Production of Pulmonary Edema by Aspiration of Water-Soluble Nonabsorbable Contrast Media

Water-soluble, nonabsorbable contrast media are frequently used when the danger of aspiration is very great. It has been stated that in such situations these contrast media are safer than barium sulfate mixtures (5). Some authors have indicated a preference for their use in conditions in which the possibility of aspiration exists—such as central nervous system abnormalities, neuromuscular disturbances, obstructing lesions of the pharynx, esophagus, etc. (2, 5). A recent report of a death after aspiration of a water-soluble contrast material (1) and a concern about the effect of hypertonic solutions on the lungs prompted this investigation. Method Long-Evans rats weighing 0.5 kg were anesthetized by injection of 30 mg of Diabutal intraperitoneally. Tracheostomies were carried out, and various media were injected into the lungs through small polyethylene catheters passed through the tracheostomies, usually into the right lower lobe main-stem bronchus. Serial chest roentgenograms were obtained, and gross anatomic and histologic examination of the lungs was performed. Results The effects of the injection of various contrast materials were studied, and the following results are reported. a. Animals injected with 1 ml water∕0.5 kg of body weight absorbed the water from their lungs rapidly and completely. b. Animals injected with 1 ml of normal saline∕0.5 kg absorbed the fluid from their lungs rapidly and completely. c. Pulmonary edema with involvement of both lungs developed rapidly in animals injected with 1 ml of Gastrografin∕0.5 kg. Dilution of the contrast medium and rapid death followed (Fig. 1). d. Animals injected with 1 ml of a 40 per cent Hypaque powder∕water mixture∕0.5 kg rapidly went into pulmonary edema in the same fashion as those injected with Gastrografin (indicating that the flavoring agents in Gastrografin had no effect on the outcome). e. Animals injected with 1 ml of 76 per cent Renografin∕0.5 kg followed the same course as those injected with Gastrografin. (∕) In animals injected with 1 ml of Barotrast-water mixture (1 g Barotrast per 30 ml of final mixture)∕0.5 kg most of the barium collected in localized areas of the lung and remained there. The rest of the lungs functioned well, and the animals survived with only the problem of mechanical inspissation of the barium (Fig. 2). f. In animals injected with 1 ml of Dionosil oily∕0.5 kg most of the material collected in localized areas of lung. They survived with some mechanical block of the major airways (similar to the finding with Barotrast) and some pulmonary edematous reaction to the contrast medium (Fig. 3).