Lung function during moderate hypobaric hypoxia in normal subjects and patients with chronic obstructive pulmonary disease

Thomas A. Dillard, Krishnan R. Rajagopal, William A. Slivka, Benjamin W. Berg, William J. Mehm, Nancy P. Lawless

Research output: Contribution to journalArticle

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Abstract

Background: We sought to describe changes in spirometric variables and lung volume subdivisions in healthy subjects and patients with chronic obstructive pulmonary disease (COPD) during moderate acute hypobaric hypoxia as occurs during air travel. We further questioned whether changes in lung function may associate with reduced maximum ventilation or worsened arterial blood gases. Methods: Ambulatory patients with COPD and healthy adults comprised the study populations (n = 27). We obtained baseline measurements of spirometry, lung volumes and arterial blood gases from each subject at sea level and repeated measurements during altitude exposure to 8000 ft (2438 m) above sea level in a man-rated hypobaric chamber. Results: Six COPD patients and three healthy subjects had declines in FVC during altitude exposure greater than the 95% confidence interval (CI) for expected within day variability (p < 0.05). Average forced vital capacity (FVC) declined by 0.123 ± 0.254 L (mean ± SD; 95% CI = -0.255, -0.020; p < 0.05) for all subjects combined. The magnitude of decline in FVC did not differ between groups (p > 0.05) and correlated with increasing residual volume (r = -0.455; <0.05). Change in maximum voluntary ventilation (MVV) in the COPD patients equaled - 1.244 ± 4.797 L · min-1 (95% CI = -3.71, 1.22; p = 0.301). Decline in maximum voluntary ventilation (MVV) in the COPD patients correlated with decreased FVC (r = 0.630) and increased RV (r = -0.546; p < 0.05). Changes in spirometric variables for patients and controls did not explain significant variability in the arterial blood gas variables PaO2, PaCO2 or pH at altitude. Conclusions: We observed a decline in forced vital capacity in some COPD patients and normal subjects greater than expected for within day variability. Spirometric changes correlated with changes in reduced maximum voluntary ventilation in the patients but not with changes in resting arterial blood gases.

Original languageEnglish (US)
Pages (from-to)979-985
Number of pages7
JournalAviation Space and Environmental Medicine
Volume69
Issue number10
StatePublished - Oct 1 1998

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Chronic Obstructive Pulmonary Disease
Lung
Ventilation
Gases
Oceans and Seas
Healthy Volunteers
Air Travel
Confidence Intervals
Lung Volume Measurements
Residual Volume
Hypoxia
Spirometry
Vital Capacity
Population

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

Cite this

Dillard, T. A., Rajagopal, K. R., Slivka, W. A., Berg, B. W., Mehm, W. J., & Lawless, N. P. (1998). Lung function during moderate hypobaric hypoxia in normal subjects and patients with chronic obstructive pulmonary disease. Aviation Space and Environmental Medicine, 69(10), 979-985.

Lung function during moderate hypobaric hypoxia in normal subjects and patients with chronic obstructive pulmonary disease. / Dillard, Thomas A.; Rajagopal, Krishnan R.; Slivka, William A.; Berg, Benjamin W.; Mehm, William J.; Lawless, Nancy P.

In: Aviation Space and Environmental Medicine, Vol. 69, No. 10, 01.10.1998, p. 979-985.

Research output: Contribution to journalArticle

Dillard, TA, Rajagopal, KR, Slivka, WA, Berg, BW, Mehm, WJ & Lawless, NP 1998, 'Lung function during moderate hypobaric hypoxia in normal subjects and patients with chronic obstructive pulmonary disease', Aviation Space and Environmental Medicine, vol. 69, no. 10, pp. 979-985.
Dillard, Thomas A. ; Rajagopal, Krishnan R. ; Slivka, William A. ; Berg, Benjamin W. ; Mehm, William J. ; Lawless, Nancy P. / Lung function during moderate hypobaric hypoxia in normal subjects and patients with chronic obstructive pulmonary disease. In: Aviation Space and Environmental Medicine. 1998 ; Vol. 69, No. 10. pp. 979-985.
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abstract = "Background: We sought to describe changes in spirometric variables and lung volume subdivisions in healthy subjects and patients with chronic obstructive pulmonary disease (COPD) during moderate acute hypobaric hypoxia as occurs during air travel. We further questioned whether changes in lung function may associate with reduced maximum ventilation or worsened arterial blood gases. Methods: Ambulatory patients with COPD and healthy adults comprised the study populations (n = 27). We obtained baseline measurements of spirometry, lung volumes and arterial blood gases from each subject at sea level and repeated measurements during altitude exposure to 8000 ft (2438 m) above sea level in a man-rated hypobaric chamber. Results: Six COPD patients and three healthy subjects had declines in FVC during altitude exposure greater than the 95{\%} confidence interval (CI) for expected within day variability (p < 0.05). Average forced vital capacity (FVC) declined by 0.123 ± 0.254 L (mean ± SD; 95{\%} CI = -0.255, -0.020; p < 0.05) for all subjects combined. The magnitude of decline in FVC did not differ between groups (p > 0.05) and correlated with increasing residual volume (r = -0.455; <0.05). Change in maximum voluntary ventilation (MVV) in the COPD patients equaled - 1.244 ± 4.797 L · min-1 (95{\%} CI = -3.71, 1.22; p = 0.301). Decline in maximum voluntary ventilation (MVV) in the COPD patients correlated with decreased FVC (r = 0.630) and increased RV (r = -0.546; p < 0.05). Changes in spirometric variables for patients and controls did not explain significant variability in the arterial blood gas variables PaO2, PaCO2 or pH at altitude. Conclusions: We observed a decline in forced vital capacity in some COPD patients and normal subjects greater than expected for within day variability. Spirometric changes correlated with changes in reduced maximum voluntary ventilation in the patients but not with changes in resting arterial blood gases.",
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