Pulmonary Thromboembolism - PE - Evaluation Pathway
Step 1: Pathway Entry
Patients with symptoms, signs and risk factors for a PE should enter the PE evaluation pathway. At this time they should also be discussed with a senior ED doctor.
Symptoms of PE
- Dyspnoea (especially if sudden and unexplained)
- Chest pain (especially if pleuritic)
- Non-productive cough
- Syncope, presyncope
- Leg pain or swelling
Signs of PE
- Tachypnoea (RR >16/min)
- Tachycardia (HR >100bpm)
- Clinical signs of a DVT
- Hypoxia (SpO2 <95%)
Risk Factors for PE
- Recent major trauma (within 1 month)
- Recent immobility (within 1 month)
- Recent surgery (within 1 month)
- Recent lower limb fracture (within 1 month)
- Hypercoagulable states (e.g. Protein C or S deficiency, antiphospholipid syndrome)
- Active malignancy (or treatment within 6 months)
- Exogenous oestrogen use
- Prior DVT/PE
- >80 years of age
Step 2: Is the Patient Stable?
Triage and initial assessment focusing on respiratory and circulatory stability.
- Rarely an issue.
- Assess and address patency, protection or ventilation requirements in a standard fashion.
- Standard assessment of respiratory rate, oxygen saturations and respiratory work and effort.
- Provision of supplemental oxygen.
- Consider respiratory support with Non Invasive or Invasive Ventilation as required.
- Standard assessment of pulse, blood pressure, and capillary refill time.
- Early ECG and cardiovascular monitoring.
- Establishment of intravenous access.
- Consider circulatory support with volume resuscitation, rhythm control and adrenaline if inotropic support is required.
Haemodynamic Instability in PE:
- SBP <90mmHg.
Consideration of alternative life-threatening diagnoses with similar symptoms including:
- Aortic Dissection
- Tension Pneumothorax
- Oesophageal Rupture (Boerhaave Syndrome)
- Ectopic Pregnancy.
Specific management in the haemodynamically unstable PE patient is a time critical emergency requiring immediate senior ED doctor involvement and will be considered under Step 8: Treatment.
Step 3: Detailed Initial Assessment
In the stable patient a thorough assessment is the next step including:
- Detailed History – including all risk factors for PE and alternative life-threatening diagnoses
- Detailed Examination – focusing on signs and symptoms of PE and alternative life-threatening diagnoses
- +/- V/ABG
- Appropriate use of bedside ultrasound (if accredited) – including BELS, AAA, Lung, E-FAST scans.
This assessment will not allow a definitive diagnosis but will influence your assessment of probability of the diagnosis of PE.
If an alternative diagnosis is made at this time then the further steps down the pathway can be curtailed and appropriate treatment for the alternative diagnosis commenced.
Step 4: Determine the Pre-Test Probability (PTP) of PE using the Wells Score
The Wells Score
Categorisation of the Wells Score (three-tier)
- Low Probability (1-4%) - 0-1 Points (can use high sensitivity D dimer for rule out)
- Intermediate Probability (16-20%) - 2-6 Points (can use high sensitivity D dimer for rule out)
- High Probability (37.5-60% >/= 7 Points) imaging required
Two-Tier Categorisation of the Wells Score (known as the modified Wells score):
- PE Likely - >4 Points
- PE Unlikely - 0-4 Points (can use high sensitivity D-dimer for rule out)
Step 5: The Pulmonary Embolism Rule out Criteria (PERC)
In those with typical symptom(s) but with a low pre-test probability apply the PERC rule.
- Age <50
- Pulse <100
- No unilateral leg swelling
- No haemoptysis
- No recent trauma or surgery (within 1 month)
- No prior DVT/PE
- No exogenous oestrogen.
Those who are negative for all 8 of the above criteria ( and low risk) are confirmed PERC negative and require no further investigation for PE.
Those who are positive for ≥1 of the above criteria are confirmed PERC positive. They require additional investigation for PE and you should proceed to Step 6.
