Pulmonary Embolism: A Nurse's Reference Guide

William Kelly, MSN, FNP-C

Updated June 2026 · Medically reviewed for nurses

14 min read

A pulmonary embolism (PE) is a blood clot that lodges in the pulmonary vasculature of the lungs. Sometimes it's asymptomatic, often it causes mild-to-moderate symptoms, and other times patients go straight into cardiac or respiratory arrest.

No matter the presentation, pulmonary embolisms can be deadly. This guide walks through the causes, assessment, diagnosis, treatment, and monitoring you need to know to care for these patients at the bedside.

What Is a Pulmonary Embolism?

A pulmonary embolism is a blood clot that lodges within the lungs. They can be large or small, single or many at once. The larger and more numerous the clots, the more dangerous — a PE can put significant strain on the heart and even cause cardiac arrest.

Causes of a PE: Virchow's Triad

Many things can cause a PE, but it all traces back to Virchow's Triad — for a clot to form, at least one of three conditions must be present. The more a patient has, the higher their risk (though a small percentage clot with none of these).

Stasis of Blood

Anything that makes blood "sit still": immobility, hospitalization, varicose veins, atrial fibrillation, heart failure, or elderly age (>65).

Endothelial Injury

Damage to vessels: recent surgery (especially orthopedic), trauma, chemotherapy, implanted devices, central lines, inflammation, or sepsis.

Hypercoagulable State

Increased clotting tendency: malignancy, estrogen (birth control), pregnancy, inherited mutations (Factor V Leiden), severe liver disease, smoking, or obesity.

Nursing Assessment

Patients with a PE usually present with shortness of breath. An area of the lung can still take in oxygen but can't exchange it for carbon dioxide at the clot site, creating a ventilation-perfusion (V/Q) mismatch.

Dyspnea

Shortness of breath — with exertion or at rest. The most common symptom.

Chest Pain

Usually pleuritic — worse with deep breaths or coughing.

Cough

Usually non-productive, but may have pink frothy or bloody sputum.

Syncope

Syncope with chest pain and SOB is suspicious for PE.

Signs of DVT

Extremity erythema, edema, or pain — clues to the clot's origin.

Inspection

Respiratory distress — tachypnea, increased work of breathing, accessory muscle use — plus cough, pallor, and diaphoresis. Tachypnea is usually the first thing you'll notice.

Vital Signs

Temp may be low-grade; BP normal, high (pain), or low (severe); HR tachycardic (>100); RR increased; SpO₂ normal or low.

Auscultation

Lungs often normal, may be diminished; crackles if pulmonary infarct or acute CHF; possible pleural friction rub. Heart tachycardic.

Pleuritic Breathing

Pleuritic chest pain limits full breaths, so patients compensate with frequent shallow breathing — driving the respiratory rate up.

Nursing Interventions

Diagnosis of a PE

Wells' Criteriaclinical risk stratification

A clinical tool that assigns points to estimate PE risk:

• Signs of DVT — 3 points
• PE the #1 likely diagnosis — 3 points
• HR >100 bpm — 1.5 points
• Immobilization ×3 days — 1.5 points
• Surgery within 4 weeks — 1.5 points
• Previous PE/DVT — 1.5 points
• Hemoptysis — 1 point
• Malignancy (treated within 6 mo or palliative) — 1 point

Low risk: 0–1 · Moderate: 2–6 · High: >6. A score of ≤4 with a negative D-dimer can effectively rule out a PE.

D-Dimersensitive, not specific

A byproduct of fibrin that rises whenever there's a clot — useful to minimize radiation in low-to-moderate suspicion. A negative D-dimer (below threshold, ~230 depending on the lab) reliably rules out a clot when suspicion is low to moderate. But it's not specific: bruising, pregnancy, heart disease, and infection all raise it, so a positive result usually forces a CTA. In high-likelihood patients, a D-dimer can miss a PE up to 15% of the time.

