Working Problem 12-Thromboembolism

Question 1

When do you perform an D dimer?

Answer 1

•It can be used to rule out(high sensitivity low specificity )a disease when the pre-test probability of venous thromboembolism is low
It can also be used to assess venom induced consumptive coagulopathy and DIC

Question 2

How do you assess pretest probability?

Answer 2

Assessed using Well score criteria for PE(

Question 3

What are the non- pathological conditions associated with elevated D dimers

Answer 3

Age
smoking
functional impairment
post operatively
Pregnancy
race(african-american)

Question 4

What are the pathological conditions associated with elevated D dimers?

Answer 4

Acute coronary syndrome
Atrial fibrillation
Arterial or venous thromboembolism
DIC or VICC
Infection
Malignancy
Sickle cell anemia
Trauma
Acute upper GI bleed
Stroke

Question 5

What situation can result in false negative D dimer assay?

Answer 5

If you don’t perform the pre test probability correctly you will get negative D dimer(false negative)

There is a small clot load(small calf only DVT)
The thrombus has matured over time
The patient has defective fibrinolysis(which can contribute to thrombus formation in the first place(you need fibrinolysis to have fibrin degradation prod

Question 6

What is pulmonary embolism?

Answer 6

Some or all of the thrombus get detached from the veins and move through the right heart and ends up lodging into the pulmonary arteries.
It causes SOB of breath(↓Q and Normal V→V/Q mismatch)
PE may cause SOB, Bloody sputum, chest pain, faintness and heart failure
Massive PE→death

Question 7

What are the symptoms of PE?

What are the signs of PE?

Answer 7

Symptoms
Dyspnea (73%)
Pleuritic chest pain (44%)
Non pleuritic chest pain (19%)
Cough
Wheezing

Signs
Tachypnea (>20/min) (54%)
Tachycardia(>100/min)
↑JVP
Lung crackles
Signs of DVT (50%)

Question 8

What are the signs and symptoms of DVT

Answer 8

Swelling 
Tenderness
Pitting edema
Engorgement of superficial veins
Post phlebitic syndrome

Question 9

How do you prevent DVT?

Answer 9

Adequate hydration
Early ambulation
Mechanical
o	Graduated compression stockings
o	Intermittent Pneumatic compression
o	Electrical calf stimulation
Pharmacological
o	Heparins including unfractionated heparin and low molecular weight heparins depending on risk
o	Direct oral anticoagulants: rivaroxaban,Apixaban,Dabigatran
o	Warfarin in some settings

Question 10

How long should be treatment given?

Answer 10

For the time period of increased risk during and after
•	Hip and knee surgery
•	Cancer
•	Immobility
•	Previous VTE
•	Pregnancy

Question 11

What is the aim of anticoagulation?

Answer 11

o Stabilisation of thrombus
o Prevention of propagation
o Prevention of PE
o It is usually not to dissolve the clot(unless very big)

Question 12

How do you manage venous thromboembolism?

Answer 12

1) anticoagulation
2) Thrombolysis(only performed when patient is hypotensive or in cardiogenic shock)
3) mechanical(eg:IVC filter)
4) Surgical (eg:removal of embolus)

Question 13

How long do you anticoagulate some for?

Answer 13

If provoked...
Calf DVT	
•	observe only(CUS  at 10-14 days)
•	10-14 days anticoagulation
•	3 months anticoagulation

– Thigh/pelvis DVT
• 3-6 months anticoagulation

– PE
• 6-12 months anticoagulation

If unprovoked...
–	Calf DVT	
•	observe only(CUS at 10-14 days)
•	10-14 days anticoagulation
•	3 months anticoagulation

– Thigh/pelvis DVT
• 6-12 months anticoagulation

– PE
• 12 months anticoagulation

Question 14

What drug do you give when the patient is having heparin induced thrombocytopenia and thrombosis

Answer 14

o Fondaparinux(anti-10a)(injection)

•	Oral anticoagulants
–	Warfarin (inhibition of Vit K)
–	Direct oral anticoagulants(DOACs)
•	Rivaroxaban
•	Dabigatran
•	Apixaban

All the novel drugs are as effective as warfarin with bans inhibiting factor 10 and dabigatran inhibiting thrombin
No drug interaction
Monitoring not required

Question 15

What imaging are done for DVT?

