Discrimination between COPD patients with and without alpha 1-antitrypsin deficiency using an electronic nose

To compare the volatile organic compound patterns of patients with COPD with and without alpha 1-antitrypsin (AAT) deficiency using electronic nose technology.

Exhaled breath condensate and pure exhaled breath of patients with COPD with (n=10) and without (n=23) AAT deficiency and healthy controls (n=10) were analysed. The effect of human recombinant AAT on the volatile organic compound profile of 11 AAT-deficient patients was also examined. Exhaled breath condensate and pure exhaled breath were measured using the Cyranose 320. Smell prints were analysed by linear discriminant analysis (LDA) using Mahalanobis distance (MD) and cross-validation values (CVVs).

Smell prints of patients with AAT-deficiency were different from those with COPD in exhaled breath condensate (LDA: P<0.0001, sensitivity of 1.00, specificity of 1.00, CVV 82.0%, MD 2.37) and in pure exhaled breath (LDA: P<0.0001, sensitivity of 1.00, specificity of 1.00, CVV 58.3%, MD 2.27). Smell prints of AAT-deficient patients before and after human recombinant AAT augmentation were different (LDA: P=0.001, sensitivity of 1.00, specificity of 1.00, CVV 53.3%, MD 1.79).

An electronic nose can detect differences in smell prints of COPD patients with and without AAT deficiency. Augmentation therapy changes the volatile organic compound pattern. The electronic nose may be helpful in the diagnosis of AAT deficiency.