EMS Zones of Care

Issues of Concern

Hot Zone 

The Hot Zone (Red Zone) represents the most dangerous area in a disaster or tactical incident, where active threats, such as gunfire, explosives, or HAZMAT agents, are present. The primary focus in this zone is threat suppression, preventing additional casualties, evacuating the wounded to safer areas, and controlling life-threatening hemorrhage. Due to the high risk posed to both responders and patients, only minimal medical intervention is allowed, prioritizing rapid extraction and hemorrhage control to prevent further injury. Life-threatening extremity hemorrhage is the sole medical intervention conducted in the Hot Zone. In many cases, only law enforcement or specialized tactical EMS units are permitted to enter, with strict requirements for protective body armor and, at times, firearms.

Acceptable medical treatments in the Hot Zone include immediate hemorrhage control, such as direct pressure and tourniquet application.[11] High mobility is essential for providers, who should carry only critical equipment to enable swift action. If HAZMAT products are involved, responders must wear the highest level of personal protective equipment (PPE), such as Level A suits, with the size of the Hot Zone determined by factors like wind direction, topography, and the type of HAZMAT agents present.[12][13] (Source: Burke, 2021) The primary medical objective in this zone is to quickly move both the patient and provider to a safer area, where more comprehensive care can be administered.[14][15]

Warm Zone

The Warm Zone (Yellow Zone), also known as the Tactical Field Care Zone, serves as a transitional area where the risk is lower than in the Hot Zone but still present. Any operational area with potential risk to patients or providers, yet without an immediate or direct threat, should be classified as a Warm Zone. (Source: Callaway, 2020) The concept of a Rescue Task Force (RTF) is crucial when delivering care in this zone. While care in the Hot Zone is primarily provided by law enforcement and fire personnel, the Rescue Task Force concept involves a 2nd wave of law enforcement escorting civilian EMS into the Warm Zone, reducing EMS response time.[16][17][18]

Although the threat level is reduced, time spent in the Warm Zone should still be limited, as a potential threat remains. Care in this zone should focus on immediate life-saving procedures. Warm Zone Care involves performing critical interventions using the MARCH algorithm while operating in a tactical environment. The MARCH algorithm, used in both TCCC and TECC, prioritizes life-saving interventions in high-risk environments. The acronym stands for:

• Massive hemorrhage: Controlling life-threatening bleeding
• Airway: Ensuring an open airway through maneuvers and positioning
• Respiration: Assessing and treating breathing issues, such as tension pneumothorax
• Circulation: Managing shock by addressing internal bleeding, monitoring pulse, and administering fluids as needed
• Hypothermia (and head injury): Preventing hypothermia and recognizing traumatic brain injuries

Table 2 describes acceptable life-saving medical interventions according to the MARCH algorithm (see Table 2. Life-Saving Medical Interventions Based on the MARCH Algorithm).[19]

Table 2. Life-Saving Medical Interventions Based on the MARCH Algorithm

Management of non-life-threatening injuries should be deferred. Rapid establishment of a casualty collection point (CCP) in the Warm Zone is essential, providing a centralized location for casualties evacuated from the Hot Zone who require further medical treatment.

The primary focus in the Warm Zone is the continued treatment of life-threatening injuries and the establishment of a CCP. A rapid and efficient CCP is essential for triaging casualties evacuated from the Hot Zone who require further medical treatment.

Acceptable medical treatments in the Warm Zone include the application of additional tourniquets or hemostatic agents, along with a quick reassessment of the patient for any unrecognized or untreated hemorrhage. Any tourniquets already in place should be reassessed for effectiveness and adjusted or reinforced with additional tourniquets as necessary. Other hemorrhage control options include wound packing with a pressure bandage or hemostatic gauze with direct pressure.

