Pulmonary Gas Exchange

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John B. West - One of the best experts on this subject based on the ideXlab platform.

  • noninvasive measurement of Pulmonary Gas Exchange comparison with data from arterial blood Gases
    American Journal of Physiology-lung Cellular and Molecular Physiology, 2019
    Co-Authors: John B. West, Daniel L Wang, Kim G Prisk, Janelle M Fine, Amy L Bellinghausen, Matthew Light, Daniel R Crouch
    Abstract:

    A new noninvasive method was used to measure the impairment of Pulmonary Gas Exchange in 34 patients with lung disease, and the results were compared with the traditional ideal alveolar-arterial Po...

  • A lifetime of Pulmonary Gas Exchange.
    Physiological reports, 2018
    Co-Authors: John B. West
    Abstract:

    Pulmonary Gas Exchange is the primary function of the lung, and during my lifetime, its measurement has passed through many stages. When I was born, many physiologists still believed that the lung secreted oxygen. When I was a medical student, the only way we had to recognize defective Gas Exchange was whether the patient was cyanosed. The advent of the oximeter soon showed that this sign could be very misleading. A breakthrough was the introduction of blood Gas electrodes that could measure the PO2 , PCO2 , and pH of a small sample of arterial blood. It was soon recognized that the commonest cause of hypoxemia was ventilation-perfusion inequality, and that this could also be responsible for CO2 retention. In the early days, the understanding of the mechanisms of Pulmonary Gas Exchange relied on graphical analysis because the oxygen and carbon dioxide dissociation curves are nonlinear and interdependent which precluded algebraic methods. However, with the introduction of digital computing, problems that had hitherto been impossible to tackle became amenable to study. A key advance was the development of the Multiple Inert Gas Elimination Technique. Now, noninvasive methods for measuring Gas Exchange show promise, and the whole subject continues to develop.

  • Measurements of Pulmonary Gas Exchange efficiency using expired Gas and oximetry: results in normal subjects
    American journal of physiology. Lung cellular and molecular physiology, 2017
    Co-Authors: John B. West, Daniel L Wang, G. Kim Prisk
    Abstract:

    We are developing a novel, noninvasive method for measuring the efficiency of Pulmonary Gas Exchange in patients with lung disease. The patient wears an oximeter, and we measure the partial pressur...

  • understanding Pulmonary Gas Exchange ventilation perfusion relationships
    American Journal of Physiology-lung Cellular and Molecular Physiology, 2004
    Co-Authors: John B. West
    Abstract:

    This essay looks at the historical significance of four APS classic papers that are freely available online: Fenn WO, Rahn H, and OTIS AB. A theoretical study of the composition of the alveolar air at altitude. Am J Physiol 146: 637-653. 1946 (http://ajplegacy.physiology.org/cgi/reprint/146/5/637). Rahn H. A concept of mean alveolar air and the ventilation-bloodflow relationships during Pulmonary Gas Exchange. Am J Physiol 158: 21-30, 1949 (http://ajplegacy.physiology.org/cgi/reprint/158/1/21)). Riley RL. And Cournand A. "Ideal" Alveolar air and the analysis of ventilation-perfusion relationships in the lungs. J Appl Physiol 1: 825-847. 1949 (http://jap.physiology.org/cgi/reprint/1/12/825). Riley RL. And Cournand A. Analysis of factors affecting partial pressures of oxygen and carbon dioxide in Gas and blood of lungs: theory. J Appl Physiol 4: 77-101. 1951 (http://jap.physiology.org/cgi/reprint/4/2/77).

