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Respiratory System > Pulmonary Embolism > Flashcards

Pulmonary Embolism Flashcards

1
Q

What is an embolism?

A

An obstruction of a blood vessel by a foreign substance or blood clot that travels through the bloodstream and lodges in a distal blood vessel

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2
Q

What is a pulmonary embolism?

A

An ebolism where the material passes through the right side of the heart and lodges in the pulmonary arteries

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3
Q

Aside from blood clots, what other things can embolise?

A
  • Tumour
  • Air
  • Fat (after bone fracture)
  • Amniotic fluid
  • Bullets
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4
Q

What is fat embolism syndrome?

A

A serious manifestation of fat emboli that affects the lungs, CNS and skin and may cause death!

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5
Q

Where do 90% of pulmonary embolism arise from?

A

DVT

Predominantly the popliteal vein and more proximal veins including pelvic veins

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6
Q

What 3 primary factors make up Virchow’s triad and predispose to blood clotting?

A
  1. Endothelial injury
  2. Stasis or turbulence of blood flow
  3. Blood hypercoagulability
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7
Q

Explain the normal clotting cascade

A
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8
Q

Give some risk factors for thromboembolism

A
  • Pregnancy
  • Prolonged immobolisation
  • Previous VTE
  • Contraceptive pill
  • Long haul travel >4 hrs
  • Cancer
  • Heart Failure
  • Obesity
  • Surgery >30 mins
  • HRT
  • Thrombophilia
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9
Q

Which cancer has the highest risk of someone getting PE?

A

Pancreatic Cancer

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10
Q

Which conditions make a patient hypercoaguable

A
  • Antithrombin III deficiency
  • Protein C or protein S deficiency/ resistance
  • Lupus anticoagulant
  • Homocystinuria
  • Occult neoplasm
  • Connective tissue disorders such as RA
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11
Q

What is the most common risk factor for DVT/ PE in younger people?

A

Factor V Leiden mutation causing resistance to activated Protein C

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12
Q

What is the main cause of death if someone has PE?

A

Acute right sided heart failure leading to:

  • cardiogenic shock and/or
  • cardiac arrest secondary to arrythmia
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13
Q

How does PE cause acute right ventricular overload?

A
  • PE causes an increase in pulmonary artery pressure if >30% of the pulmonary artery bed is occluded
  • Increased right ventricular dilation and strain
  • Inotropes released by the body in an attempt to maintain systemic BP cause further pulmonary artery vasoconstriction which further exacerabates the situation
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14
Q

What increases risk of severe hypoxaemia, paradoxical emboli and stroke?

A

Patent Foramen Ovale

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15
Q

How does PE lead to respiratory failure?

A
  • Areas of V/Q mismatch
  • Right ventricle has low output
  • R → L shunt if patent foramen ovale causes deoxygenated blood to go into systemic circulation causing profound hypoxaemia
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16
Q

How does pulmonary embolism cause pulmonary infarct?

A
  • Small distal emboli may create areas of alveolar haemorrhage
  • Results in haemoptysis, pleuritis and small pleural effusion
  • Only happens in 10-20% cases
  • May be visible of CXR as a wedge shape
17
Q

What are some of the symptoms of PE?

A
  • Dyspnoea (60-75%)
  • Pleuritic chest pain (40-65%)
  • Substernal chest pain (15%)
  • Cough (25-35%)
  • Haemoptysis (8-15%)
  • Syncope (6%)
  • Unliateral leg pain (6%)
  • Fever (10-15%)
  • Chest wall tenderness on palpation
18
Q

What are some of the physical signs of PE?

A
  • Tachypnea (>16 resp rate) (90-96%)
  • Rales/ decreased breath sounds (50%)
  • Accentuated second heart sounds loud P2 (50-55%)
  • Tachycardia >100bpm (44-50%)
  • Fever (30-45%)
  • Siaphoresis
  • Clinical signs and symptoms of thromboplebitis
  • Lower exremity oedema
  • Cardiac murmor
  • Cyanosis
19
Q

What investigations would you you carry out to diagnose PE?

A
  • Blood gases
  • CXR
  • ECG
  • D dimers
20
Q

What may you see on blood gases that would indicate PE?

A
  • Hypoxaemia and hypocapnia (respiratory alkalosis) due to hyperventilation
  • PaO2 may be normal in a minority
21
Q

What would you see on CXR if someone has PE?

A

Chest X-Ray will be normal!!

Done to exclude other diagnoses

22
Q

What might you see on ECG if someone has PE?

A

Signs of right ventricular strain

  • T wave inversion in right precordial leads (V1-V4 and the inferior leads II, III and aVF)
  • Classical finding is SI QIII TIII
23
Q

What are D-dimers?

A

D dimers are products of fibrin degredation that are released into the blood when a thrombus is degreated by fibrinolysis

A normal D-Dimer would rule out PE

24
Q

What is the criteria used for assessing PE?

A

Well’s Criteria

A score >4 = PE is likely and imaging is recommended

A score <4 and D dimers + = imaging recommended

A score <4 and D dimers are negative = PE unlikely

25
Q

What is the best imaging technique for diagnosing PE?

A

CT pulmonary angiography (CTPA)

Can see a straddle embolism over the pulmonary trunk

26
Q

How do you treat PE?

A
  • Give O2
  • Immediate heparin (anti-coagulant) low molecular weight
27
Q

How does heparin reduce mortality?

A
  • Stops thrombus propogation to the pulmonary arteries and allows body;s fibrinloytic system to lyse the thrombus
  • Reduces frequency of further PE
  • DOES NOT DISSOLVE THE CLOT- the body does this
28
Q

What is heparin-induced thrombocytopenia?

A

A rare side effect of low molecular weight heparin

  • body produces antibodies to a portion of heparin and heparin-platelet complexes
  • Causes antibodies to platelets → low platelets
  • Paradoxically increaes risk of thrombosis
29
Q

What additional treatment do you give patients who are high risk of PE?

A
  • Haemodynamic support
  • Respiratory support
  • Exogenous fibrinolytics (streptokinase/ tPA tissue plasminogen activator)
  • Percutaneous catheter directed thrombectomy
  • Surgical pulmonary embolectomy
30
Q

What can you give patients who cannot be safely anticoagulated with heparin?

(due to oesophageal varices, previous haemorrhagic stroke, severe thrombocytopenia)

A

Direct Oral Anti Coagulant (DOAC) e.g. Rivaroxaban has a lower risk of bleedinh

31
Q

What can you give if no anti-coagulation can be used?

A

IVC Filter

An umbrella that stops clots- doesn’t really improve mortality

32
Q

How can you prevent DVT in outpatients?

A
  • Avoid obese, smoking women being placed on COCP/ HRT
  • Advice for people with thrombophilia who travel >4 hours
33
Q

How can you prevent DVT in inpatients?

A
  • DVT prophylaxis after surgery
  • DVT prophylaxis for patients with malignancy

Respiratory System (20 decks)

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