Influence of exercise on the pulmonary function in systemic sclerosis

Objective : Pulmonary complications are the leading cause of mortality in patients with systemic sclerosis (SSc). Pulmonary arterial hypertension (PAH) and interstitial lung disease (ILD) are the most important complications. However, patients are often diagnosed at a late stage of the disease. The important goal is to find a tool for early diagnosis of these complications. The purpose of this study was to investigate the influence of exercise on changes in pulmonary parameters.

Methods : The study was conducted in a group of 32 patients with SSc: 72% of patients had limited systemic sclerosis (lSSc) and 28% had diffuse systemic sclerosis (dSSc). Before and after exercise, lung diffusing capacity for carbon monoxide (DLCO), forced vital capacity (FVC), forced expiratory 1 second volume (FEV1) and the total lung capacity (TLC) were measured.

Results : After exercise, DLCO increased from 59.7% of predicted value to 68.1% of predicted value (p < 0.005). FVC, FEV1 and TLC did not change significantly after exercise.

Conclusions : In TU patients, lung diffusing capacity for carbon monoxide increased from rest to peak exercise. It was associated with increased capillary blood flow during exercise and it is critical for maintaining a normal arterial oxygen saturation. Clinical interpretation of DLCO should take into account not only haemoglobin concentration and alveolar lung volume, but also influence of exercise on the cardiac output.