Pulmonary Embolism Flashcards
What is a pulmonary embolism?
An embolism becoming lodged in a pulmonary artery
Through what vessels does blood return to the heart?
Superior and inferior vena cava into the right atrium
What mechanisms allow blood in deep veins to return to the heart?
Skeletal muscle contraction and valves
Where does the emboli usually originate from?
Deep vein thrombosis
How does an emboli form? (6)
Endothelial damage Local vasoconstriction Platelet plug formation Coagulation cascade Fibrin Reinforcement Clot grows and may naturally break down (D-dimers formed) or clot breaks free forming thromboembolus.
What is a ventilation perfusion mismatch and how does it occur in PE?
When there is one of either adequate ventilation or perfusion to the alveoli but not both.
There is adequate ventilation of air but no perfusion due to the ischaemia.
The larger the V/Q mismatch the worse.
How does a respiratory alkalosis occur in PE?
Due to V/Q mismatch hyperventilation occurs, this means excessive CO2 is released and an alkalosis occurs
If someone has a PE, what congenital abnormality should be checked for?
Atrial septal defect
They can go on to have an embolic stroke as can pass into left atrium
What are the components of Virchow’s triad?
- Stasis (slow blood flow e.g. can be caused by skeletal muscle inactivity)
- Hypercoagulation (genetic or acquired reasons - surgery of COCP)
- Damage to endothelium (infections, chronic inflammation, smoking)
What are the symptoms of PE?
Chest Pain SOB Fatigue Swollen and erythmatous calf Dyspnoea Crackles Tachycardia Tachypnea Fever Hemoptysis Sudden Death (if in pulmonary saddle)
What is the sequale of multiple PEs happening over time?
Pulmonary hypertension
Right ventricular failure
How is a PE diagnosed?
CT Pulmonary Angiogram
Ventilation Perfusion Scan
D-dimer blood test
What is the treatment of a PE?
Thrombolysis - IV alteplase
Pulmonary Thrombectomy
What is the long-term management to prevent future PE?
Anticoagulation medication:
Warfarin
Heparin
Compression stockings
Lifestyle changes
What is the typical triad of symptoms a fat emboli?
Hypoxemia
Neurologic abnormalities
Petechial rash
What are risk factors of fat emboli?
Long bone fractures
Liposuction
What is an amniotic fluid embolism?
A type of pulmonary embolism that can occur in pregnant women leading to disseminated intravascular coagulation
What are risk factors for PE?
Obesity Malignancy Immobilization COCP Cancer (due to hypercoagulability)
What changes are seen on an electrocardiogram in PE?
Prominent S-wave in lead I
Q-wave in lead III
Inverted T wave in lead III
SQT-133
If severe right bundle branch block and right axis deviation
What signs may be seen on a chest x-ray in PE?
Westermark sign
Hampton hump
What signs may be seen on a echocardiogram in PE?
McConnell Sign
When might a CTPA with contrast be avoided in a patient with suspected PE? What might be used instead?
CTPA with contrast should be avoided in patients with chronic renal failure
A VQ lung scan is a good alternative
What are the components of the Wells Score?
Clinical signs and symptoms of DVT: +3
PE is #1 diagnosis or equally likely:+3
Heart rate >100: +1.5
Immobilisation at least 3 days or surgery in the previous 4 weeks: +1.5
Previous, objectively diagnosed PE or DVT: +1.5
Haemoptysis: +1
Malignancy w/treatment within 6 months or palliative: +1
What do the levels of Wells score correspond to?
0-1 low risk group
2-6 Moderate risk group
>6-12.5 High risk group
If > 4 points likely: Immediate CTPA, if delay get interim therapultic anticoagulation: DOAC: apixaban or rivaroxaban
If < 4 points unlikely: D dimer test, if positive CTPA, if negative consider alternative diagnosis.
What are the contraindications for thrombolytic treatment?
Intracranial hemorrhage, stroke or head trauma within the past 3 months, Blood pressures >185 mm Hg systolic or >110 mm Hg diastolic Active bleeding, or known arteriovenous malformation
What are good interim anticoagulation mediations?
DOACs
Apixaban or Rivaroxaban
When are DOACs used in place of LMWH?
DOACs first-line for most people (2020)
DOACs in patients with active cancer
Is cancer screening now routine following VTE diangosis?
Not since 2020
What are the first line anticoagulant recommendations?
What are the alternatives?
Apixaban or Rivaroxaban
if not suitable
LMWH followed by dabigatran or edoxaban or LMWH followed by a vitamin K antagoist (i.e. warfarin)
(Still LMWH + warfarin in severe renal impairment or in antiphospholipid syndrome)
What is the recommended length of anti-coagulation therapy?
At least 3 months
Then depends on if provoked or unprovoked
If provoked stop at 3 months
If unprovoked 6 months in total