  • understanding Pulmonary Gas Exchange ventilation perfusion relationships
    Journal of Applied Physiology, 2004
    Co-Authors: John B. West
    Abstract:

    This essay looks at the historical significance of four APS classic papers that are freely available online: Fenn WO, Rahn H, and Otis AB . A theoretical study of the composition of the alveolar air at altitude. Am J Physiol 146: 637—653, 1946 ( ). Rahn H . A concept of mean alveolar air and the ventilation-bloodflow relationships during Pulmonary Gas Exchange. Am J Physiol 158: 21—30, 1949 ([http://ajplegacy.physiology.org/cgi/reprint/158/1/21][1]). Riley RL and Cournand A . “Ideal” alveolar air and the analysis of ventilation-perfusion relationships in the lungs. J Appl Physiol 1: 825—847, 1949 ( ). Riley RL and Cournand A . Analysis of factors affecting partial pressures of oxygen and carbon dioxide in Gas and blood of lungs: theory. J Appl Physiol 4: 77—101, 1951 ( ). [1]: http://ajplegacy.physiology.org/cgi/reprint/158/iss/21

Leighton Chan - One of the best experts on this subject based on the ideXlab platform.

Martin Buchheit - One of the best experts on this subject based on the ideXlab platform.

  • Respiratory sinus arrhythmia and Pulmonary Gas Exchange efficiency: time for a reappraisal.
    Experimental physiology, 2010
    Co-Authors: Martin Buchheit
    Abstract:

    In many cases parents still rely on the belief that ‘playing basketball makes you taller’ or better still ‘gymnastics will lead to shortness’ when orienting their child’s sports participation. Although these convictions naively dismiss strong selection bias, they demonstrate that opinions based upon faulty logic can have a long duration, unless being meticulously challenged. The main physiological role of respiratory sinus arrhythmia (RSA), which refers to the shortening and lengthening of beat-tobeat cardiac cycle intervals throughout the respiratory cycle, was first proposed 15 years ago (Hayano et al. 1996). Hayano’s initial work (Hayano et al. 1996) set a progressive acceptance that RSA could be regarded as an intrinsic function of the cardioPulmonary system, with the clustering and scattering of heartbeats during inspiration and expiration, respectively, suggested to improve Pulmonary Gas Exchange efficiency via efficient ventilation–perfusion matching and to save unnecessary heartbeats during the ebb of perfusion that may result in wasted Pulmonary blood flow. This ‘theory’ has important clinical applications, and may partly account for the association between low RSA and a variety of cardiovascular/cardioPulmonary risk factors and disease processes (see references in the article by Sin et al. 2010). Nevertheless, while the pioneering demonstrations in dogs (Hayano et al. 1996) and humans (Giardino et al. 2003) were appealing, recent findings by Tzeng, Galletly, Larsen and co-workers came, with time, to question Hayano’s views (e.g. Tzeng et al. 2007, 2009). After having exemplified the lack or inconsistencies of heartbeats clustering during inspiration in a series of wellconducted experiments in humans (e.g. Tzeng et al. 2007, 2009), the same group of authors provide, in this issue of Experimental Physiology, additional evidence for the lack of causal links between RSA and Pulmonary Gas Exchange efficiency (Sin et al. 2010). In this very simple but intelligent study design, Peter Y. W. Sin et al. (2010) compared the response of ventilatory equivalents (VE/VO2 and VE/VCO2 ) to fast and slow breathing in control subjects and in patients with fixedrate cardiac pacemakers. While the slowing of breathing frequency was associated, as expected (Giardino et al. 2003), with increased RSA amplitude and improved Pulmonary Exchange efficiency in healthy control subjects (i.e. decreased ventilatory equivalents), similar improvements in Pulmonary function were also observed in patients, despite unchanged RSA. Additionally, in healthy control subjects, Sin et al. (2010) could not find any correlation between the changes in RSA and ventilatory equivalents. These interesting findings are in line with the authors’ previous provocative conclusions (Tzeng et al. 2009), and clearly confirm that it may be too simplistic to assume that temporal variation in heart rate necessarily accounts for putative improvements in ventilation– perfusion matching and, conversely, that redistribution of heartbeats throughout the respiratory cycle is compulsory for improved Pulmonary Gas Exchange efficiency. In addition, the findings of Sin et al. (2010) have important and immediate clinical implications, since they give support, irrespective of the mechanisms involved, to respiratory training at slow frequencies to improve Pulmonary Gas Exchange efficiency in cardiovascular and Pulmonary diseases (see references in the article by Sin et al. 2010). As discussed by the authors (Tzeng et al. 2009; Sin et al. 2010), other mechanisms might be responsible (and possibly effective enough) for the improved Pulmonary Exchange efficiency with slower breathing rates in cardiac patients lacking RSA, such as improved cardiac efficiency (via facilitation of venous return as a consequence of changes in intrathoracic pressure) and/or changes in the ratio of alveolar to dead-space ventilation. Future studies investigating (both in healthy individuals and patients) the influence of changes in intrathoracic pressure, central blood volume, cardiac function and Pulmonary blood flow/O2 partial pressure on both RSA and Pulmonary Gas Exchange efficiency might facilitate the understanding of their improbable associations. To conclude, and this is the beauty of research, this study (Sin et al. 2010) shows once again that the common beliefs of today do not always become the certitudes of tomorrow.

