Abstract : Noninvasive monitoring and distant assessment of status of the injured may revolutionize critical care if data analysis techniques can be validated that identify physiologic deterioration before changes in conventional vital signs. For the last several decades, monitoring and diagnosing injury severity have been based on changes in time averaged means of heart rate and blood pressure interpreted in context of visual assessment of the patient. However, changes in heart rate and blood pressure generally do not occur until compensatory mechanisms are exhausted. The latter may explain why conventional vital signs are poor and late descriptors of life threatening changes in the patients' condition. A recent study reported that 23% of prehospital trauma patients with normal vital signs required life saving interventions. To make matters worse, visual assessment of the patient may not be possible during mass casualty and natural disaster situations or may need to be postponed during combat to avoid danger to the medic's life. To improve our ability to monitor and diagnose critical illness in the civilian setting and to assess combat casualties from a distance, we need new vital signs that are superior to conventional vital signs in their ability to provide timely assessment of injury severity and predict the need for life saving interventions. The 2 presentations by Dr Batchinsky provide an insight into the research pertinent to the development of new vital signs carried out within the US Army Institute of Surgical Research Combat Critical Care Engineering Task Area. The first presentation, Complexity in Animal Models, is an overview of recently completed and ongoing research at the US Army Institute of Surgical Research involving various animal models of hemorrhagic shock, resuscitation, trauma, inhalation injury, apnea, and other critical states.