Week One - Case Two Flashcards
what is a pulmonary embolism most common secondary to
a VTE from another source that becomes dislodged, flows via bloodstream, through the right side of the heart and gets lodged into the pulmonary circulation
what is the mortality rate of PE with VTE if there is no haemodynamic instability
<5%
what is the mortality rate of a PE with VTE if shock is present
30%
what is the mortality rate of a PE with VTE if cardiac arrest happens
70%
what are the risk factors for a PE
age
Malignancy
Infection
Family history
Immobility
Bed rest >24 hours
Immobility >48 hours
Plaster of Paris over limbs
pregnancy - oestrogen (4 weeks after birth)
Previous DVT
Trauma or surgery
Dehydration
Smoking
Congestive heart failure
Antithrombin and protein C
deficiency
Obesity
Varicose veins
what are the signs of a PE
Pyrexia
Cyanosis
Tachypnoea
Tachycardia
Hypotension
Raised JVP
Pleural rub
Pleural effusion
Look for signs that could indicate a cause – e.g. DVT, recent surgery, air travel –
Atrial fibrillation (rare)
what percentage of people have tachypnoea with a PE
90% of patients have RR>16
what percentage of people have tachycardia with a PE
45%
what percentage of people have hypotension with a PE
25%
what are the most common symptoms of a PE
Pleuritic chest pain (pain worse on inspiration) –75% of patients
Breathlessness –85% of patients
Cough –50% of patients
Haemoptysis – as a result of pulmonary infarct –30% of patients
Dizziness / pre-syncope –15% of patients
Syncope (loss of consciousness/fainting) –15% of patients
Non-pleuritic chest pain – 15% of patients
what is the first symptom to occur
shortness of breath occurs within seconds and pain develops later
what is the PERC score used for diagnosis
stands for pulmonary embolism rule-out criteria
it is useful to rule out PE in low risk patients
what happens if patient’s PERC score is 0
there is less than 2% chance of PE
how is PERC score scored
Each factor below gives a score of 1. All factors must be negative for a negative PERC score. Any positive factor results in the need for further work up (move onto the Well’s Score)
Age >50
HR >100
SaO2 on room air <95%
Unilateral leg swelling
Haemoptysis
Recent surgery or trauma
Previous PE or DVT
Exogenous Oestrogen
what is the Well’s Score for PE
this can stratify patients as low risk or high risk.
what should happen with low and high risk patients
with high risk patients you should proceed straight to imaging
in low risk patients you should consider a D dimer test
look up the scores used in the Wells Score
what is the traditional interpretation used of Well’s Score
Score >6.0 — High (probability 59%)
Score 2.0 to 6.0 — Moderate (probability 29%)
Score <2.0 — Low (probability 15%)
what is the alternative interpretation of the Well’s Score
Score > 4 — PE likely. Consider diagnostic imaging.
Score 4 or less — PE unlikely. Consider D-dimer to rule out PE.
what is D dimer
a fibrin deviation product - and as such, levels are raised by the presence of a blood clot in the circulation
what does a negative D-dimer plus a low Well’s score mean
that PE or DVT is extremely unlikely
when should a D dimer only be used
should only be used as a rule out test in low probability cases - based on the Well’s scoreb
what does a positive D-dimer test in a low probability case indicate
the need for further investigation
what should you do with a high probability case
skip the D dimer and go straight to imaging
what, apart from a PE results in a positive D dimer
any factor that causes inflammation will also result in a raised D-dimer
when is a D-dimer test not appropriate as an investigation approach
if the patient recently had cellulitis or another infection
what happens with age to the D dimer value
D dimer also rises with age.
what is the traditional reference range for D dimer
normal <0.5
Example of age adjusted:
Age <50 – normal <0.50
Age >50 – normal range is <0.50PLUS0.1 for every decade of life over the age of 50, e.g.:
Age 60 – normal <0.60
Age 70 – normal <0.70
what other factors may cause an increased D dimer
Other factors that caused an increased D-Dimer includeliver disease, high rheumatoid factor, malignancy, trauma, pregnancy and recent surgery.
what would a CXR normally look like in PE
often be normal
the main reason it is performed is to exclude other causes
what are the potential, rare findings on a PE CXR
the CXR may show pulmonary oedema signs such as raised hemidiaphragm.
May also show atelectasis - this is little areas of collapsed lung
why does this occur
because there is a loss of blood to some areas - a conservative mechanism
what raises the suspicion of a PE
if the CXR is normal but the patient is breathless
what happens if the CXR has bilateral changes, but the patient only has unilateral pain
this also raises the suspicion of a PE
what are the most common findings in ECG
T wave inversion and sinus tachycardia
what can large emboli cause to show on an ECG
cause right heart strain, which will result in the ‘classical’ S1Q3T3 pattern
what percentage of PE patents will have ECG changes
80%
what its the classical S1Q3T3 pattern
S waves presentin lead I
Q waves present in lead III
T wave inversion in lead III
what is a CTPA
a CT-pulmonary angiogram
CT with contrast, assessing the pulmonary blood vessels.
what is its main use
the diagnosis of a PE
what is the typical diagnostic scan used for a PE
a CTPA
are VQ or CTPA scans more accurate in diagnosing PE
CTPA -VQ scans are much less accurate
the result of a VQ scan is usually given as a risk probability - high risk, intermediate risk or low risk
when would a VQ scan be used instead
as an alternative in young females, or pregnant females
what do the results of an ABG show
02 may be low
C02 may often be normal or low
why is there low C02
the patient is hyperventilating
what is common seen in patients with a massive PE and cardiovascular collapse
metabolic acidosis
in what percentage of PE patients is troponin raise
20-40% as a result of the extra stress and stretch placed on the right ventricle with PE patients (due to increased pulmonary arterial pressure)
higher troponin has been associated with a worse prognosis
what should a patient with signs of right heart strain and haemodynamic instability be considered for
thrombolysis
what is used for thromboylsis
50mg alteplase - long list of contraindications
what is a saddle PE
a PE sitting at the major bifurcation of the pulmonary veins
what is the other main treatment
anticoagulation
what can this be done with
warfarin, or a NOAC
what is an example of an NOAC
rivaroxaban
what is most favourable
NOAC as it dos not require monitoring and does not require the use of heparin at the start of the treatment period
what is an example of warfarin treatment
Anticoagulate with LMWH – e.g. dalteparin 200u/Kg/24hrs. The max dose is 18,000.
At the same time start oral warfarin 10mg
Stop the heparin when the INR is >2, and continue warfarin for a minimum of 3 months, aiming for an INR of 2-3.
when is a vena cava filter considered
in patients with recurrent thrombus despite anticoagulation, - but remember that implanting a filter without adequate anticoagulation will increase the risk of thrombus
what is the minimum amount of time for continuation of anticoagulant therapy
at the very minimum 6 weeks
what about those with an identifiable and reversible risk factor
3 months
what about those with idiopathic disease
6 months
