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Pulmonary Embolism

Dr Rajesh Varma

NICE guideline [NG158] Venous thromboembolic diseases:
diagnosis, management and thrombophilia testing: 26 March 2020

NICE guideline 3 page PDF pictorial summary

Definition

Pulmonary embolism (PE) is a condition in which one or more emboli, usually arising from lower limb deep venous thrombosis (DVT), lodges in and obstructs the pulmonary arterial system, causing severe respiratory dysfunction.

Risk Factors for PE

Major

  • DVT

  • Previous DVT or PE

  • Active cancer

  • Recent surgery

  • Lower limb trauma

  • Significant immobility, for example, due to hospitalization

  • Pregnancy and, in particular, for 6 weeks' postpartum

Other

  • combined oral contraception or hormone replacement therapy

  • known thrombophilias

  • long-distance travel

  • obesity

  • increasing age (older than 60 years of age).

Assessment

Symptoms
dyspnoea
chest pain
cough
haemoptysis
features of DVT (including leg pain and swelling)
dizziness or syncope

Signs
tachypnoea or tachycardia
hypoxia
pyrexia
elevated jugular venous pressure
gallop rhythm, a widely split second heart sound, tricuspid regurgitant murmur
pleural rub
hypotension
shock
lower limb DVT

Complications

Death
Chronic thromboembolic pulmonary hypertension

Main differential diagnosis to exclude

Respiratory
Pneumothorax
Pneumonia
Acute exacerbation of asthma/COPD

Any cause for collapse:
Vasovagal syncope
Postural hypotension
Cardiac arrhythmias
Seizures
Cerebrovascular disorders

Cardiac causes:
ACS / myocardial infarction
Acute congestive heart failure
Dissecting or rupturing aortic aneurysm
Unstable angina
Pericarditis

Other possibilities:

Musculoskeletal chest pain. Note that chest pain with chest wall palpation occurs in up to 20% of people with confirmed PE.

Gastro-oesophageal reflux disease

Suspected PE: diagnosis and initial management

Immediate admission to hospital if:
Signs of haemodynamic instability (including pallor, tachycardia, hypotension, shock, and collapse).
Patient is pregnant or has given birth within the past 6 weeks.

For all other people, determine two-level PE Wells score

Two-level PE Wells Score

  1. Clinical features of DVT (minimum of leg swelling and pain with palpation of the deep veins) (+3 points)

  2. An alternative diagnosis is LESS likely than PE (+3 points)

  3. Heart rate>100 (+1.5 points)

  4. Immobilization for more than 3 days or surgery in the previous 4 weeks (+1.5 points)

  5. Previous DVT or PE (+1.5 points)

  6. Haemoptysis (+1 point)

  7. Cancer (receiving treatment, treated in the last 6 months, or palliative) (+1 point)

If PE unlikely (two-level PE Wells score ≤4)

  1. Quantitative D-dimer test and result in 4 hours

    OR
    Interim therapeutic anticoagulation while awaiting test result.

  2. If D-dimer positive, for immediate CTPA (ensure interim therapeutic anticoagulation if CTPA is not immediate)

  3. If D-Dimer test is negative, stop any anticoagulation and consider an alternative diagnosis.

If PE likely (two-level PE Wells score >4)

  1. Immediate CTPA
    OR
    Interim therapeutic anticoagulation while awaiting CTPA

  2. If PE is confirmed (CTPA positive), continue anticoagulation treatment

  3. If PE excluded (CTPA negative), but DVT is suspected, then organise proximal leg vein ultrasound scan

This guidance now supports DOAC therapy as an interim treatment in most patients, unless contraindicated.

Consider use of pulmonary embolism rule-out criteria (PERC)

If clinical suspicion of pulmonary embolism is low (the clinician estimates the likelihood of pulmonary embolism to be less than 15% based on the overall clinical impression and other diagnoses are feasible), consider using PERC to help determine whether any further investigations for pulmonary embolism are needed.

A negative PERC reduces the post-test probability of PE to <2%; test has a high sensitivity owing to low false-negative rate.

In patients at low risk of pulmonary embolism, no further investigation for pulmonary embolism is needed if all the following are ALL ABSENT:

  • Age ≥ 50

  • Heart rate ≥ 100

  • Saturated oxygen on air ≤ 94%

  • Previous pulmonary embolism or deep vein thrombosis

  • Surgery or trauma requiring general anaesthetic within four weeks

  • Haemoptysis

  • Use of oestrogen

  • Unilateral swollen leg.

