1. Post-Op Pulmonary Embolism
Linda P. Zhang, MS III
Scott Q. Nguyen, M.D.
Celia M. Divino, M.D.
Mount Sinai School of Medicine

2. Mrs. Margo
Your patient in the hospital is a 62 year- old female with a 1 hour history of shortness of breath, s/p a right total hip replacement 4 days ago.

3. History
What other points of the history do you want to know?

4. History, Mrs. Margo Consider the following:
Alleviating/Exacerbating factors:
Aggravated by breathing
Pertinent PMH
L breast cancer, s/p modified radical mastectomy and radiation 2 yr ago.
ROS: no palpitations, no peripheral edema.
MEDS: Percocet
Characterization of Symptoms:
New sudden onset SOB and tachypnea while lying in bed. Pain with breathing. Intermittent cough with no hemoptysis. Feeling of apprehension.
Temporal sequence
Total hip replacement 4 days prior, no complications since surgery. Has not been ambulating since surgery.

5. Differential Diagnosis ?

6. Differential Diagnosis Based on History and Presentation
Pulmonary embolism
Aspiration pneumonitis
Myocardial infarction
Heart failure / Pulmonary Edema
Pneumothorax
ARDS

7. Physical Examination
What would you look for?

8. Physical Examination, Mrs. M
Vital Signs: T 37.5, pulse 105, BP 135/85, RR 26,
O2 Sat: 89% Room air
Appearance: AAOx3, anxious
Chest: CTAB
CV: RRR, tachycardic, accentuated P2. (+) S4
Abd: normo-active bowel sound, soft, nontender non-distended
Rectal: guaiac negative
Extremities: No thigh or calf swelling. No localized tenderness or erythema along veins. (-) calf pain upon passive dorsiflexion of feet (what sign is this?). No clubbing/edema/cyanosis
Remaining Examination findings non-contributory

9. Would you like to revise your Differential Diagnosis?

10. Revised Differential Diagnosis
Pulmonary Embolism
Heart Failure / Pulmonary Edema MI
Aspiration pneumonitis

11. Laboratory
What would you obtain?

12. Labs ordered, Mrs. Margo CBC: Hb/Hematocrit/WBC PT/PTT/ Platelets ABG
Cardiac Enzymes

13. Lab Results, Mrs. Margo CBC: Hb Hematocrit WBC 13.3 37 12.1
PT/PTT/Platelet:
11/24/375
ABG:
7.48/27/55 O2 sat 89%
Cardiac enzyme:
Troponin 1.2

14. Lab Results, Discussion
CBC: can be done to r/o elevated WBC secondary to pulmonary infection, and to r/o decreasing H/H secondary to occult bleeding.
ABGs: can be done to determine acid-base imbalance and to r/o pulmonary or renal disease.
Hypoxemia, hypocapnia, respiratory alkalosis secondary to tachypnea, and ↑ A-a gradient may suggest PE.
However, massive PE with respiratory collapse can present as hypercapnia and combined respiratory and metabolic acidosis.
Troponin I and T: can do done to r/o MI. May be elevated in moderate to large PE secondary to acute right heart overload.

15. Interventions at this point?

16. Interventions at this point?
Supplemental Oxygen

17. Studies
What further studies would you want at this time?

18. Studies, Mrs. Margo
EKG
Chest x-ray

19. EKG, Discussion
EKG:
Can be used to r/o arrhythmias, ischemia, MI, and axis-deviation.
For PE: see tachycardia, R axis deviation and nonspecific ST and T wave changes.
Classic findings of S wave in Lead I, Q wave in Lead III, and T wave inversion in Lead III seen in <20% of cases.
May also see RBBB, P pulmonale, atrial fib.

20. Chest x-ray, Discussion

21. Chest x-ray, Discussion
Can be used to r/o pneumothorax, ARDS, pneumonia.
For PE, abnormal chest x-ray findings are common but nonspecific: atelectasis, pleural effusion, infiltrates. May see Hampton’s hump or Westermark’s sign. In most cases, the CXR will be clear.
Cardiomegaly is a common radiographic finding in PE

22. Intervention at this point?

23. Intervention at this point?
Start therapeutic-dose heparin:
Given the strong clinical suspicion for PE, it may be necessary to start heparin prior to initiating any diagnostic studies.
Must watch out for post-surgical bleeding when patient is placed on heparin.

24. What next?
To diagnose PE (initial study):

25. V/Q scan, Discussion Initial diagnostic tool for PE: V/Q scan:
The most frequently used test in diagnosing PE.
Advantages: Noninvasive
Disadvantages:
diagnostic value is dependent on the result:
A normal V/Q scan = 5% chance of patient having PE
A high probability V/Q scan = 85% chance of patient having PE
An intermediate or low probability V/Q scan = non-diagnostic, a pulmonary angiogram is needed for definitive diagnosis.
In over 50% of cases, the V/Q scan result will be either intermediate or low probability, thus rendering the result non-diagnostic.
Not always readily available as a diagnostic test.

