Lecture 9: Pulmonary Circulation Disorders Flashcards
What # cause of death is PE for hospitalized patients and for cardiac deaths?
3rd in both.
When does a fat embolus tend to cause PE?
Long bone fx (usually femur)
What demographic tends to have foreign body emboli for PE?
- IVDU (talc)
- Joint replacements (cement)
What is the pathophysiology of impaired gas exchange in PE?
- Altered V/Q ratio
- Inflammation => surfactant dysfunction => atelectasis => functional intrapulmonary shunting
- Stimulation of the respiratory drive => hypocapnia and respiratory alkalosis
What happens to the heart as a PE progresses?
- Increased pulmonary pressure => R sided heart strain => reduced preload => reduced CO => hypotension
Ultimately, this kills a patient.
What is Virchow’s triad?
- Venous stasis
- Hypercoagulable state
- Injury to the vessel wall
What is the MC inherited gene defect that results in hypercoagulability?
Factor V Leiden
What two medications are commonly known to cause hypercoagulable states?
- OCPs
- Hormonal Replacement Therapy
What kind of malignancy puts someone in a hypercoagulable state?
Active malignancy being treated.
What are the usual PE S/S?
- Sudden onset dyspnea
- Pleuritic chest pain
- Cough
- Tachypnea (Most reliable exam finding)
DVT may precede a PE:
- Lower leg pain
- Unilateral swelling/warmth/erythema of calves.
Pleuritic chest pain is most associated with small PE’s causing infarction.
What is considered high risk and mod risk Well’s criteria?
- High-risk: > 6 pts
- Mod-risk: 2-6 pts
What are the Well’s Criteria for PE and the point values?
- Suspected DVT: 3
- PE is most likely: 3
- Tachycardia: 1.5
- Prior VTE: 1.5
- Immobilization of >=3 days or sx in past 4 weeks: 1.5
- Tx for malignancy within 6 months or palliative: 1
- Hemoptysis: 1
When is PERC Rules used?
Low-risk Well’s score
What are the PERC Rules?
- Hormones
- Age > 50
- DVT/PE History
- Coughing blood
- Leg Swelling
- O2 < 95%
- Tachycardia
- Surgery/trauma in past 4 weeks.
HAD CLOTS
If any of these are positive, advised to get a D-Dimer.
How do we order testing and diagnostics based on Well’s and PERC Rules?
- High-risk Well’s = imaging
- Low-risk with 1 positive PERC or mod-risk = high sens D-dimer
- Low-risk + no PERC Rules = no d-dimer.
As we get older, what happens to the d-dimer range?
Threshold is lower to be positive for an abnormal d-dimer.
What is the first-line imaging modality for most suspected PE patients?
CTA
Requires contrast, and pre-testing BUN/Cr
It will show filling defect.
Be careful of metformin use! Contrast is nephrotoxic, so hold metformin for the next 2 days.
What can cause a falsely-elevated d-dimer?
- Age > 50
- Recent surgery or trauma
- Acute illness
- Pregnancy/postpartum
- Rheumatologic disease
- Renal dysfunction
- SCD
When do we use V/Q scans?
- Pregnancy
- Renal insufficiency
- Prior reaction to contrast
What kind of V/Q scan is most suggestive for a PE?
Abnormal perfusion with normal ventilation.
What is the GOLD STANDARD for diagnosing PE?
Pulmonary angiography.
Only use if CTA was inconclusive.
What causes leukocytosis in PE?
Marginal pool of WBCs shifts into circulation.
Usually above 20k
What ABG findings are typical of a PE?
- Low pO2
- Respiratory alkalosis with hypocapnia
Can appear in other conditions besides PE.
What are the probable findings on EKG for a PE?
- Sinus tach
- S1Q3T3 pattern (boards)
- new incomplete RBB
Generally non-specific. More used to r/o STEMI.
S wave in lead I
Q wave in lead III
T-wave inversion in lead III
What are the two possible findings suggestive of PE on a CXR?
- Westermark’s sign: lung oligemia 2/2 complete lobar artery obstruction
- Hampton’s hump: dome-shaped dense opacification in lung periphery.
Westermark makes one lung look much blacker.
Hampton’s hump presents as consolidation.
When is a venous doppler of the LE recommended?
Positive PE so we can look for evidence of a DVT.
Determining PE etiology.
What are the 3 levels of risk stratification for PE?
- High-risk = hemodynamic instability
- Mod-risk = hemodynamic stability with signs of R-sided heart strain.
- Low-risk = normotensive with no signs of right ventricle dysfunction.