Predictive equations for white adults at a breath-hold time of ∼6 s, inspired nitric oxide (NO) of ∼35 ppm and inspired oxygen of ∼19.5%, from three studies [57, 106, 107]

Height cmAge2SexConstantAdjusted R2seeLLN and ULN
DLCO mL·min−1·mmHg−10.23−0.0026.0−8.50.684.2±8.2
DLNO mL·min−1·mmHg−10.81−0.01034.49.70.6920.0±39.2
DMCO mL·min−1·mmHg−1−0.01156.4129.60.6127.3±53.5
VC mL0.84−0.004−59.90.4912.0±23.5
VA L0.0790.73−7.70.670.72±1.4
VC/VA mL·L−1−0.0006−1.2513.90.271.89±3.70
DMCO/VA mL·min−1·mmHg−1·L−1−0.200−0.0025.956.60.413.81±7.47
KCO mL·min−1·mmHg−1·L−1−0.000275.50.340.6±1.2
KNO mL·min−1·mmHg−1·L−1−0.0013726.40.392.8±5.5
  • Alveolar–capillary membrane diffusing capacity for carbon monoxide (DMCO) and total volume of blood in the lung capillaries exposed to alveolar air (VC) values in these studies [57, 106, 107] have been recalculated according to the formulas and constants in table 4 and then re-analysed for the regression. A predictive model was not found for the ratio of diffusing capacities of the lung for nitric oxide and carbon monoxide (DLNO/DLCO). Sex: 1 for male, 0 for female; see: standard error of the estimate. To convert DLNO, DLCO and DMCO to mmol·min−1·kPa−1, divide by 3. Lower limit of normal (LLN)=2.5th percentile; upper limit of normal (ULN)=97.5th percentile. n=490. VA: alveolar lung volume; KCO: rate of uptake of carbon monoxide from alveolar gas; KNO: rate of uptake of nitric oxide from alveolar gas. Supplementary appendix H allows the patient's individual values to be inserted in relation to the predicted values.