Abstract
Background: Simultaneous measurement of carbon monoxide (CO) and nitric oxide (NO) diffusing capacity (DL,CO,NO) is an important development as it has the ability to divide the diffusing capacity (DL) into its two components: the diffusing capacity of the alveolo-capillary membrane (Dm) and the pulmonary capillary volume (Vc). At present, its clinical applicability is hampered by a lack of reference equations and the lack of consensus regarding methodology of the measurement including calculation of Dm and Vc.
Objective: The aim of this study was to determine reference equations for the DL,CO,NO measurement based on state-of-the-art methodology. In addition we wanted to appeal for consensus regarding this emerging methodology.
Methods: DL,CO,NO was measured in 316 healthy individuals aged 18-97 years using the single breath technique and a breath-hold time of 5 seconds. The following values were used: 1) specific conductance of NO (θNO) = 4.5 mLNO×mLblod-1×min-1×mmHg-1, 2) ratio of diffusing capacity of the membrane for NO and CO (DmNO/DmCO) = 1.97, and 3) 1/red cell CO conductance (1/ θCO) = 1.710 mLblod×min×mmHg×mLCO-1 (males); 1.863 mLblod×min×mmHg×mLCO-1 (females).
Results: Reference equations were established for the outcomes of DL,CO,NO including diffusing capacity of CO (DL,CO) and NO (DL,NO) and the calculated values Dm and Vc. As an example Vc = exp(2.519119+0.007099*Age-0.000146*Age^2+0.076585*Sex+0.009169*Height).
Conclusion: By providing new reference equations based on today's state-of-the-art methodology and by appealing for consensus regarding this methodology, we hope to provide a basis for future studies and clinical use of this novel and interesting method.
- Copyright ©ERS 2015