Pulmonary embolism Flashcards
1
Q
what is a PE?
A
common complication of VTE
usually from DVT
clot becomes lodged in pulmonary circulation
2
Q
what is a PE?
A
common complication of VTE
usually from DVT
clot becomes lodged in pulmonary circulation
3
Q
what are the causes of PE?
A
fat
amniotic fluid
blood clot
air - iatrogenic
4
Q
what are the risk factors?
A
age malignancy infection family history immobility pregnancy previous DVT/embolism oestrogen therapy - HRT and COCP trauma surgery recent MI dehydration smoking congestive heart failure antithrombin deficiency protein C deficiency inherited clotting deficiencies obesity varicose veins recent air travel AF
5
Q
immobility
A
> 24 hours of bed rest
48 hours of immobility
plaster of paris over limb
6
Q
pregnancy
A
oestrogen increases risk of PE
risk highest 4 weeks postpartum
7
Q
clinical features of PE
A
wide range
asymptomatic - death
8
Q
signs of PE
A
pyrexia cyanosis tachypnoea - >16 tachycardia hypotension raised JVP pleural rub pleural effusion AF
9
Q
symptoms of PE
A
pleuritic chest pain - worse of inspiration breathlessness cough haemoptysis dizziness syncope non-pleuritic chest pain SOB
10
Q
diagnosis
A
PERC score
Wells score
D-dimer
11
Q
what else can increase D-dimer?
A
liver disease high rheumatoid factor malignancy trauma pregnancy recent surgery
12
Q
normal D-dimer
A
<0.5
13
Q
CXR
A
excludes other causes
often normal
may show pulmonary oedema, atelectasis
14
Q
atelectasis
A
little areas of collapsed lung due to blood loss
15
Q
ECG
A
non-specific changes common to see some changes most common = sinus tachycardia T wave inversion right heart strain S1Q3T3
16
Q
what is S1Q3T3?
A
S waves in lead 1
Q waves in lead III
T wave inversion in lead III
17
Q
CTPA
A
CT-pulmonary angiogram
radioactive dye
diagnostic of PE
more sensitive and specific than VQ scan
18
Q
when is VQ scan used over CTPA?
A
CTPA is highly radiating so VQ is better in young, pregnant females
19
Q
VQ scan
A
negative has very high negative predictive value but positive scans are less useful
20
Q
ABG results
A
low O2
CO2 normal or low due to hyperventilation
metabolic acidosis
cannot exclude PE
21
Q
troponin
A
raised in 20-40% of PE patients due to extra stress and stretch on right ventricle
higher = worse prognosis
22
Q
echo
A
look for RV strain and dilatation
right ventricular dysfunction = predictor of mortality
23
Q
treatment
A
anticoagulation with LMWH oral warfarin vena cava filter thrombolysis if massive embolectomy
24
Q
anticoagulation doses for PE treatment
A
200u/kg/24 hours of dalteparin (18,000 = max dose)
start oral warfarin - 10mg at same time
stop heparin when INR >2
continue warfarin for min of 3 months, aiming for INR of 2-3
25
when to fit a vena cava filter?
when patients continue to develop thrombi despite anticoagulation
26
thrombolysis
50mg alteplase
27
what are the causes of PE?
fat
amniotic fluid
blood clot
air - iatrogenic
28
what are the risk factors?
```
age
malignancy
infection
family history
immobility
pregnancy
previous DVT/embolism
oestrogen therapy - HRT and COCP
trauma
surgery
recent MI
dehydration
smoking
congestive heart failure
antithrombin deficiency
protein C deficiency
inherited clotting deficiencies
obesity
varicose veins
recent air travel
AF
```
29
immobility
>24 hours of bed rest
>48 hours of immobility
plaster of paris over limb
30
pregnancy
oestrogen increases risk of PE
| risk highest 4 weeks postpartum
31
clinical features of PE
wide range
| asymptomatic - death
32
signs of PE
```
pyrexia
cyanosis
tachypnoea - >16
tachycardia
hypotension
raised JVP
pleural rub
pleural effusion
AF
```
33
symptoms of PE
```
pleuritic chest pain - worse of inspiration
breathlessness
cough
haemoptysis
dizziness
syncope
non-pleuritic chest pain
SOB
```
34
diagnosis
PERC score
Wells score
D-dimer
35
what else can increase D-dimer?
```
liver disease
high rheumatoid factor
malignancy
trauma
pregnancy
recent surgery
```
36
normal D-dimer
<0.5
37
CXR
excludes other causes
often normal
may show pulmonary oedema, atelectasis
38
atelectasis
little areas of collapsed lung due to blood loss
39
ECG
```
non-specific changes
common to see some changes
most common = sinus tachycardia
T wave inversion
right heart strain
S1Q3T3
```
40
what is S1Q3T3?
S waves in lead 1
Q waves in lead III
T wave inversion in lead III
41
CTPA
CT-pulmonary angiogram
radioactive dye
diagnostic of PE
more sensitive and specific than VQ scan
42
when is VQ scan used over CTPA?