Other Lab Worktroponin, BNP, renal, coags

Order a troponin for chest pain/SOB (may be mildly elevated, or high if the PE causes an MI). A BNP if heart-failure signs are present. Check renal function before a CTA — a GFR >30 is usually adequate for dye. Coagulation studies may be done inpatient to find genetic clotting predispositions.

ABGif significant distress

Obtained if the patient is in significant respiratory distress or has AMS. A PE causing distress typically shows: PaO₂ low (<80), PCO₂ low (<35), pH alkalotic (>7.45), and HCO₃ possibly low (<22) — see ABG interpretation.

Chest X-rayrules out mimics

Almost always ordered — it rules out pneumothorax or pneumonia, but won't show the PE itself. It may reveal nonspecific atelectasis or effusions, or be completely normal.

CTA (CT Pulmonary Angiography)the definitive test

Radiopaque dye is injected to visualize the pulmonary vasculature on CT, letting the radiologist directly see the embolism. Avoid contrast if GFR <30 (facility-dependent). If dye can't be given (low GFR or anaphylaxis), the alternative is a V/Q scan.

V/Q Scannuclear medicine alternative

Uses radioisotopes with X-rays to detect ventilation/perfusion mismatches. Less definitive than a CTA — it gives probabilities (e.g., "very low probability"). The CXR should be clear, since significant consolidation or effusions make the scan unreliable.

Treatment of a PE

For a hemodynamically stable patient, treatment is admission, parenteral anticoagulation, then transition to oral anticoagulation. Patients with significant hemodynamic compromise may need reperfusion therapy.

Parenteral Anticoagulationheparin drip

Usually IV unfractionated heparin as a titratable drip guided by PTT (checked ~every 6 hours per protocol): a bolus IV, then a slow drip. SQ Lovenox 1 mg/kg BID is an alternative. Anticoagulants don't dissolve the existing clot — they prevent new clots and stabilize the existing one from breaking off and embolizing further.

Oral Anticoagulationlong-term therapy

Stable patients may start directly on an oral agent (Eliquis, Coumadin) and go home, depending on the provider. Most need at least 3 months of therapy (the clot typically reabsorbs in ~6 weeks). Some need lifelong anticoagulation (genetic clotting disorders, atrial fibrillation). Not started in very recent surgery, hemorrhagic stroke, or active bleeding.

IVC Filtercatches clots

An inferior vena cava filter "catches" clots before they reach the right atrium. Used for patients who can't be anticoagulated or who get repeat PEs despite therapy. Can be temporary or permanent.

Thrombolyticsfor unstable patients

In hemodynamically unstable patients, thrombolytics dissolve the clot — like TPA in a stroke, but for a PE. There are many contraindications and a real bleeding risk.

Procedural Removalembolectomy

An embolectomy can be performed when thrombolytics fail or are contraindicated, if the facility is capable. Options include ultrasound-assisted thrombolysis, rheolytic/rotational/suction embolectomy, thrombus fragmentation, and surgical embolectomy. Most facilities have thrombolytics but not all of these.

Patient Monitoring

Monitoring mainly consists of watching vital signs and supporting the patient through treatment.

Cardiac Rhythm

Continuous monitoring for tachycardia and arrhythmias — sinus tach that doesn't fully resolve with fluids is common.

Oxygenation

Track SpO₂ and work of breathing; escalate support (NC → NRB → BiPAP → intubation) as needed.

Anticoagulation Labs

On a heparin drip, follow PTT (usually every 6 hours per protocol) and titrate accordingly.

Hemodynamics

Watch for hypotension and shock — signs a large PE is straining the right heart.

Related Guides

Respiratory

Lung Auscultation & Respiratory Assessment

Assessment

Advanced Cardiovascular Assessment

Cardiac

AFib RVR: Managing Atrial Fibrillation

Assessment

Blood Pressure Crash Course