PATHOPHYS: Pulmonary Embolism and DVT Flashcards
True or false: 90% of emboli in pulmonary thromboembolism arise from the lower extremities.
TRUE
True or false: bronchospasm and wheezing are seldom a part of the physical findings in pulmonary thromboembolism.
FALSE
True or false: the reason for hypoxia in pulmonary thromboembolism is usually alveolar ventialtions.
FALSE: it is due to V/Q mismatch
True or false: anticoagulation therapy should not be initiated until the diagnose is proven.
FALSE
True or false: the pathogologic EKG finding of S1Q3T3 is seen only in a minority of patients.
TRUE! it is only seen in LARGE PEs (shows right ventricle strain)
True or false: PE is usually diagnosed during routine CXR.
FALSE: 67% are diagnosed after death at autopsy
True or false: most people with a PE die from it.
False, 11% die suddenly but most people do not even realize they have them
If an elderly patient has mental status change, thrombocytopenia, and petechiae after a long bone break, what should be on the differential?
Fat embolus
What are the factors of Virchow’s Triad?
- Venous stasis
- Hypercoagulability
- Endothelial injury
What are some causes of venous stasis that can lead to a PE?
immobility
bed rest
anesthesia
CHF
What are some congenital causes of hypercoagulability that can lead to a PE?
Factor V Leiden mutation (V cannot be broken down by protein C)
What are some acquired causes of hypercoagulability that can lead to a PE?
Estrogen use Hormonal changes during pregnancy malignancy (via TF activation) HIT Nephrotic syndrome
What is the most common cause of thrombocytopenia int he ICU?
DIC (due to sepsis/cancer)
True or false: HIT is a bleeding disorder.
FALSE: though it does cause thrombocytopenia it causes tons of clots!
How do risk factors and DVT incidence coorelate?
4 or more met risk factors coorelates with 100% confirmation of DVT
What are the determinants of the physiologic consequences of PE?
- Size of embolus
- Cardiopulmonary reserve status
- neurohormal substances
True or false: PE will decrease pulmonary vascular resistance.
FALSE: increases it due to vascular obstruction and neurohormonal agents like serotonin and endothelin causing vasoconstriction
True or false: PE impairs gas exchange.
TRUE! increased alveolar dead space from vascular obstruction (ventilated but NOT perfused–leads to V/Q mismatch)
What finding on a PFT is very suggestive of PE?
low DLCO (but PFTs are rarely done on PE patients)
How can PE lead to a right to left shunt?
if a PE is large enough, it will “shut off” circulation to one lung. All of right heart blood will have to go to a single lung (and some of this blood will not be oxygenated because not enough alveoli are left to be recruited!)
Why are infarcts NOT common in the lung?
lung has dual circulation
What is the most common abnormality on a CXR of a patient with PE?
atelectasis
True or false: patients with PE will be hypercapnic.
FALSE: hypocapnic, because they will increase their respirations to fight hypoxia
True or false: PEs always have a negative effect on a person’s oxygenation?
FALSE: vasodilation of uninvolved vasculature (part of lung that is not blocked) helps to increase the pulmonary vascular resistance and improves V/Q relationship in uninvolved areas (ex. involves apex more)
What are some fates of clots in the lung?
1) Fibrinolysis
2) Organization
3) Partial resolution/ compensation
What is the gold standard diagnostic test for PE?
(pulmonary angiography)
but now a helical CT is more commonly done
What are D-dimers?
by-products of fibrinolysis (increase after trauma)
What is the most common finding of a CXR of a PE patient?
normal CXR
What is PITCHED?
Way to clinically predict PE Previous DVT/PE (1.5) Immobilizaiton/Surgery past 4 weeks (1.5) Tacycardia (HR> 100) (1.5) Cancer(1) Hemoptysis (1) Edema/Symptoms of DVT (3) Diagnosis other than PE less likely (3)
If ? 6 points–high risk
What is Hampton’s Hump?
triangular area of infarcted lung
What is “Westermark’s Sign”?
When you do not see any vasculature on one side
Why might you get an elevated hemidiaphragm with PE?
decreased surfactant may lead to atelectasis (so lung not able to deep diaphragm down
True or false: you can confirm PE with a high clinical suspicion and a high probability V/Q scan.
TRUE: and you can rule one out with a low clinical suspicion and low probability V/Q scan
What are pitfalls to V/Q scanning?
- 15 second breath hold
- Better results in patients without structural disease
- 30% observer variability
- Majority of scans are indeterminate
What will a PE look like on a pulmonary angiography?
- filling defect
- cutoff sign
True or false: a normal perfusion scan excludes PE.
TRUE
In low clinical probability settings, when is the possibility of PE very low (after what tests)?
Normal perfusion scan
d-dimer <500
What are some clinical manifestations of DVT?
swelling of leg duskiness Homan's sign palpable deep thrombi tender cord in femoral triangle
What is the gold standard for testing DVT?
ascending contrast venography
but not practical
What is the most practical test for diagnosis of DVT?
Real-time (B-mode) ultrasonogrpahy
How do you prevent DVTs?
- Early mobilization
- compression stockings
- Heparin 5000 units SQ every 8 hours
- Enoxaparin (low molecular weight heparin)
How do you test for efficacy of low molecular weight heparin?
Factor Xa
enoXaparin
How do you test for efficacy of heparin?
aPTT (activated partial thromboplastin time)
What are some treatment options for DVT?
- Thrombolysis (ex. t-PA)
- Radiological intervention (clot disruption catheters)
- Surgical (pulmonary embolectomy)
