A pulmonary embolism is a blockage of a pulmonary artery or one of its branches, most often by a thrombus that breaks off from a deep vein thrombosis (DVT) in the legs or pelvis. DVT and PE together are called venous thromboembolism (VTE). Less common emboli: fat (long-bone fractures), air, amniotic fluid, tumor.
Consequences
- Ventilation without perfusion (dead space) plus mediator-induced bronchoconstriction and atelectasis → V/Q mismatch → hypoxemia → impaired gas exchange
- Sudden rise in pulmonary vascular resistance → right ventricular (RV) strain and dilation → falling left ventricular filling and cardiac output → obstructive shock and cardiac arrest in large PE
- Pulmonary infarction (pleuritic pain, hemoptysis) when distal branches are blocked
Virchow's triad — risk factors
| Element | Examples |
|---|
| Venous stasis | Immobility, bed rest, long-distance travel, paralysis, heart failure, obesity |
| Endothelial injury | Recent surgery (especially hip/knee replacement, hip fracture), trauma, central venous catheters, prior DVT |
| Hypercoagulability | Cancer, pregnancy and postpartum, estrogen-containing contraceptives or hormone therapy, inherited thrombophilia, antiphospholipid syndrome, dehydration, smoking, COVID-19 and sepsis |
Severity — 2026 American clinical categories
The 2026 AHA/ACC multisociety PE guideline replaces "massive/submassive" terminology with Clinical Categories A–E, based on physiologic impact rather than clot size:
| Category | Meaning | Usual setting |
|---|
| A | Incidental, asymptomatic PE | Outpatient |
| B | Symptomatic, low clinical severity score | Early discharge / outpatient |
| C | Elevated severity score ± RV dysfunction or elevated biomarkers | Hospital |
| D | Incipient cardiopulmonary failure — D1: transient hypotension responsive to fluids; D2: normotensive shock (e.g., rising lactate or creatinine) | ICU / PE response team |
| E | Overt cardiopulmonary failure — persistent hypotension, cardiogenic shock, cardiac arrest | ICU; advanced therapy |
A respiratory modifier is added when there is hypoxemia or an escalating oxygen need. Many other countries still use the European risk classes (high, intermediate, low risk); the principle — severity is defined by hemodynamics and RV function — is the same.
- Sudden dyspnea (most common symptom) and tachypnea
- Pleuritic chest pain, cough, hemoptysis
- Tachycardia, anxiety, sense of impending doom, diaphoresis
- Hypoxemia; low-grade fever possible
- Signs of DVT: unilateral calf or thigh swelling, pain, warmth
- Large PE: syncope, hypotension, JVD, cyanosis, altered mental status, cardiac arrest (often pulseless electrical activity)
Symptoms are nonspecific — suspect PE in any at-risk client with sudden unexplained dyspnea or chest pain, especially after surgery.
Stepwise approach (hemodynamically stable)
- Estimate clinical (pretest) probability with a validated tool such as the Wells score — the first screening step and something nurses can help calculate
- Low probability: apply PE rule-out criteria (PERC); if not ruled out, obtain a D-dimer. A normal D-dimer excludes PE in low/intermediate probability. An age-adjusted cutoff (age × 10 µg/L FEU in clients over 50) reduces false positives
- High probability or positive D-dimer: CT pulmonary angiography (CTPA) — the main confirmatory test
- V/Q scan when contrast is contraindicated (severe kidney disease, contrast allergy) and often in pregnancy
Unstable client: bedside echocardiography showing RV dilation supports treatment while arranging CTPA when safe.
