E-nose and Inflammatory Asthma Phenotypes

Patients with persistent asthma have different inflammatory phenotypes. The electronic nose is a new technology capable of distinguishing volatile organic compound breath-prints in exhaled breath among different pulmonary diseases. Question of the study. Is the electronic nose breath-print analysis able to discriminate among different inflammatory asthma phenotypes?

Materials/patients and methods. Fifty-two consecutively enrolled patients with persistent asthma were included in a cross-sectional proof of concept study. Inflammatory asthma phenotypes were recognized by inflammatory cell counts in induced sputum. Breath-prints were analyzed by discriminant analysis on principal component reduction, resulting in cross-validated accuracy values. Receiver Operating Characteristics (ROC) was calculated. Legal and ethical aspects The study was conducted in accordance with the Declaration of Helsinki principles (18th Word Medical Assembly, 1964) and was approved by the Clinical Research Ethics Committee (approval number: IIBSP/10/122/1161) of our institution. The participants provided their written informed consent to participate in this study and personal identification data were anonymized.

Electronic nose can discriminate the inflammatory asthma phenotypes, supporting their potential as a non-invasive alternative tool to induced sputum.

Exhaled gas to assess e-nose VOC profiles was collected as described. Briefly, patients breathed through a mouthpiece into a 2-way nonrebreathing valve (Hans rudolph 2700, Hans rudolph, Kansas City, Mo) with an inspiratory VOC filter and an expiratory silica reservoir to dry the expired air. Expiratory air was collected in a 10-L "Tedlar bag". Within not more than 10 minutes, the bag was connected to the e-nose device (Cyranose 320®; Smith Detections, Pasadena, CA), provided with a 32 organic polymeric nano-composite sensor array, for 5 minutes and changes in the nano-sensor electrical resistance generated a breath-print VOC profile.

The recognition of volatile organic compound profiles in exhaled air by an electronic nose device can discriminate the inflammatory phenotype of patients with persistent asthma.

Inclusion Criteria: Adults with persistent asthma, defined as per the Global INitiative for Asthma Management (GINA) criteria, and specifically with positive bronchodilator test, or a daily peak expiratory flow (PEF) variability greater than 20%, or a positive methacholine challenge test documented in case history. Subjects were consecutively enrolled from the outpatient visits of a specialized Asthma Unit located in a tertiary University Hospital. Exclusion Criteria: Subjects were excluded if they had a respiratory tract infection or asthma exacerbation within 30 days prior to inclusion or were receiving oral steroids or immunosuppressive treatments.

Department of Respiratory Medicine, Hospital de la Santa Creu i Sant Pau. Institut d'Investigació Biomédica Sant Pau (IIB Sant Pau). Universitat Autònoma de Barcelona, Department of Medicine. Barcelona Respiratory Network (BRN). Barcelona, Spain.

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