Computed chest tomography in an animal model for decompression sickness: radiologic, physiologic, and pathologic findings

This study was conducted to investigate the early pulmonary effects of acut e decompression in an animal model for human decompression sickness by CT a nd light microscopy. Ten test pigs were exposed to severe decompression str ess in a chamber dive. Three pigs were kept at ambient pressure to serve as controls. Decompression stress was monitored by measurement of pulmonary a rtery pressure and arterial and venous Doppler recording of bubbles of iner t gas. Chest CT was performed pre- and postdive and in addition the inflate d lungs were examined after resection. Each lung was investigated by light microscopy. Hemodynamic data and bubble recordings reflected severe decompr ession stress in the ten test pigs. Computed tomography revealed large quan tities of ectopic gas, predominantly intravascular, in three of ten pigs. T hese findings corresponded to maximum bubble counts in the Doppler study. T he remaining test pigs showed lower bubble grades and no ectopic gas by CT. Sporadic interstitial edema I was demonstrated in all animals - both test and control pigs - by CT of resected lungs and on histologic examination. A severe compression-decompression schedule can liberate large volumes of in ert gas which are detectable by CT. Despite this severe decompression stres s, which led to venous microembolism, CT and light microscopy did not demon strate changes in lune structure related to the experimental dive. Increase d extravascular lung water found in all animals may be due to infusion ther apy.