The transfer factor and its subdivisions in patients with pulmonary emboli.

The carbon monoxide transfer factor and its subdivisions, the pulmonary membrane diffusing capacity and the pulmonary capillary volume were measured in fourteen subjects following submassive pulmonary emboli, as demonstrated by a ventilation-perfusion scan, and in fourteen matched controls. Transfer factor and alveolar volume were significantly lower in patients with pulmonary emboli (p less than 0.02). Patients were given six weeks anticoagulant therapy and the measurements repeated three months later. There was a significant increase in the transfer factor and the alveolar volume (p less than 0.01) and the membrane diffusing capacity (p less than 0.05). It has previously been assumed that the reduction in the transfer factor following a pulmonary embolus is due to a reduction in the pulmonary capillary volume. Results of this study however, suggest that it is more likely to be due to a loss of alveolar volume, at least in subjects with submassive emboli.