Assessment and management of CBRN casualties is complex because it involves not only life-threatening symptoms but also the threat of contamination of all first responders. An added source of complexity is the frequent mixing of CBRN and penetrating trauma injuries (Figure 3). Working through this complexity involves a stepwise approach that first rules in or rules out CBRN injuries so that first responders can protect themselves if necessary before rendering aid. The next step integrates assessment and management of both CBRN and traumatic injuries, prioritizing the recognition and management of life-threats first.

CRESS: A SIMPLIFIED APPROACH TO  CBRN CASUALTY ASSESSMENT

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 initially 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.

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 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. Clinical clues can be aggregated to identify the most likely agent responsible for symptoms according to the CRESS assessment. Infectious agent exposure, for example, is unlikely to cause early symptoms (see CBRN CPG Part 4), while toxins, chemical and high dose radiologic exposures may lead to symptoms in minutes to hours (see CBRN CPGs Part 2-4). A CRESS assessment can be used to assess which chemical toxidrome exposure may be linked to. Each letter in CRESS corresponds to physical exam findings that can be used to categorize the suspected chemical based on the constellation of findings (Table 3). A depiction of time to onset of signs/symptoms as well as common chemical toxidromes and biological and radiological syndromes can be found in Figure 4.

Source: Calder A, Bland S. CBRN considerations in a major incident. Surgery. Volume 36, Issue 8. Pages 417-423. 201

Antidote Treatment - Nerve Agent, Auto-Injector (ATNAA) [2.1 mg atropine and 600mg pralidoxime (2-PAM)]; Convulsant Antidote for Nerve Agent (CANA) [10mg diazepam]; Advanced Anticonvulsant System (AAS) [10mg midazolam]; Rapid Opioid Countermeasure System (ROCs) [10mg naloxone]

¹May be variable due to agent characteristics, exposure dose, individual response variability, PPE worn at time of exposure, and whether antidotes administered.

²May be variable due to agent characteristics, exposure dose, individual response variability, PPE worn at time of exposure, and whether anticholinergics administered.

³ROCS (naloxone) does not have any significant drug interactions with the drugs contained in ATNAA, CANA or AAS.

⁴Depending on the agent and dose there may be convulsions.

⁵If wearing PPE may be diaphoretic.

⁶Reference ATP 4-02.85/MCRP 4-11.1A/NTRP 4-02.22/AFTTP(I) 3-2.69 for nuances of self-aid, buddy aid, combat lifesaver care, or treatment by the combat medic/corpsman/Air Force medic.

(MARCHE)²: INTEGRATING TCCC MARCH WITH CBRN FIRST RESPONSE

After initial assessment of casualties for the presence or absence of CBRN symptoms using the CRESS algorithm (and donning of PPE by first responders), the integrated assessment and management of TCCC and CBRN injuries can proceed.

The acronym (MARCHE)² integrates the established TCCC MARCH algorithm (Massive Hemorrhage, Airway, Respirations, Circulation, Hypothermia) with CBRN MARCHE priorities (Mask, Antidotes, Rapid spot decontamination, Countermeasures, Extraction and Evacuation). Combining these two approaches gives the acronym (MARCHE)² or “MARCH-squared.”

Similar to TCCC, (MARCHE)² can be broken into phases of care from highest threat (care under fire or active CBRN threat), to intermediate threat (tactical field care or warm zone casualty management), to lowest threat (Prolonged Field Care (PFC)/evacuation or cold zone care of decontaminated casualties) (Figure 6 below).

PUTTING IT ALL TOGETHER:  CRESS AND (MARCHE)²

Step 1: Hot Zone / Care Under Fire

The hot zone is an area where there is an immediate and ongoing threat to casualties and responders. During “hot zone” care, the agent itself is similar to enemy fire. As such, the priorities are protection and egress away from the threat (CBRN agent) for both casualty and provider. Both the casualty and provider should don protective masks. If the casualty is incapacitated, the provider must ensure the casualty’s protective gear is applied and functional.

Only rapid interventions for immediate life-threats should be addressed. This typically includes management of catastrophic hemorrhage, airway problems, and antidote administration before evacuating out of the hot zone for decontamination and further treatment. Massive hemorrhage, if present, is the most immediate life threat and control of hemorrhage supersedes other interventions. Massive hemorrhage, if compressible, should be treated according to TCCC guidelines with limb or junctional tourniquets, as applicable.

Perform a rapid assessment of the airway and respirations. Excessive secretions and increased respirations may indicate nerve agent exposure. Completion of the CRESS assessment will help determine if the symptoms are due to trauma or chemical agent exposure. Most airway and respiratory interventions should be deferred, though there are some interventions that may take priority over mask application. The decision to unmask a casualty to provide these interventions needs to be weighed against the risk of the contaminated environment.

