Pulmonary Embolism Flashcards
What is the leading cause, accounting for approximately 95% of cases, of pulmonary embolism (PE)?
Deep vein thrombosis (DVT)
Define pulmonary embolism
Blockage of a pulmonary artery by an embolus
Explain how atrial fibrillation causes pulmonary embolism.
Blood clots form in the atria due to stasis, and then embolism to the pulmonary arteries
Explain how Septic emboli causes pulmonary embolism.
Right-sided endocarditis
Infected DVT
Septicaemia
IV drug users
Explain what occurs due to pulmonary embolism happening
(1) Perfusion is limited
(2) V/Q mismatch - oxygen in alveoli but not enough RBCs
(3) So, decreased O2 sat in blood (hypoxemia)
(4) Pulmonary vasoconstriction
(5) Results in respiratory alkalosis as increased ventilation leads to hyperventilation so CO2 lost
Which cardiac arrhythmia is commonly associated with the formation of blood clots in the atria, potentially leading to pulmonary embolism?
Atrial fibrillation
What term is used to describe the phenomenon where blood clots form in the atria due to stasis and then embolize to the pulmonary arteries?
Atrial thromboembolism
What are the primary symptoms that are commonly associated with pulmonary embolism, often manifesting suddenly?
(1) Dyspnoea (Acute onset)
- difficult breathing
(2) Pleuritic chest pain
- sharp chest pain when breathing deeply
(3) Haemoptysis
- coughing up blood from lungs or bronchial tubes
(4) Symptoms of DVT - leg pain, swelling etc.
(5) Collapse (/sudden death)
(6) Fever
Signs of pulmonary embolism
- Tachycardia
- Hypoxia
- Cyanosis
- Low BP
- Hyperventilation
What are complications of a pulmonary embolism?
PE with atrial septal defect may cuase embolic stroke
Which imaging modality is typically used to confirm the diagnosis of pulmonary embolism?
CT Pulmonary Angiogram (CTPA)
When is a V/Q scan used instead of CTPA for patients?
Renal impairment
Contrast dye allergy
Pregnancy
At risk from radiation where a CTPA is unsuitable
If pregnant and severely unwell what should you use? V/Q scan or CTPA?
CTPA - accept risk of radiation
What does a “wedge-shaped infarct” on a chest X-ray indicate?
Pulmonary embolism
Besides CTPA and V/Q scan, what additional imaging study might be performed for suspected pulmonary embolism?
CXR - will be normal early in PE (before infarction), used to rule out other causes, ‘wedge-shaped infarct’ indicates PE
Ultrasound of leg - if radiation is to be avoided or DVT suspected
What ECG finding is associated with right heart strain in pulmonary embolism?
S1Q3T3, sinus tachycardia
What laboratory test might indicate strain on the right ventricle in pulmonary embolism?
Elevated troponin levels.
What type of respiratory failure is commonly associated with pulmonary embolism?
Type I respiratory failure (hypoxemia)
- respiratory alkanosis
What is the first-line pharmacological treatment for acute pulmonary embolism causing circulatory failure?
Thrombolytic drugs like streptokinase
What are the surgery options that can be offered to a person who has a pulmonary embolism?
Pulmonary thrombectomy
= surgical removal of pulmonary embolism
Prevention of secondary PE
= Filter over the vena cava
Acute management of PE
- Anticoagulation - apixaban or rivaroxaban (first line)
- If neither apixaban nor rivaroxaban is suitable then either LMWH
- followed by dabigatran or edoxaban
- OR LMWH followed by a vitamin K antagonist (VKA, i.e. warfarin)
Secondary prevention (long-term)
- Inhibit clotting cascade, prevent clot formation (don’t breakdown the clots)
- Long-term anticoagulation - warfarin, LMWH
- Treatment with a should be continued for at least 3 months
Provoked DVT with reversible factors for how long?
3 months
Provoked DVT with irreversible factors, or unprovoked DVT for how long?
3-6 months, potentially life-long depending on patient factors (e.g. genetic clotting disorder)
A massive PE may present with what signs?
Hypotension
Cyanosis
Signs of right heart strain (eg. a raised JVP, parasternal heave and loud P2)
What is a concomitant DVT?
A unilaterally swollen, tender calf
What would the D Dimer in Bloods be like?
Highly nonspecific but has a 95% negative predictive value
(ie. it is useful in ruling out a PE if negative)
Fleischner sign is what?
an enlarged pulmonary artery
Hampton’s hump is what?
a peripheral wedge-shaped opacity
Westermark sign is what?
regional oligaemia
How would a patient get a score of 1 on the wells score?
(1) If the patient presents with haemoptysis
(2) If there is an active malignancy
How would a patient get a score of 1.5 on the wells score?
(1) Tachycardia (heart rate >100 beats/minute)
(2) If the patient has been immobile for more than 3 days or has had major surgery within the last month
(3) If the patient has had a previous PE or DVT
How would a patient get a score of 3 on the wells score?
(1) Clinical signs and symptoms of a DVT
(2) If no alternative diagnosis is more likely than a PE
A low D dimer excludes what?
PE
A raised D dimer suggests what?
Indication for diagnostic imaging
When is an Embolectomy used?
May be considered in patients with a massive PE when thrombolysis is contraindicated
When would you consider IV fluids when a person hs a PE?
Systolic is less than 90
Treatment is thrombolysis - what drugs is this?
IV bolus or Alteplase
What is a potential complication of infective endocarditis
Perivalvular aortic abscess
A 45-year-old man presents with pleuritic chest pain and sudden-onset breathlessness. He has a past medical history of end-stage renal failure on dialysis and heart failure.
A CTPA is performed which shows evidence of pulmonary emboli in both arteries.
Could you tell me what the best treatment at this stage is and why?
Unfractionated heparin is used preferentially to direct oral anticoagulants (DOACs) if a patient has severe renal insufficiency
A 30-year-old male patient presents to the Emergency Department with right-sided pleuritic chest pain. This started suddenly when he was unpacking his suitcase from his recent holiday to New Zealand. He has no past medical or surgical history and is on no regular medications. His observations are as follows:
Heart rate (HR): 107
Respiratory rate (RR): 28
Oxygen saturations (SATS): 88% on room air
Blood pressure (BP): 81/57 (Despite fluid resuscitation)
Temperature: 37’
ECG shows evidence of right heart strain.
Bedside echocardiogram shows evidence of a massive saddle pulmonary embolus
Why is Thrombolysis treatment the most appropriate treatment next?
This patient is clinically unstable with a blood pressure of <90/60 representing cardiovascular compromise
What is an absolute contraindication for thrombolysis treatment?
Previous hermharrage stroke
Recurrence of venous thromboembolism in a patient already on warfarin requires a target INR of what?
3-4
