Electronic nose analysis of exhaled breath to diagnose ventilator-associated pneumonia.
BACKGROUND
Exhaled breath analysis is an emerging technology in respiratory disease and infection. Electronic nose devices (e-nose) are small and portable with a potential for point of care application. Ventilator-associated pneumonia (VAP) is a common nosocomial infection occurring in the intensive care unit (ICU). The current best diagnostic approach is based on clinical criteria combined with bronchoalveolar lavage (BAL) and subsequent bacterial culture analysis. BAL is invasive, laborious and time consuming. Exhaled breath analysis by e-nose is non-invasive, easy to perform and could reduce diagnostic time. Aim of this study was to explore whether an e-nose can be used as a non-invasive in vivo diagnostic tool for VAP.


METHODS
Seventy-two patients met the clinical diagnostic criteria of VAP and underwent BAL. In thirty-three patients BAL analysis confirmed the diagnosis of VAP [BAL+(VAP+)], in thirty-nine patients the diagnosis was rejected [BAL-]. Before BAL was performed, exhaled breath was sampled from the expiratory limb of the ventilator into sterile Tedlar bags and subsequently analysed by an e-nose with metal oxide sensors (DiagNose, C-it, Zutphen, The Netherlands). From further fifty-three patients without clinical suspicion of VAP or signs of respiratory disease exhaled breath was collected to serve as a control group [control(VAP-]). The e-nose data from exhaled breath were analysed using logistic regression.


RESULTS
The ROC curve comparing [BAL+(VAP+)] and [control(VAP-)] patients had an area under the curve (AUC) of 0.82 (95% CI 0.73-0.9). The sensitivity was 88% with a specificity of 66%. The comparison of [BAL+(VAP+)] and [BAL-] patients revealed an AUC of 0.69; 95% CI 0.57-0.81) with a sensitivity of 76% with a specificity of 56%.


CONCLUSION
E-nose lacked sensitivity and specificity in the diagnosis of VAP in the present study for current clinical application. Further investigation into this field is warranted to explore the diagnostic possibilities of this promising new technique.
['Schnabel|R M|RM|', 'Boumans|M L L|ML|', 'Smolinska|A|A|', 'Stobberingh|E E|EE|', 'Kaufmann|R|R|', 'Roekaerts|P M H J|PM|', 'Bergmans|D C J J|DC|']
D000328:Adult D000368:Aged D000369:Aged, 80 and over D001419:Bacteria D001944:Breath Tests D018893:Bronchoalveolar Lavage D001992:Bronchoalveolar Lavage Fluid D016022:Case-Control Studies D062609:Electronic Nose D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D018410:Pneumonia, Bacterial D053717:Pneumonia, Ventilator-Associated D011446:Prospective Studies D012680:Sensitivity and Specificity D055815:Young Adult
Electronic nose Pneumonia Bronchoalveolar lavage Critical care