CTPA is highly radiating so VQ is better in young, pregnant females
43
VQ scan
negative has very high negative predictive value but positive scans are less useful
44
ABG results
low O2
CO2 normal or low due to hyperventilation
metabolic acidosis
cannot exclude PE
45
troponin
raised in 20-40% of PE patients due to extra stress and stretch on right ventricle
higher = worse prognosis
46
echo
look for RV strain and dilatation
| right ventricular dysfunction = predictor of mortality
47
treatment
```
anticoagulation with LMWH
oral warfarin
vena cava filter
thrombolysis if massive
embolectomy
```
48
anticoagulation doses for PE treatment
200u/kg/24 hours of dalteparin (18,000 = max dose)
start oral warfarin - 10mg at same time
stop heparin when INR >2
continue warfarin for min of 3 months, aiming for INR of 2-3
49
when to fit a vena cava filter?
when patients continue to develop thrombi despite anticoagulation
50
thrombolysis
50mg alteplase
51
what is paradoxical embolism?
embolism that travels through heart defect and can cause stroke
travels from vein to artery
can cause stroke
52
complications of PE
```
recurrence
cardiac arrest
pleural effusion
pulmonary infarction
arrhythmia - AF
pulmonary hypertension
heart failure
abnormal bleeding due to anticoagulants
embolectomy complications
```
53
prognosis
most risk of mortality if the first few hours after embolism
high risk of another PE within 6 weeks of initial one
most people make full recovery if treated promptly
existing serious illness can cause poorer prognosis
54
differential diagnoses
- acute coronary syndrome
- pleuritic chest pain – pneumonia
- pericarditis
- MSK back pain
- other embolus – fat, amniotic fluid or air
- dissecting aortic aneurysm
- anxiety
- syncope of another cause
- exacerbation of COPD
55
PERC
PE rule-out criteria
56
PERC scoring
0 = <2% chance of PE as long as there are no clinical signs
positive factors needs further work up
each factor gives 1 point
57
what are the PERC factors?
```
>50 years old
HR >100
SaO2 >95% on room air
unilateral leg swelling
haemoptysis
recent surgery or trauma
previous PE/DVT
exogenous oestrogen
```
58
gold standard DVT investigation
venography
59
other diagnostics
```
D-dimer
leg measurement
ultrasound (higher sensitivity above knee)
venometer
doppler ultrasound
fibrinogen testing
S1Q3T3
```
60
epidemiology of DVT
25-50% of all surgical patients
more common in veins due to slower blood flow
can occur in any vein more common in legs and veins
61
causes of DVT
```
stasis/ immobility - hospital bed, long flight
dehydration
oestrogen - pregnancy, COCP, HRT
genetic clotting defect - protein C deficiency
obesity - atherosclerosis
age
varicose vein
surgery
previous DVT/ embolism
trauma
infection
malignancy
```
62
what is virchow's triad of risk factors?
stasis
hypercoagulability
vessel wall injury
63
signs/ symptoms of DVT
```
red, swollen leg
tenderness
pitting oedema
fever
horman's sign
well's score
pain
```
64
horman's sign
increased resistance/pain on forced foot dorsiflexion
| don't do this test as it can dislodge the clot
65
pathology of DVT
clot develops at site of damage to vessel wall - atherosclerotic plaque or site of trauma
impairs venous leg drainage
66
clinical diagnosis of DVT
highly unreliable
50%
coupled with D-dimer = 80%
67
treatment of DVT
```
prevention is best
LMWH
warfarin
bed rest
elasticated stockings
IVC filter
thrombolysis
```
68
anticoagulation for DVT
ASAP LMWH and continued for 5 days minimum
stop LMWH when INR = 2-3
6 weeks of LMWH for patients with below knee DVT
start warfarin at same time
69
benefit of elasticated stockings
reduces risk of superficial thrombphlebitis
70
IVC filter
used if anticoagulation fails
71
continuation of warfarin
6 months if 1st DVT
3 months if first DVT and occurred post-op
permanently if recurrent DVT or there is a genetic clotting disorder or other large risk factors
72
prognosis for DVT
```
recurrence depends on risk factors
if post-op when first experienced recurrence is unlikely
5 year recurrence = 30%
risk of PE fatality = 3%
often self-resolves
```
73
complications of DVT
```
PE
post-phlebitic syndrome
ulcers
pain
skin colour changes
sudden death from PE
```
74
How to prevent DVT?
```
stop pill 4 weeks pre-op
mobilise early post-op
pre-op LMWH
stay active
maintain a healthy weight
hydration
```
75
how to prevent PE?
```
treat DVTs
anticoagulation
compression stockings
keep active - post-op, long haul flights
stop smoking
regular exercise
not sitting for long time
healthy balanced diet
healthy weight maintenance
reducing DVT risk
```
76
differential diagnoses for DVT
ruptured Baker's cyst
lymphadenopathy
superficial thrombophlebitis
injury - muscle haematoma
77
what is pitting oedema?
observable swelling of body tissues due to fluid accumulation
causes indentation that persists some time after release of pressure.
Associated with retention of sodium and occurs when more than 3 litres of interstitial fluid collects.
