Abstract
Background: There is limited data on the relationship between arterial oxygen tension (PaO2) and computed tomography (CT) derived data on emphysema and airway wall thickness.
Objective: To examine the predictive value of measures of emphysema and airway wall thickness from CT scans on PaO2.
Methods: The study sample consisted of 271 smoking or ex-smoking COPD patients from the Bergen COPD Cohort Study examined in 2007-2008. Emphysema was assessed as percent of low-attenuation areas < -950 Hounsfield units (%LAA), and airway wall thickness as standardized measures at an internal perimeter of 10mm (Pi10). Multiple linear regression models were fitted with PaO2 as the outcome variable, and %LAA, Pi10, DLCO and/or KCO as predictor variables. Also, adjustments for gender, age, smoking status (current/ex), and haemoglobin (in analyses with DLCO and KCO) were made.
Results: 62% of the subjects were men, mean(SD) age was 64(7) years, mean(SD) FEV1 in percent predicted was 50(15)%, and mean PaO2(SD) was 9.3(1.1) kPa. The adjusted regression coefficient (SE) for PaO2 was - 0.32 (0.06) per 10% increase in %LAA (p <0.01). When DLCO was added to the equation, the significant relationship between level of emphysema and PaO2 disappeared. No relationship between airway wall thickness and PaO2 was found.
Conclusion: Computed tomography assessment of airway wall thickness did not predict arterial oxygen tension. Emphysema, on the other hand, predicts level of arterial hypoxemia in COPD patients, but not beyond the information offered by DLCO.
- Copyright ©ERS 2015
