Expiratory flow rate, breath hold and anatomic dead space influence electronic nose ability to detect lung cancer

BACKGROUND: Electronic noses are composites of nanosensor arrays. Numerous studies showed their potential to detect lung cancer from breath samples by analysing exhaled volatile compound pattern ("breathprint"). Expiratory flow rate, breath hold and inclusion of anatomic dead space may influence the exhaled levels of some volatile compounds; however it has not been fully addressed how these factors affect electronic nose data. Therefore, the aim of the study was to investigate these effects. METHODS: 37 healthy subjects (44 +/- 14 years) and 27 patients with lung cancer (60 +/- 10 years) participated in the study. After deep inhalation through a volatile organic compound filter, subjects exhaled at two different flow rates (50 ml/sec and 75 ml/sec) into Teflon-coated bags. The effect of breath hold was analysed after 10 seconds of deep inhalation. We also studied the effect of anatomic dead space by excluding this fraction and comparing alveolar air to mixed (alveolar + anatomic dead space) air samples. Exhaled air samples were processed with Cyranose 320 electronic nose. RESULTS: Expiratory flow rate, breath hold and the inclusion of anatomic dead space significantly altered "breathprints" in healthy individuals (p 0.05). These factors also influenced the discrimination ability of the electronic nose to detect lung cancer significantly. CONCLUSIONS: We have shown that expiratory flow, breath hold and dead space influence exhaled volatile compound pattern assessed with electronic nose. These findings suggest critical methodological recommendations to standardise sample collections for electronic nose measurements

Standardised exhaled breath collection for the measurement of exhaled volatile organic compounds by proton transfer reaction mass spectrometry

BACKGROUND: Exhaled breath volatile organic compound (VOC) analysis for airway disease monitoring is promising. However, contrary to nitric oxide the method for exhaled breath collection has not yet been standardized and the effects of expiratory flow and breath-hold have not been sufficiently studied. These manoeuvres may also reveal the origin of exhaled compounds. METHODS: 15 healthy volunteers (34 +/- 7 years) participated in the study. Subjects inhaled through their nose and exhaled immediately at two different flows (5 L/min and 10 L/min) into methylated polyethylene bags. In addition, the effect of a 20 s breath-hold following inhalation to total lung capacity was studied. The samples were analyzed for ethanol and acetone levels immediately using proton-transfer-reaction mass-spectrometer (PTR-MS, Logan Research, UK). RESULTS: Ethanol levels were negatively affected by expiratory flow rate (232.70 +/- 33.50 ppb vs. 202.30 +/- 27.28 ppb at 5 L/min and 10 L/min, respectively, p < 0.05), but remained unchanged following the breath hold (242.50 +/- 34.53 vs. 237.90 +/- 35.86 ppb, without and with breath hold, respectively, p = 0.11). On the contrary, acetone levels were increased following breath hold (1.50 +/- 0.18 ppm) compared to the baseline levels (1.38 +/- 0.15 ppm), but were not affected by expiratory flow (1.40 +/- 0.14 ppm vs. 1.49 +/- 0.14 ppm, 5 L/min vs. 10 L/min, respectively, p = 0.14). The diet had no significant effects on the gasses levels which showed good inter and intra session reproducibility. CONCLUSIONS: Exhalation parameters such as expiratory flow and breath-hold may affect VOC levels significantly; therefore standardisation of exhaled VOC measurements is mandatory. Our preliminary results suggest a different origin in the respiratory tract for these two gasses

(PTR-MS) for a non-invasive method of early lung cancer detection

Investigations on the use of breath gas analysis with Proton Transfer Reaction Mass Spectrometry (PTR-MS) for a non-invasive method of early lung cancer detectio

Untersuchungen zum Einsatz von Atem Gasanalyse mit Proton-Transfer-Reaktions-Massenspektrometrie (PTR-MS) für eine nicht-invasive Methode zur Früherkennung Lungenkrebs

The analysis of volatile organic compounds (VOCs) in exhaled air is an inexpensive and non-invasive method for early detection and diagnosis of human disease. This biophysical methodology in the context of a clinical study based on whether certain lung diseases (including cancer) can be identified early using proton-transfer mass spectrometry (PTR-MS) has been tested. For different groups, such as lung cancer patients, patients with other lung diseases and healthy controls in different environments and lifestyles (e.g. smoking) the measured exhaled VOCs found a significant effect of lung disease on the measured signals.Die Analyse von flüchtigen organischen Verbindungen (VOC) in der Atemluft ist eine billige und nicht-invasive Methode für die Diagnostik und Früherkennung menschlicher Erkrankungen. Mittels Protonen-Transfer-Massenspektrometrie (PTR-MS) wurde mit dieser biophysikalischen Methode im Rahmen einer klinischen Studie getestet, ob gewisse Lungenerkrankungen (u.a. Lungenkrebs) so früh erkannt werden können. Für verschiedene Gruppen, wie etwa Lungenkrebs-Patienten, Patienten mit anderen Lungenerkrankungen und "Kontroll-Gesunde" wurden in verschiedenen Umgebungen, bei verschiedenen Lebensstilen (z.B. Rauchen) und nach unterschiedlicher Nahrungsaufnahme die ausgeatmeten VOCs gemessen und ein signifikanter Effekt von Lungenerkrankungen auf die Messsignale gefunden

Investigations on the use of breath gas analysis with Proton Transfer Reaction Mass Spectrometry (PTR-MS) for a non-invasive method of early lung cancer detection.

The analysis of volatile organic compounds (VOCs) in exhaled air is an inexpensive and non-invasive method for early detection and diagnosis of human disease. This biophysical methodology in the context of a clinical study based on whether certain lung diseases (including cancer) can be identified early using proton-transfer mass spectrometry (PTR-MS) has been tested. For different groups, such as lung cancer patients, patients with other lung diseases and healthy controls in different environments and lifestyles (e.g. smoking) the measured exhaled VOCs found a significant effect of lung disease on the measured signals