 Data on demographic, physiologic, and radiographic characteristics, coexisting conditions, and medication will be recorded within 4 h prior to randomization. For the first 10 days post-randomization, at least 3 sets physiologic measurements blood-gas analysis, hemodynamics, and respiratory mechanics during CMV will be obtained daily. Laboratory, radiographicimaging, and physiologic data will be collected daily until ICU discharge or death. Patients will be monitored daily for signs of failure of nonpulmonary organs and systems. Patient clinical course will be documented until hospital discharge or death. 