Chest
Clinical Investigations: OxyzenThe Preflight Evaluation: A Comparison of the Hypoxia Inhalation Test With Hypobaric Exposure
Section snippets
METHODS
Group 1 consisted of 15 ambulatory outpatients, 3 women and 12 men, with COPD by clinical criteria10 who were recruited from the Pulmonary Disease Clinic at Walter Reed Army Medical Center to participate in a clinical investigation protocol These subjects comprised the patient study group for HIT. Table 1 shows characteristics for the study patients. The range of values for FEV1 varied from 0.52 to 2.02 L for the patients. Cigarette smoking contributed to the pathogenesis of COPD in most
RESULTS
Table 1 shows anthropometric, arterial blood gas, and pulmonary function data for each group. Eight of 15 patients in group 1 had PaO2 values during the hypoxia inhalation test below 50 mm Hg. None of the group 2 subjects, who were younger than the patient groups, and 12 of the 18 patients in group 3 had PaO2alt values below 50 mm Hg.
The arterial partial pressure of oxygen at sea level (PaO2sl) explained significant variability in PaO2 during hypoxia exposure (Fig 1, Table 2). Figure 1 shows
DISCUSSION
In a comparison between groups, the present study found that a 15.1% HIT at sea level produced a PaO2 relationship comparable to a 2,438-m (8,000-foot) hypobaric chamber exposure in patients with COPD. These data strengthen the empiric basis for using the HIT. To our knowledge, no previous study compared the HIT with an altitude of 2,438-m above sea level despite the clinical relevance of this exposure as a realistic worst case possibility for many long flights.6
We found that healthy subjects
ACKNOWLEDGMENTS
The authors thank Thomas R. McCumber and Vanessa McKee for technical assistance on this project.
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Supported by WRAMC DCI protocol 1740.
The opinions contained herein represent solely the views of the authors and are not to be construed as representing the views of the Department of Defense or the Department or the Army.
Reprint requests: Dr. Dillard, Pulmonary Function Lab, Walter Reed Army Medical Center, Ward 77, Room 7735, Bldg. 2, Washington, DC 20307-5001