Pulmonary Embolism: Saving your Patient, your Rand and making sense of the “clot” !

1. Pulmonary Embolism:Saving your Patient, your Rand and making sense of the “clot” ! Dr Sa’ad Lahri Emergency Medicine Registrar

2. Outline and Objectives Clinical Presentation Lab Tests and the ECG in PE Risk Stratification PE in Pregnancy Do you understand your Imaging? Treatment Protective documentation Take Home Points

3. Background More than 600,000 cases / yrand 60,000 – 100,000 deaths / yr 70% diagnosed at autopsy 25 - 35% = Mortality if untreated 2 - 8% = Mortality if treated Background • It’s common • We miss it • It kills you • Detecting it makes a difference Carson, NEJM, 92

5. N Engl J Med 2008;358:1037-52

6. Pathophysiology

7. Is the Presentation “boring?” Is the clinical presentation “boring” ? Movie …

8. Clinical Presentation Classic teaching: Dyspnoea,tachycardic, tachypnoeic, and has pleuritic pain

9. ðAcute PE - Spectrum that ranges from: ðClinically unimportant / incidental Haemoptysis ðMinor emboli ± infarction Pleuritic pain Pulmonary signs ðLarge pulmonary emboli Dyspnoea Ischaemic pain ðMassive emboli Collapse /Cardiac

10. Symptoms Signs Clinical Presentation Stein, Chest 1991 & Miniati Am J Resp CC 1999 Dyspnoea 73% Pleuritic pain 66% Cough 37% Leg Swelling 28% Leg Pain 26% Haemoptysis 13% RR>20 70% Rales 51% Tachycardia 30% Loud P2 23% Temp>38.5 C 7% Wheezes 5%

11. Symptoms Signs Clinical Presentation Stein, Chest 1991 & Miniati Am J Resp CC 1999 Dyspnoea 73% vs 59% Pleuritic pain 66%vs 43% Cough 37% vs 25% Leg Swelling 28% Leg Pain 26% Haemoptysis 13% vs 7% RR>20 70% vs 68% Rales 51% Tachycardia 30%vs 23% Loud P2 23% Temp>38.5 7%vs 17% Wheezes 5%

12. Dyspneoa, Tachypneoa, or Pleuritic CP – the Triggers! History and Physical Exam Ask about recent travel, surgery, or leg swelling O2 Sat & Respiratory Rate - Measure yourself Examine and even measure the extremities (> 3cm asymmetry 10 cm below tibial tuberosity) Don’t make an alternate diagnosis by misinterpreting non-specific findings (ex. Partially reproducible pain => Costochondritis) Signs/Symptoms Pearls

13. Risk factors for PE

14. Risk factors for PE Acute Medical Illness CHF/COAD - not recognised / similar presentation Obesity - under recognised

15. Risk Factors - Pearls Risk Factors increase your suspicion However 20% of patients with PE have no known Risk Factors Therefore Lack of Risk Factors by no means excludes PE Risk factor Pearls

16. Risk Stratification Clinical Gestalt Clinical Algorithms – Wells/ Wicki/ Kline/ Miniati Hard to remember … memorise?? Do not agree on any single finding that is predictive of PE

17. Clinical Gestalt

18. Runyon et al., Acad EM, 2005 The unstructured clinical estimate of low pretest probability for PE compares favorably with the Canadian score and the Charlotte rule. Interobserver agreement for the unstructured estimate is moderate. Clinical Gestalt: Works Just as well

19. Clinical Algorithms We Don’t Remember Them!!!!! Runyon et al., Acad EM, 2007 Half of all clinicians reporting familiarity with the rules use them in more than 50% of applicable cases. Spontaneous recall of the specific elements of the rules was low to moderate.

20. Gestalt appears equivalent to Algorithms Algorithms may be beneficial for trainees Algorithms may be beneficial for institutional uniformity Risk Stratification Pearls

21. SpPin: with high Specificity, a Positive result tends to rule in SnNout: with high Sensitivity, a Negative result tends to rule out Some Essential Stats

22. D Dimer and PE

23. D Dimer and PE +>0.5mg/l , -ve <0.25mg/l Quantitative D Dimer (Elisa) High sensitivity (>96%) Low specificity (AMI, pneumonia, dissection, sepsis) High negative predictive value (99%)

24. D Dimers continued… NHLS have D Dimer Latex reagent (agglutination assay) Latex kits demonstrate inadequate sensitivity to reliably exclude PE in multiple studies (pooled sensitivity=70% and specificity=76% Positive samples … semi Quantitative method Private Labs?

25. D Dimer and PE • ðCombing Clinical Probability & D-Dimer • ðChristopher Study1 (n = 3,306) • ðDichotomized Wells score ≤ 4 • ðD-Dimer ≤ 500 ng/ml • ðNegative predictive value > 99.5% • ðUseful in excluding PE in outpatients ðSafe to withhold treatment 1. Van Belle A, et al. Effectiveness of Managing Suspected Pulmonary Embolism Using an Algorithm Combining Clinical Probability, D-Dimer Testing, and Computed Tomography. JAMA 2006;295(2):172-179

26. D Dimer and PE • ðCombing Clinical Probability & D-Dimer • ðPatients with high probability1 (n = 1,722) • ðDichotomized Wells score > 4 • ðD-Dimer ≤ 500 ng/ml • ðVTE confirmed in 9.3% ! • ðVTE in 1.1% with low probability • (p<0.001) 1. Gibson NS, et al. The Importance of the Clinical Probability Assessment in Interpreting a Normal D-Dimer in Patients with Suspected Pulmonary Embolism. Chest 2008;134:789-793

