Pulmonary Embolism: Field Suspicion

Why this matters

Pulmonary embolism can look like anxiety, a heart attack, pneumonia, or a simple faint. You will not diagnose it with a D-dimer on scene. A D-dimer is a hospital blood test. First, keep the clot on the list. Give oxygen, get a 12-lead, support blood pressure with cautious fluids, and choose the destination. Do not wait for a CT scan. Do not give a large fluid bolus as if this were sepsis when the problem is a blockage of flow. See shock categories.

Clinical sequence

1. Keep pulmonary embolism on the list when sudden shortness of breath, low saturation, fainting, or arrest is out of proportion to the lung exam.
2. Ask the risk story: recent surgery, cancer, immobilization, estrogen, a prior clot, pregnancy, a clotting disorder, or a recent COVID illness.
3. Give oxygen, get a 12-lead, and support blood pressure with cautious fluids. If this is a blockage of flow, do not give fluids the way you would for sepsis.
4. Move. Clot-busting drugs and catheter treatment are hospital decisions, except in systems with a written arrest protocol for pulmonary embolism. Do not give a fibrinolytic dose on your own.

Field Picture

• Look for sudden unexplained shortness of breath, pain that is worse with a breath, coughing blood (uncommon), fainting, or shock from a blockage of flow.
• A low saturation may not match the lung exam. Wheeze can happen. Do not treat every case as asthma.
• One swollen leg helps when you see it. Most real pulmonary emboli do not have a red, swollen calf. Do not require that sign.
• Cardiac arrest, especially pulseless electrical activity with a fitting history, is a classic teaching picture of death from pulmonary embolism. It remains one of the reversible causes.

What You Can Do

• Give oxygen for hypoxia and support the airway. High-flow oxygen is reasonable in a crashing hypoxic patient. This is not the same decision as oxygen titration in a talking patient with a heart attack. See oxygen titration.
• On the 12-lead, look for heart-attack mimics and for right-ventricular strain, such as T-wave inversion in V1 through V4. S1Q3T3 is neither sensitive nor required. A normal ECG does not clear pulmonary embolism. Transmit the tracing if it looks abnormal.
• Start an IV, monitor, and transport. Fluids are only a cautious bridge, per protocol, when a clot is blocking return to the left heart. Do not run a liter wide open.
• Thrombolysis and catheter therapy are hospital decisions unless your system has a specific arrest protocol. Do not give a fibrinolytic dose on your own.

Common errors

• Do not call it an anxiety attack in a postoperative patient who cannot catch their breath.
• Do not treat undifferentiated shock with a pressor-and-fluid package that ignores a blockage of flow.
• Do not skip the 12-lead because you think it is only a lung problem.

Practice

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; your protocol still decides care
• AHA 2025 Part 10: Special Circumstances — PE as a reversible cause of arrest
• 2026 AHA/ACC Acute Pulmonary Embolism Guideline — diagnosis and reperfusion are hospital work (imaging, D-dimer, severity categories). The field job is suspicion, oxygen, a 12-lead, cautious fluids, and destination. A Wells score does not rule out pulmonary embolism in the field