Step 6: Perform an age-adjusted D-dimer on the PERC positive low probability group and intermediate probability group9
- A negative D-dimer = NO pulmonary embolus. The patient does not require any radiological imaging to assess for a PE and you must now look for alternate diagnosis.
- A positive D-dimer will require radiological testing.
Refer to D-dimer for full explanation on age-adjusted D-dimer levels.
Step 7: Perform Appropriate Radiological test on Positive D-dimer and High Probability Groups
- Low dose CT pulmonary angiogram (CTPA) is the preferred method of diagnosis when it is available and there is no contraindication.
- When low dose CTPA is unavailable or contraindicated a radionucleotide V/Q scan should be considered in patients with a normal CXR, no history of lung disease and age<55. Otherwise a CTPA should be done.
- Contraindications to CTPA include moderate to severe renal disease, previous allergy to contrast or iodine and pregnancy (relative contraindication).
- A bilateral lower limb Doppler Ultrasound is the investigation of choice during pregnancy (see below) or if CTPA and V/Q scans are contraindicated.
Interpretation of CT result
- CTPA positive = PE. Commence treatment. See Step 8: Treatment.
- Negative + low pre-test probability (PTP) = No PE
- Negative + high PTP = No PE. However, further testing may be required (1.5% incidence of venous thromboembolism within 3 weeks)
- Alternate diagnosis discovered = Treat as appropriate
V/Q Scan is the method of investigation if:
- CTPA unavailable
- Contraindications to CTPA (see above)
- Normal CXR, no history of lung disease, age <55
Interpretation of VQ
- Normal Scan = No PE. Consider alternate diagnosis
- Low Probability Scan + Low PTP = No PE. Consider alternate diagnosis
- Low Probability Scan + Intermediate or High PTP = Inconclusive result – Further testing (CTPA) required
- Intermediate Probability Scan = Inconclusive result – Further testing (CTPA) required
- High Probability Scan = PE. Commence treatment. See Step 8: Treatment
It should be noted that the most recent literature suggests that patients with low-risk PE (see recurrent VTE risk), whose home circumstances are adequate can be considered for treatment at home or early discharge as an option over standard discharge (i.e. after first 5 days of treatment). This should be discussed and guided by the treating physician (respiratory, haematology, vascular or general medicine) to make appropriate and evidence based management decisions for your specific clinical setting.
Step 8: Treatment
Treatment of PE is rapidly evolving in current medical practice with new guidelines and therapies being established frequently. We advise consulting with your local guidelines and admitting physician (respiratory, haematology, vascular or general medicine) to guide appropriate evidence based management of an acute PE.
In the absence of contraindications (see bleeding risk), all patients with suspected PE and a high pre-test probability should be treated with Low Molecular Weight Heparin or Unfractionated Heparin until the diagnosis is confirmed or excluded. If CTPA is readily available and the patient is haemodynamically stable, anticoagulation may be withheld until the CTPA has confirmed the diagnosis of PE. However, if imaging is not readily available or there is a delay to imaging or reporting, then anticoagulation should be administered in the absence of contraindications.
Massive PE – Haemodynamic Instability (SBP <90mmHg) is a time critical emergency requiring immediate senior ED doctor involvement.
Mortality is >15%.
- Immediate Intravenous Heparinisation
- Intravenous Unfractionated Heparin – bolus + infusion as per local policy
- Systemic Intravenous Thrombolysis (if available expertise and equipment options may exist for local thrombolysis and PCI clot removal
- Decision to be made at consultant level, see PE Rapid Response Teams
- Patients must not have a high bleeding risk (see bleeding risk)
- r-tPA (Alteplase) – 10mg IV bolus, followed by an infusion of 90mg over 2 hours (dosing regimens are evolving d/w local specialists and senior ED at your place)
- In cardiac arrest an IV bolus of 50mg should administered
- If there are contraindications to thrombolysis then consider clot retrieval (an intravenous unfractionated heparin infusion should be commenced). There are only small studies in this area, and there may be a high risk of complications. The decision should be made at specialist level after team discussion (ED/ICU/Medicine/IR).
