The use of radioisotopes to measure regional lung water

A new technique for measuring regional lung water is described. The technique involves single-breath inhalation of C15O2 and 11CO2, with monitoring by external scintillation counters of lung clearance during breathhold. Preliminary studies in anaesthetised dogs and in isolated dog lungs, which validade the technique, are briefly presented. The results show a good correlation with directly measured lung water in non-oedematous lungs, but a tendence to overestimate lung water in the presence of oedema. The potential value of this non-invasive technique for sensitively detecting early pulmonary oedema in man is discussed.