Abstract
BackgroundExhaled 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.Methods15 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).ResultsEthanol 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.ConclusionsExhalation 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.
Highlights
Exhaled breath volatile organic compound (VOC) analysis for airway disease monitoring is promising
In view of the potential usefulness of VOCs as markers of lung disease we developed a simple method for their measurement using Proton Transfer Reaction Mass Spectrometry (PTR-MS) and crucially, we standardised the breath collection and studied the effect of different breath parameters such as exhalation flow and breath hold on the levels of the measured gases
Parameters affecting VOCs levels Exhalation flow Exhaled ethanol levels were significantly lower at an exhalation flow of 10 L/min (202.30 ± 27.28 ppb) compared to 5 L/min (232.70 ± 33.50 ppb, p = 0.03, Figure 1, Panel A) whereas the concentrations of acetone were not affected by different exhalation flow rates (1.40 ± 0.14 ppm, 1.49 ± 0.14 ppm for 5 and 10 L/min exhalations respectively, Figure 1, Panel B)
Summary
Exhaled breath volatile organic compound (VOC) analysis for airway disease monitoring is promising. 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 reveal the origin of exhaled compounds. There is a need for disease biomarkers that reflect the activity of the underlying pathogenetic pathways that characterise lung disease These could help diagnose and monitor lung disorders besides providing information on the efficacy of treatment. In the last decades breath analysis, and the measurement of exhaled nitric oxide (NO), has received compared to controls, and the measurement of VOCs has been suggested as a tool for early detection and monitoring of disease. Even though back in 1971 Pauling et al [18] detected more than 200 VOCs in the human breath, to date, breath analysis is still an underused research tool with no current clinical application
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