In the course of developing a model of inhalation injury, the relationship between the severity of pulmonary injury and specific techniques and doses of smoke exposure was examined in pairs of rabbits simultaneously exposed to smoke. In group I (5 pairs), one animal in each pair was exposed to smoke with a breath hold (BH) at the end of each exposure; the second animal received an exposure producing the same level of carboxyhemoglobin without BH. In group II (6 pairs), both animals were exposed to 25 units of smoke simultaneously, with BH. In group III (3 pairs), one animal received a 20-unit exposure and the other a 25-unit exposure, both with BH. In group IV, 9 animals received 25-unit exposures with BH and were observed for 4 days. Groups V and VI served as controls. Smoke exposure with BH regularly produced severe injury in terms of decreased Pao2 and histopathologic changes, while exposure without BH did not, despite high levels of carboxyhemoglobin after smoke inhalation. The mean differences in percent residual Pao2 (Pao2 at 48 hours x 100/pre-injury Pao2) and in extravascular lung water (EVLW) at 48 hours within pairs of animals receiving 25 units with BH were 12.3% ± 5.33%, and 0.271 ± 0.157 mL/g, respectively. Histologic findings such as necrotic tracheobronchitis with pseudomembrane were consistently present. No differences were observed between animals receiving exposures of 20 and 25 units. During the 4 days of observation, three animals in group IV died. Pao2 was lowest on the second day and rose thereafter in all surviving animals except in one that had massive pneumonia. Extravascular lung water levels were still elevated on the fourth day after injury. Histologically, the destroyed surface epithelium in the airway was covered by a nonciliated epithelium, and focal pneumonia was found frequently in the pulmonary parenchyma. These results indicate an advantage of the extended exposure afforded by BH in creating consistent, severe injury and the important part played by pneumonia in determining prognosis beyond the second postinjury day. The model appears useful for evaluating the effects of inhalation injury with concurrent cutaneous burn or wound infection, and for assessing various regimens for the treatment of inhalation injury.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Trauma - Injury, Infection and Critical Care|
|State||Published - Mar 1993|
ASJC Scopus subject areas
- Critical Care and Intensive Care Medicine