A 28-year-old research assistant is brought to the emergency department for severe chemical burns 30 minutes after accidentally spilling hydrochloric acid on himself. The burns cover both hands and forearms. His temperature is 37°C (98.6°F), pulse is 112/min, respirations are 20/min, and blood pressure is 108/82 mm Hg. Initial stabilization and resuscitation is begun, including respiratory support, fluid resuscitation, and cardiovascular stabilization. The burned skin is irrigated with saline water to remove the chemical agent. Which of the following is the most appropriate method to verify adequate fluid infusion in this patient?

Pulmonary capillary wedge pressure

A 25-year-old man is brought to the emergency department 3 hours after rescuing babies and puppies from a burning daycare center. He complains of headache and nausea, which he attributes to running. He is breathing comfortably. What is another likely finding in this patient?

Oxygen saturation of 86% on pulse oximetry

Arterial oxygen partial pressure of 20 mmHg

Oxygen saturation of 99% on pulse oximetry

Four days after being hospitalized, intubated, and mechanically ventilated, a 30-year-old man has no cough response during tracheal suctioning. He was involved in a motor vehicle collision and was obtunded on arrival in the emergency department. The ventilator is at a FiO2 of 100%, tidal volume is 920 mL, and positive end-expiratory pressure is 5 cm H2O. He is currently receiving vasopressors. His vital signs are within normal limits. The pupils are dilated and nonreactive to light. Corneal, gag, and oculovestibular reflexes are absent. There is no facial or upper extremity response to painful stimuli; the lower extremities show a triple flexion response to painful stimuli. Serum concentrations of electrolytes, urea, creatinine, and glucose are within the reference range. Arterial blood gas shows: pH 7.45 pCO2 41 mm Hg pO2 99 mm Hg O2 saturation 99% Two days ago, a CT scan of the head showed a left intracerebral hemorrhage with mass effect. The apnea test is positive. There are no known family members, advanced directives, or individuals with power of attorney. Which of the following is the most appropriate next step in management?

Court order for further management

A 3-month-old boy is brought to the emergency department by his mom for breathing difficulty after a recent fall. His parents say that he rolled off of the mattress and landed on the hard wood floor earlier today. After an extensive physical exam, he is found to have many purplish bruises and retinal hemorrhages. A non-contrast head CT scan shows a subdural hemorrhage. He was treated in the hospital with full recovery from his symptoms. Which of the following is the most important follow up plan?

Inform child protective services

Provide parents with anticipatory guidance

Referral to genetics for further testing

Reassurance that accidents are common

A 78-year-old woman is brought to the emergency ward by her son for lethargy and generalized weakness. The patient speaks in short utterances and does not make eye contact with the provider or her son throughout the interview and examination. You elicit that the patient lives with her son and daughter-in-law, and she reports vague weakness for the last couple days. The emergency room provider notices 3-4 healing bruises on the patient's upper extremities; otherwise, examination is not revealing. Routine chemistries and blood counts are unremarkable; non-contrast head CT demonstrates normal age-related changes. Which of the following is the most appropriate next step in management?

Ask the patient's son to leave the room

Question the patient's son regarding the home situation

Call Adult Protective Services to report the patient's son

Question the patient regarding abuse or neglect

A 28-year-old soldier is brought back to a military treatment facility 45 minutes after sustaining injuries in a building fire from a mortar attack. He was trapped inside the building for around 20 minutes. On arrival, he is confused and appears uncomfortable. He has a Glasgow Coma Score of 13. His pulse is 113/min, respirations are 18/min, and blood pressure is 108/70 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 96%. Examination shows multiple second-degree burns over the chest and bilateral upper extremities and third-degree burns over the face. There are black sediments seen within the nose and mouth. The lungs are clear to auscultation. Cardiac examination shows no abnormalities. The abdomen is soft and nontender. Intravenous fluid resuscitation is begun. Which of the following is the most appropriate next step in management?

Intubation and mechanical ventilation

Insertion of nasogastric tube and enteral nutrition

Intravenous corticosteroid therapy

A mass casualty incident occurs with 25 casualties arriving simultaneously at a community hospital emergency department. The trauma team has limited resources with 2 operating rooms available and 4 surgeons present. Among the arriving patients: Patient A has traumatic amputation of forearm with tourniquet in place and stable vitals; Patient B has flail chest, respiratory distress, and unstable vitals; Patient C is in cardiac arrest with penetrating chest wound; Patient D has a femur fracture with stable vitals; Patient E has GCS 4 with bilateral blown pupils. Evaluate the triage priority according to ATLS mass casualty protocols.

Priority order: B, A, D, with E and C designated expectant

Priority order: C, E, B, A, D - treat most severely injured first

Priority order: A, D, B, E, C - treat all patients equally regardless of prognosis

Priority order: B, A, E, D, C - based on severity alone

Immediate evacuation of all patients to a higher level trauma center

Mass casualty triage for USMLE Step 3: High-Yield Surgery Lessons

MCI Principles - Sorting the Chaos

The core principle of Mass Casualty Incident (MCI) triage is to provide the greatest good for the greatest number. The most common system is START (Simple Triage and Rapid Treatment).

Assessment: Uses the 📌 RPM mnemonic:
- Respirations
- Perfusion (Radial Pulse / Capillary Refill)
- Mental Status

⭐ In an MCI, critical but expectant patients (e.g., massive burns, high spinal cord injury) may be triaged as DECEASED/EXPECTANT (Black) to allocate resources to more salvageable victims. This is a major deviation from standard trauma care.

START Triage - 30-2-Can Do

A rapid (<60s per patient) system for mass casualty triage based on the acronym RPM (Respirations, Perfusion, Mental Status). It sorts patients into four categories: Minor (Green), Delayed (Yellow), Immediate (Red), and Deceased (Black).

📌 Mnemonic: "30-2-Can Do"

Respirations: Is the rate > 30/min?
Perfusion: Is capillary refill > 2 seconds or is there no radial pulse?
Mental Status: Can the patient not follow simple commands (Do)?

⭐ Exam Favorite: The JumpSTART triage system is the pediatric equivalent. Key modifications include assessing respiratory rate between 15-45/min and giving 5 rescue breaths to an apneic child to stimulate breathing before declaring them deceased.

Pediatric Triage - JumpSTART Your Engines

Modified START protocol for children (<8 years or <100 lbs / 45 kg). Key difference: assesses airway and breathing more leniently due to higher apnea rates in children.

Assessment: Use "RPM" (Respirations, Perfusion, Mental Status) framework.
Breathing: Apneic with a pulse? Give 5 rescue breaths.
Respiratory Rate: Abnormal if <15 or >45 breaths/min.

⭐ High-Yield: The most critical modification in JumpSTART vs. adult START is giving 5 rescue breaths to an apneic child with a pulse. If breathing starts, they are triaged as IMMEDIATE (Red).

High‑Yield Points - ⚡ Biggest Takeaways

The guiding principle of mass casualty triage is to do the greatest good for the greatest number of casualties.

Utilize the START (Simple Triage and Rapid Treatment) protocol, assessing Respirations, Perfusion, and Mental Status (RPM).

Red tags (Immediate) signify life-threatening conditions (e.g., RR >30, cap refill >2s, altered mental status) that are likely survivable with intervention.

Black tags (Expectant) are for victims who are apneic after airway repositioning or have catastrophic injuries.

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