Some CBRN agents are rapid killers. The CRESS assessment will quickly determine whether immediate antidotes are required. If exposure to a rapidly killing agent (i.e. nerve agent, cyanide, opioid incapacitating agent) is suspected, administer the appropriate antidotes (ATNAA/AAS, hydroxocobalamin, naloxone). Cyanide treatment can be considered in the hot zone, but the need to establish IV/IO access to administer hydroxocobalamin makes this a judgment call weighed against the time needed to reach the warm zone and the ongoing threat in the hot zone location. If nerve agent exposure is suspected (decreased level of consciousness, increased respirations, constricted pupils, increased secretions, diaphoretic skin), then the provider should direct self-administration of Antidote Treatment Nerve Agent Auto-injector (ATNAA) and Convulsant Antidote for Nerve Agent (CANA) or administer the antidotes for an incapacitated casualty. 

Rapid spot decontamination of skin or wounds is indicated when there is gross contamination on the skin or wounds or when protective gear is breached. If wound contamination with a chemical agent is suspected, immediately expose the wound to perform rapid spot decontamination even in a contaminated environment. This step is necessary even in a contaminated environment and may be lifesaving.

As in TCCC, non-essential interventions should be deferred until the next phase of care.

Step 2: Warm Zone / Tactical Field Care

In the warm zone, or tactical field care phase, attention is given to decontamination and reassessment of the casualty. This phase occurs at a dirty CCP (hotline) and requires personnel dedicated to triage, decontamination, and patient treatment.  At this phase, interventions may have altered the clinical presentation of the casualty, so it is important to take into account prior interventions and changes in the clinical status of the casualty and administer life-saving treatments.

Note: Casualty Flow moves from top to bottom in this diagram. Triage flows immediate to delayed from left to right in the hot zone diagram. Medical personnel, at least one provider designated clean and one provider designated dirty

Decontamination and treatment should be a synchronous process. Medical personnel need to clearly communicate with non-medical personnel responsible for decontamination. “Expose to treat” is used by decontamination personnel when the provider deems it in the best interest of the casualty to remove PPE to provide life-saving medical intervention. For example, the mask may be removed and the head, face, and chest quickly decontaminated for the provider to ventilate the casualty and insert a sternal IO if parenteral antidotes, blood product, or fluid resuscitation are immediately indicated. It may also be appropriate to prioritize decontamination of an extremity to establish an IV or IO access, should a sternal IO not be an option.

Circulation should be assessed to identify external hemorrhage and shock. Per TCCC guidelines, fluid resuscitation is only indicated for altered mental status in the absence of brain injury and/or a weak or absent radial pulse. The provider can also assess the effects of both CBRN agents and antidotes on the patient’s circulatory status. As decontamination ensues, dirty treatments are replaced with clean. Due to cold water and the need to fully expose the casualty in order to conduct thorough decontamination, hypothermia is a significant risk. Added to the hypothermia risk is the fact that exposure to many of the chemical warfare agents will themselves cause hypothermia of the casualty. Ensure rapid transit through the decontamination line with careful attention to hypothermia mitigation to prevent iatrogenic injury from the decontamination process due to exposure. Additionally, it is important to recognize that personnel working within the warm zone in full protective gear are at risk of heat injury and stressors associated with operating in PPE.

Step 3: Cold Zone / Tactical Evacuation Care / Prolonged Field Care

Once the decontaminated casualty has passed into the cold zone, they should be re-evaluated and receive needed interventions including tactical evacuation or prolonged field care. The decontamination process can result in significant change in the casualty’s condition, so re-triage and reassessment are the first priority. A secondary survey should be done immediately after re-assessment of the primary survey. Documentation throughout the phases of care is vital to facilitate information transfer as the patient transitions from one phase to another. The CBRN casualty card (Appendix C) is a useful tool to ensure comprehensive documentation relevant to the CBRN casualty. In the absence of a CBRN casualty card, the TCCC casualty card is sufficient if duration of care before transfer is short. If handoff of care is delayed, PFC documentation will likely be necessary.⁹

It is important to consider that receiving providers at all roles of care may have limited experience with CBRN patients. Communication is crucial to ensure receiving providers understand previous decontamination, care, and exposures that may be suspected as to prevent unnecessary repetitive decontamination or redundant treatments. 

Casualties that reach the cold zone have been decontaminated and are now suitable for the full spectrum of care appropriate to the clinical environment and capabilities. There are, however, some unique concerns to address in a combination CBRN/trauma casualty. Consider the casualty may have retained foreign material or contaminated dressings in wounds. Such material may pose a risk to treating personnel from off-gassing or secondary contamination. Additionally, this residual contamination may represent a source of exposure to the patient via a route that bypasses the normal skin barriers resulting in rapid systemic distribution of the agent. Larger fragments should be removed from the wound using a “no touch” technique with surgical instruments and placed in a sealed container with hypochlorite solution, minimizing the risk to providers. The contaminated wound should be further irrigated with clean water. Providers dealing with contaminated foreign material or dressings can wear 3 pairs of nitrile gloves. The outer gloves should be discarded every 20 minutes. In the absence of suspected retained debris, the fully decontaminated patient in the cold zone can be treated as all other patients at that level of care.