Pulmonary Embolism Flashcards
What is DVT?
DVT is an obstructive disease caused by obstruction to venous flow, involving the lower limb deep calf veins and propagating proximally. Acute thrombosis formation results in extensive remodelling process where neutrophils and macrophages infiltrate the fibrin clot over several weeks, leading to cytokine release and fibroblast and collagen replacement of fibrin
What age group most commonly experiences DVT?
Over 40 age group.
What is a sign of DVT?
Pain may occur with passive dorsiflexion, known as Homan’s sign.
List the common sites affected by DVT.
- Isolated calf vein
- Femoropopliteal vein
- Iliofemoral vein
The more proximal the vein, the more severe the thrombosis.
What is the relationship between the location of the vein and the severity of thrombosis in DVT?
The more proximal the vein, the more severe the thrombosis.
What are transient risk factors for DVT?
- HRT (hormone replacement therapy)
- Pregnancy
What are some risk factors for DVT?
- Increased venous pressure (CRP, malignancy, pregnancy, congenital conditions)
- Increased blood viscosity (polycythaemia, thrombocytosis, dehydration)
- Conditions like anticoagulation protein C and S, antithrombin III deficiency, and factor V mutation
What does Virchow’s triad include?
- Stasis
- Hypercoagulability
- Endothelial injury
What causes stasis of blood?
Post operative state, paralysis, long travel time
What causes hypercoagulability of blood?
Malignancy
Pregnancy
Nephrotic syndrome (due to reduction of clotting factors)
anti-phospholipid syndrome due to anti-cardio lipid antibodies
-> heparin-induced thrombocytopenia
-> burns
->sepsis
-> mypocardial infarction, heart failure, IBS
What causes endothelial injury?
Smoking, surgical procedures and venous catheters
What are common symptoms of DVT?
- Leg pain with redness and swelling
- Limb oedema
- Red/hot skin with dilated veins
- Tenderness
*Homan’s sign
Which leg tends to be affected in DVT?
Left leg due to compresssion of left iliac vein by the right common iliac artery.
What is Phlegmasia cerulea dolens?
Progression of phlegmasia alba dolens, Iliofemoral DVT causing near-total venous occlusion causing cyanosis with blue lower extremity, leading to venous gangrene and circulatory shock. There may be skin bullae.
It is managed with thromboectomy.
What characterizes Phlegmasia alba dolens?
Arterial compression from DVT causing limb ischemia with a ‘white limb.’ It presents with oedema, pain and blanching of leg
What is post-thrombotic syndrome?
Chronic venous insufficiency occurring after an acute DVT. The veins have undergone persistent thrombosis hat has led to fibrosis of vessel wall which leads to increased venous wall pressure, tissue swelling and tissue oxygen deprivation. In the long-term, there may be skin ulceration and chronic pain.
What are the features of post-thrombotic syndrome?
It is characterized by leg discomfort, heaviness, vein dilatation, oedema, skin discolouration, and venous ulcers.
What is the Villalta score used for?
To classify the severity of post-thrombotic syndrome based on cramps, heaviness, paraesthesia, pruiritus, oedema, redness, hyperpigmentation and venous ulcer.
What is used to determine the pre-clinical probability of DVT?
Well’s score
What are the features of Well’s score?
Previous DVT/PE
Active cancer
Recent immobilisation
Leg swelling
Asymmetric
Pitting oedema
Collateral superficial non-varicose veins
What should be done for patients with high pre-clinical probability of DVT?
D-dimer test and proximal leg vein ultrasound.
What should be suspected in unprovoked DVT?
Investigate for the possibility of undiagnosed cancer
Thrombophilia.
How is thrombophilia tested?
antiphospholipid syndrome
When diagnosis is uncertain, what should be offered?
Interim therapeutic anticoagulation with apixaban or LMWH.
