Zones of care are the term used in the prehospital setting to delineate locations that require different levels of care and/or safety. Operationally speaking these zones help delineate the personnel and equipment that can and should be used depending on the type of incident. Color or name delineate these zones, and they vary from agency to agency, so a cohesive response and the use of "regular language" are important to make sure the right people and resources are in the correct location.
Numerous organizations and types of scenarios, from disasters to weapons of mass destruction to the military, use zones of care, but in different terms.
The most dangerous zone of care within tactical medicine is care under fire, also known as a hot zone or red zone). This zone poses the highest risk to life, and therefore limited care should be provided. This is a location that is not safe for anyone, regardless of firepower or training. It is an active area of shooting, and there is a possibility of imminent injury. The quickest and most life-saving treatments should be deployed here as to limit the risk to the caretaker and patient. The only medical treatment in this zone should be essential hemorrhage control, for example, pressure or tourniquet use. The secondary goal is to get to a safer area. This could mean either moving within the hot zone where there is cover or moving to the warm zone or what is also known as tactical field care zone. Getting to a protected area to prevent further injury is also critical. Preventing further injury is one of the top priorities within the hot zone when care is being rendered. The personnel providing care in this location needs to be mobile and steady on their feet, so limited equipment is expected and required in this zone.
In terms of a hazardous materials scenario this zone is where the release or agent in question is and may require greater levels of personal protective equipment.This is usually a level A suit. The size of this zone is dictated by the nature of the incident, wind direction, topography, and type of agent. Guidelines based on suspected agent can be found in the emergency response guidebook or a number of mobile phone applications.
The second zone of care is tactical field care also known as a yellow zone or warm zone. This is a zone that is not as dangerous as the care under fire or hot zone but is still not completely safe from danger. This zone is dynamic in nature and dependent on the location of the threat, the mobility of the threat, and the mobility of the patient. This zone is where most of the care of the sick and injured is accomplished, in respect to tactical medicine. Care can be varied depending on the equipment available, the location of local hospitals, and expertise of personnel. In this zone, additional hemorrhage control with tourniquets and/or hemostatic agents continues. While the previous treatment is similar to the care under fire zone, further treatments are limited to the tactical field care zone and green zone to ensure the safety of the provider and patient. These treatments require additional equipment that is not conducive to being carried into a hot zone. Basic airway maneuvers (chin lift, nasal airway) are easy to provide, require no equipment, and can be life-saving. If these maneuvers fail due to airway compromise or distorted anatomy from injury the next maneuver is cricothyroidotomy. This seems to go against current emergency medicine practice where intubation is usually the next step. In this tremulous location, a cricothyroidotomy is quicker and provides a definitive airway faster than intubation. This is imperative due to the fluid nature of the zones of care and the need to mobilize at a moments notice. Tension pneumothorax is a condition that is also treated in this zone with needle decompression. Watching for rapid deterioration due to a tension pneumothorax is important. Rapid treatment with needle decompression is paramount. It is fast and easy to perform when the patient is exposed.
This zone is may require additional personal protective equipment depending on whether or not gross decontamination has already occurred during a hazardous materials incident. Otherwise, it may be initiated here. It is still a very highly operational zone and great care needs to be taken as exposures may still occur.
The third and safest is the tac-evac zone, also known as the green zone or cold zone where basic emergency management services can be performed. This is the zone outside of immediate danger and transportation is usually available. This location is the safest, and there is no immediate danger to the provider or patient. This zone can be thought of like a regular operational zone. In this zone, continued care and reassessment are the keys to ensure patient safety. Since the patient would have had to be moved from a hot zone to a warm zone to the cold zone, alteration of equipment location may occur. One should reexamine tourniquets to make sure they have not loosened or moved, airway equipment needs to be checked to make sure the patient is still ventilating, and needle decompression catheters need to be checked that they have not kinked or been occluded (with blood or debris). The last step to provide in the cold zone is hand off to the transporting team. This can be a team of equal, less, or higher trained individuals. It is important to give a summary of what was done. Also, not all transportation teams are familiar with tactical medicine, and a quick bedside education on what was done and why it was done would be helpful to make sure proper care is continued en route to definitive care.
While the threat of exposure is less likely in a hazardous materials incident, normal operational hazards must still be considered.
All zones are dynamic and depend on where a perpetrator or agent may be located or move to in the course of any situation. Responders must also take into account the effects of weather and how this can alter the zones of care in real time.
Zones of care are dynamic and fluid. Each zone has its inherent risks on top of the overall risk to a provider of personal protective equipment. These scenarios are usually chaotic and messy, which can lead to further injury to the provider or patient.