THE USE OF RADIONUCLIDE TECHNIQUES IN THE ASSESSMENT OF ALVEOLAR-CAPILLARY MEMBRANE-PERMEABILITY ON THE INTENSIVE-CARE UNIT

Three isotopic methods of estimating alveolar-capillary membrane permeability have been described. The first, radiolabelled HSA, is crude, and appears to have no clinical applications. Pulmonary99mTc-DTPA clearance studies are relatively easy to perform, but suffer from their high sensitivity and variations in technique from centre to centre. The double isotopic measurement of PAI has only been adopted by a few centres, but may offer reliable assessment of the pulmonary endothelial permeability which is probably an early marker of acute lung injury. None of these techniques has proved predictive of outcome in ARDS. However, trials where alveolar-capillary membrane permeability is assessed before clinical evidence of lung injury is apparent have yet to be conducted. Thus at present, methods of assessing alveolar-capillary membrane permeability, particularly capillary endothelial integrity, may prove to be more useful in monitoring new therapeutic interventions in lung injury, rather predicting outcome. © 1990 Springer-Verlag.