| Other tests | Findings |
|---|
| ABG | Hypoxemia, respiratory alkalosis (low PaCO₂) from hyperventilation |
| ECG | Sinus tachycardia most common; RV strain, right bundle branch block, S1Q3T3 (uncommon) |
| Chest X-ray | Often normal; used to exclude other causes |
| Troponin, BNP/NT-proBNP, lactate | RV injury/strain and hypoperfusion → higher category |
| Leg compression ultrasound | Finds DVT |
| Baseline CBC, platelets, PT/INR, aPTT, creatinine | Before anticoagulation |
Anticoagulation — start promptly when PE is suspected with intermediate/high probability, unless contraindicated
| Drug | Key points and safety |
|---|
| Direct oral anticoagulants (DOACs) — apixaban, rivaroxaban (start directly); dabigatran, edoxaban (after ≥ 5 days of parenteral anticoagulant) | Preferred over warfarin in most clients. No routine INR monitoring, no vitamin K diet limits. Check kidney function (dose adjustment/avoidance) and drug interactions (strong CYP3A4/P-gp inhibitors or inducers, antiplatelets, NSAIDs). Not used in pregnancy or in antiphospholipid syndrome. Reversal: idarucizumab (dabigatran); 4-factor prothrombin complex concentrate for factor Xa inhibitors in the US (andexanet alfa was withdrawn from the US market in December 2025; availability elsewhere may differ) |
| Low-molecular-weight heparin (LMWH) — enoxaparin | Preferred over unfractionated heparin for most hospitalized clients; SC injection into the abdomen, do not expel the air bubble in prefilled syringes, do not rub; adjust for kidney function; anti-Xa levels in selected clients; drug of choice in pregnancy |
| Unfractionated heparin (UFH) — IV infusion | Used in unstable clients, severe kidney failure, or when thrombolysis or procedures may be needed. Monitor aPTT (target about 1.5–2.5 × control) or anti-Xa per protocol; platelets for heparin-induced thrombocytopenia (HIT) (fall > 50% or new thrombosis, typically days 5–10); antidote protamine sulfate |
| Warfarin | Used when DOACs are unsuitable (e.g., mechanical valve, antiphospholipid syndrome). Overlap with heparin for ≥ 5 days and until INR ≥ 2 for 24 hours; target INR 2–3; consistent vitamin K intake; many interactions; teratogenic; reversal vitamin K ± prothrombin complex concentrate |
Duration: at least 3 months; longer or indefinite for unprovoked PE or persistent risk factors (e.g., active cancer).
Reperfusion (categories D–E)
- Systemic thrombolysis is harmful in categories A–C and is not given there
- Systemic thrombolysis (e.g., alteplase) for persistent hypotension/shock. Absolute contraindications include any prior intracranial hemorrhage, ischemic stroke within 3 months, recent head trauma or brain/spinal surgery, intracranial tumor, active internal bleeding. Monitor closely for bleeding and neurologic change; avoid unnecessary punctures
- Catheter-directed thrombolysis or mechanical thrombectomy; surgical embolectomy or ECMO in selected cases
- Coordinated by a multidisciplinary PE response team
Supportive: oxygen to target; cautious fluids (excess fluid can worsen RV failure); norepinephrine for hypotension; avoid deep sedation and intubation when possible because they can precipitate collapse.
Inferior vena cava filter — only when anticoagulation is contraindicated or has failed; retrieve when no longer needed.
Listed in priority order.
