Pulm HTN and PE + B&B

Question 1

how is pulmonary HTN defined and what are 2 mechanisms by which it can occur?

Answer 1

pulm HTN: >25mmHg pressure at rest

due to either decrease in cross-sectional area of pulmonary vascular bed (most common) or increased pulmonary vascular blood flow

Question 2

how does chronic obstructive or interstitial lung disease cause pulmonary HTN?

Answer 2

damaged alveolar capillaries —> increased resistance to blood flow —> increased pulmonary blood pressure

Question 3

how can recurrent thromboemboli lead to the development of pulmonary HTN?

Answer 3

recurrent pulmonary emboli reduce the functional cross-sectional area of the pulmonary vascular bed —> increased pulmonary vascular resistance and HTN

Question 4

what gene mutation is implicated in idiopathic/primary pulmonary arterial HTN?

Answer 4

germline mutations in BMPR2 (bone morphogenetic protein receptor 2) - leads to endothelial dysfunction and proliferation of vascular smooth muscle cells

Question 5

which pulmonary vessels are most affected by pulmonary HTN?

Answer 5

arterioles and small arteries - most affected by medial hypertrophy and intimal fibrosis

Question 6

describe the histological changes that occur in pulmonary vessels in pulmonary HTN

Answer 6

medial hypertrophy of pulmonary muscular and elastic arteries

also pulmonary arterial sclerosis and right ventricular hypertrophy

Question 7

in which patients is idiopathic/primary pulmonary HTN most common?

Answer 7

women 20-40 years old

present with dyspnea/fatigue, sometimes anginal chest pain

over time (2-5 years) - respiratory distress, cyanosis, RV hypertrophy, cor pulmonale + thromboembolism + pneumonia

Question 8

what is the origin of most pulmonary embolisms?

Answer 8

result of thrombus originating in lower extremity - begins where blood flow is turbulent (such as venous bifurcation or behind venous valve)

piece (emboli) breaks off and migrates via venous systems to the lungs

Question 9

what kind of patients are at risk of pulmonary embolism originating from an emboli in the pelvic veins?

Answer 9

pregnant women, males with prostate disease, individuals with pelvic infection, etc

Question 10

what kind of patients are at risk of pulmonary embolism originating from an upper extremity venous thrombosis?

Answer 10

patients with central venous catheter

(thrombus originate in sites with turbulent blood flow)

Question 11

what is the typical clinical picture of a patient with a fat embolism that causes pulmonary embolism?

Answer 11

patient with long bone or pelvis trauma (such as closed fracture) - fat from bone marrow becomes embolus

patient will decompensate and develop ARDS

Question 12

how does an amniotic fluid embolism develop into pulmonary embolism?

Answer 12

during delivery, premature rupture of amniotic sac causes amniotic fluid to enter mother’s blood through placenta

allergic reaction to amniotic fluid causes it to become embolus which travels via veins to lung

Question 13

what is Virchow’s triad of peripheral clotting?

Answer 13

hypercoagulability
venous stasis
endothelial damage

Question 14

explain why hypercapnia and acidosis are unusual findings in pulmonary embolism, unless shock is present?

Answer 14

PE increases dead space ventilation (wasted air, because alveoli is not being perfused) —> stimulates respiratory drive (tachypnea), resulting in HYPOcapnia and alkalosis

Question 15

what is the most key finding of pulmonary embolism?

Answer 15

tachypnea!! very high respiratory rate is a major concerning finding!!

Question 16

what is the scoring system used to evaluate a patient’s probability of having a pulmonary embolism?

Answer 16

Wells score: clinical pre-test probability scoring system, helps establish diagnosis of DVT or PE, used to estimate probability before imaging is ordered

Question 17

high levels of what biomarker is important in diagnosing pulmonary embolism?

Answer 17

D-dimer: high levels when there is clotting or inflammation occurring in the body

negative D-dimer can help rule out PE in some clinical situations (such as outpatients, patients who are clinically stable, patients with low probability on Wells score)

Question 18

why does pulmonary embolism cause hemodynamic collapse?

Answer 18

essentially a cause of acute right ventricular failure (pressure sharply rises, and RV cannot hold up)

Question 19

what are the 5 types of pulmonary HTN?

Answer 19

1. Pulmonary arterial HTN (idiopathic/primary - normal PCWP)
2. PH with left heart disease [2 ventricles in heart]
3. PH associated with lung disease/ hypoxemia [rotate 3, it looks like the lungs]
4. chronic thrombotic embolic hypertension [4 words]
5. miscellaneous (HIV, hepatic diseases, sarcoidosis, IV drug use, etc) [miscellaneous = 5 syllables]

Question 20

how can chronic hypoxemia (from sleep apnea, for example) cause pulmonary HTN?

Answer 20

hypoxic vasoconstriction in lungs (meant to divert blood away from less ventilated regions)

Question 21

what is the most common cause/ type of pulmonary HTN?

Answer 21

type 2 - PH with left heart disease

right heart catheterization will show elevated pulmonary capillary wedge pressure (PCWP)

Question 22

What is the classic blood gas finding of pulmonary embolism?

Answer 22

low PaO2, low PCO2

increased dead space - ventilation without perfusion

Question 23

how can deep vein thrombosis be diagnosed?

Answer 23

lower extremity ultrasound

Often asymptomatic until PE

calf pain, palpable cord (thrombosed vein), Homan’s sign (calf pain with dorsiflexion of foot)

Question 24

What is the characteristic ECG finding of patients with pulmonary embolism?

Answer 24

S1Q3T3

deep S wave in lead I,
prolonged Q wave in lead III,
elevated T wave in lead III

*note this is not a specific finding

Question 25

Blood levels of what molecule can be important in ruling out pulmonary embolism when levels are normal?

Answer 25

D-dimer: degradation product of fibrin, sensitive but not specific

Useful when normal in setting of low to moderate Wells score

Question 26

what 2 diagnostic tools can be used in pulmonary embolism and which one is preferred?

Answer 26

1. CT angiogram - preferred
2. VQ (ventilation/perfusion) scan

Question 27

What setting is fat embolism most classically seen and how does a present?

Answer 27

long bone fracture (fat leaks from bone marrow)

—> ARDS (lung), confusion (neuro), petechiae (skin)

Question 28

What are the key features of amniotic fluid embolism?

Answer 28

during/shortly after labor – amniotic fluid enters maternal circulation and causes inflammatory/allergic reaction – often fatal

phase I: Respiratory distress, low oxygen, hypotension
phase II (hemorrhagic): bleeding, seizures