Development and Evaluation of New Products for the Far-Forward Care of Combat Casualties With Acute Lung Injury
Annual rept. 1 Feb 2004-31 Jan 2005
TRUE RESEARCH FOUNDATION SAN ANTONIO TX
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To characterize the acute respiratory distress syndrome ARDS caused by chlorine gas Cl2. Toxic industrial chemicals TICs have recently been identified as potential terrorist weapons. Several TICs act primarily on the respiratory tract, but more work is needed to define the pathophysiology and treatment of these injuries. Anesthetized female sheep n35, 42.4kg - 5.4 SD were ventilated with 300 L of a Cl2airoxygen mixture over 30 min. Doses were 0 ppm Control, Group 1 120 ppm Low Dose, Group 2 240-350 ppm Medium, Group 3 and 400-500 ppm High, Group 4. After injury they were maintained for 96 h in an animal ICU. Gentle mechanical ventilation peak airway pressure 40 cmH2O was required to limit barotrauma. Cardiopulmonary data were collected every 6 h, and CT scans daily. The multiple inert gas elimination technique MIGET was used to characterize the etiology of hypoxemia. Lung function was well maintained in Group 1 Cl2 caused immediate and sustained acute lung injury PaO2-to-FiO2 ratio, PFR300 in Group 2, and ARDS PFR200 in Groups 3-4 ANOVA p.0001 betweenwithin groups. Cl2 also rapidly caused hypotension and decreased cardiac output, lasting 48 h in survivors. All animals in Groups 1-2 survived 96 h. Kaplan-Meier analysis showed dose-related differences in survival Log Rank test, p.OO0l. Logistic regression identified 280 ppm as the lethal dose 50. CT and histopathology demonstrated lesions of both small airways and alveoli. MIGET showed diversion of blood flow from normal to true-shunt lung segments. Cl2 causes severe, dose-related lung injury, with features seen in both smoke inhalation small airway lesions and ARDS secondary to systemic disease alveolar-endothelial lesions. This model will be used to test the Intravenous Membrane Oxygenator being developed by ALung Technologies, Inc. in collaboration with the University of Pittsburgh.
- Medicine and Medical Research
- Unconventional Warfare