Long COVID Atlas
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Long COVID Atlas › Glossary › Gas transfer (DLCO)

Physiology

Gas transfer (DLCO)

https://longcovidatlas.org/glossary/gas-transfer

In plain language

What it is

How well oxygen crosses from the air sacs in your lungs into your blood.

Why it matters

It can be reduced in long COVID even when an ordinary scan and breathing test look normal.

Think of it like

A measure of how easily air gets through the final gate into the bloodstream.

Where oxygen crosses, and where long COVID slows it alveolus · oxygen in the air barrier: epithelium · interstitium · ENDOTHELIUM (where damage sits) in long COVID, fewer oxygen molecules complete the crossing capillary · red blood cells (RBC) RBC : tissue-plasma transfer (xenon MRI) healthy 0.45 long COVID 0.31
Oxygen has to cross three layers to reach your red blood cells: the air-sac wall, the tissue and plasma in between, and the vessel lining. A xenon-gas MRI measures how much actually completes the last step into red cells. In long COVID that transfer drops, to about 0.31 against 0.45 in healthy volunteers, even when an ordinary scan is normal, because the bottleneck sits at the lining rather than in the airways.

For specialists

Formal definition

Diffusing capacity of the lung for carbon monoxide (DLCO/TLco), or the xenon MRI red-blood-cell to tissue-plasma ratio, measuring alveolar-capillary transfer.

Mechanism

Damage at the vessel-lining side of the barrier can lower transfer while airways and routine imaging stay normal.

Sources

Related terms

Endothelial dysfunction