3.1 Pre-Arrival Plan of Action

The five components of scene size-up

Scene size-up is the first formal step of patient care on every EMS call, and the National Registry tests it as a structured task with five required components. Memorize them, because exam stems are written so that the correct first action is almost always one of these five:

1. Scene safety — Is it safe for you, the crew, the patient, and bystanders to be here?
2. Mechanism of injury (MOI) or nature of illness (NOI) — What happened, and how much force or what kind of illness is involved?
3. Number of patients — How many people need care? Count before committing to the first one you see.
4. Need for additional resources — More ambulances, fire, law enforcement, rescue, utilities, or hazmat?
5. Standard precautions (BSI) — What body-substance isolation and PPE does the suspected exposure require?

Scene Size-Up and Safety is a large, heavily weighted block on the updated EMR test plan, so a large number of scenarios begin before you ever touch the patient. The exam wants proof that an entry-level Emergency Medical Responder (EMR) — the first tier of the NHTSA National EMS Scope of Practice Model, below EMT, AEMT, and Paramedic — can convert raw scene information into safe, effective action with limited equipment.

Plan before you arrive

Pre-arrival planning uses dispatch notes, caller statements, address, time of day, weather, access, and early visual clues to decide what you will do first. The plan should answer simple operational questions. Where will you park? What PPE is likely needed? Could the scene become violent, unstable, contaminated, or hard to leave? Are there probably more patients than the caller reported?

Do not treat dispatch information as a diagnosis. Treat it as a starting risk picture and update it continuously. A call for a fall could be a fainting episode, a trauma on stairs, or an assault in an unsafe residence. A call for trouble breathing could involve infection, chemical exposure, panic, an obstructed airway, or a cardiac event.

Order your priorities

A strong plan keeps priorities in a fixed order. First, protect yourself and the crew. Second, prevent the scene from getting worse for the patient and public. Third, decide whether you can safely reach the patient. Fourth, begin the primary assessment only once the scene permits. The test often rewards the answer that delays contact until hazards are controlled.

Use a mental arrival script: confirm location, note safe parking, scan for visible hazards, choose PPE, count patients, request help if needed, then move to patient contact. This is not separate from patient care — it is the first patient-care decision, because unsafe care is ineffective care and an injured rescuer doubles the workload while halving the help.

Exam items often add tempting but lower-priority facts. If the stem mentions downed power lines, leaking fuel, weapons, smoke, aggressive animals, unstable crowds, or unknown powder, the first move is safety and resources. If the scene is clearly safe and one patient is accessible, the first move shifts toward the primary assessment. Read the scene before you read the patient.

Worked scenario

Dispatch sends you to "an unknown medical problem" at a single-family home on a winter evening; the caller hung up. Before arrival you already have a plan forming. The unknown nature means you prepare for either trauma or medical and bring a full jump kit and oxygen. Winter evening means low light and possible ice — you will park to avoid sliding and use a flashlight. A hang-up call means information is thin, so you stay alert for a scene that does not match the dispatch.

You arrive and stop short of the driveway. The garage door is open, a vehicle is running inside, and a person is slumped near the steps to the house. This single observation rewrites the plan: a running car in a closed or semi-closed garage strongly suggests carbon monoxide (CO), a colorless, odorless gas. CO is a classic exam trap because the patient looks like a simple "unconscious" call, but entering the space could make you the next patient.

The correct sequence is to recognize the CO hazard, not enter the garage, request fire (for atmospheric monitoring and ventilation) and additional EMS, and move the patient to fresh air only if you can do so without entering the contaminated atmosphere yourself. If others may still be inside, you note that the patient count is likely more than one and relay it to dispatch.

This scenario shows the whole size-up working as one continuous loop: the pre-arrival plan set your equipment and parking, the on-scene observation identified the hazard and nature of illness, the hazard drove the resource request, and the patient count was updated the moment new information appeared. None of it required touching the patient first — and on the exam, the choice that protects you and triggers the right resources scores over the choice that rushes to grab a pulse.

Specific takeaways:

• Recite the five size-up components on every call.
• Plan from facts you already have, then revise after arrival.
• Do not enter until obvious hazards are controlled or help arrives.
• Request resources early when the scene exceeds EMR capacity.
• Keep scene safety connected to the primary assessment that follows.