carbon monoxide transfer factor

- transfer factor is a measure of transfer of gas across the alveolar capillary membrane and reflects the uptake of oxygen from alveoli into the red cells.Transfer coefficient is KCO.
- TLCO is the product of KCO and alveolar volume
- any factors which increases the number of red cells that come into contact with carbon monoxide will increase TLCO and KCO - alveolar hemorrhage, alveolar inflammation, asthma, exercise, polycythemia, left to right shunt (eg:ASD)
- causes of decreased TLCO and KCO - anemia, interstitial lung disease, multiple pulmonary emboli, lymphangitis, primary pulmonary hypertension, obstructive airway disease
- extrapulmonary restriction (thoracic cage deformities,pleural disease, respiratory muscle weakness) causes reduced TLCO but raised KCO (increase density of blood per unit lung volume)