Cardiovascular · Topic 30 of 34
Pulmonary Embolism
A DVT patient who suddenly becomes tachycardic, hypoxic, and short of breath may have minutes — not hours.
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Pulmonary Embolism
A clot, usually from a leg vein, blocks blood flow in the lung. Sit up, oxygen, rapid response.
A map of the veins and the lungs. A clot forms in a deep vein of the leg: a deep vein thrombosis. It breaks loose and rides the vena cava up to the right side of the heart, and the right ventricle pumps it out into the pulmonary artery. It lodges where a branch narrows in the lung, and the lung tissue beyond it gets no blood flow: a pulmonary embolism.
- A clot forms in a deep leg vein: a DVTNurse seesnew calf pain or edemaNurse doesreport it
- It breaks loose and rides up to the right heart
- It lodges in a pulmonary artery: a PENurse seesJVD, low BP, cyanosis, syncope: right heart failingNurse doescall for help immediately
High Fowler's · continuous monitoring · call the rapid response team and the provider
With sudden dyspnea and tachypnea · the lungs often sound clear
Heparin, LMWH or a DOAC · IV heparin: aPTT 1.5–2.5× control
Why the oxygen falls
Air in, no bloodOne alveolus and its capillary. Air fills the alveolus and oxygen crosses into the blood. A clot plugs the capillary and the blood flow past it stops. The oxygen stays in the alveolus with no blood to carry it away, and the SpO₂ falls: air gets in but blood does not, a V/Q mismatch.
- Air fills the alveolus; O₂ crosses into the bloodNurse seesthe lungs often sound clear
- A clot blocks the capillary: no blood flowNurse seessudden dyspnea, tachycardia, sharp pain on breathing inNurse doessit upright, oxygen, monitor; call rapid response
- The O₂ has nowhere to go: SpO₂ fallsNurse seesSpO₂ won't rise on high-flow oxygenNurse doesdeteriorating: rapid response now
Who is at risk
Virchow's triadAnything that slows the blood, injures a vein or thickens the blood
What you'll see
SignsLabs & diagnostics
Confirm itCT pulmonary angiography (CTPA) confirms a PE
Red flags
Act nowTreatment: stop the clot growing
In this orderAnticoagulants stop the clot growing — only a thrombolytic dissolves it, for massive PE
Stops the clot growing; does not dissolve it. Nursing texts lead with IV heparin; LMWH or a DOAC is now preferred for most stable PE.
Keep the aPTT 1.5–2.5× control. Below it the clot can grow; above it, bleeding.
Dissolves the clot. For massive PE: systolic BP under 90 mmHg, a drop of 40+ or on vasopressors.
Bleeding is the main risk: pressure for oozing puncture sites · stop and notify for serious or internal bleedingMore detail
How anticoagulants work
HeparinA clot on the wall of a blood vessel grows layer by layer as new fibrin strands form. Heparin arrives with the blood and coats the clot, and the next layer never forms: the clot stops growing. The clot is still there, the same size, because heparin does not dissolve it; the body breaks it down slowly.
- The clot grows, layer by layerNurse doesstart the anticoagulant as ordered
- Heparin arrives: the clot stops growingNurse seesaPTT 1.5–2.5× controlNurse doescheck the aPTT; watch for bleeding
- The clot is still there: the body breaks it down slowlyNurse doesanticoagulation continues at least 3 months
Nursing priorities
In orderChest pain: PE or MI?
Don't confuse| Feels like | Sudden, sharp |
|---|---|
| The clue | Worse on breathing in (pleuritic) |
Teach your patient
Before dischargeSudden dyspnea and tachycardia after immobility or surgery — think PE. Sit up, oxygen, rapid response.
Sources · Acute Pulmonary Embolism (StatPearls) · Medical-Surgical Nursing 16.6 Thrombotic Disorder (OpenStax) · Pharmacology for Nurses 20.2 Anticoagulants (OpenStax) · Pharmacology for Nurses 20.4 Thrombolytics (OpenStax) · Activase (alteplase) label (DailyMed) · Thrombolytic Therapy (StatPearls) · Acute Myocardial Infarction (StatPearls) · Films: the NurseSavvy learning-flow visuals. Follow your facility's protocol.
Pulmonary Embolism
A DVT patient who suddenly becomes tachycardic, hypoxic, and short of breath may have minutes — not hours. Recognizing PE fast changes survival.
A pulmonary embolism occurs when a thrombus — most often originating from a deep leg vein — lodges in the pulmonary vasculature, creating a ventilation-perfusion (V/Q) mismatch: the lung is ventilated but not perfused. The hallmark triad is sudden-onset dyspnea, tachypnea, and pleuritic chest pain, but tachycardia is often the earliest detectable sign. Hypoxemia develops rapidly, and SpO2 may drop despite supplemental oxygen. A massive PE can cause right ventricular failure, hemodynamic collapse, and cardiac arrest. CT pulmonary angiography (CTPA) is the gold-standard diagnostic. D-dimer is a sensitive but nonspecific screening tool — a negative D-dimer helps rule out PE, but a positive result does not confirm it. Nursing priorities include high-flow oxygen, continuous pulse oximetry and cardiac monitoring, IV access, and positioning the patient in high Fowler's. Anticoagulation with IV unfractionated heparin is the first-line treatment; monitor aPTT (therapeutic goal 1.5–2.5× control). For massive PE with hemodynamic instability, thrombolytics (e.g., alteplase) may be administered — monitor closely for bleeding. Virchow's triad (stasis, endothelial injury, hypercoagulability) underpins risk, but DVT is the sibling atom — PE teaching focuses on what happens after the clot migrates.
Key Distinctions
Don't confuse PE chest pain (sudden, pleuritic, worse with breathing) with MI chest pain (crushing, substernal, radiating). A negative D-dimer is clinically useful to exclude PE; a positive D-dimer is not diagnostic — students frequently reverse this logic. PE causes right-sided heart strain (distended neck veins, right axis deviation on ECG), not left-sided failure signs like pulmonary crackles.
Clinical Pearl
Sudden dyspnea + tachycardia + clear lung sounds = think PE. Crackles point elsewhere. Clear lungs in a hypoxic patient should alarm you.
Knowledge Check
3 quick questions on the must-knows for this topic.
Where does the clot in a PE most often originate?
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Go further
- Commonly confusedDVT vs Pulmonary EmbolismClot in the leg vs clot in the lung — one can become the other.
- Commonly confusedAtrial Fibrillation vs Atrial FlutterIrregular chaos vs organized sawtooth — rate, rhythm, and stroke risk compared.
- QuizNursing specialty quizNine real scenarios, then your top specialties ranked — with every result visible, not just one.
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