patients: 3 females / 4 males. The mean age was 45.5±15 years (range 22-73 years). All patients presented as major symptom dyspneea, with a mean 2.8±0.4 on mMRC scale. The functional pattern was restrictive, with decreased TLC < 70% predicted in 5 cases, with a mean value of 69.3±13% of predicted. DLCO was < 70 % predicted in 6 cases, with a mean value 46.5±16% of predicted. Mean 6MWT distance was 537.5±59 m (84 ±11% of predicted). Significant desaturation (>4%) was found in 5/7 cases. Mean oxyhemoglobin saturation (SaO2) at rest was 92.8±1%. CONCLUSION: In our series of patients with alveolar proteinosis, despite an impairment of lung function, the exercice tolerance assesed by 6MWT is still preserved.