Single-exhalation profiles of NO and CO<sub>2</sub>in humans: effect of dynamically changing flow rate

Tsoukias, Nikolaos M.; Tannous, Ziad; Wilson, Archie F.; George, Steven C.

doi:10.1152/jappl.1998.85.2.642

Cited by 109 publications

(115 citation statements)

References 29 publications

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“…It has been estimated to occur in 1-3% of people with chronic asthma and 2-15% of those with cystic fibrosis [1]. The natural history of ABPA is characterised by exacerbations that can threaten the patient's survival and prognosis [1].…”

Section: To the Editorsmentioning

confidence: 99%

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Bronchial and alveolar components of exhaled nitric oxide and their relationship

et al. 2012

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Section: To the Editorsmentioning

confidence: 99%

“…The Cystic Fibrosis Foundation Consensus Conference on ABPA did not propose a specific treatment plan [1]. Two small, uncontrolled clinical trials evaluated glucocorticoids in ABPA with different glucocorticoid regimens that varied in doses and durations (from 2 to 6 months) [2].…”

Section: To the Editorsmentioning

confidence: 99%

Bronchial and alveolar components of exhaled nitric oxide and their relationship

et al. 2012

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“…The most commonly used technique to estimate CA NO is a plot of V NO vs. V E (30). For exhalation flow rates Ͼ50 ml/s in adults, the slope of this plot is an estimate of CA NO and the intercept an estimate of JЈaw NO .…”

Section: Impact Of Axial Diffusion On Flow-independent No Parametersmentioning

confidence: 99%

Probing the impact of axial diffusion on nitric oxide exchange dynamics with heliox

Shin

Condorelli

Rose-Gottron

et al. 2004

Journal of Applied Physiology

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Shin, Hye-Won, Peter Condorelli, Christine M. Rose-Gottron, Dan M. Cooper, and Steven C. George. Probing the impact of axial diffusion on nitric oxide exchange dynamics with heliox. J Appl Physiol 97: 874 -882, 2004. First published April 30, 2004 10.1152/ japplphysiol.01297.2003.-Exhaled nitric oxide (NO) is a potential noninvasive index of lung inflammation and is thought to arise from the alveolar and airway regions of the lungs. A two-compartment model has been used to describe NO exchange; however, the model neglects axial diffusion of NO in the gas phase, and recent theoretical studies suggest that this may introduce significant error. We used heliox (80% helium, 20% oxygen) as the insufflating gas to probe the impact of axial diffusion (molecular diffusivity of NO is increased 2.3-fold relative to air) in healthy adults (21-38 yr old, n ϭ 9). Heliox decreased the plateau concentration of exhaled NO by 45% (exhalation flow rate of 50 ml/s). In addition, the total mass of NO exhaled in phase I and II after a 20-s breath hold was reduced by 36%. A single-path trumpet model that considers axial diffusion predicts a 50% increase in the maximum airway flux of NO and a near-zero alveolar concentration (CA NO) and source. Furthermore, when NO elimination is plotted vs. constant exhalation flow rate (range 50 -500 ml/s), the slope has been previously interpreted as a nonzero CANO (range 1-5 ppb); however, the trumpet model predicts a positive slope of 0.4 -2.1 ppb despite a zero CANO because of a diminishing impact of axial diffusion as flow rate increases. We conclude that axial diffusion leads to a significant backdiffusion of NO from the airways to the alveolar region that significantly impacts the partitioning of airway and alveolar contributions to exhaled NO. gas exchange; model; exhaled breath NITRIC OXIDE (NO) performs many important functions in the lungs and has been regarded as a potential noninvasive marker of lung inflammation (2). The characteristics of NO gas exchange are unique compared with other endogenous gases because exhaled NO is thought to have a significant alveolar and airway source (6,8,15,22). A two-compartment model is commonly used to characterize NO exchange dynamics for healthy and diseased lungs (9,11,13,20,21,23,24,27,29), by partitioning exhaled NO into airway and alveolar contributions using three flow-independent NO exchange parameters: maximum flux of NO from the airways (JЈaw NO ), the diffusing capacity of NO in the airways (Daw NO ), and the steady-state alveolar concentration (CA NO ). However, the two-compartment model considers only convection of NO in the airways as a transport mechanism and has neglected axial diffusion of NO in the gas phase to preserve mathematical simplicity.Recently, our laboratory (17) and others (31) separately demonstrated theoretically that axial diffusion may play an important role in NO transport. During exhalation, the concentration of NO is higher in the airways compared with the alveoli, creating a gradient for diffusion of NO from the air...

