Case Answers:

Answer 1

  1. Sharp chest pain with radiation to left shoulder, pleuritic
  2. Shortness of breath
  3. Hemoptysis
  4. Swelling, tender calf

Answer 2

  1. DVT/PE, MI, pneumothorax.

Answer 3

  1. Oral contraceptives + smoking

Answer 4

  1. The diagnosis of DVT/PE is difficult to make with the exam and is often not sensitive or specific. 
  2. Pertinent positives: tachycardia with increased P2, tachypnea, respiratory distress, dullness to percussion/decreased breath sounds (suggestive of pleural effusion)
  3. Pertinent negatives: no rhonchi, no crackles, no bronchophony, egophony or tactile fremitus, lack of fever (all argue against infectious etiology – pneumonia).  PTX also less likely given bilateral breath sounds and would sound hyperresonant on exam
  4. There is no tracheal deviation.  If there was tracheal deviation to the right – this would suggest left sided tension  pneumothorax or massive pleural effusion.  Deviated to the left would suggest left-sided volume loss due to atelectasis or tumor causing volume loss
  5. Physical exam findings for DVT (calf swelling, erythema, tenderness, warmth, palpable cord, Homan’s sign) have poor sensitivity and specificity and are of no value in ruling a DVT in or out.

Answer 5

  1. Dullness to percussion and decreased breath sounds indicates pleural effusion.  Pleural effusion associated with decreased voice transmission. 
  2. Accentuated P2 suggests pulmonary hypertension

Answer 6

  1. Acute respiratory alkalosis.  Note that for a 10 torr change in pCO2 there is an associated predicted 0.08 change in the pH.  If a chronic respiratory alkalosis, would be expect a 0.03 change in pH for every 10 torr change in pCO2
  2. PE → increased CO2 → increased minute ventilation → resp alkalosis

Answer 7

The gradient on room air is the best use of the alveolar-arterial oxygen gradient.
PAO2 = FiO2(PATM – PH20)– (PaCO2/0.8)
PATM = 760mmHg
PH20 = 47mmHg
PAO2 = .21 (760-47) – (30/0.8) = 150-37.5 = 112.5

PAO2 – PaO2 = 112.5 – 80 = 32.5


Normal predicted alveolar-arterial oxygen gradient is:  4 + (Age/4)
Age 20 yr = 4 + (20/4) = 9
Age 80 yr = 4 + (80/4) = 24

Answer 8

  1. The EKG shows sinus tachycardia.  EKG is neither sensitive or specific for PE.  Most common EKG finding for PE is sinus tachycardia.
  2. You can also see signs of right-heart sided strain patterns including axis deviation and right bundle branch block.   S1Q3T3 (S wave in lead 1, Q wave and flipped T wave in lead 3) is a sign of acute cor pulmonale (PE, pneumothorax, bronchospasm). It is a manifestation of acute pressure and volume overload of right ventricle

Answer 9 
You need to calculate your pre-test probability with the modified Well’s criteria

Clinical symptoms of DVT (leg swelling, pain with palpation)


Other diagnosis less likely than pulmonary embolism


Heart rate >100


Immobilization (>3 days) or surgery in the previous four weeks


Previous DVT/PE






PE likely >4
PE unlikely </= 4
Our patient’s score is 8.5

Answer 10
Based on her pre-test probability of 8.5, the next test should be a CXR.

  1. CTA is very specific for PE (80-97%) but sensitivity can vary (53-100%).  The primary limitation of CTA is that it can miss distal emboli (but clinical significance of peripheral clots is unknown).  Therefore, if CTA is negative or non-diagnostic for PE, think of your pre-test probability.  If PTP is high, get an additional study to rule out VTE such as LE Doppler. 
  2. Another option would be to go straight to LE Doppler given the history of lower extremity pain and swelling.  If this is positive, you will treat with anticoagulation and an avoid any additional imaging. 
  3. If pt is too hemodynamically unstable for CTA or if CTA is not available, start anticoagulation and get TTE to look for RV dysfunction or TEE to look for emboli in the main pulmonary arteries.

