Predictors of oxygen desaturation during submaximal exercise in 8,000 patients.
OBJECTIVE
To determine predictors of oxygen desaturation during submaximal exercise in patients with various lung diseases.


METHODS
This retrospective case series used pulmonary function laboratory results from all patients referred to a major tertiary-care center.


METHODS
All patients > or = 35 years old who underwent spirometry, diffusing capacity of the lung for carbon monoxide (DLCO), lung volumes, and pulse oximetry during 3-min submaximal step-test exercise during 1996 were included (4,545 men and 3,472 women). Logistic regression models, correcting for gender, age, and weight, determined the odds ratios (ORs) for oxygen desaturation of > or = 4% during exercise for each category of lung function abnormality (compared to those with entirely normal lung function).


RESULTS
Approximately 74% of the patients had airways obstruction, while only 5.6% had restriction of lung volumes. One third of those with obstruction had a low DLCO, compared to 56% with restriction, while 2.7% had a low DLCO without obstruction or restriction. The risk of oxygen desaturation during submaximal exercise was very high (OR, 34) in patients with restriction and low DLCO (as in interstitial lung disease) and in patients with obstruction and low DLCO (as in COPD; OR, 18), intermediate (OR, 9) in patients with only a low DLCO, and lowest in those with a normal DLCO (OR, 4 if restricted; OR, 2 if obstructed). A cut point of DLCO < 62% predicted resulted in 75% sensitivity and specificity for exercise desaturation. No untoward cardiac events occurred in any patients during or following the submaximal exercise tests.


CONCLUSIONS
The risk of oxygen desaturation during submaximal exercise is very high in patients with a low DLCO. Submaximal exercise tests are safe, even in elderly patients with heart and lung diseases.
Hadeli
K O
KO
University of Arizona, Tucson, AZ, USA.
Siegel
E M
EM
Sherrill
D L
DL
Beck
K C
KC
Enright
P L
PL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002248:Carbon Monoxide / Q000502:physiology; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D016015:Logistic Models; D017563:Lung Diseases, Interstitial / Q000097:blood / Q000503:physiopathology; D008173:Lung Diseases, Obstructive / Q000097:blood / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010100:Oxygen / Q000097:blood*; D011653:Pulmonary Diffusing Capacity; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013147:Spirometry
D002248:Carbon Monoxide; D010100:Oxygen