Secondary care investigations

  • CTPA Computed tomographic pulmonary angiography

  • D-dimer testing (consider using quantitative point-of-care tests, and in people over 50, consider using an age-adjusted D-dimer)

  • Arterial blood gases

  • Chest X-ray

  • Electrocardiography (ECG)

  • Lower limb compression venous ultrasound

  • Ventilation-perfusion or perfusion scintigraphy (isotope lung scanning)

  • Echocardiography (clinically 'massive' PE causes right heart strain/right heart failure)

Unprovoked DVT or PE

Do not offer further screening investigations for cancer to people with unprovoked DVT or PE unless they have relevant clinical symptoms or signs.
Although there is a known association between cancer and VTE, no evidence supports a wide variety of mandatory tests,

Treatment of Pulmonary Embolism

  1. Measure baseline full blood count, renal and hepatic function, PT and APTT but start anticoagulation (as an interim treatment) before results available.

    The risk of not treating VTE is greater than the risk associated with giving a single or couple of doses of anticoagulant to people who do not have VTE.
    Review and if necessary act on blood results within 24 hours.

  2. Consider outpatient treatment for suspected or confirmed low-risk pulmonary embolism, using a validated risk stratification tool to determine the suitability of outpatient treatment

  3. The guidance now recommends anticoagulant treatment of VTE with apixaban or rivaroxaban in most cases, apart from individuals with triple positive antiphospholipid syndrome.

  4. Offer anticoagulation for at least 3 months.
    Thereafter, assess and discuss the benefits and risks of continuing, stopping or changing the anticoagulant with the person.
    If the provoking factor for VTE is no longer present and the clinical course has been uncomplicated, then stop anticoagulation (i.e.treatment duration 3 months).
    If the VTE was unprovoked, consider continuing anticoagulation treatment, taking bleeding risk, risk of recurrence, and patient preference into account:
    the benefits of continuing anticoagulation treatment are likely to outweigh the risks (particularly if patient has a low bleeding risk).

  5. Offer DOAC (Apixaban OR Rivaroxaban) for 3 to 6 months individuals with active cancer.
    Take into account tumour site, drug interactions including cancer drugs, and bleeding risk.

  6. For patients with a second episode of pulmonary embolus, long-term treatment is recommended although bleeding risk must be taken into account

  7. Ensurie person is provided with an anticoagulant information booklet, an anticoagulant alert card (which they should be advised to carry at all times), and verbal and written information on anticoagulation treatment.

Four patient scenarios to be considered:

1. Individuals WITHOUT renal impairment, active cancer, antiphospholipid syndrome, haemodynamic instability

Preferred option: DOAC (Apixaban OR Rivaroxaban)
Alternative options:
LMWH for at least 5 days followed by dabigatran or edoxaban
LMWH and a Vitamin K Antagonist VKA for at least 5 days, or until INR at least 2.0 on 2 consecutive readings, then a VKA alone

Consider outpatient treatment for low risk patients with pulmonary embolism

2. Individuals WITH renal impairment (CrCl estimated using the Cockcroft and Gault formula)

CrCl 15 to 50 ml/min, offer one of:

  • DOAC (Apixaban OR Rivaroxaban)

  • LMWH for at least 5 days followed by edoxaban or dabigatran if CrCl ≥ 30 ml/min

  • LMWH or UFH and a VKA for at least 5 days, or until INR at least 2.0 on 2 consecutive readings, then a VKA alone

CrCl < 15 ml/min, offer one of:

  • no DOAC

  • LMWH

  • UFH

  • LMWH or UFH and a VKA for at least 5 days, or until INR at least 2.0 on 2 consecutive readings, then a VKA alone

3. Individuals WITH active cancer (receiving antimitotic treatment, diagnosed in past 6 months, recurrent, metastatic or inoperable)

Preferred option:DOAC (Apixaban OR Rivaroxaban)
Alternative options:
LMWH
LMWH and a VKA for at least 5 days or until INR at least 2.0 on 2 consecutive readings, then a VKA alone

4. Individuals with Antiphospholipid syndrome (triple positive, established diagnosis)

DOACs are not recommended
Use LMWH and a VKA for at least 5 days or until INR at least 2.0 on 2 consecutive readings, then a VKA alone

Other treatments for PE

Thrombolytic therapy (PE with haemodynamic instability)
Peripheral vein (systemic thrombolysis streptokinase, urokinase, and rt-PA) or directly into the pulmonary arteries via a catheter (catheter-directed thrombolysis)

Combination techniques
Specialist mechanical devices inserted via a catheter into the major pulmonary arteries: thrombolysis + mechanical clot break up + clot aspiration (pharmacomechanical thrombolysis)

Open pulmonary embolectomy (surgical removal of clots in the pulmonary arteries)

Inferior vena caval (IVC) filter
Inferior vena caval (IVC) filters inserted on temporary basis (for example in people with PE who cannot have anticoagulation treatment) or a permanent basis (for example in people with recurrent PE). Before fitting an IVC filter, ensure that there is a strategy in place for it to be removed at the earliest possible opportunity.