Predictors for PaO2 and hypoxemic respiratory failure in COPD-A three-year follow-up.
BACKGROUND
Knowledge about predictors for developing hypoxemia in the course of chronic obstructive pulmonary disease (COPD) progression is limited. The objective of the present study was to investigate predictors for overall PaO2, for a potential change in PaO2 over time, and for first occurrence of hypoxemia.


METHODS
419 patients aged 40-76 years with COPD GOLD stages II-IV underwent clinical and pulmonary function measurements, including repeated arterial blood gases over three years. Airway obstruction, lung hyperinflation, markers of systemic inflammation and cardiovascular health, exacerbation frequency, smoking habits, and body composition were tested as possible predictors of PaO2 and first episode of hypoxemia.


RESULTS
In multivariate adjusted longitudinal analyses, forced expiratory volume in 1 second, total lung capacity and functional residual capacity (all in% predicted), resting heart rate and fat mass index were all associated with overall PaO2 (all P < 0.005). We found no change in PaO2 over time (ρ = 0.33), nor did we find evidence that any of the tested variables predicted change in PaO2 over time. In multivariate adjusted survival analyses, functional residual capacity and resting heart rate were predictors of episodic hypoxemia (both ρ < 0.005).


CONCLUSIONS
This longitudinal study identified pulmonary, cardiac and metabolic risk factors for overall PaO2 and episodic hypoxemia, but detected no change in PaO2 over time.
1Department of Clinical Science, Pulmonary Division, University of Bergen, Bergen, Norway.
E W
EW
Saure
T M L
TM
Eagan
R L
RL
Jensen
P S
PS
Bakke
A
A
Johannessen
M
M
Aanerud
R M
RM
Nilsen
E
E
Thorsen
J A
JA
Hardie
D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D002318:Cardiovascular Diseases / Q000097:blood / Q000150:complications; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume; D005652:Functional Residual Capacity; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000209:etiology; D007249:Inflammation / Q000097:blood / Q000150:complications; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D012131:Respiratory Insufficiency / Q000097:blood* / Q000209:etiology; D012307:Risk Factors; D012720:Severity of Illness Index; D014109:Total Lung Capacity
D010100:Oxygen
arterial blood gases; longitudinal study; lung function; risk factor