Utility of Breath-holding Test in Systemic Sclerosis

Systemic sclerosis (SSc) is a chronic autoimmune disease of unknown etiology with high morbidity and mortality. SSc manifests by fibrosis of skin and internal organs. Although the underlying mechanisms are still subject to investigation, endothelial dysfunction and abnormal immune response are thought to contribute to vascular dysfunction and fibrosis in SSc.

Pulmonary involvement, such as pulmonary arterial hypertension (PAH) and interstitial lung disease (ILD) is a major cause of death in SSc. Although the 6MWT is generally used for evaluating PAH and ILD, the utility in SSc is undetermined. Several investigators have found weak or moderate correlations of 6MWT in pulmonary involvement in SSc. The 6MWT is influenced by the status of all organ systems involved in exercise (pulmonary, cardiac, peripheral vascular, neuromuscular unit and muscle metabolism) as well as by specifics of test conditions. There is a pressing need for new, practical method which corroborates the current 6MWT for the evaluation of pulmonary disease severity in SSc.

Breath-holding test (BHT) is one of the most useful methods for assessing the sensitivity of peripheral chemoreflex. Recent studies have demonstrated that BHT was correlated to pulmonary function test. BHT can be safely conducted and doctors handle a medical emergency during test easily as well. Therefore, this study evaluates the utility of BHT as surrogate marker of pulmonary involvement in patients with SSc.

Inclusion criteria

• A diagnosis of systemic sclerosis according to 2013 ACR/EULAR criteria
• Must understand and voluntarily sign an informed consent form including writing consent for data protection

Exclusion criteria

• The resting oxygen saturation by pulse oximetry < 90% in room air
• Unstable angina or myocardial infarction during the previous month
• Patients considered unable to the breath-holding test or 6 minute walk test