Single-breath diffusing capacity of the lung for carbon monoxide: a predictor of PaO2, maximum work rate, and walking distance in patients with emphysema.
OBJECTIVE
The National Emphysema Treatment Trial (NETT) is a randomized, multicenter, clinical trial comparing two different methods of lung volume reduction surgery plus medical therapy to medical treatment alone in patients with advanced emphysema. The purpose of this article was to use the data obtained from the NETT to assess the ability of the single-breath diffusing capacity of the lung for carbon monoxide (DLCO) to predict the need for supplemental oxygen during rest and exercise, as well as overall exercise capacity.


METHODS
One thousand seventy-one patients with a mean (+/- SD) FEV(1) of 0.76 +/- 0.24 L were studied.


RESULTS
The mean DLCO was 8.0 +/- 3.1 mL/min/mm Hg (28 +/- 10% of predicted). The mean resting PaO(2) was 64 +/- 10 mm Hg. There was a positive association between DLCO and both resting PaO(2) and the requirement for oxygen during a walk at 1 mile per hour (mph). The odds of requiring supplemental oxygen while walking at 1 mph was nine times greater in patients with a DLCO of < or = 20% of predicted than for patients with a DLCO of > 35% of predicted, after adjusting for age and gender. Eighty four percent of individuals with a DLCO of < or = 20% required supplemental oxygen with low levels of exercise compared to 38% of those with a DLCO of > 35%.


CONCLUSIONS
Our results demonstrated that patients with reduced DLCO, particularly when < or = 20% of predicted, are more likely to have reduced PaO(2) at rest and are more likely to require supplemental oxygen with low levels of activity. Thus, DLCO is useful in evaluating whether supplemental oxygen is required for exercise.
Mohsenifar
Zab
Z
Cedars-Sinai Medical Center, Division of Pulmonary/Critical Care Medicine, Los Angeles, CA 90049, USA. mohsenifarz@cshs.org
Lee
Shing M
SM
Diaz
Philip
P
Criner
Gerard
G
Sciurba
Frank
F
Ginsburg
Mark
M
Wise
Robert A
RA
D000368:Aged; D002248:Carbon Monoxide / Q000502:physiology*; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D010102:Oxygen Inhalation Therapy; D011653:Pulmonary Diffusing Capacity; D011656:Pulmonary Emphysema / Q000503:physiopathology* / Q000628:therapy; D016032:Randomized Controlled Trials as Topic; D014797:Vital Capacity; D016138:Walking
D002248:Carbon Monoxide; D010100:Oxygen