27. Conclusion on D-Dimers IF your patient has low pretest probability for venous thromboembolic disease, and… IF you use an ELISA, rapid ELISA, turbidimetric, or erythrocyte agglutination D-dimer test…

28. Conclusion on D-Dimers …THEN you can drive your false negative rate to below 2% and safely rule out pulmonary embolism Dimers

29. Conclusion on D-Dimers IF pretest probability is high, then NO D-dimer can safely rule out VTE D-dimer is NOT a “screening test.” It is a diagnostic test to “Rule out” in appropriate patients

30. ðModified Wells score1 (“dichotomised”) 1. Wells PS, Anderson DR, Rodger M, et al. Derivation of a simple clinical model to categorize patients’ probability of pulmonary embolism: increasing the model’s utility with the SimpliRED D-dimer. ThrombHaemost. 2000;83:416-420. ≤ 4 PE “unlikely” > 4 PE “likely” Score

32. Diagnostic Pathway PE? Clinical Probability: Wells Score ≤ 4 > 4 D-Dimer ≤ 0.5 > 0.5 Imaging, e.g. CTPA Pulmonary Embolism excluded

33. PERC Rule < 2% Kline et al J ThrombHaemost 2008; 6: 772–80. 8138 – suspected PE 2/3 Low suspicion 20% low suspicion and met PERC rule Sensitivity 97.4% Specificity 21.9% PERC rule takes a low probability subgroup of patients and makes the risk even lower The combination of gestalt estimate of low suspicion for PE and PERC reduces the probability of VTE to below 2%

34. PERC Rule

35. B-type natriuretic peptide Cardiac troponin Cardiac Biomarkers and PE Those with positive BNP and troponin testing should be considered for ECHO assessment of RV function elevated in congestive heart failure/Pulm Hypt negative predictive value for an uneventful outcome of 99%. not sensitive as a diagnostic tool significantly associated with RV dysfunction on ECHO &complicated in hospital course and mortality

36. Utility of CXR? http://www.bestbets.org/bets/bet.php?id=611 Hampton’s Hump Clinical Bottom Line Alone little value in diagnosis Value is in ruling out other causes or as part of a risk stratification strategy

37. CXR in Pulmonary Embolism Stein PD - Chest - 01-SEP-1991; 100(3): 598-603 Chest - Volume 118, Issue 1 (July 2000) Atelectasis and/or pulmonary parenchymal abnormalities were most common, 79 of 117 (68 percent) cardiac enlargement (27% ), normal (24% ), pleural effusion (23% ), elevated hemidiaphragm (20% ), pulmonary artery enlargement (19% ), atelectasis (18% ), and parenchymal pulmonary infiltrates (17%)

38. ECG in Pulmonary Embolism Poor sensitivity Cannot be used alone! T-wave inversions, especially in right precordial leads (V1-V3) + inferior leads S 1Q3T3 pattern in acute cor pulmonale (12%). Right axis deviation, transient right bundle branch block (RBBB), Arrhythmias (sinus tachycardia, atrial flutter, atrial fibrillation, atrial tachycardia, and atrial premature contractions) Normal The most common abnormalities are nonspecific ST segment-T wave changes with sinus tachycardia, unfortunately, these findings are extremely nonspecific

39. ECG in Pulmonary Embolism • Classic “SIQ3T3 pattern” • Mistakenly considered pathognomonic for acute PE by many clinicians • Seen less frequently--15% to 25% of patients ultimately diagnosed with PE will have this pattern Panos R J, Barish RA, Depriest WW, et al: The Electrocardiographic manifestations of pulmonary embolism. J Emerg Med 1988; 6:301-7

40. ECG in Pulmonary Embolism

41. ECG in Pulmonary Embolism T wave Inversions in anteroseptal and inferior leads Highly specific for PE (99%) Kosuge (Am J Cardiology 2007)

42. Chest Pain Tunnel Vision

43. ECG in Pulmonary Embolism PE often causes ECG changes that resemble cardiac ischemia Don’t just “rule out MI” when the ECG appears to show cardiac ischemia

44. ABG? The PO2 on arterial blood gases analysis (ABG) has a zero or even negative predictive value in a typical population of patients in whom PE is suspected clinically Other diseases that may masquerade as PE (eg, [COPD, pneumonia, CHF) affect oxygen exchange > PE High incidence of PE and a lower incidence of other respiratory ailments (eg, postoperative orthopedic patients with sudden onset of shortness of breath), a low PO2 has a strongly positive predictive value for PE. Use it in conjunction with other tests

45. Imaging studies

46. Advantages Disadvantages Ventilation Perfusion Scanning Low complication rate Moderate radiation exposure Can be used in renal dysfunction • Far away • Majority non diagnostic – add testing • Major abn on CXR – (collapse/P effusions) indeterminate scan

47. V/Q Scan High Probablity PE Diagnosed Normal Excludes PE Debate! Low risk and low probability D/C Intermediate and D Dimerneg ? No or additional/CTPA +u/s Low/ Intermediate N Engl J Med 2008;358:1037-52.

48. CTPA Preferable to V/Q in patients with prexisting lung disease Specificity (93-99%) Sensitivity (85%) Combined with CTV – Sensitivity (90%) Other causes of chest pain imaged/found CTV using dye from CTPA image venous system Renal dysfunction/contrast allergies … Problem Radiation dosing high … !!! N Engl J Med 2008;358:1037-52.

49. Echocardiography Rapid and accurate – PE instability Exclude other causes of hypotension and raised JVP Can be performed in resus room and guide thromobolytic therapy for unstable patient

50. N Engl J Med 2008;358:1037-52.