Abnormal exhaled ethane concentrations in scleroderma

Abstract

Scleroderma (systemic sclerosis) is a chronic multisystem autoimmune disease in which oxidative stress is suspected to play a role in the pathophysiology. Therefore, it was postulated that patients with scleroderma would have abnormally high breath ethane concentrations, which is a volatile product of free-radical-mediated lipid peroxidation, compared with a group of controls. There was a significant difference (p<0.05) between the mean exhaled ethane concentration of 5.27 pmol ml^–1 CO₂ (SEM=0.76) in the scleroderma patients (n=36) versus the mean exhaled concentration of 2.72 pmol ml⁻¹ CO₂ (SEM=0.71) in a group of healthy controls (n=21). Within the scleroderma group, those subjects taking a calcium channel blocker had lower ethane concentrations compared with patients who were not taking these drugs (p=0.05). There was a significant inverse association between lung diffusion capacity for carbon monoxide (per cent of predicted) and ethane concentration (b=−2.8, p=0.026, CI=−5.2 to −0.35). These data support the presence of increased oxidative stress among patients with scleroderma that is detected by measuring breath ethane concentrations.

Keywords: :

• Breath analysis
• ethane
• ethanol
• oxidative stress
• systemic sclerosis
• scleroderma

Acknowledgements

The authors thank Maria Fiesta and Adrianne Woods for help in gathering data from the scleroderma database for the study. They acknowledge the support of a US Air Force Office of Scientific Research Grant F49620-98-1-0403, a National Institute of Environmental Health Sciences Training Grant T32 ES-07141, The Advisory Board of The Johns Hopkins Scleroderma Center, and the Scleroderma Research Foundation.