2 Mechanism of Injury and Nature of Illness
Learn how to assess scene safety, identify a likely mechanism of injury or nature of illness, and use those findings to anticipate patient care and resource needs.
Assess the scene before contact
A begins before patient contact and continues throughout the response. It helps identify hazards, understand what may have happened, estimate how many people need help, and decide what precautions and resources are needed.
Do not enter an unsafe scene. Pause at a safe distance, use appropriate personal protective equipment, and request qualified assistance when hazards exceed your training or equipment. Because conditions can change, reassess safety as you work.
Recognize and manage hazards
Look for hazards to responders, patients, and bystanders. These may include:
Moving traffic, unstable vehicles, fire, smoke, and electrical hazards.
Weapons, violence, an agitated person, or an uncontrolled crowd.
Chemicals, gases, unknown powders, or other hazardous materials.
Unstable structures, falling objects, confined spaces, or difficult terrain.
Blood and body fluids, sharps, infectious exposure, extreme temperatures, or animals.
Keep a safe distance, use PPE appropriate to the risks, and follow local procedures. If the scene is unsafe, withdraw or remain staged and request appropriate support, such as law enforcement, fire or rescue, a utility provider, or a hazardous-materials team. Safety considerations also include vehicle safety, protection from infectious and hazardous substances, and awareness of violence and lifting risks.
Consider patient-related risks as well. A patient may deteriorate, remain exposed to danger, or be injured by unnecessary movement. Move a patient from danger when it is safe and necessary, using available help and local protocols.
Interpret injury and illness clues
The is how an injury occurred and the forces involved. A fall from height, vehicle collision, penetrating wound, or strike by an object can suggest injuries that may not be obvious, including possible internal bleeding after a forceful impact. MOI does not prove that an injury is present, and an event that seems minor does not rule one out.
Consider relevant details such as the event’s height, speed, direction, and impact points; restraint use; vehicle damage; ejection; and entrapment. Ask witnesses what they saw and observe the surroundings. Use these details alongside the patient’s symptoms and examination, not as a substitute for them.
The is the patient’s primary medical problem or reason for seeking help. Clues may include the patient’s complaint, appearance, breathing, behavior, and medical history, along with witness reports and scene evidence such as medication containers or medical identification. Treat these as clues rather than conclusions and confirm information with the patient or reliable sources when possible. An altered or unresponsive patient may be unable to describe what is wrong.
Use findings to plan care and resources
Use the scene, patient, and witness information to guide initial decisions:
Check safety and PPE needs. Identify hazards and decide whether additional responders must make the scene safe.
Establish what happened or what illness is likely. Consider the MOI or NOI using information from the scene, patient, and witnesses.
Count patients. Look beyond the first person found, especially after a collision or another incident involving multiple people.
Request resources. As indicated, request additional EMS, advanced care, rescue or extrication, law enforcement, fire services, or specialized support. For a multi-patient incident, follow local and incident-management procedures.
Anticipate care and transport needs. Findings may indicate possible hidden injuries, a need for prompt assessment, appropriate equipment, help with access or movement, and a suitable destination under local protocols.
A person found after a high-impact collision may have a serious injury despite being awake and having no obvious wound. The collision details should prompt careful assessment and readiness to manage deterioration, while the patient’s actual findings guide care. Conversely, a confused person with no clear injury may need prompt medical assessment; witness accounts and scene clues may help identify a medical cause.
Assessment findings guide care for injured and ill patients. Treatment, transport, and destination decisions should follow the responder’s certification level, medical direction, and local protocols.