| 1. |
- Bondesson, Eva, et al.
(författare)
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Exhaled breath condensate-site and mechanisms of formation
- 2009
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Ingår i: Journal of Breath Research. - : IOP Publishing. - 1752-7163 .- 1752-7155. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Exhaled breath condensate (EBC) analysis is a promising tool for diagnosis and management of pulmonary diseases. Its clinical usefulness is still limited however due to unresolved issues around e. g. reproducibility, anatomical site of origin of EBC solutes and mechanisms of EBC formation. To gain some knowledge on these issues, three different airway deposition patterns of an aqueous aerosol containing technetium-99m were studied in eight healthy non-smoking subjects. EBC was collected 20 min after each radioaerosol administration and analyzed for gamma radiation and electrolytes. Radioaerosol deposition in preferentially central lung compared with preferentially peripheral lung resulted in 3.8 times higher EBC radioactivity. EBC concentrations of Na+ and K+ correlated significantly indicating dilution by water vapor to be a major source of variability. Since Na+/K+- and Na+/S2--concentration ratios, but not Na+/Cl--or Na+/Ca2+-, were comparable to those previously reported for alveolar lining fluid (ALF), some mechanisms other than dilution are likely also to be involved. In conclusion, our findings indicate that EBC derives mainly from the central airways, that the electrolyte composition of EBC does not consistently reflect that of ALF, and that EBC concentrations of electrolytes are determined not only by ALF dilution with water vapor but also by other mechanisms.
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| 2. |
- Högman, Marieann, et al.
(författare)
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Extended NO analysis in asthma
- 2007
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Ingår i: Journal of Breath Research. - : IOP Publishing. - 1752-7155 .- 1752-7163. ; 1:2, s. 024001-
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Forskningsöversikt (refereegranskat)abstract
- The discovery of the flow dependence of exhaled NO made it possible to model NO production in the lung. The linear model provides information about the maximal flux of NO from the airways and the alveolar concentrations of NO. Nonlinear models give additional flow-independent parameters such as airway diffusing capacity and airway wall concentrations of NO. When these models are applied to patients with asthma, a clear-cut increase in NO flux is found, and this is caused by an increase in both airway diffusing capacity and airway wall concentrations of NO. There is no difference in alveolar concentrations of NO compared to healthy subjects, except in severe asthma where an increase has been found. Inhaled corticosteroids are able to reduce the airway wall concentrations but not diffusing capacity or alveolar concentrations. Oral prednisone affects the alveolar concentration, suggesting that in severe asthma there is a systemic component. Steroids distributed by any route do not affect the airway diffusing capacity. Therefore, the airway diffusing capacity should be in focus in testing new drugs or in combination treatment for asthma. Exhaled NO analysis is a promising tool in characterizing asthma in both adults and children. However, there is a strong need to agree on the models and to standardize the flow rates to be used for the modelling in order to perform a systematic and robust analysis of NO production in the lung.
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| 3. |
- Jones, A Wayne, et al.
(författare)
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Determination of ethanol in breath for legal purposes using a five-filter infrared analyzer : studies on response to volatile interfering substances
- 2008
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Ingår i: JOURNAL OF BREATH RESEARCH. - : Institute of Physics. - 1752-7155 .- 1752-7163. ; 2:2
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Tidskriftsartikel (refereegranskat)abstract
- The analysis of ethanol in exhaled breath is widely accepted and used worldwide for legal purposes to gather evidence of alcohol-impaired driving. Most evidential breath-alcohol instruments incorporate infrared (IR) spectroscopy as the analytical principle focusing on C-H or C-O stretching frequencies in ethanol molecules. The instrument approved for legal purposes in Sweden is called Evidenzer and is equipped with five infrared filters of which four are used for identification and quantification of ethanol and the fifth is a reference filter. The response of Evidenzer was tested against 21 volatile organic compounds (VOCs), and the instrument was programmed to deduct any bias caused by these VOCs if present in a sample of breath. If the amount deducted exceeds a certain threshold value, the entire test is aborted. Whenever this happens, the police request a specimen of venous blood for analysis by gas chromatography. Of a total of 24 072 drunken drivers, the evidential breath-alcohol test was aborted on 27 occasions (0.11%) because an interfering substance was present above the critical threshold. The VOCs most commonly identified in blood were acetone, isopropanol and/or methyl ethyl ketone (MEK). Elevated levels of acetone and isopropanol might arise during ketogenesis in people suffering from diabetes, or in those who eat low carbohydrate diets. High concentrations of acetone and MEK are probably caused by people drinking a technical alcohol product (T-Red), which is available in Sweden and is denatured with these agents. This study confirms that relatively few apprehended drivers in Sweden have elevated concentrations of VOCs in breath other than ethanol. Even the aborted breath tests, to a large extent, contained ethanol above the legal limit for driving.
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| 4. |
- Kaisdotter Andersson (Jonsson), Annika, et al.
(författare)
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Methodology investigation of expirograms for enabling contact free breath alcohol analysis
- 2009
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Ingår i: Journal of Breath Research. - : IOP Publishing. - 1752-7155 .- 1752-7163. ; 3:3, s. 036002-
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Tidskriftsartikel (refereegranskat)abstract
- The present techniques for breath alcohol determination have usability limitations concerning practical use and the time and effort required for the test person. The rationale of the physiological assumptions in a recently demonstrated technique for breath analysis without a mouthpiece is investigated in this paper. Expirograms quantifying ethanol, carbon dioxide (CO2) and water (H2O) from 30 test subjects were analysed, with respect to the influence of individual variations in end-expiratory CO2 and H2O concentrations, and possible benefits from simultaneous measurement of CO2 or H2O. Both healthy subjects and patients suffering from pulmonary diseases performed breath tests with small and maximum volume expiration. The breath tests were recorded basically with a standard evidential instrument using infrared absorption spectroscopy, and equipped with a mouthpiece. Average concentrations were significantly higher for the maximum than for the small expirations. For the maximum expirations, the healthy subjects had a significantly higher end-expired PCO2 of 4.4 ± 0.5 kPa (mean ± standard deviation) than the patients (3.9 ± 0.7 kPa). The corresponding values for H2O were 39 ± 1 and 38 ± 1 mg l−1. The results indicate that the CO2 variability is consistent with the requirements of accuracy for alcohol ignition interlocks. In addition, CO2 as tracer gas is preferable to H2O due to its low concentration in ambient air. In instruments for evidential purposes H2O may be required as tracer gas for increased accuracy. Furthermore, the study provides support for early determination of breath alcohol concentration, indicating that determination after 2 s will introduce an additional random error of 0.02 mg l−1 or less.
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