NREMT Scene Size-Up & Hazard Management 2 — Questions and Answers

Question 1: Upon arriving at a scene, the EMT observes a patient lying on the ground and bystanders running away. The first priority is:

Immediately rush to the patient to begin assessment
Ensure scene safety before approaching; identify what caused bystanders to flee (Correct answer)
Contact medical direction for guidance
Begin treating from a distance without approaching

Correct answer: Ensure scene safety before approaching; identify what caused bystanders to flee

Scene safety always precedes patient contact. If bystanders are fleeing, there is likely an active hazard. The EMT must identify and address the hazard or stage at a safe distance until the scene is cleared.

Scene safety is the most fundamental principle in emergency medical services: EMTs cannot help patients if they become victims themselves. The behavior of bystanders provides critical environmental clues. Bystanders fleeing a scene suggests an active, ongoing hazard — gunfire, chemical release, structural collapse, violent perpetrator, or other immediate threat. Rushing to the patient without first identifying the hazard could result in the EMT becoming a second victim. The proper approach: stop at a distance where the EMT can observe the scene without being in immediate danger, try to communicate with fleeing bystanders to identify the hazard, contact dispatch with updated scene information and request appropriate resources (law enforcement, hazmat, fire), and stage the unit at a safe location. The EMT should not approach until the scene is declared safe by the appropriate authority. This principle is difficult in practice because the instinct to help is strong. Training emphasizes 'don't rush in' to counteract this instinct. The most common errors in scene size-up are: failing to identify a hazard before approaching, approaching too quickly, and not updating dispatch about changing scene conditions. A staged EMT who is safe is infinitely more valuable than an EMT who has become a second patient.

Question 2: At a motor vehicle crash, the EMT observes a downed power line touching one of the involved vehicles. The appropriate action is:

Touch the vehicle to assess the patient through the window
Stage at a safe distance, contact dispatch for utility company response, and do not allow anyone to approach the vehicle (Correct answer)
Ask the patient to exit the vehicle immediately
Attempt to move the power line with a wooden stick

Correct answer: Stage at a safe distance, contact dispatch for utility company response, and do not allow anyone to approach the vehicle

Downed power lines represent an electrocution and arc flash hazard. The vehicle is electrified and anyone touching it or the ground near it can be electrocuted. Stage safely and await utility company response.

Electrical hazards at MVC scenes are among the most dangerous situations EMTs encounter. A downed power line creates multiple electrocution risks: direct contact with the line, contact with the electrified vehicle, step potential (current flowing through the ground in decreasing voltage rings away from the contact point — walking near the contact point can result in one foot at a higher voltage than the other, causing current to flow through the body), and arc flash (the electrical discharge can jump significant distances). The safe perimeter around downed power lines varies by voltage but should be at minimum one full span of lines in each direction — typically 30-60 feet or more. EMTs should not approach the vehicle, should not instruct the patient to exit (stepping onto the ground from an electrified vehicle completes a circuit), and should not attempt to move the line with any material. Even dry wood is not safe in high-voltage situations. Notify dispatch to contact the electrical utility company immediately — only the utility company can de-energize the line safely. Law enforcement should control the perimeter. If the patient is visible and their condition is clear, communicate reassurance from a safe distance. Document all observations and actions taken.

Question 3: What does the 'mechanism of injury' (MOI) assessment tell the EMT at a trauma scene?

The exact injuries the patient has sustained
The forces involved in the incident, which predict the likelihood and pattern of injuries (Correct answer)
The patient's medical history prior to the trauma
The legal responsibility for the incident

Correct answer: The forces involved in the incident, which predict the likelihood and pattern of injuries

MOI analysis helps the EMT predict injury patterns based on the forces involved. A significant MOI (high-speed MVC, fall from height) warrants a higher index of suspicion for hidden injuries even without obvious external findings.

Mechanism of injury (MOI) analysis is a systematic evaluation of the forces, directions, and magnitudes involved in a traumatic event to predict the likely injury patterns. The human body responds to applied forces in predictable ways based on physics — deceleration, compression, penetration, and rotation cause characteristic injury patterns. For motor vehicle crashes: speed, restraint use (seatbelt, airbag), vehicle deformation, steering wheel impact, windshield damage, and airbag deployment each provide information about force transmission to specific body regions. For falls: the height, landing surface, and body part that struck first determine energy transfer. For penetrating trauma: the type of instrument, trajectory, and energy of the projectile or blade predict involved structures. A significant MOI — even in the absence of obvious external injuries — warrants a comprehensive head-to-toe rapid trauma assessment, spinal precautions, and transport to a trauma center. Children especially can have significant internal injuries with minimal external signs due to their compliant body walls. Conversely, a minor MOI with significant pain or obvious injury may warrant focused assessment. MOI is not a diagnosis but a tool for guiding the scope and urgency of assessment.

Question 4: At a multi-casualty incident (MCI), the START triage system categorizes patients into four priorities. A patient who is breathing spontaneously after airway repositioning is assigned which color?