Answer 15

Compression Ultrasonography(Most commonly used for DVT,operator dependent)

Contrast venography(gold standard reserved for those with clinical findings highly suggestive of DVT but doesn’t show in CUS)

Question 16

What imaging is used for PE?

Answer 16

CT pulmonary angiography(diagnostic method of choice,fairly readily available,is easy and fast to perform and has good sensitivity(85%) and specificity(95%)
Large radiation burden and contrast required(not suitable for people with renal problems)

V/Q scan(used for renal patients and those allergic to contrast but has lower sensitivity and specificity as compared to CTPA)

Chest x ray(used only to rule out other causes as not reliable)BUT IT IS THE FIRST TEST TO BE ORDERED
look out for westermark’s sign(peripheral oligaemia) and Hampton’s hump which is a reliable sign(reliable sign of pulmonary infarction)

Question 17

What are other test that are done for pulmonary embolism

Answer 17

1) ECG
a) It is to differentiate pulmonary embolism from myocardial infarction which can present in the same way(chest discomfort ,dyspnea ,raised JVP and hypotension)
b) ECG in pulmonary embolism relatively normal but might show signs of heart strain(Cor pulmonale, right axis deviation, right bundle branch block)
2) Troponin
a) Cardiac troponin levels may be elevated in patients with massive acute pulmonary embolism.
b) As such, it gives a clue as to the magnitude of the embolism.

Question 18

when is thrombolytic therapy indicated?

Answer 18

a. The most widely accepted indication for thrombolytic therapy is proven pulmonary embolism with cardiogenic shock
b. Therapy may also be considered when a patient presents with systemic hypotension without shock
c. Complication due to intracranial bleed reported to occur in 2% of patients

Question 19

What are the absolute and relative contraindications when treating someone with thrombolytic therapy?

Answer 19

ABSOLUTE
•history of intracranial bleeding
•CVA within past 3 months
•closed head or facial trauma within past 3 months
•suspected aortic dissection
•active internal bleeding
•uncontrolled hypertension  (> 180/100)

RELATIVE
•current anticoagulation or bleeding diathesis
•surgery or invasive procedure within past 2 weeks
•recent prolonged CPR (> 10 mins)
•controlled severe hypertension
•diabetic or haemorrhagic retinopathy
•Pregnancy

Question 20

What is the purpose of wearing graduated stockings? after acute DVT?

Answer 20

wear for 2 years

Prevent post phlebitic syndrome

Question 21

How is warfarin administered?

and why must it be administer with heparin till it reaches therapeutic level?

Answer 21

Warfarin given for 3 months
INR maintained between 2-3
Levels below 2 not therapeutic and above 4 risk bleeding

Heparin used for prevention of hypercoagulable state due to inhibition of protein C cause the circulating gamma carboxylated factors to result in a hypercoagulable state

Question 22

What are the clinical manifestation of acute massive PE?

Answer 22

Major haemodynamic effects; decreased CO;acute RHF

Symptoms
Faintness or collapse,central chest pain,apprehension
Severe dyspnea

Signs
Major circulatory collapse,tachycardia,hypotension,increased JVP

Question 23

What is the are the clinical manifestations of acute/medium PE?

Answer 23

occlusion of segmental pulmonary artery leading to infarction with effusion or not

Symptom
Pleuritic chest pain(not central chest pain)
restricted breathing
hemoptysis

Signs
tachycardia
pleural rub
crackles
Low grade fever

Question 24

What is the clinical manifestation of chronic PE?

Answer 24

chronic occlusion of pulmonary microvasculature

Symptoms
Exertional Dyspnea
Late symptoms of pulmonary hypertension or right heart failure

Signs
May be minimal in the early disease and chronically produce heaves and may even cause terminal RHF

Question 25

What is paradoxical embolism and what causes it?

Answer 25

Passage of embolus from systemic vein into systemic artery through ASD or patent foramen ovale
Contributes to 2 % of all arterial emboli
Patent foramen ovale much more common cause

Question 26

Who requires indefinite anticoagulation?

Answer 26

People who have recurrent DVTs or have inherited thrombophilic conditions(based on family hx)