Pulmonary embolism Flashcards
what is a PE?
common complication of VTE
usually from DVT
clot becomes lodged in pulmonary circulation
what is a PE?
common complication of VTE
usually from DVT
clot becomes lodged in pulmonary circulation
what are the causes of PE?
fat
amniotic fluid
blood clot
air - iatrogenic
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
immobility
> 24 hours of bed rest
48 hours of immobility
plaster of paris over limb
pregnancy
oestrogen increases risk of PE
risk highest 4 weeks postpartum
clinical features of PE
wide range
asymptomatic - death
signs of PE
pyrexia cyanosis tachypnoea - >16 tachycardia hypotension raised JVP pleural rub pleural effusion AF
symptoms of PE
pleuritic chest pain - worse of inspiration breathlessness cough haemoptysis dizziness syncope non-pleuritic chest pain SOB
diagnosis
PERC score
Wells score
D-dimer
what else can increase D-dimer?
liver disease high rheumatoid factor malignancy trauma pregnancy recent surgery
normal D-dimer
<0.5
CXR
excludes other causes
often normal
may show pulmonary oedema, atelectasis
atelectasis
little areas of collapsed lung due to blood loss
ECG
non-specific changes common to see some changes most common = sinus tachycardia T wave inversion right heart strain S1Q3T3
what is S1Q3T3?
S waves in lead 1
Q waves in lead III
T wave inversion in lead III
CTPA
CT-pulmonary angiogram
radioactive dye
diagnostic of PE
more sensitive and specific than VQ scan
when is VQ scan used over CTPA?
CTPA is highly radiating so VQ is better in young, pregnant females
VQ scan
negative has very high negative predictive value but positive scans are less useful
ABG results
low O2
CO2 normal or low due to hyperventilation
metabolic acidosis
cannot exclude PE
troponin
raised in 20-40% of PE patients due to extra stress and stretch on right ventricle
higher = worse prognosis
echo
look for RV strain and dilatation
right ventricular dysfunction = predictor of mortality
treatment
anticoagulation with LMWH oral warfarin vena cava filter thrombolysis if massive embolectomy
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
when to fit a vena cava filter?
when patients continue to develop thrombi despite anticoagulation
thrombolysis
50mg alteplase
what are the causes of PE?
fat
amniotic fluid
blood clot
air - iatrogenic
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
immobility
> 24 hours of bed rest
48 hours of immobility
plaster of paris over limb
pregnancy
oestrogen increases risk of PE
risk highest 4 weeks postpartum
clinical features of PE
wide range
asymptomatic - death
signs of PE
pyrexia cyanosis tachypnoea - >16 tachycardia hypotension raised JVP pleural rub pleural effusion AF
symptoms of PE
pleuritic chest pain - worse of inspiration breathlessness cough haemoptysis dizziness syncope non-pleuritic chest pain SOB
diagnosis
PERC score
Wells score
D-dimer
what else can increase D-dimer?
liver disease high rheumatoid factor malignancy trauma pregnancy recent surgery
normal D-dimer
<0.5
CXR
excludes other causes
often normal
may show pulmonary oedema, atelectasis
atelectasis
little areas of collapsed lung due to blood loss
ECG
non-specific changes common to see some changes most common = sinus tachycardia T wave inversion right heart strain S1Q3T3
what is S1Q3T3?
S waves in lead 1
Q waves in lead III
T wave inversion in lead III
CTPA
CT-pulmonary angiogram
radioactive dye
diagnostic of PE
more sensitive and specific than VQ scan
when is VQ scan used over CTPA?
CTPA is highly radiating so VQ is better in young, pregnant females
VQ scan
negative has very high negative predictive value but positive scans are less useful
ABG results
low O2
CO2 normal or low due to hyperventilation
metabolic acidosis
cannot exclude PE
troponin
raised in 20-40% of PE patients due to extra stress and stretch on right ventricle
higher = worse prognosis
echo
look for RV strain and dilatation
right ventricular dysfunction = predictor of mortality
treatment
anticoagulation with LMWH oral warfarin vena cava filter thrombolysis if massive embolectomy
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
when to fit a vena cava filter?
when patients continue to develop thrombi despite anticoagulation
thrombolysis
50mg alteplase
what is paradoxical embolism?
embolism that travels through heart defect and can cause stroke
travels from vein to artery
can cause stroke
complications of PE
recurrence cardiac arrest pleural effusion pulmonary infarction arrhythmia - AF pulmonary hypertension heart failure abnormal bleeding due to anticoagulants embolectomy complications
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
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
PERC
PE rule-out criteria
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
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
gold standard DVT investigation
venography
other diagnostics
D-dimer leg measurement ultrasound (higher sensitivity above knee) venometer doppler ultrasound fibrinogen testing S1Q3T3
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
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
what is virchow’s triad of risk factors?
stasis
hypercoagulability
vessel wall injury
signs/ symptoms of DVT
red, swollen leg tenderness pitting oedema fever horman's sign well's score pain
horman’s sign
increased resistance/pain on forced foot dorsiflexion
don’t do this test as it can dislodge the clot
pathology of DVT
clot develops at site of damage to vessel wall - atherosclerotic plaque or site of trauma
impairs venous leg drainage
clinical diagnosis of DVT
highly unreliable
50%
coupled with D-dimer = 80%
treatment of DVT
prevention is best LMWH warfarin bed rest elasticated stockings IVC filter thrombolysis
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
benefit of elasticated stockings
reduces risk of superficial thrombphlebitis
IVC filter
used if anticoagulation fails
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
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
complications of DVT
PE post-phlebitic syndrome ulcers pain skin colour changes sudden death from PE
How to prevent DVT?
stop pill 4 weeks pre-op mobilise early post-op pre-op LMWH stay active maintain a healthy weight hydration
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
differential diagnoses for DVT
ruptured Baker’s cyst
lymphadenopathy
superficial thrombophlebitis
injury - muscle haematoma
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.