Marlowe W Eldridge - One of the best experts on this subject based on the ideXlab platform.

  • Pulmonary Gas Exchange and exercise capacity in adults born preterm
    Annals of the American Thoracic Society, 2015
    Co-Authors: Emily T Farrell, Melissa L Bates, David F Pegelow, Mari Palta, Jens C Eickhoff, Matthew J Obrien, Marlowe W Eldridge
    Abstract:

    Rationale: Preterm birth, and its often-required medical interventions, can result in respiratory and Gas Exchange deficits into childhood. However, the long-term sequelae into adulthood are not well understood.Objectives: To determine exercise capacity and Pulmonary Gas Exchange efficiency during exercise in adult survivors of preterm birth.Methods: Preterm (n = 14), very low birth weight (<1,500 g) adults (20–23 yr) and term-born, age-matched control subjects (n = 16) performed incremental exercise on a cycle ergometer to volitional exhaustion while breathing one of two oxygen concentrations: normoxia (fraction of inspired oxygen, 0.21) or hypoxia (fraction of inspired oxygen, 0.12).Measurements and Main Results: Ventilation, mixed expired Gases, arterial blood Gases, power output, and oxygen consumption were measured during rest and exercise. We calculated the alveolar-to-arterial oxygen difference to determine Pulmonary Gas Exchange efficiency. Preterm subjects had lower power output at volitional exh...

  • Pulmonary Gas Exchange and Exercise Capacity in Adults Born Preterm.
    Annals of the American Thoracic Society, 2015
    Co-Authors: Emily T Farrell, Melissa L Bates, David F Pegelow, Mari Palta, Jens C Eickhoff, Matthew J. O’brien, Marlowe W Eldridge
    Abstract:

    Rationale: Preterm birth, and its often-required medical interventions, can result in respiratory and Gas Exchange deficits into childhood. However, the long-term sequelae into adulthood are not well understood.Objectives: To determine exercise capacity and Pulmonary Gas Exchange efficiency during exercise in adult survivors of preterm birth.Methods: Preterm (n = 14), very low birth weight (

  • Effect of a patent foramen ovale on Pulmonary Gas Exchange efficiency at rest and during exercise
    Journal of applied physiology (Bethesda Md. : 1985), 2011
    Co-Authors: Andrew T. Lovering, Michael K. Stickland, Matthew J. O’brien, Markus Amann, John S. Hokanson, Marlowe W Eldridge
    Abstract:

    The prevalence of a patent foramen ovale (PFO) is ∼30%, and this source of right-to-left shunt could result in greater Pulmonary Gas Exchange impairment at rest and during exercise. The aim of this...

Nicholas D Giardino - One of the best experts on this subject based on the ideXlab platform.

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