What should be prescribed for confirmed DVT in haemodynamically unstable patients?
continuous unfractionated heparin infusion and thrombolytic therapy
What should be prescribed for haemodynamically stable patients with renal impairment?
apixaban/dabigatra should be offered to treat confirmed proximal DVT/PE in patients with renal impairment or failure.
What are the two types of pulmonary embolism (PE)?
- Haemodynamically stable PE
- Haemodynamically unstable PE
What causes pulmonary embolism?
FATAL:
Fat embolus
Amniotic embolus
Thrombosis
Atheroma
Less common such as septic embolism
What is the pathophysiology of pulmonary embolism?
Thrombus blocks pulmonary circulation, typically affecting the lower lung lobes and obstructs the main pulmonary artery. There is greater resistance so pulmonary artery pressure increases. This results in V/Q mismatch with type 1 respiratory failure with hypoxia. There is reduced right ventircle outflow and right bundle branch block, causing it to dilate and cause the left ventricle septum to shift and reduce filling of the left ventricle, that reduces cardiac output and result in obstructive shock.
There will be release of mediators like serotonin for vasospasm but this worsens the low pulmonary flow and causes increased respiratory drive and respiratory akalaosis.
How does the thrombus size affect the Vessels?
Large embolism obstruct the main pulmonary artery while smaller-sized embolism block the peripheral arteries and cause luminary infarction, with intra-alveolar haemorrhage.
What are the Clincial features of pulmonary embolism?
type 1 respiratory failure with hypoxia, Tachypnoea, dyspnoea and tachycardia
Respiratory alkalosis may occur due to tachypnoea
What characterizes haemodynamically unstable PE?
Hypotension due to obstruction of the pulmonary artery, which may result in syncope. There may be sudden cardiac arrest due to acute right ventiruclar failure.
What are the warning signs for sudden cardiac arrest with PE?
Tachycardia on presentation -> sudden bradycardia with new right bundle branch block on ECG, hypotension and JVP distention
What is a haemodynamically stable PE?
Haemodynamically stable PE causes mild hypotension and there may be right ventiruclar dysfunction but it stabilises with fluid therapy
What are common symptoms of pulmonary embolism?
- Acute onset pleuritic chest pain
- Dyspnea
- Hemoptysis
What is the risk factor for pulmonary embolism?
- Immobilisation
- Smoking
- Younger age (under 40)
- Central venous lines
- HRT
- Postpartum and pregnancy
What are the complications with PE?
Reccurrent thromboembolism 1-2 weeks following diagnosis due to inadequate anticouagulation
Chronic thromboembolic pulmonary hypertension; persistent or progressive dysnpea
Right heart failure
Cardiogenic shcok
What are the investigations for suspected PE?
12 lead ECG
Troponin test
CXR
D-dimer
CTPA/V/Q scan
Obtain echocardiogram to assess RV dilatation or dysfunction to determine high risk PE
What does ECG show for PE?
Right bundle branch block, with right axis deviation and Q wave in Lead I and inverted T waves in Lead III
What does ABG show in PE?
ABG: shows hypoxia and respiratory alkalosis (respiratory acidosis or lactic acidosis may occur in PE assoicated with obstructive shock and respiratory arrest0
What does a D-dimer test indicate?
Normal value means PE or DVT is unlikely however the specificity of the test decreases with age
What is a specific marker for PE on CXR?
CXR typically has no changes: Westermark sign may be present but is rare, where distal to the embolus, there is increased lucency
What imaging is used to visualize the pulmonary arteries?
CT pulmonary angiogram and assess right ventiruclar enlargement or ventiruclar dysfunction -> but it is less accurate in patients with a high preclinical proaility
What is used as an alternative for patients contraindicated for CTPA?
V/Q scan ideal for patients where CTPA is contraindicated, ideal for pregnant or CKD patinets -> may cause false positives in patients with abnormal CXR
What is the PERC criteria used for?
To assess pre-test probability for obtaining a D-dimer.
What is part of the PERC criteria?
