First: is the patient haemodynamically unstable? An unstable pulmonary embolism is a reperfusion problem; a stable pulmonary embolism is a diagnostic pathway.
The unstable patient
Hypotension (systolic < 90 mmHg for > 15 minutes, or a need for a vasopressor), obstructive shock or cardiac arrest with suspected pulmonary embolism.
- Urgent bedside echocardiography, looking for right ventricular strain.
- If CT pulmonary angiography can be performed immediately, do it. Otherwise the echocardiographic findings plus the clinical picture are sufficient for a treatment decision.
- Systemic thrombolysis is the first-line treatment in high-risk embolism, unless there is an absolute contraindication. The agent and dose are according to the local protocol.
- Alternatives when there is a contraindication: catheter-directed treatment or surgical embolectomy where available.
- A vasopressor (noradrenaline) and cautious fluid administration. Large fluid volumes worsen an already strained right ventricle.
Clinical probability in the stable patient
The Wells criteria for pulmonary embolism:
| Criterion | Points |
|---|---|
| Clinical signs of deep vein thrombosis | 3 |
| Pulmonary embolism is the most likely diagnosis | 3 |
| Heart rate > 100/min | 1.5 |
| Immobilisation ≥ 3 days or surgery in the last 4 weeks | 1.5 |
| Previous deep vein thrombosis or pulmonary embolism | 1.5 |
| Haemoptysis | 1 |
| Active malignancy | 1 |
Two-level interpretation: ≤ 4 points means pulmonary embolism unlikely, > 4 points means pulmonary embolism likely.
| Probability | Next step |
|---|---|
| Unlikely | D-dimer. A negative D-dimer excludes pulmonary embolism |
| Likely | CT pulmonary angiography straight away. A D-dimer must not be used to rule it out |
The age-adjusted D-dimer in patients over 50: the threshold becomes age × 10 micrograms/L (FEU). Check which unit and which reference system your own laboratory uses before applying it.
The D-dimer is raised in pregnancy, malignancy, infection, surgery, trauma and old age. A positive value is not a diagnosis.
Risk grading in confirmed pulmonary embolism
| Risk | Haemodynamics | Right ventricular strain (echo or CT) | Troponin | Management |
|---|---|---|---|---|
| High | Unstable | Yes | Often raised | Reperfusion, intensive care |
| Intermediate–high | Stable | Yes | Raised | Admission with monitoring. Be prepared for rescue thrombolysis |
| Intermediate–low | Stable | One of the two positive | Admission | |
| Low | Stable | No | Normal | Anticoagulation. Outpatient management may be considered |
The sPESI (simplified Pulmonary Embolism Severity Index) gives 1 point each for age > 80 years, cancer, chronic cardiac or pulmonary disease, a pulse ≥ 110/min, a systolic blood pressure < 100 mmHg and a saturation < 90 per cent. An sPESI of 0 indicates low risk.
Anticoagulation
- A DOAC is the first choice in pulmonary embolism without malignancy and without antiphospholipid syndrome. The doses in venous thromboembolism include an initial high-dose phase and differ from the doses used in atrial fibrillation. Follow the Swedish medicines compendium (FASS) and the local protocol.
- Low-molecular-weight heparin is the first choice in pregnancy and an alternative in cancer-associated thrombosis.
- Warfarin in antiphospholipid syndrome and in marked renal failure.
- Duration of treatment: at least 3 months. Extended treatment in unprovoked pulmonary embolism, a persisting risk factor, or recurrence.
Special situations
| Situation | Comment |
|---|---|
| Pregnancy | Leg ultrasound first. CT pulmonary angiography or lung scintigraphy according to local procedure. Low-molecular-weight heparin, not a DOAC |
| Active cancer | A DOAC or low-molecular-weight heparin. Consider the bleeding risk with gastrointestinal and urogenital tumours |
| Marked renal failure | Low-molecular-weight heparin with dose adjustment, or warfarin |
| Subsegmental pulmonary embolism without deep vein thrombosis | An individual assessment; in selected cases the patient can be observed without anticoagulation |
Red flags and pitfalls
- A normal saturation and a normal ECG do not exclude pulmonary embolism.
- Syncope may be the only symptom.
- Requesting a CT in an unstable patient who cannot survive the transfer. Bedside echocardiography first.
- Giving large volumes of fluid in right ventricular failure.
- Withholding anticoagulation while awaiting the CT when the clinical probability is high. Start treatment if the bleeding risk allows.
- Not investigating the cause. Investigation for malignancy guided by the history and examination, and thrombophilia testing only where indicated.
Sources
- ESC Guidelines for the diagnosis and management of acute pulmonary embolism.
- The Swedish Society for Thrombosis and Haemostasis (SSTH), clinical advice.
- Internetmedicin, Pulmonary embolism.
