Pulmonary Circulation Disorders Flashcards
What is the MC PE? What are some other causes?
Thrombus that starts in the venous system, gets lodged into the pulmonary system
Air embolus
Amniotic fluid (during delivery, travels through the placenta, into the circulation of the female)
Fat
Foreign bodies (talc in injection from IV users, cemement from surgery)
Parasite eggs (schistosomiasis, not in the US)
Septic emboli (IV drug users w/ infective endocarditis)
Tumor cells (kidney specifically)
How does fat lead to PE?
long bone fractures (disruption in vascular supply, and fat inside the fat that gets sucked up into the system)
What is the overview of the pathophys of PE?
- Infarction (Most often occurs when small emboli lodge distally where there is little collateral blood flow)
- Impaired gas exchange
- Cardiovascular compromise
What does surfactant do?
Dawn dish soap (allows alveoli to open and close easily)
Explain how PE leads to impaired gas exchange
Altered ventilation to perfusion ratio
Inflammation → Surfactant dysfunction → Atelectasis → Functional intrapulmonary shunting
Stimulation of the respiratory drive → hypocapnia and respiratory alkalosis
all because of lack of CO2 O2 exchange
Explain the cardiovascular compromise of PE
Obstruction of the vascular bed → Increased pulmonary vascular resistance → Right heart and intraventricular septal strain
Less blood returning to the left ventricle → Reduced cardiac output → Hypotension
this is what kills them
What is virchow’s triad?
Venous stasis
Injury to vessel
hyper-coagulability
risk factors for PE
What are the risk factors for Venous Stasis?
Immobility
obesity, stroke, bed rest, post-op
Hyperviscosity (polycythemia, increased in RBC makes it thicker)
Increased central venous pressures
low cardiac output states, pregnancy
What does pregnancy lead to venous stasis?
Baby get big and then when you sit flat, it pushes pressure in the IVC and then this coagulates to the lower extremity
What can cause injury to vessel wall?
Prior episodes of thrombosis (makes it more likely to clot), orthopedic surgery, or trauma
anything that disrupts normal blood vessel anatomy
What medications can lead to hypercoagubility?
Oral contraceptives, estrogen and testosterone
What disease makes someone more likely to have a blood clot?
malignancy, surgery
What is the MC gene defect that causes hypercoagubility?
Factor V Leiden
can also be other problems
What are the MC symptoms of PE
Tachypnea (increased RR) is most reliable exam finding (70%), Pleuritic Chest pain (hurts more when you take a breath), dyspnea, cough
tachpnea, crackles, and tachycardia are most important physical exam finding
often preceded by a DVT
What is the wells criteria for PE and if it does not meet it, what do you use?
If greater then 6, straight to D dimer
PERC, if they have ANY then you do a d-dimer
What is a d-dimer and what is normal?
a protein fragment from a broken down blood clot
<50 is normal
if >50 years old, then
10 x their age (70 yo x 10 = 700)
what are the false positives of d-dimer?
age >50 years (should adjust by calculating 50x10), recent surgery or trauma, acute illness, pregnancy or postpartum state, rheumatologic disease, renal dysfunction and sickle cell disease
What is the first-line imaging modality?
CTA
CT angiography which only show pulmonary vessels and you see filling defect (you see it turn from white to grey = grey spot is filling defect)
What are the caution of CTA for PE
Pregnancy
Metformin (med is hard on the kidneys and the contrast is also hard on kidneys. Should withhold use for 48 hours).
Allergy to contrast dye (promedicate with methyoprolcin)
What do you see in V/Q scan of PE?
Good ventilation and poor profusion
indicated for those who are CI for CTA
Good profusion rules it out
What is the gold standard of PE?
Pulmonary angiography, but not first line because it is invasive
Indicated when there is high pre-test probability and inconclusive CTA results
What do you see in CBC of PE and why?
CBC: shows leukocytosis (because the marginal pool WBCs detach thinking they can help)
What does ABG show for PE?
Normal or low
respiratory alkalosis with hypocapnia (results from hyperventilation)
What does troponin and BNP show in PE?
elevated in up to 25-50% of patients
related to size of PE causing acute right ventricular myocardial stretch
What EKG finding is classic of PE?
S1Q3T3 specifically
S wave on lead 1
Q wave and inverted T waves in lead 3
New RBBB
What does the CXR show in PE?
Normal typically, but can also see
Westermark’s sign (an area of lung oligemia - usually from complete lobar artery obstruction)
Hampton’s hump (dome-shaped dense opacification in the periphery of the lung - indicative of pulmonary infarction)
When do you order a venous doppler of lower extremity for sus PE?
Always even if no DVT s/s
