Table. 15—

Summary of the considerations for diffusing capacity for carbon monoxide(DL,CO) interpretation

Refer to a scheme to grade the severity of reductions in DL,CO (table 14)
Interpreting DL,CO in conjunction with spirometry and lung volumes may assist in diagnosing the underlying disease (fig. 2)
Adjustments of DL,CO for changes in haemoglobin and carboxyhaemoglobin are important
The relationship between DL,CO and lung volume is not linear, so DL,CO/VA or DL,CO/TLC do not provide an appropriate way to normalise DL,CO for lung volume
Nonlinear adjustments may be considered, but their clinical utility must be established before they can be recommended
  • VA: alveolar volume; TLC: total lung capacity.