- Breathing and circulation
- Raise the head of the bed, give oxygen, monitor SpO₂, RR, heart rate, BP, and mental status continuously
- Notify the rapid response team for hypotension, syncope, or worsening hypoxemia; prepare for thrombolysis or advanced therapy
- Establish IV access
- Anticoagulation safety — before starting
- Screen for bleeding risks: recent head trauma, stroke, surgery, active bleeding (GI, urinary), uncontrolled hypertension, low platelets, pregnancy, kidney and liver function
- Obtain baseline labs; verify weight-based dosing and double-check heparin infusions with a second nurse
- Monitor for bleeding
- Gums, nose, urine, stool (melena), bruising, IV sites, drop in hemoglobin, hypotension, headache or neurologic change (possible intracranial bleeding)
- Epistaxis: sit the client upright and leaning forward, apply firm continuous pressure to the soft part of the nose for 10–15 minutes; notify provider if bleeding continues; check hemoglobin and coagulation values
- Therapeutic monitoring — aPTT/anti-Xa, platelets, INR, creatinine per drug
- Comfort and anxiety — calm presence, explanations, analgesia for pleuritic pain
- Prevent further VTE
- Early mobilization once anticoagulated and stable (per provider)
- Intermittent pneumatic compression devices for immobile clients
- Hydration; do not restrict fluids (dehydration increases blood viscosity)
- Avoid pillows under knees and crossing legs; leg exercises
- Take the anticoagulant exactly as prescribed; never double doses. DOACs have short half-lives — missed doses quickly lose protection
- Check with the provider or pharmacist before starting any new medication, supplement, or herbal product
- Avoid aspirin and NSAIDs (ibuprofen, naproxen) unless specifically prescribed — they add to bleeding risk; acetaminophen is preferred for pain
- DOACs: no routine INR testing and no dietary vitamin K limits, but periodic kidney function tests. Warfarin: regular INR tests and consistent intake of vitamin K–rich foods (do not suddenly increase or eliminate green leafy vegetables)
- Soft toothbrush, electric razor, avoid contact sports; wear medical identification; tell all providers and dentists
- Report bleeding: black or bloody stools, pink/red urine, vomiting blood, severe headache, prolonged nosebleeds
- Report new leg swelling or pain, or sudden shortness of breath or chest pain
- Travel: walk every 1–2 hours, ankle and calf exercises while seated, stay hydrated, avoid crossing legs
- Discuss estrogen-containing contraception or hormone therapy with the provider; contraception with warfarin (teratogenic)
- Stop smoking; maintain a healthy weight
| Complication | What to watch for |
|---|
| Obstructive shock / cardiac arrest | Hypotension, syncope, PEA arrest |
| RV failure | JVD, hypotension, rising troponin/BNP |
| Bleeding (anticoagulants, thrombolytics) | Falling hemoglobin, hypotension, neurologic change (intracranial hemorrhage) |
| HIT | Platelets fall > 50%, new clots — stop all heparin, notify |
| Recurrent VTE | New leg swelling or dyspnea |
| Chronic thromboembolic pulmonary hypertension (CTEPH) | Persistent or progressive dyspnea 3–6 months after PE — requires evaluation |
| Post-thrombotic syndrome | Chronic leg pain, swelling, skin changes |
- Most PEs come from DVT in the legs; recent hip/knee surgery or hip fracture is a classic major risk factor
- Classic presentation: sudden dyspnea, tachypnea, pleuritic chest pain, tachycardia; large PE → syncope, hypotension
- Priority nursing diagnosis: impaired gas exchange
- Diagnostic sequence: Wells score → D-dimer (low/intermediate) → CTPA; V/Q scan if no contrast
- Normal D-dimer rules out PE in low-probability clients; it cannot confirm PE
- 2026 US guideline: Clinical Categories A–E; "massive/submassive" retired
- DOACs preferred over warfarin; LMWH in pregnancy
- UFH → aPTT/anti-Xa, platelets (HIT), protamine
- Warfarin → INR 2–3, overlap until INR ≥ 2 for 24 h
- Thrombolytics for shock; recent head trauma is an absolute contraindication
- No aspirin/NSAIDs with anticoagulants unless prescribed
- Prevention: early ambulation, pneumatic compression, prophylactic anticoagulants, hydration
Country Notes
United States
- The 2026 AHA/ACC/ACCP/ACEP/CHEST and partner societies guideline introduced PE Clinical Categories A–E; hospital protocols may still use older terms during transition.
- Many hospitals have formal PE response teams activated through a single call.
Philippines
- Laboratories commonly report hemoglobin in g/L and creatinine in µmol/L (SI units); check units when applying dosing thresholds.
- Warfarin remains widely used where cost limits access to DOACs, so INR monitoring and dietary teaching are especially important.