Transfer of 99mTc-DTPA, lung surfactant and lung injury: a review of the literature.

Measurement of the alveolo-capillary transfer of radiolabelled solutes provides information about the integrity of the alveolo-capillary barrier. The transfer of 99mTc-diethylen triamine penta-acetate ( 99mTc-DTPA) can be easily measured after tracer delivery in aerosol form and external monitoring of radiation over the lung. Although the technique has been used extensively for more than ten years, the basic mechanisms for pulmonary clearance of 99mTc-DTPA remain incompletely understood. Experimental evidence that the rate of clearance partly reflects the functional integrity of the pulmonary surfactant system is reviewed together with clinical studies with possible relation to surfactant function.