A physiological approach to reading critical care unit films.

Radiologic assessment of pulmonary vascular pressure and flow and quantitation and determination of the etiology of pulmonary edema is reviewed and new data provided to calculate "true" cardiac size from portable films. The quantitation of changes in intra- and extravascular water and a more accurate approach to the assessment of left atrial pressure are discussed and new anatomical observations offered to explain post-operative left lower lobe atelectasis, and severe soft tissue emphysema which may follow chest tube insertion in a patient with very stiff lungs. Radiographic data have now been shown to be sufficiently objective so that when a discrepancy occurs between the radiologic analysis and laboratory data, the laboratory data should be cross-checked and its accuracy confirmed before treatment based on these data alone is instituted.