- Respiratory Support
- As above. Supplemental oxygen then graded escalation of non-invasive an invasive respiratory support including endotracheal intubation and mechanical ventilation.
- Vasopressor Support
- Intravenous adrenaline infusion is advised if blood pressure is not rapidly restored to > 90mmHg with evidence of shock and hypoperfusion.
- Commence as per local policy and guidelines.
- IV Fluids
- A modest fluid challenge (250mL IV crystalloid) can be initiated and assessed for fluid responsiveness.
- Caution must be taken as intravenous fluid may increase RV dilatation in massive PE and worsen RV function and hence haemodynamics.
- Extracorporeal membrane oxygenation (ECMO)
- Consideration of ECMO if available locally or patient is a potential candidate for ECMO retrieval.
- This will occur at consultant level with co-ordination and facilitation by the Aeromedical Retrieval Service
If the patient is too unstable for CTPA and the diagnosis of a massive PE causing haemodynamic instability is highly suspected or further stratification of sub massive PE is required to make treatment decisions then:
Consideration of bedside investigations:
- Transthoracic echocardiogram (TTE)
- Evidence of RV dysfunction as a surrogate marker for PE in a haemodynamically unstable patient
- RV dilatation, hypokinesis, tricuspid regurgitation
- Bilateral lower limb doppler ultrasound
- Evidence of proximal DVT
A pulmonary embolus with evidence of right ventricular dysfunction (TTE) but haemodynamic stability (SBP >90mmHg)
Do a PESI score as part of your initial assessment and to drive decisions by your specialist group. PESI on MDCALC
- Intravenous Heparinisation
- Recommended management
- Systemic Intravenous Thrombolysis
- Not routinely recommended
- Potential to administer thrombolysis in selected patients with acute PE who deteriorate after starting anticoagulant therapy, but have yet to develop hypotension and have a low bleeding risk.
- Cardiopulmonary deterioration defined as – progressive increase in HR, decrease in SBP (remains >90mmHg), increase in JVP, worsening gas exchange or signs of hypoperfusion (increasing lactate, decreasing urine output). Progressive RV dysfunction on TTE or increase in cardiac biomarkers.
There is a lack of evidence for benefits in clinical outcomes following aggressive treatment of submassive PE. Delineation of this group may not have clinical significance. Consideration of thrombolysis should only be made in consult with your local specialist.
PE with Haemodynamic Stability
Novel Oral Anticoagulants (NOAC)
- Dabigatran, Rivaroxaban, Apixaban or Edoxaban
- Recommended first choice long term (3 months) anticoagulant in PE with no cancer
- Low Molecular Weight Heparin (LMWH) (Enoxaparin / Clexane)
- 1mg/kg, subcutaneously, every 12 hours
- Required before Dabigatran, Edoxaban and Vitamin K antagonists (VKA) – not required before Rivaroxaban and Apixaban
- Recommended first choice long term (3 months) anticoagulant in PE with cancer (“cancer-associated thrombosis”)
- Recommended first choice long term (3 months) anticoagulant with a recurrent PE whilst on a NOAC or VKA.
- In severe renal failure (eGFR2) offer dose adjusted of LMWH (using anti-Xa assays) or consider intravenous unfractionated heparin with dose adjustment based on APTT.
Vitamin K Antagonists
- Aim for INR 2.0–3.0
- Second choice long term (3 months) anticoagulant in PE with no cancer
- i.e. those in whom a NOAC in contraindicated
Suggested treatment d/w local referring partners:
- In patients with subsegmental PE (no involvement of proximal pulmonary arteries) and evidenceproximal DVT in the legs:
- Anticoagulation (as for PE with Haemodynamic Stability)
- In patient with subsegmental PE (no involvement of proximal pulmonary arteries) and NO evidence proximal DVT in the legs who have:
- Patients with subsegmental PE must have bilateral lower limb venous Doppler ultrasound performed to guide subsequent management.
It is mandatory to manage your patients as per local guidelines in addition to advice from the treating physician (respiratory, haematology, vascular or general medicine) to guide appropriate and evidence based management for your specific clinical setting.