Airway management in the Warm Zone involves basic maneuvers such as chin lifts and the insertion of nasopharyngeal airways. In cases of severe airway compromise, a cricothyroidotomy is preferred over intubation due to its speed and effectiveness in tactical settings.[20] For tension pneumothorax, needle decompression should be performed with frequent reassessments to ensure effectiveness.[21]

For open chest wounds (open pneumothorax), chest seals should be placed, with vented chest seals recommended over unvented ones based on evidence from animal models and updated international guidelines.[22] Any chest seal placed must be monitored frequently for the development of a tension pneumothorax, with appropriate treatment provided.[23] Additional measures to prevent and treat hypothermia and shock, such as rewarming techniques and administering intravenous fluids, may also be appropriate during Warm Zone care.

The treatment of non-life-threatening bleeding or injuries, such as fractures or moderate burns, should be deferred to the Cold Zone. These non-life-threatening injuries do not require immediate care in the Warm Zone.

The Warm Zone remains fluid, requiring constant awareness of the evolving threat environment. Due to the dynamic nature of this zone, medical procedures should be performed quickly, with the understanding that evacuation to the Cold Zone may be necessary at any moment. Formal triage does not occur in this zone. Ambulatory patients should bypass the Warm Zone and go directly to the Cold Zone. If HAZMAT substances are involved, additional personal protective equipment may be required to ensure responder safety during medical interventions and decontamination procedures.

Cold Zone

The Cold Zone (Green Zone), also known as the Casualty Evacuation Zone, is the safest area where comprehensive medical care can be provided without immediate threats to providers or patients. Establishing a treatment area in the Cold Zone is essential for effectively managing patient care. This zone serves as the location for 2 main patient populations: ambulatory patients who self-extricated from the Hot Zone, and nonambulatory patients who were treated in and evacuated from Warm Zone CCPs.

Formal triage is critical in the Cold Zone to ensure both ambulatory and nonambulatory patients receive appropriate care. Ambulatory patients may have unrecognized life-threatening injuries, while nonambulatory patients require thorough evaluation and reassessment of prior interventions, as care in the Hot and Warm Zones may have been provided under duress. In the Cold Zone, standard EMS teams deliver care according to established local, regional, or state protocols. Timely evacuation to local medical facilities is essential, with the highest-priority patients transported to the most suitable nearby facility.

In mass casualty incidents, transporting lower-acuity patients to facilities farther away may be more appropriate to prevent overwhelming the closest medical centers. Patient tracking must be coordinated across the entire medical system, including hospitals, fire services, and EMS, to facilitate family reunification. Hospitals must collaborate with first responder services, especially since some patients may arrive by private transport, and technologies such as barcode scanners and facial recognition should be utilized to maintain accurate records and streamline the process. (Source: Callaway and Burnstein, 2020)

The primary focus in the Cold Zone is the stabilization of patients and preparation for transport. Standard EMS protocols apply, with interventions including full airway management, fluid resuscitation, and wound care as necessary. Although the Cold Zone is generally safe, responders must remain vigilant for any operational hazards that may arise.

A thorough reassessment of all interventions should be conducted in the Cold Zone. Steps include checking the effectiveness of tourniquets, verifying airway management devices, and inspecting decompression catheters for potential blockages. Effective communication during patient transfer is crucial, as transport teams may not be familiar with tactical medicine protocols. Ensuring that all interventions are clearly documented and communicated can help prevent complications during transport and ensure continuity of care.

Clinical Significance

Zones of care are fluid and dynamic, requiring responders to maintain continuous situational awareness and adaptability. Each zone presents distinct risks and demands specific medical and safety protocols. Weather, environmental factors, and the evolving nature of the emergency can alter zone boundaries in real-time, adding complexity to care delivery.

In high-threat rescue missions, the core principle is to deploy a minimal number of personnel into the Hot Zone to evacuate the wounded to the Warm Zone for stabilization swiftly. Subsequently, casualties should be rapidly transported to the Cold Zone for definitive care and further evacuation. The ultimate goal is to transition patients from high-risk areas to definitive care as safely and efficiently as possible, ensuring the safety of both providers and patients throughout the process.