Using the Electronic Nose to Identify Airway Infection during COPD Exacerbations.
BACKGROUND
The electronic nose (e-nose) detects volatile organic compounds (VOCs) in exhaled air. We hypothesized that the exhaled VOCs print is different in stable vs. exacerbated patients with chronic obstructive pulmonary disease (COPD), particularly if the latter is associated with airway bacterial infection, and that the e-nose can distinguish them.


METHODS
Smell-prints of the bacteria most commonly involved in exacerbations of COPD (ECOPD) were identified in vitro. Subsequently, we tested our hypothesis in 93 patients with ECOPD, 19 of them with pneumonia, 50 with stable COPD and 30 healthy controls in a cross-sectional case-controlled study. Secondly, ECOPD patients were re-studied after 2 months if clinically stable. Exhaled air was collected within a Tedlar bag and processed by a Cynarose 320 e-nose. Breath-prints were analyzed by Linear Discriminant Analysis (LDA) with "One Out" technique and Sensor logic Relations (SLR). Sputum samples were collected for culture.


RESULTS
ECOPD with evidence of infection were significantly distinguishable from non-infected ECOPD (p = 0.018), with better accuracy when ECOPD was associated to pneumonia. The same patients with ECOPD were significantly distinguishable from stable COPD during follow-up (p = 0.018), unless the patient was colonized. Additionally, breath-prints from COPD patients were significantly distinguished from healthy controls. Various bacteria species were identified in culture but the e-nose was unable to identify accurately the bacteria smell-print in infected patients.


CONCLUSIONS
E-nose can identify ECOPD, especially if associated with airway bacterial infection or pneumonia.
Department of Respiratory Medicine, Hospital Universitario Son Espases. IdISPa. Palma de Mallorca, Spain; Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt.
Hanaa
H
Shafiek
Department of Respiratory Medicine, Hospital Universitario Son Espases. IdISPa. Palma de Mallorca, Spain.
Federico
F
Fiorentino
Electronic Systems Group, University of the Balearic Islands (GSE-UIB), Palma de Mallorca, Spain.
Jose Luis
JL
Merino
Department of Microbiology, Hospital Universitario Son Espases. IdISPa. Palma de Mallorca, Spain.
Carla
C
López
Department of Microbiology, Hospital Universitario Son Espases. IdISPa. Palma de Mallorca, Spain.
Antonio
A
Oliver
Electronic Systems Group, University of the Balearic Islands (GSE-UIB), Palma de Mallorca, Spain.
Jaume
J
Segura
Electronic Systems Group, University of the Balearic Islands (GSE-UIB), Palma de Mallorca, Spain.
Ivan
I
de Paul
Department of Respiratory Medicine, Hospital de la Santa Creu i Sant Pau, Institut d'Investigació Biomédica Sant Pau (IIB Sant Pau), Barcelona, Spain.
Oriol
O
Sibila
Thorax Institute, Hospital Clinic, IDIBAPS, University of Barcelona, Barcelona, Spain; CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.
Alvar
A
Agustí
Department of Respiratory Medicine, Hospital Universitario Son Espases. IdISPa. Palma de Mallorca, Spain; CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.
Borja G
BG
Cosío
D000368:Aged; D001419:Bacteria / Q000737:chemistry / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000150:complications* / Q000175:diagnosis* / Q000382:microbiology; D001944:Breath Tests / Q000295:instrumentation; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D062609:Electronic Nose; D004867:Equipment Design; D045853:Exhalation; D005260:Female; D006801:Humans; D008168:Lung / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000150:complications / Q000175:diagnosis / Q000382:microbiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications*; D055549:Volatile Organic Compounds / Q000032:analysis*
D055549:Volatile Organic Compounds