Just as trauma casualties present differently (blunt, trauma, GSW, blasts, etc.), CBRN casualties also have varied presentations. For example, chlorine casualties will require more attention to the toxic inhalation symptoms contrasted with a mustard casualty whose associated trauma may require more prompt intervention than the mustard-specific effects. CBRN casualties can be categorized by circumstances of exposure and presence or absence of trauma and CBRN effects. The acronym CRESS (Consciousness, Respirations, Eyes, Secretions, Skin) is employed to improve rapid identification of the type of chemical agent exposure.

In a CBRN-threat environment, casualties may have traumatic, CBRN or mixed injuries. Before applying TCCC, it is important to identify whether CBRN injuries are present and identify a suspected agent to allow first responders to protect themselves before treating the patient. While this often can be deduced using intelligence reports, technologic agent identification resources, and circumstances of the CBRN event, there will be times when agent identification will need to be made solely based on clinical assessment of symptoms. Some CBRN agents, such as nerve agents, can be rapidly fatal; therefore, recognition of such symptoms is the equivalent of identifying massive hemorrhage in the trauma patient. Clinical clues can be aggregated to identify the most likely agent responsible for symptoms according to the CRESS assessment. Each letter in CRESS corresponds to physical exam findings that can be used to categorize the suspected agent based on the constellation of findings. CRESS findings associated with specific chemical agents are shown in Table 3.

Figure 3. The acronym CRESS

The acronym CRESS is used to differentiate exposures to chemical agents. Exposure to biological agents is unlikely to cause early symptoms. Radiologic exposure may lead to early onset of symptoms (<1 hour post exposure) such as nausea, vomiting, diarrhea, and fever with high dose exposures (>6 Gray). CRESS findings for select chemical agents are summarized in Table 3.