Age over 50, heart rate over 100, o2 saturation less than 95%, unilateral leg swelling, haemoptysis, leg surgery/trauma, hormone use or prior DVT.
What is the Geneva score?
An objective measure to assess pre-clinical probability of DVT.
Low score is 0 to 3
Intermediate score is 4 to 10
High score is above 11
What is part of the Geneva score?
Age over 65
Previous DVT/PE
Recent surgery under general aneaesthesia on lower limb
Active malignant condition
Unilateral limb pain
Pain in lower limb on palpation with oedema
What is the role of LMWH in PE management?
Preferred due to reduced incidence of major bleeding and heparin-induced thrombocytopenia.
What is the management for massive PE?
Priamry reperfusion therapy for rapid thrombolysis using LMWH or Tissue-type plasminogen activator such as alteplas, which is ideal for haemodynamically unstable patients
What therapy should be used for patients with right ventiruclar dilataiton?
thrombolytic therapy
What is the contraindications for thrombolytic therapy?
Contraindications to thrombolysis is structural cerebrovascular disease such as arteriovenous malformation, recent ischaemic stroke or facial trauma
What is used in secondary prevention of PE?
minimum of 3 months of oral anticouagulation for provoked PE. Longer therapy is reccomended for unproved PE or persistent risk factors.
What is a poor Rovno’s is for PE?
Shock and right ventiruclar dysfunction
What should be used for patients that are contraindicated for anticoagulants?
IVC filter should be used for where anticouagulation is contraindicated, and there should be a strategy to remove it at earliest possible opportunity because it significantly reduces the risk of PE but increases the risk of DVT. It blocks the path of the emboli.
How should PE be prevented in hospitalised patients?
LMWH or subcutaneous heparin
Mechanical pneumatic compression of the legs
How should PE be prevented in cancer patients?
Tumours Release clotting factors Patients with active cancer and confirmed proximal DVT or PE should be on anticouagulation treatment for 3-6 months
-> direct acting oral anticoagulant is ideal for those with active cancer and proximal DVT or PE
What do graduated compression stockings do?
Facilitate venous return, improve lymphatic drainage, reverse venous hypertension.
What are direct oral anticoagulants?
- Apixaban
- Dabigatran
- Edoxaban
- Rivaroxaban
What is the HAS-BLED score used for?
To assess the risk of bleeding in patients on anticoagulation.
What is part of HAS-BLED score?
Hypertension
Renal disease
Liver disease
Stroke history
Predisposition to bleeding
Age over 65
Alcohol use
Anticouagulation medication
What is warfarin used for?
Warfarin is licensed for treatment and prophylaxis of DVT nad PE. It causes an increased INR (time taken for blood to clot) which should be monitored
What is the difference between provoked and unprovoked PE?
- Provoked PE is associated with risk factors in the last 3 months.
- Unprovoked PE occurs in the absence of risk factors within the last 3 months.
What may ABG show in cases of PE?
Respiratory alkalosis due to tachypnea from hypoxia.
What is INR?
Measures time taken for clotting to occur.
What is INR?
Blood test used to measure time it takes for blood to clot. Normal INR is 1.1
What is the target INR for patients taking warfarin?
INR range will be 2.0 to 3.0
How should patients with recurrent venous thromboembolic disease despite maximum treatment be managed?
Inferior vena cava filter once there is failure with
-> INR that has been increased to 3-4 with long term high intensity oral anticoagulant therapy
-> Treatment was switched to LMWH
Which anticoagulant is ideal for patients with severe renal impairment?
LMWH or unfractionated heparin followed by a vitamin K antagonist
Which medication is reccomended for antiphospholipid syndrome?
LMWH followed by vitamin K antagonist
What is used to assess risk of bleeding?
ORBIT score based on:
-> Sex
-> Age over 74 years
-> Bleeding history
-> GFR less than 60 ml/min
-> Treatment with anti-platelet songs
What is the reccomended medication for circulatory failure with PE?
Thrombolysis
