| 1. |
- King, Julian, et al.
(författare)
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Physiological modeling of exhaled compounds
- 2020. - 2
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Ingår i: Breathborne biomarkers and the human volatilome. - : Elsevier. - 9780128199671 - 9780128223970 ; , s. 43-62
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Bokkapitel (refereegranskat)abstract
- Blood flow and ventilatory flow strongly influence the concentrations of volatile organic compounds (VOCs) in exhaled breath. The physicochemical properties of a compound (e.g., water solubility) additionally determine if the concentration of the compound in breath reflects the alveolar concentration, the concentration in the upper airways, or a mixture of both. Mathematical modeling based on mass balance equations helps to understand how measured breath concentrations are related to their corresponding blood concentrations and physiological parameters, such as metabolic rates and endogenous production rates. In addition, the influence of inhaled compounds on their exhaled concentrations can be quantified and appropriate correction formulas can be derived. Isoprene and acetone, two endogenous VOCs with very different water solubility, have been modeled to explain the essential features of their behavior in breath. This chapter introduces the theory of physiological modeling of exhaled VOCs, with examples of isoprene and acetone.
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| 2. |
- Schmidt, Florian M., et al.
(författare)
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Optical spectroscopy
- 2020. - 2
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Ingår i: Breathborne biomarkers and the human volatilome. - : Elsevier. - 9780128199671 - 9780128223970 ; , s. 221-238
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Optical spectroscopy is widely used for quantitative detection of small molecules in complex gas matrices. Employing a laser as a light source enables highly sensitive, selective, and accurate trace gas analysis in exhaled breath without the need for frequent calibration. Many volatile species with direct physiological relevance, especially small molecules such as CO2, CO, NO, CH4, NH3, HCN, C2H4, and their isotopoloques, can be measured with high time resolution using compact optical analyzers. Thus, laser-based sensors are an important complement to other analytical platforms and contribute to establishing breath gas analysis in the clinical practice. This chapter introduces the basics of optical spectroscopy and describes the most relevant techniques currently used in the field, such as nondispersive, laser absorption, and photoacoustic spectroscopy. Successful applications of optical methods are presented, and the future prospects are discussed. Owing to the advent of novel light sources, such as quantum cascade lasers and optical frequency combs, spectroscopy will continue to play a significant role in breath gas analysis.
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| 3. |
- Högman, Marieann
(författare)
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Exhaled nitric oxide physiology and modeling
- 2020
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Ingår i: Breathborne Biomarkers and the Human Volatilome. - : Elsevier. - 9780128199671 ; , s. 63-77
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Nitric oxide (NO) is involved in many processes in the respiratory system. Its detection in exhaled breath and the subsequent discovery of its flow dependency led to the development of a two-compartment model for NO in the respiratory system. Based on this model, alveolar NO and bronchial NO flux can be calculated by measuring fractional exhaled NO (FENO) at several high exhalation flows. If FENO is additionally measured at a very low flow, the airway wall NO concentration and diffusivity of NO that make up bronchial NO flux can be determined. In addition to facilitating research, these parameters may have clinical value in estimating airway inflammation and pathophysiological processes for several pulmonary diseases. Reference values and standardized mathematical methods to determine NO parameters have been established and are accepted for use of FENO in clinical practice.
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| 4. |
- Malinovschi, Andrei, 1978-, et al.
(författare)
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Exhaled nitric oxide in clinical practice
- 2020. - 2
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Ingår i: Breathborne Biomarkers and the Human Volatilome. - : Elsevier. - 9780128223970 ; , s. 81-92
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The fraction of exhaled nitric oxide (FENO) in exhaled breath, at the recommended flow of 50 mL/s, reflects the production of NO in the airways in both health and disease. Current understanding of FENO in asthma is that it is a marker of type 2 inflammation, reflecting activation of IL-4 and IL-13 pathways. FENO is helpful in asthma diagnosis, monitoring of inhaled corticosteroid treatment effects and adherence to medication, and for selecting patients for biological treatment. The clinical use of FENO in asthma will likely increase when reference FENO values have been established, and the relationship between FENO and airway caliber is better understood. Nasal NO is useful in the diagnosis of primary ciliary dyskinesia. The devices for measuring FENO are becoming widely available, and the technological advances have led to devices for home monitoring in view of asthma control. This chapter reviews the use of FENO in clinical practice, presents recent advances, and discusses new challenges.
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