26. VQ picture
Low Probability Ventilation Perfusion Scan

27. Studies – Results for Mrs. Margo
V/Q scan result:
Intermediate probability scan
What is the differential diagnosis at this point?

28. Revised Differential Diagnosis
Pulmonary Embolism
Possible early MI

29. What next?

30. What Next?
CT angiography

31. CT angiography, Discussion
Frequently used as follow-up test after a non-diagnostic V/Q scan.
Advantages:
Noninvasive, but requires contrast. Do not give for patients with renal insufficiency/failure.
Readily available test.
Sensitivity and specificity greater than 90%.
Disadvantages:
Can detect emboli in proximal pulmonary arteries and segmental arteries, but very limited in detection of emboli beyond segmental arteries.
Immediate post-op PE are fresh clots that are easily fragmented, and thus more likely to be found in the periphery. As such, CT angio would not be a good diagnostic tool for immediate post-op PE.
Technician- and reader-dependent. Positive and negative results must be interpreted with caution.
Difficult to see obliquely/horizontally oriented vessels within the right middle lobe and left lingula.

32. CT angiography of PE
Large clot in Right pulmonary artery (arrow).

33. Other studies, Discussion
There are multiple other diagnostic tools that can be used to help diagnose PE:
Pulmonary Angiography
Considered the historical gold standard for diagnosing PE
On image, see a filling defect or sharp cutoff of small vessels.
Advantages:
Best diagnostic yield. If negative result, PE can be excluded from differential.
Disadvantages:
Invasive, and requires contrast.
Patients who have long-standing pulmonary arterial hypertension and right ventricular failure should not undergo a pulmonary angiography.
Pulmonary angiography should be the initial test for critically ill patients. It should be obtained immediately after clinical episode. Otherwise, it may result in a false negative.

34. Other studies, Discussion
Venography/duplex ultrasound
For stable patients with suspect PE and adequate cardiopulmonary reserve (absence of hypotension or severe hypoxemia), a duplex ultrasound can be done to rule in DVT if the V/Q scan was inconclusive.
Advantages:
Noninvasive. Easily available. Fast
Disadvantage:
High sensitivity (89-100%) and specificity (89-100%) for detection of proximal DVT in symptomatic patients. However, in patients without symptoms of DVT, sensitivity is only 38% and positive predictive value is 26%.
If suspect PE but duplex scan is negative, must perform follow-up imaging. If positive scan for DVT, start anticoagulation
D-dimer:
Rarely helpful in diagnosing PE in patients with recent surgery
In non-post-op situations where D-dimer is done, PE can be excluded from the differential if D-dimer result is negative (negative predictive value of 95%). If the result is positive, further workup needs to be done.

35. Doppler Venous US
Normal Common Femoral Vein by Doppler US

36. Management

37. Initial Management, Mrs. Margo
After initial intervention of heparin and supplemental oxygen:
RR decreased to 18 breaths per minute
O2 sat increased to 93%
What should be done next?

38. Management, Mrs. Margo Unfractionated heparin – Warfarin –
Continue for next 7 days
Maintain PTT level between sec
Warfarin –
Give warfarin simultaneously with heparin
Maintain INR between
Long term management: continue warfarin for 6 months.

39. PE Management, Discussion
PE management focuses on preventing further blood clot formation, lysis of current clot, and prevention of recurrent PE.
Initial intervention: unfractionated heparin or low molecular weight heparin:
Unfractionated heparin: IV, PTT should be secs ( x’s the control)
LMWH: SQ, greater bioavailability, fixed dose, QD or BID, no need to monitor PTT
LMWH is equally effective as unfractionated heparin in treatment of PE.
Complications: retroperitoneal bleeding, intracranial bleeding, heparin-induced thrombocytopenia (HIT)

40. PE Management, Discussion
Addition of oral anticoagulant: Warfarin
Initiate at the same time as heparin, or after diagnosis of PE.
Overlap with heparin for at least 5 days and continue until INR is within therapeutic range for 2 consecutive days before discontinuing heparin.
Maintain INR between Must check INR 2x/wk for 1st few weeks, once weekly for next several months, and once monthly thereafter if patient is stable.

41. PE Management, Discussion
Long term prophylaxis: Warfarin
For 1st PE event with reversible or time-limited risk factor (i.e. surgery, immobilization, trauma), continue warfarin for 3-6 months.
For idiopathic 1st thromboembolic event, continue warfarin for at least 6 mos.
For 2nd PE event, cancer, non-modifiable risk factors, continue warfarin for at least 12 mos or indefinitely.

42. Hospital Course, Mrs. Margo
Pt remains clinically stable, with only mild hypoxemia for the remainder of that day. No signs of right ventricular failure.
Pt recovers uneventfully, and is discharged home on Day 10 with warfarin for 6 months.