Black (deceased/expectant)
Red (immediate) (Correct answer)
Yellow (delayed)
Green (minor)

Correct answer: Red (immediate)

In START triage, a patient who is not breathing but begins breathing after airway repositioning is tagged RED (immediate) — they require urgent intervention to maintain the airway and survive.

The START (Simple Triage And Rapid Treatment) system is used at mass casualty incidents to rapidly sort patients by survivability with minimal resources. It uses three assessments: respirations, perfusion, and mental status. Each patient is tagged within 30-60 seconds. START algorithm: (1) If not breathing after airway repositioning → BLACK (expectant/deceased); (2) If breathing after repositioning → RED (immediate — needs airway maintained); (3) If breathing is present: check respiratory rate: above 30/min → RED; below 30/min → check perfusion (radial pulse or capillary refill over 2 seconds → RED); (4) If perfusion is adequate: check mental status: unable to follow commands → RED; able to follow commands → YELLOW; (5) Patients who are ambulatory (walking wounded) → GREEN. RED (immediate) patients have life-threatening but survivable injuries requiring immediate intervention. YELLOW (delayed) patients have serious injuries but can wait. GREEN (minor) patients are walking wounded with minor injuries. BLACK (expectant) patients are deceased or have injuries incompatible with survival given available resources. Understanding these categories and the triage criteria allows EMTs to function effectively as triage officers at MCIs.

Question 5: What is the primary purpose of body substance isolation (BSI) precautions in EMS?

To protect the patient from the EMT's illnesses
To protect the EMT from exposure to potentially infectious materials in all patient contacts (Correct answer)
To protect bystanders from the patient's illness
To comply with legal documentation requirements

Correct answer: To protect the EMT from exposure to potentially infectious materials in all patient contacts

BSI precautions protect the EMT from exposure to blood, body fluids, and other potentially infectious materials. They are applied to all patients regardless of known diagnosis, based on the principle that infection status cannot be reliably determined from appearance.

Body substance isolation (BSI) is an infection control approach that treats all blood and body fluids as potentially infectious, regardless of the patient's known or suspected diagnosis. This is based on the epidemiological reality that many patients with infectious diseases are unaware of their status, may not disclose it, or may present with non-specific complaints that do not suggest infection. The EMT cannot reliably determine infectious status from appearance. Minimum BSI requirements for all patient contacts: gloves. Additional precautions based on anticipated exposure: eye protection and mask for any splash risk (intubation, suctioning, vomiting, childbirth, hemorrhage control); gown for situations with extensive contact with body fluids. For suspected airborne infectious diseases (TB, meningococcal meningitis), an N95 respirator is required rather than a standard surgical mask. After every patient contact, gloves should be removed using the proper technique (don't touch the outside of the gloves with bare skin), hands should be washed or hand sanitizer applied, and equipment should be decontaminated. Exposure incidents (needle sticks, splash to mucous membranes) should be reported immediately per agency protocol for post-exposure evaluation and prophylaxis. BSI protects EMTs, their families, and other patients from cross-contamination.

Question 6: During a nighttime scene size-up at a reported 'person down,' the EMT notices a strong smell of natural gas. What should the EMT do?

Enter the structure to locate the patient and open windows to ventilate
Stage upwind and uphill from the structure, evacuate nearby residents, and call for hazmat response (Correct answer)
Turn off the gas meter on the side of the building before entering
Use a cigarette lighter to find the patient in the dark structure

Correct answer: Stage upwind and uphill from the structure, evacuate nearby residents, and call for hazmat response

Natural gas is highly flammable and explosive. The scene is unsafe. The EMT must stage at a safe distance, initiate evacuation of nearby buildings, and call for hazmat/fire department response. Never enter a gas-involved structure.

Natural gas (methane) is highly flammable and explosive when mixed with air in concentrations of 5-15% (the lower and upper explosive limits). In an enclosed space, gas accumulation can reach explosive concentration rapidly. Any ignition source — including electrical switches, cell phones, metal on metal contact, or static electricity — can trigger detonation. EMS staging protocol for gas leak: approach from upwind and uphill (gas is lighter than air and rises, so uphill is safer than downhill in outdoor scenarios, though enclosed spaces trap gas regardless). Establish a perimeter at least 100-300 feet from the structure. Evacuate adjacent buildings in the direction the unit was staged. Do not use any electrical equipment, radio, cell phone, or vehicle ignition within the perimeter (any of these can create a spark). Do not turn off the gas meter yourself — this is the utility company's role and performing it incorrectly can cause a spark. The patient inside the structure must wait for the fire department and/or hazmat team to make the scene safe before any rescue or medical care can occur. This is a profoundly difficult reality — a patient may be critically ill inside, but entering an unsafe structure is likely to create additional casualties without saving the original victim. Documented, early notification of fire and hazmat dramatically reduces the time to safe entry.

NREMT Scene Size-Up & Hazard Management 2

Upon arriving at a scene, the EMT observes a patient lying on the ground and bystanders running away.
The first priority is: