7 research outputs found
Suggested VOC profile consisting of the most influencing substances for each mycobacterial species.
<p>↑ - substance is significantly higher above bacteria than above control vials; ↓ - substance is significantly lower above bacteria than above control vials; <b>Ø</b> –substance is not measurable above bacteria; bold: the values of the indicator substance of a species are higher than all values of all other species; ME–methyl ester.</p
VOC concentration above inoculated slants compared to control vials.
<p>VOC concentration above inoculated slants compared to control vials.</p
VOC concentrations above different mycobacterial species and pure media control slants inoculated with MB-Bouillon, forming four groups of substances.
<p>Ia—VOC concentrations above inoculated slants were higher than or equal to control vials; Ib—VOCs were detectable above inoculated slants only and not above control vials; II—VOC concentrations above inoculated slants were equal to or lower than above control slants; III—VOC concentrations above inoculated slants were higher than, equal to or lower than above control slants; ME–methyl ester.</p
Significant differences in VOC concentration above vials with poor bacterial growth at the time point of analysis and above non-inoculated control vials.
<p>*—significant when p-value < 0.05.</p
Inter-strain variability of VOCs tested per species by means of Mann-Whitney-U-Test.
<p>Inter-strain variability of VOCs tested per species by means of Mann-Whitney-U-Test.</p
Differentiation of mycobacterial species by VOC profile.
<p>Illustration is based on a principal component analysis (PCA).</p
Continuous Real Time Breath Gas Monitoring in the Clinical Environment by Proton-Transfer-Reaction-Time-of-Flight-Mass Spectrometry
Analysis of volatile organic compounds (VOCs) in breath holds great promise for noninvasive diagnostic applications. However, concentrations of VOCs in breath may change quickly, and actual and previous uptakes of exogenous substances, especially in the clinical environment, represent crucial issues. We therefore adapted proton-transfer-reaction-time-of-flight-mass spectrometry for real time breath analysis in the clinical environment. For reasons of medical safety, a 6 m long heated silcosteel transfer line connected to a sterile mouth piece was used for breath sampling from spontaneously breathing volunteers and mechanically ventilated patients. A time resolution of 200 ms was applied. Breath from mechanically ventilated patients was analyzed immediately after cardiac surgery. Breath from 32 members of staff was analyzed in the post anesthetic care unit (PACU). In parallel, room air was measured continuously over 7 days. Detection limits for breath-resolved real time measurements were in the high pptV/low ppbV range. Assignment of signals to alveolar or inspiratory phases was done automatically by a matlab-based algorithm. Quickly and abruptly occurring changes of patients’ clinical status could be monitored in terms of breath-to-breath variations of VOC (e.g. isoprene) concentrations. In the PACU, room air concentrations mirrored occupancy. Exhaled concentrations of sevoflurane strongly depended on background concentrations in all participants. In combination with an optimized inlet system, the high time and mass resolution of PTR-ToF-MS provides optimal conditions to trace quick changes of breath VOC profiles and to assess effects from the clinical environment