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Pulmonary Embolism Flashcards

1
Q

what does a blockage in the pulmonary artery result in?

A

decreased oxygenated blood to body and decrease in blood flow downstream in lungs

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2
Q

what are PEs associated with?

A

DVTs

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3
Q

how to DVTs form?

A

Damage to endothelium
Immediate vasoconstriction – limits blood flow
Platelets adhere and become activated by collagen and tissue factor
Recruit more platelets to form plug = primary haemostasis
Coagulation cascade is activated – clotting factors activated ot activate fibrinogen to fibrin – forms mesh around platelets = secondary haemostasis

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4
Q

what is V/Q mismatch

A

no blood is flowing past alveoli, there are some alveoli getting perfused with fresh air but not with blood

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5
Q

what form can the embolus take?

A

clot, fat, air, amniotic fluid etc

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6
Q

what are the consequences of V/Q mismatch

A

Hyperventilation is a physiological response

Release of CO2¬ causing a respiratory alkalosis (↑pH)

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7
Q

how does a DVT become a PE

A

Clot grows in size and ↓blood flow, ↑blood pressure
Sometimes break down – fibrin → d-dimers
Increased pressure can cause part of main clot to break free = thromboembolus
Travels to pulmonary arteries

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8
Q

What is Virchows Traid?

A

Blood Stasis
Hypercoagulation
Damage to blood vessels

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9
Q

mechanism and causes of blood stasis

A

turbulence causes slow or static blood -Platelets contact endothelium – leads to clotting factor adhesion and activation of coagulation cascade
Causes - bed rest, long flights, pregnancy

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10
Q

hypercoagulation mechanism and cause

A

Altered amounts of clotting factors increase primary or secondary haemostasis
Causes - Genetics, surgery, medications (birthcontrol)

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11
Q

blood vessel damage mechanism and causes

A

exposures tissue factor and collagen

Causes - infections, chronic inflammation, toxins (cigarettes)

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12
Q

what are other risk factors to developing PE

A

Age, malignancy, infection, FH, immobility, pregnancy (compression and oestrogen), previous DVT/embolism, oestrogen therapy (pill, HRT), trauma, surgery, recent MI, dehydration, smoking, congestive heart failure, antithrombin deficiency, protein C deficiency, inherited clotting deficiencies, obesity, varicose veins

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13
Q

what is an important risk factor to explore in PE?

A

family history

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14
Q

What are the clinical signs of a PE (10)

A

Pyrexia, Cyanosis, Tachypnoea, Tachycardia, Hypotension, Raised JVP Pleural rub, Pleural effusion, Look for signs that could indicate a cause, Atrial fibrillation (rare)

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15
Q

What are the clinical symptoms of PE (7)

A

Pleuritic chest pain (pain worse on inspiration
Breathlessness
Cough
Haemoptysis – as a result of pulmonary infarct
Dizziness / pre-syncope
Syncope (loss of consciousness/fainting)
Non-pleuritic chest pain

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16
Q

Small emboli tend to be…

A

asymtpomatic

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17
Q

embolism at the pulmonary saddle causes

A

sudden death

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18
Q

multiple PEs result in

A

pulmonary hypertension, right ventricular failure

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19
Q

What criteria makes up the PERC?

A 
Age >50
HR >100
SaO2 on room air <95%
Unilateral leg swelling
Haemoptysis
Recent surgery or trauma
Previous PE or DVT
Exogenous Oestrogen – oral contraceptives, hormone replacement or other oestrogen hormones
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20
Q

what makes a negative PERC score?

A

all factors must be negative.

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21
Q

what do you if there is a positive PERC score?

A

move onto Wells

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22
Q

what criteria make up the Wells Score?

A 
Clinically suspected DVT = 3
PE is most likely diagnosis = 3
Tachycardia >100bpm = 1.5
Immobilisation >3 days OR surgery – in previous 4 weeks = 1.5
History of DVT or PE in past = 1.5
Haemoptysis = 1
Malignancy = 1
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23
Q

what do different wells scores mean?

A

Score >6.0 — High (probability 59%)
Score 2.0 to 6.0 — Moderate (probability 29%)
Score <2.0 — Low (probability 15%)

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24
Q

What diagnostic tests can you do for pulmonary embolism?

