Explained variance for blood gases in a population with COPD

Authors

  • Eirunn Waatevik Saure,

    Corresponding author
    1. Section of Pulmonary Medicine, Institute of Medicine, University of Bergen, Bergen, Norway
    2. Department of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway
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  • Tomas Mikal Lind Eagan,

    1. Section of Pulmonary Medicine, Institute of Medicine, University of Bergen, Bergen, Norway
    2. Department of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway
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  • Robert Leroy Jensen,

    1. Internal Medicine, Pulmonary Division, University of Utah, Salt Lake City, UT, USA
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  • Marianne Voll-Aanerud,

    1. Section of Pulmonary Medicine, Institute of Medicine, University of Bergen, Bergen, Norway
    2. Department of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway
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  • Pål Aukrust,

    1. Research Institute for Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway
    2. Section of Clinical Immunology and Infectious Diseases, Oslo University Hospital Rikshospitalet, Oslo, Norway
    3. Faculty of Medicine, University of Oslo, Oslo, Norway
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  • Per Sigvald Bakke,

    1. Section of Pulmonary Medicine, Institute of Medicine, University of Bergen, Bergen, Norway
    2. Department of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway
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  • Jon Andrew Hardie

    1. Section of Pulmonary Medicine, Institute of Medicine, University of Bergen, Bergen, Norway
    2. Department of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway
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  • Authorship and contributorship

  • Dr. Saure collected and analyzed the data, and was the principal author for the manuscript. Dr. Eagan contributed significantly to this manuscript with designing the study, data collection, planning of analyses, writing process and manuscript review. Dr. Jensen contributed with data organization, planning of analyses, writing process and manuscript review. Dr. Voll-Aanerud contributed with the writing process and manuscript review. Dr. Aukrust performed the analyses of plasma C-reactive protein and contributed with manuscript review. Dr. Bakke contributed significantly to this manuscript with designing the study, data collection, planning of analyses, writing process and manuscript review. Dr. Hardie contributed significantly to this manuscript with designing the study, data collection, planning of analyses, writing process and manuscript review.

  • Ethics

  • The study was performed in accordance with the ethical standards laid down in the 2008 (sixth revision) Declaration of Helsinki. The study was approved by the Western Norway Regional Research Ethics Committee, approval number 165.08. Written informed consent was obtained from each participant prior to their inclusion in the study.

  • Conflict of interest

  • Dr. Saure has received sponsorship for travel and accommodation to international conferences from several pharmaceutical companies (AstraZeneca, Boehringer Ingelheim, Pfizer and GlaxoSmithKline), and lecture fees from AstraZeneca and Boehringer Ingelheim. Dr. Eagan has received sponsorship for travel and accommodations to the ATS congress from GSK, and received grant monies from AstraZeneca (unrelated to this study). Dr. Jensen has no conflicts of interest to disclose. Dr. Voll-Aanerud has received sponsorship for travel and accommodation to international conferences from several pharmaceutical companies (AstraZeneca, Boehringer Ingelheim, Pfizer and GlaxoSmithKline), and lecture fees from AstraZeneca. Dr. Aukrust has no conflicts of interest to disclose. Dr. Bakke has received lecture fees from GSK and AstraZeneca. Dr. Bakke is also a principle investigator in a GSK-sponsored study.

  • Dr. Hardie has received sponsorship for travel and accommodations to the ATS congress from GSK, and received grant monies from AstraZeneca, GlaxoSmithKline, Boehringer Ingelheim and Pfizer (unrelated to this study).

Eirunn W. Saure, MD, Section of Pulmonary Medicine, Institute of Medicine, University of Bergen, 5021 Bergen, Norway, Tel: +47 91 17 19 16, Fax: +47 55 97 40 49, email: eirunn.saure@med.uib.no

Abstract

Introduction:  Variation of blood gas levels in chronic obstructive pulmonary disease (COPD) patients has not been extensively reported and there is limited knowledge about predictors of chronic respiratory failure in COPD patients.

Objectives:  The aim of this study was to identify predictors of hypoxemia, hypercapnia and increased alveolar-arterial oxygen difference in COPD patients. We hypothesized that prediction of arterial blood gases will be improved in multivariate models including measurements of lung function, anthropometry and systemic inflammation.

Methods:  A cross-sectional sample of 382 Norwegian COPD patients, age 40–76, Global Initiative for Chronic Obstructive Lung Disease stage II–IV, with a smoking history of at least 10 pack-years, underwent extensive measurements, including medical examination, arterial blood gases, systemic inflammatory markers, spirometry, plethysmography, respiratory impedance and bioelectrical impedance. Possible predictors of arterial oxygen (PaO2), arterial carbon dioxide (PaCO2) and alveolar-arterial oxygen difference (AaO2) were analyzed with both bivariate and multiple regression methods.

Results:  We found that various lung function measurements were significantly associated with PaO2, PaCO2 and AaO2. In addition, heart rate and Fat Mass Index were predictors of PaO2 and AaO2, while heart failure and current smoking status were associated with PaCO2. The explained variance (R2) in the final multivariate regression models was 0.14–0.20.

Conclusions:  With a wide assortment of possible clinical predictors, we could explain 14–20% of the variation in blood gas measurements in COPD patients.

Please cite this paper as: Saure EW, Eagan TML, Jensen RL, Voll-Aanerud M, Aukrust P, Bakke PS and Hardie JA. Explained variance for blood gases in a population with COPD. Clin Respir J 2012; 6: 72–80.

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