Pulmonary Embolism: Field Suspicion
Objective: Suspect PE from story and exam, treat hypoxia and obstructive shock, and do not wait for a hospital CT to take a crashing patient seriously.
Why This Is Hard
PE looks like anxiety, ACS, pneumonia, and “just a faint.” You will not diagnose it with D-dimer on the porch. Your job is to keep it on the list, support oxygenation and blood pressure, get a 12-lead, and not dump fluids like it is sepsis if this is obstructive shock (see shock categories).
- Sudden dyspnea / hypoxia / syncope / arrest out of proportion to lung sounds
- Risk: surgery, cancer, immobilization, estrogen, prior VTE, pregnancy, COVID-era/hypercoagulable stories
- Clear lungs + hypoxia is a clue, not a rule-out if they have crackles
- 12-lead: sinus tach is common; RV strain is a gift when present
Field Picture (Education)
- Sudden unexplained dyspnea, pleuritic pain, hemoptysis (uncommon), syncope, or obstructive shock.
- Hypoxia that does not match the lung exam. Wheeze can happen (not only asthma).
- Unilateral leg swelling is helpful when present and absent in most real PEs — do not require a red, swollen calf.
- Cardiac arrest, especially PEA with a history that fits, is a classic teaching PE death. AHA 2025 special circumstances still lists PE among reversible causes.
What You Can Do
- Oxygen for hypoxia; support the airway. High-flow is reasonable in a crashing hypoxic patient — this is not the talking ACS titration debate (see oxygen titration).
- 12-lead: look for ACS mimics and for RV strain (T inversion V1–V4, S1Q3T3 is neither sensitive nor required). Transmit if it is ugly.
- IV, monitor, rapid transport. Fluids only as a cautious protocol bridge in obstructive/preload-sensitive shock — not a liter-wide open habit.
- Thrombolysis / catheter therapy is a hospital decision except in systems with a specific arrest-PE protocol. Do not freestyle lytics.
Field Pitfalls
- “Anxiety attack” in a post-op patient who cannot catch their breath.
- Treating undifferentiated shock with a pressor-and-fluid package that ignores obstruction.
- Skipping the 12-lead because “it’s lungs.”
Practice
60-second drill
Partner: (1) 28-year-old on OCP, sudden SOB, SpO2 88%, clear lungs; (2) 70-year-old cancer, syncope, now hypotensive; (3) PEA arrest after a long-haul flight. One-sentence PE suspicion + first two actions.
Related: Shock Categories, Syncope, PEA.
Sources & Further Study
Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.
- NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language; protocol still wins
- AHA 2025 Part 10: Special Circumstances — PE as a reversible cause of arrest
- ESC 2019 Acute Pulmonary Embolism Guideline — diagnosis is hospital-based (CT, scores, reperfusion). Field win is suspicion, support, 12-lead, and destination — a Wells score does not rule PE out on the porch
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Street decisions from this lesson only. After you check, the key is highlighted. Education practice — not a certification exam.