Hypoxemia during air travel in patients with chronic obstructive pulmonary disease.
OBJECTIVE
To quantitate and identify determinants of the severity of hypoxemia during air travel in patients with chronic obstructive pulmonary disease.


METHODS
Prospective study of physiologic variables before and during intervention.


METHODS
Referral-based pulmonary disease clinic at a U.S. Army medical center.


METHODS
Eighteen ambulatory retired servicemen (age 68 +/- 6 [SD] years) with severe chronic obstructive pulmonary disease (forced expiratory volume in the first second [FEV1] 31% +/- 10% of predicted).


METHODS
Altitude simulation equivalent to 2438 meters (8000 feet) above sea level in a hypobaric chamber.


RESULTS
Radial artery catheter blood oxygen tension in the patients declined from a ground value (PaO2G) at sea level of 72.4 +/- 9 mm Hg to an altitude value (PaO2Alt) of 47.4 +/- 6 mm Hg after 45 minutes of steady state hypobaric exposure. The PaO2G correlated with PaO2Alt (r = 0.587; P less than 0.01). Multiple regression analysis revealed that the preflight FEV1 reduced the variability in PaO2Alt not explained by PaO2G in the equation: PaO2Alt = 0.453 [PaO2G] + 0.386 [FEV1% predicted] + 2.440 (r = 0.847; P less than 0.001). Residuals from two previously published formulas using PaO2G also correlated with FEV1 (r greater than or equal to 0.765; P less than 0.001).


CONCLUSIONS
Arterial blood oxygen tension declined to clinically significant levels in most patients during hypobaric exposure. When combined with the preflight arterial PO2 at ground level (PaO2G), the measurement of the preflight FEV1 improved prediction of PaO2 at altitude (PaO2Alt) in patients with severe chronic obstructive pulmonary disease.
Dillard
T A
TA
Walter Reed Army Medical Center, Washington, DC.
Berg
B W
BW
Rajagopal
K R
KR
Dooley
J W
JW
Mehm
W J
WJ
D000328:Adult; D000337:Aerospace Medicine; D000368:Aged; D000531:Altitude; D001274:Atmospheric Pressure; D005541:Forced Expiratory Volume; D006801:Humans; D000860:Hypoxia / Q000209:etiology*; D008173:Lung Diseases, Obstructive / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012044:Regression Analysis; D014195:Travel