43. Discussion Epidemiology: Pathophysiology:
Pulmonary embolism occurs in over 500,000 patients in the US annually, resulting in approximately 200,000 deaths. Without prophylaxis, 4-7% of patients with hip surgery will die of PE. Untreated PE results in approximately 30% mortality rate.
Patients presenting with PE who survive the initial insult usually die from recurrent PE during the initial treatment period.
Pathophysiology:
Significant PE are generally from thrombosis formation from deep veins of the thigh and pelvis. Large thrombi, after dislodging from DVT, travel to the lung and become lodged at the main pulmonary artery or lobar branches, causing hemodynamic compromise. Small thrombi travel to distal areas of lung, producing pleuritic pain secondary to inflammatory response by parietal pleura.
Only 10% of PE cause pulmonary infarction.
Most PE are multiple and are more likely to travel to lower lobes
Risk factors: immobilization, surgery within last 3 months, malignancy, stroke, and history of venous thromboembolism, Factor V Leiden mutation, Protein C and Protein S deficiency, or Antithrombin III deficiency.

44. Discussion
Minor PE
Patients with minor PE can present with transient dyspnea and cardiac irritability, which may resolve in a few moments. The onset of symptoms can be immediately post surgery to 7 days post-op. If patient is considered to be at substantial risk and anticoagulation is not contraindicated, heparin therapy can be given while diagnostic tests are being ordered. If anticoagulation may be risky and/or PE seems unlikely, a D-dimer can be performed (in cases of non-post-operative patients). A negative result excludes PE from the differential. If the result is positive, a pulmonary angiography must be done to confirm the diagnosis of PE. In the meantime, heparin therapy should be continued.
If PE occurred within 10 days after surgery, a D-dimer test can give a false positive result. As such, a pulmonary angiography should be obtained.
For critically ill patients who do not tolerate diagnostic tests well, pulmonary angiography should be the initial study.

45. Discussion Moderate PE
Patients with moderate PE will present with transient hypotension, tachycardia, cardiac dysrhythmia, apprehension, tachypnea with ↓ O2 and ↑ CO2, and possible signs of pulmonary infarction. EKG will show acute right axis deviation, nonspecific ST and T wave changes, and possible RBBB. Initial intervention with heparin therapy should be started in patients where diagnosis is probable and where there are no likely alternative diagnoses. Consider lytic therapy for patients without recent surgery or vascular injury.
A D-dimer can be done in non-post-operative patients to rule out PE. If the result is positive, a pulmonary angiography should be done to confirm the diagnosis.
If a diagnosis of PE is not confirmed by pulmonary angiography but patient has risk factors for PE, prophylactic-dose heparin should be continued.
With a confirmed diagnosis of PE, continue heparin and add warfarin for long-term treatment. If anticoagulation is contraindicated, consider an IVC filter.

46. Discussion Catastrophic PE
Patients with catastrophic PE will present with cardiac arrest, brady-arrhythmia, severe hypotension, circulatory collapse, or left heart failure. It generally occurs 7-10 days after injury or onset of clinical illness, when the embolus has matured and is resistant to lysis. A large embolus is usually mobilized after patient performs a Valsalva maneuver, resulting in immediate circulatory collapse and cardiac arrest.
Treatment consists of intubation with 100% oxygen, cardiotonic agents, and large doses of heparin.
Consider Trendelenburg’s procedure (rarely performed and rarely successful) or cardiopulmonary bypass
If patient survives initial resuscitation, continue heparin and consider lytic therapy or IVC filter.
Survival rate is minimal.

47. Discussion Other PE management options
Thrombolytics: t-PA, streptokinase, urokinase.
Contraindicated in patients with surgery in previous 10 days, active bleeding, previous cerebrovascular accident, serious GI bleed in previous 3 mos.
Given for hemodynamically unstable PE. Most effective when initiated within hours.
Should discontinue heparin while giving lytic therapy, unless there is a life-threatening clot.

48. Discussion Other PE management options
Inferior vena cava filter - indicated if:
Patient has an absolute contraindication to anticoagulant therapy (eg. recent surgery, hemorrhagic stroke, significant recent/active bleeding)
Patients with a history of massive PE in whom a recurrent embolism may be fatal
Recurrent DVT during adequate anticoagulant therapy

49. IVC Filter

50. QUESTIONS ??????

51. Summary
PE carries a high mortality rate and should be high on the differential for patients presenting with sudden shortness of breath.
If anticoagulant therapy is not contraindicated, therapeutic-heparin should be initiated early with suspected PE.
V/Q scan, CT angiography, and D-dimer are diagnostic tools for PE, however, each test has their own advantages and disadvantages.
Pulmonary angiography continues to be the gold standard for diagnosing PE.
Management of PE consists of initiating heparin and warfarin simultaneously for the first 5-7 days, followed by long-term treatment and prophylaxis with outpatient warfarin for 3 months, 6 months, or indefinitely depending on patient’s risk factors for recurrent PE.

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