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“…Indeed, Exhaled NO has been widely used in asthma as a measure of severity of inflammation in the lungs [5] and in the management during drug therapy [6,7]. NO is produced by many cells in the lung and is released into the airspace including airways and alveoli [8][9][10]. Having both alveolar and airway components, the manner used to measure exhaled NO can affect the outcome and continues to be a subject for debate [11].…”

Section: Introductionmentioning

confidence: 99%

Measurement of Exhaled Nitric Oxide Using End Tidal Value during Normal Breathing

Hakim¹

2014

J Pulm Respir Med

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Increased nitric oxide (NO) production in the expired air has been associated with a number of disease conditions and may reflect the severity of inflammation in the lungs. Measurement of exhaled NO concentration has been proposed as a novel clinical tool for assessing airway inflammation and response to drug therapy. In spite of international guidelines aimed at standardizing the measurement of exhaled NO, clinicians remain skeptical due to the necessity of a significant degree of subject collaboration required by the procedure to obtain meaningful measurements. We hypothesized that exhaled NO concentration may be best measured by using end tidal NO concentration during a breath by breath monitoring. We tested laboratory staff and monitored their NO concentration online using a fast response chemiluminescence NO analyzer during normal breathing at rest for 5 minutes. First we confirmed that the NO analyzer was adequately fast to record fully the swings during normal breathing. We then compared the average end tidal NO value (NOet) from 6 to 10 breaths, to the NO value obtained from the plateau from a single slow vital capacity maneuver as recommended by the ATS guidelines (NOplat). End of exhalation was identified using end tidal carbon dioxide measurement. NOet while breathing room air was 24.3 ± 4.2 (SE) ppb and was not significantly different compared to 22.4 ± 2.8 (SE) ppb using NOplat. Additionally breathing high level of NO of up to 88 ppb did not affect either NOet or NOplat significantly suggesting that both measurements are independent of inhaled NO concentration. NO value at end of exhalation was very reproducible from breath to breath and did not require any special effort on the part of the subject. We recommend using NOet measurement instead of the NOplat value that is highly dependent on the exhalation rate and cooperation of the subject. NOet is much easier to record in children, elderly and patients with respiratory disease. The main requirement for measuring NOet is to have a fast response NO analyzer to record the full swings in NO concentration during normal breathing and to have a way of identifying end exhalation.

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Single-exhalation profiles of NO and CO₂in humans: effect of dynamically changing flow rate

Cited by 109 publications

References 29 publications

Bronchial and alveolar components of exhaled nitric oxide and their relationship

Bronchial and alveolar components of exhaled nitric oxide and their relationship

Probing the impact of axial diffusion on nitric oxide exchange dynamics with heliox

Measurement of Exhaled Nitric Oxide Using End Tidal Value during Normal Breathing

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Single-exhalation profiles of NO and CO2in humans: effect of dynamically changing flow rate

Cited by 109 publications

References 29 publications

Bronchial and alveolar components of exhaled nitric oxide and their relationship

Bronchial and alveolar components of exhaled nitric oxide and their relationship

Probing the impact of axial diffusion on nitric oxide exchange dynamics with heliox

Measurement of Exhaled Nitric Oxide Using End Tidal Value during Normal Breathing

Contact Info

Product

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Single-exhalation profiles of NO and CO₂in humans: effect of dynamically changing flow rate