Related Experiment Video
Updated: Mar 8, 2026

Author Spotlight: Integrating Alveolar-Capillary Reserve Measurements in Exercise Adaptation and Therapeutic Strategies
Published on: February 2, 2024
The DLNO/DLCO ratio: Physiological significance and clinical implications
1National Heart and Lung Institute, Imperial College, London, United Kingdom.
Abstract:
DLNO/DLCO directly measures the ratio of the diffusing capacities of the lung for nitric oxide (NO) and carbon monoxide (CO). In terms of the Roughton and Forster (1957) equation, 1/DL=1/Dm+1/θVc, where Dm is the membrane (Dm) and θVc is the red cell component of the overall diffusing conductance (DL); DLNO mostly reflects the Dm component and DLCO the θVc red cell component. The DLNO/DLCO ratio is positively related to the DmCO/Vc ratio and the CO red cell resistance (1/θCOVc) as a percentage of the total resistance (1/DLCO), independent of the absolute values of DLNO or DLCO. In clinical studies, a raised DLNO/DLCO ratio (≥110% predicted versus a control group), plus a low DLNO and DLCO (<67% pred), predicts pulmonary vascular disease, while a low DLNO/DLCO ratio, with similarly reduced DLNO and DLCO, is associated with interstitial lung disease with fibrosis. More clinical studies are needed, and reference values need to be better defined.
More Related Videos
Related Concept Videos
Difference from Background: Limit of Detection
The LOD indicates the presence or absence...
Physiological Control of Respiration
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
Carbon Dioxide Transport in the Blood
Forms of CO2 Transport
1. Dissolved in plasma: A small percentage (7-10%) of CO2 is transported and dissolved directly in the plasma.
2. Carbaminohemoglobin: Just over 20% of CO2 is chemically bound to...
Odds Ratio
Pharmacokinetic–Pharmacodynamic Relationship: Dose to Pharmacological Effect
Chronic Obstructive Pulmonary Disease-II: Pathophysiology
Chronic Inflammation

