Our basic approach to casualty modeling is to (1) generate a set of wounds and determine appropriate injuries on a simulated casualty either based on Army probabilities (conditioned on weaponry, battlefield layout, etc.) or through penetration path models (Section 3.1) ; (2) map them to likely findings through information in our trauma management decision support system, TraumAid (see Section 5.1); and (3) instantiate their physical and behavioral manifestations in a human figure simulated in Jack and their physiological manifestations in simulated PSM data.
Given the weaponry in use, battlefield layout, etc., conditional probabilities specify the likelihood of different wound(s). Given particular wounds, further conditional probabilities specify the types of injuries a casualty is likely to suffer. We will use these probabilities to generate simulated casualties. Alternatively, the stealth instructor can generate specific casualty types and responses (cf. Section 3.2).
Rules used in TraumAid to reason from findings and test results forward to diagnostic and therapeutic goals can be inverted to map penetrating injuries of the abdomen and chest, back to findings that in connection with wound specifications give evidence for those injuries. The problem that test results will not be available can be solved in the same way as in TraumAID's retrospective evaluation [8]: for diagnostic tests that were not performed during actual care, a realistic ``default'' database associated the likely result of each test with each particular discharge diagnosis.
Findings can manifest through a casualty's physical appearance or his behavior. On an actual casualty, physical appearance can be observed visually (e.g. distended abdomen, evisceration) or aurally (e.g., decreased breath sounds, stridor). Observation may be passive or require activity on the part of the corpsman (e.g., tactile probing for signs of tenderness and/or guarding). Behaviors that give evidence of injuries or degree of injury include confusion, level of response to commands, gasping muscle spasms, etc.
Although the current TraumAid system only covers penetrating injuries to the chest and abdomen, small TraumAid rule sets for upper and lower extremity injuries developed for the Navy's Submarine Center at Groton [7] will allow us to generate at least a subset of appropriate findings for such injuries as well.
We have demonstrated casualties exhibiting physical manifestations of selected integument and musculo-skeletal injuries. In the coming year, casualties will exhibit both physical and behavioral manifestations of additional integument, musculo-skeletal and internal injuries; for example, swelling, pale skin color, exposed viscera, breathing anomalies, muscle spasms, or facial expressions.