Predicting Pulmonary Diffusing Capacity in Adults

 

Crapo and Morris (1981)

 

ages: 15-91 years

 

diffusing capacity in males =

= (0.416 * (height in cm)) - (0.219 * (age in years)) - 26.34

 

diffusing capacity in nonsmoking males =

= (0.410 * (height in cm)) - (0.210 * (age in years)) - 26.31

 

diffusing capacity in females =

= (0.256 * (height in cm)) - (0.144 * (age in years)) - 8.36

 

diffusing capacity in nonsmoking females =

= (0.282 * (height in cm)) - (0.157 * (age in years)) - 10.89

 

where:

• The diffusing capacity is reported in mL of CO (at STPD) per minute per mm Hg.

• The first equation in the pair for each gender is from Table 2 (page 186), the second is from Table 4 (page 187).

• Although the authors list equations corrected for hemoglobin in Table 2 (page 186), patient hemoglobin is not a factor. I would use the general equation to estimate the diffusing capacity, then use the equations in 08.03.03 to adjust.

• The study was done in Utah at an altitude of 1400 meters, while the other below were done close to sea level.

 

Teculescu (1970) for Nonsmokers

 

ages: 19-67 years

 

diffusing capacity in males =

= (0.333 * (height in cm)) - (0.298 * (age in years)) - 12.26

 

Salorinne (1976) for Nonsmokers

 

ages: 20-69 years

 

diffusing capacity in males =

= (0.142 * (height in cm)) - (0.232 * (age in years)) + 16.3

 

diffusing capacity in females =

= (0.219 * (height in cm)) - (0.115 * (age in years)) - 5.97

 

Frans (1975) for Nonsmokers

 

ages: mean 38.5, standard deviation 11.7 years

 

diffusing capacity in males =

= (0.285 * (height in cm)) - (0.14 * (age in years)) - 10.3

 

where:

• The table in Crapo and Morris have the intercept as +10.3, but this gives values much higher than the other estimates.

 

Hall (1979) for Nonsmokers

 

ages: 27-74 years

 

diffusing capacity in females =

= (0.283 * (height in cm)) - (0.185 * (age in years)) - 8.28

 

Observed as Percentage of Predicted

 

diffusing capacity as percent of predicted =

= (measured diffusing capacity) / (predicted diffusing capacity) * 100

Percent of Predicted	Interpretation
> 80%	normal
61 - 80%	mild impairment
40 - 60%	moderate impairment
< 40%	severe impairment