A 
D-Dimer
CXR
ECG
VQ Scan
CT Pulmonary angiogram
ABG
Troponin
Echo
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25
What is D-Dimer?
fibrin degradation product many factors can cause raised levels
26
What does raised D-Dimer indicate?
should only be used as a rule out test in low probability cases based on Wells score D-Dimer + in a low probability case indicates further investigations In high probability can skip and go onto imaging
27
what features will be present in a Xray of someone with PE?
will often be normal, to exclude other causes | may show raised hemidiaphragm, atelectasis
28
what if the CXR in a PE is normal/bilateral?
If the CXR is normal, but the patient is breathless, this raises the suspicion of a pulmonary embolism. If the CXR has bilateral changes, but the patient only has unilateral pain, this also raises the suspicion of pulmonary embolism.
29
what ECG features are present in PE
Sinus tachycardia and T wave inversions Non specific – t wave changes, new onset AF, RBBB axis deviation S1Q3T3 pattern - S waves present in lead I, Q waves present in lead III, T wave inversion in lead III
30
what is the predictive value of V/Q scans?
negative scan has high negative predicative value, but positive scans are less useful
31
What will ABG show in PE?
↓PaO2 ↓PaCO2 Respiratory alkolisis Metabolic acidosis
32
what will an echo show in a PE?
right ventricle strain and dilation
33
what is the drug treatment of a PE?
Anticoagulate with LMWH – e.g. dalteparin 200u/Kg/24hrs
34
what is the surgical management of a PE?
vena cava filter | used in those who continue to develop thrombus despite anticoagulation
35
when can thrombolysis be used in a PE?
when it is deemed massive - 50mg alteplase
36
what preventative measures can be used in PE?
compression stockings, exercise, heparin for immobile patients
37
what are the differentials of a PE?
``` Acute Coronary Syndrome Pleuritic chest pain Pneumonia (viral or bacterial) Pericarditis Musculoskeletal back pain Embolus of other cause (fat, amniotic fluid, air) Dissecting Aortic Aneurysm Anxiety Syncope of another cause Exacerbation of COPD ```
38
what is a pleural effusion?
• Pleural Effusion is when there is excess fluid in the pleural space
39
what is the pleural cavity?
Pleural cavity lies between parietal pleura (stuck to chest wall) and visceral pleura (stuck to lungs) – these lie close together In the thin space, layer of fluid = lubrication to allow lungs to slide back and forth as the expand and contract
40
what are the 2 mechanisms of a pleural effusion?
too much fluid is produced | too little is drained away
41
what 2 types of pleural effusions are caused by too much fluid production?
transudative and exudative
42
what type of pleural effusion is caused by too little fluid drainage?
lymphatic (chylothorax)
43
what are the mechanism of a transudative pleural effusion?
raised hydrostatic pressure (BP - blood back up, HF) reduced oncotic pressure in blood vessels due to reduced protein content (osmosis - low to high, low on BV means fluid leaves into pleural space)
44
what are the causes of a transudative effusion?
Hypoalbuminaemia - Nephrotic syndrome, chronic infection, malabsorption, liver failure Hypothyroidism Meigs Syndrome Cardiovascular - Fluid overload, HF, constrictive pericarditis
45
what is the fluid make up of a transudative pleural effusion?
Lower protein content, contain fewer cells, fluid typically only contains mononuclear cells, protein content <25g/L
46
what is the mechanism of a exudative effusion?
Inflammation of pulmonary capillaries – making them more leaky Larger spaces between endoltehlial cells allows fluid, immune cells, large proteins to leak out
47
what are the causes of a exudative effusion?
Inflammation - RA, granulomatous disorders, SLE, pulmonary infarct Malignancy - Bronchial carcinoma, Metastasis Infection - Acute – empyema, Chronic - TB
48
content of exudative effusion?
The composition of an exudate varies, but it can include pretty much anything that is in blood. It will nearly always have water and dissolved solutes, and may also have white and red blood cells, as well as platelets. Exudates have a high protein content, Protein content >35g/L
49
mechanism of a lymphatic effusion
Thoracic duct us disrupted and lymphatic fluid accumulates in the pleural space
50
causes of lymphatic effusion
damage during surgery, tumours in mediastinum (compressing TD)
51
what are the symptoms of a pleural effusion?
Reduced chest expansion on the affected side Mediastinal displacement away from the affected side Stony dull to percussion Reduced or absent breath sounds Reduced or absent vocal resonance There will be no additional unusual sounds
52
how do you diagnose a pleural effusion?
XRay and Thoracentesis
53
what features are present on the CXR of a pleural effusion?
Standing – fluid displaces air, dulling of costophrenic angle Lying down – fluid settles along chest wall (widespread haze) Flat horizontal line = also pneumothorax present
54
why do you a thoracentesis?
to remove fluid and to find a cause of pleural effusion
55
how do you perform a thoracentesis?
Percuss the upper border of the effusion, then go 1-2 intercostal spaces below Use 5-10ml of lideocaine and inject down to the pleura Insert a 21G needle with syringe just above the ribs upper boarder (to avoid the neurovascular bundle) Take 10-30ml of fluid Send sample for: Clinical biochem – glucose, protein, pH, amylase, LDH, Bacteria culture, Cytology, Immunology
56
how do you treat a pleural effusion?
treat cause and remove fluid (exudative not transudate)
57
what are the different ways in which fluid can be removed in a pleural effusion
``` Small effusions (from HF) – diuretics, sodium restriction Large Effusion (from cancer) – draining with tube, long term chest drains Large Loculated Effusion (pneumonia, TB) – surgery (as fluid can form paste = emphyema) ```
58
what does transudative fluid look like?
clear
59
what does exudative fluid look like?
cloudy
60
what does Empyema/ parapneuoic effusion fluid look like?
yellow/white, foul smelling
61
what does the pleural fluid with trauma, maligannyc or pulmonary infarct is the underlying cause?
blood
62
what is light criteria used for?
distinguish transudative fluid vs exudative fluid
63
what is lights criteria?
Is exudative if: Fluid protein: serum protein >0.5 Fluid LDH: serum LDH > 0.6 Fluid LDH > 2/3 Normal upper limit serum LDG Also, exudative have cholesterol level >45

Respiratory (12 decks)

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