Pulmonary embolism Flashcards
What is a PE?
Formation of a thrombus in the pulmonary arteries
What are the main risk factors of PE?
Immobility
Recent surgery
Pregnancy (due to hypercoagulable state)
Long-haul flights
Malignancy
Hormone therapy with oestrogen
Polycythaemia
Thrombophilia
Anti-phospholipid syndrome
SLE
How can PE present?
SOB
Pleuritic chest pain (i.e., pain on inspiration)
Cough (with or without haemoptysis)
Tachycardia
Hypoxia
Reduced RR
Low grade fever
Haemodynamic instability causing hypotension
Could also see signs of DVT e.g., unilateral leg swelling + tenderness
Who should you do a VTE assessment for?
Every patient that is admitted to hospital
What should you give patients that are at high risk of VTE (after completing a VTE assessment)?
Prophylactic low molecular weight heparin e.g., Enoxaparin
Anti-embolic compression stockings
What are the contraindications for LMWH?
Active bleeding
Existing anti-coagulation with warfarin or NOAC
What is a major contraindication for compression stockings?
Peripheral artery disease
What is the Well’s score?
A scoring system that predicts the risk of a patient having a DVT or PE
According to NICE guidelines what is the cut-off Wells score for a patient having a likely PE?
> 4 points
According to NICE guidelines what imaging should be offered immediately for people with likely PE?
CTPA
If allergic to contrast (or for patients with severe chronic renal impairment (eGFR <30 ml/min/1.73 m2) or acute renal impairment) = V/Q scan (i.e., ventilation perfusion scan)
Could also do CXR - oligaemic crisis
If you can’t do imaging immediately what should you do instead?
Interim anticoagulation
Choose an anticoagulant that can be continued if PE is diagnosed e.g., apixaban or rivaroxaban
What tests should be done before starting people on anticoagulants?
Baseline bloods = FBCs, renal function, liver function, PT and APTT
TRUE or FALSE
Before starting interim anticoagulation you must wait for the blood test results
FALSE
NICE guidelines states:
do not wait for the results of baseline blood tests before starting anticoagulation treatment
review, and if necessary act on, the results of baseline blood tests within 24 hours of starting interim therapeutic anticoagulation
What is the conventional Tx of PE?
Apixaban or Rivaroxaban
If neither are suitable then offer:
LMWH for at least 5 days followed by dabigatran or edoxaban
LMWH concurrently with a vitamin K antagonist (VKA) - e.g., warfarin for at least 5 days, or until the INR is at least 2.0 in 2 consecutive readings, followed by a VKA on its own
Should you routinely offer unfractionated heparin + vitamin K antagonists (VKA) (e.g., warfarin) to patients with PE?
NO
Unless they have renal impairment/established renal failure or increased risk of bleeding
(NICE GUIDELINES)
Should you routinely offer self-monitoring of INR to patients on VKA?
No
(NICE GUIDELINES)
If the Wells score is 4 or less what should you do?
D-dimer (a -ve test can reliably exclude PE)
If positive do a CTPA
What are the disadvantages of D-dimer?
Sensitive for other diseases too.
Will be raised in hypercoagulable states e.g., infection/inflammation, pregnancy
What are D-dimers?
Protein products of cross-linked fibrin degradation
Fibrin is an essential component of blood clots
What are the options for long term anticoagulation in PE?
DOACs
Warfarin
LMWH
What is the first line drug for long term anticoagulation in pregnancy or cancer?
LMWH
What is the target INR for warfarin?
2 - 3
What is used in the bridging therapy for when a patient is started on warfarin? How long?
LMWH
For 5 days
OR
Until INR is 2-3 for 24 hours on warfarin
How long should you anti-coagulate for the different causes of PE?
Provoked = 3 months
Unprovoked = 6 months (in clinical practice sometimes this can be extended to lifelong)
Active cancer = 6 months (then review)
When is thrombolysis used?
Massive PE with haemodynamic compromise
What does thrombolysis involve?
Injection of fibrinolytic injection e.g., alteplase, streptokinase, or tenecteplase
What are the two ways thrombolysis can be performed?
IV - using cannula
Directly into arteries - using a central catheter i.e., catheter directed thrombolysis
How is catheter directed thrombolysis done? What is a major risk?
Catheter is inserted into the venous system, through the right side of the heart and in to the pulmonary arteries
Administrator administers thrombolytic agent directly to where the thrombus is
MAJOR RISK = pulmonary artery damage
How is a V/Q scan carried out? How will a PE appear?
- Isotopes are inhaled to fill the lungs and a picture is taken = VENTILATION.
- Contrast containing isotopes is injected and a picture is taken = PERFUSION.
PE will show deficit in perfusion because thrombus blocks blood flow to the lung tissue
What is the hallmark finding of PE on ECG
S1Q3T3
What would be ABG findings and why?
Respiratory alkalosis
Tachypnoeic patients blow off a lot of CO2 causing the PaCO2 to drop and the pH to drop
NOTE: the other main cause of respiratory alkalosis is hyperventilation syndrome
Sources
https://zerotofinals.com/medicine/respiratory/pe/
https://acutecaretesting.org/en/journal-scans/causes-of-increased-d-dimer/
https://www.nice.org.uk/guidance/ng158/chapter/Recommendations#diagnosis-and-initial-management
https://www.nice.org.uk/guidance/ng158/resources/visual-summary-pdf-11193380893
https://www.rcr.ac.uk/sites/default/files/Intravasc_contrast_web.pdf