Answer 11

  1. There is a small left sided pleural effusion.  CXR is often normal with PE but one can also see diminished lung volumes, atelectasis, pleural effusions, infarct that appears as wedge-shaped infiltrate (Hampton’s Hump) or Westermark’s sign (prominent central pulmonary artery with local oligemia 

Answer 12

  1. Pleural effusion is small and does not need to be tapped. 
  2. 30% of pts with PE have an effusions, usually unilateral, <1/3 of hemithorax
  3. Only 1/3 of pts have classic bloody exudative effusion with neutrophilic predominance
  4. Effusions is 2/2 ischemia → increased capillary permeability → protein rich fluid leakage
  5. Even though fluid is bloody, can still anticoagulate!

Answer 13

  1. Referred pain from the diaphragm results from any inflammatory process (e.g., pleural effusion) that affects the diaphragm.

Answer 14

  1. High probability scan: >2 large segmental defects without corresponding ventilation or CXR abnormalities or any perfusion defect substantially larger than radiographic abnormality
  2. Intermediate (indeterminate) probability: borderline high or borderline low, not falling into normal, low or high prob
  3. Low probability:
  4. Normal scan: normal perfusion, normal ventilation (very good sens and spec)

Again, think about pre-test probability!

  1. If PTP is high and you have a high probability VQ scan, specificity is very good (88-96%)
  2. If PTP is low and you have a low or normal VQ scan, sensitivity is very good (94-100%)
  3. BUT, if PTP is low and you have a high prob scan, sensitivity drops to 55%

Answer 15

  1. She does not need to be admitted.  Those with low risk PE based on the PESI calculator (takes into account vitals, comorbidities, age, mental status), good social support and good compliance can be discharged home same day.
  2. Bedrest is no longer recommended.  ACCP suggests early ambulation (no period of bedrest) to decrease post-thrombotic syndrome and improve quality of life.
  3. If edema and pain are severe, ambulation may need to be deferred; compression stockings are recommended 
  4. ACCP recommends low molecular weight heparin (LMWH) or fondaparinux instead of unfractionated heparin
  5. Start warfarin on day of starting LMWH and overlap at least 5 days (even if INR >2 earlier than that)
  6. Factor Xa inhibitors (rivaroxaban, apixaban) and direct thrombin inhibitors (dabigatran) have recently been approved as long term anticoagulants for VTE (instead of warfarin)

Answer 16

  1. Check stool for occult blood
  2. CBC/platelet count to obtain baseline
  3. BUN/CR to adjust LMWH for creatinine clearance

Answer 17

  1. BLEEDING and HIT (though lovenox and fondaparinus are lower risk for developing HIT)
  2. PTT, INR and platelet count should be monitored during therapy.

Answer 18
She has a VTE provoked by a nonsurgical reversible risk factor (estrogen + smoking) and should be treated for 3 months


Risk of recurrence after 1 year

Risk of recurrence after 5 years

Recommended duration of anticoagulation

VTE provoked by surgery:



3 months

VTE provoked by nonsurgical reversible factor (estrogen, pregnancy, leg injury, flight >8hrs):






3 months


Unprovoked VTE





If low/mod bleeding risk: “extended anticoagulation therapy” = lifelong
If high bleeding risk: 3 months

VTE in setting of cancer

15% annual risk

(LMWH suggested over warfarin)


Second unprovoked VTE


50% higher risk of recurrence compared with first VTE

If low/mod bleeding risk: “extended anticoagulation therapy” = lifelong
If high bleeding risk: 3 months

Answer 19

  1. ACCP recommends thrombolytics in pts with acute PE + SBP < 90mmHg
  2. No thrombolytics for acute PE without hypotension

Answer 20

  1. As mentioned in above table, her risk of recurrent VTE is 5% within 1 year and 15% within 5 years.  It is important to consider reducing all possible risks factors which includes smoking cessation.

Answer 21

  1. IVC filter.  Indications for IVC filter include:
  2. Note that insertion of IVC filter does not eliminate the risk of PE and increases risk for DVT.  Therefore, IVC filter should be “removable” and anticoagulation should be initiated once bleeding risk resolves.