1 / 28

Diagnosing Pulmonary Embolism in 2003

Diagnosing Pulmonary Embolism in 2003. Dr. Peter Jones Emergency Medicine Specialist Auckland Hospital. Case 1 43f. 5 days post LUSCS Sudden onset pleuritic R chest pain HR 104 WCC 13, D-Dimer <500 -> 500-4000 3/7 later CxR blunting R CP angle CTPA negative Diagnosis: pleurisy

woodrow
Download Presentation

Diagnosing Pulmonary Embolism in 2003

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Diagnosing Pulmonary Embolism in 2003 Dr. Peter Jones Emergency Medicine Specialist Auckland Hospital

  2. Case 143f • 5 days post LUSCS • Sudden onset pleuritic R chest pain • HR 104 • WCC 13, D-Dimer <500 -> 500-4000 3/7 later • CxR blunting R CP angle • CTPA negative • Diagnosis: pleurisy • Subsequently well

  3. Case 2 19f smoker • Dry cough and pleuritic central chest pain <1/7 • RR 20 • ABG • pO2 10.3kPa (77mmHg) • A-a 3.7kPa (24mmHg – expected 9mmHg) • D-Dimer <500, CxR normal, ECG normal • CTPA negative, no positive (maybe) • Anticoagulated 5 days • V/Q ‘low probability’ day 4 • Diagnosis: Chest pain ?cause

  4. Case 329f • 1/12 ago “blackout” • 3/7 SOB and central chest pain (not pleuritic) • 2/7 ago right leg cramp • Occasional crepitation right base • ECG RBBB, CxR normal • ABG • pO2 10kPa (75mmHg) • A-a 3.3kPa (21mmHg – expected 11mmHg) • D-Dimer <500 • Medical referral • Tender R costochondral junction,”flu” 1/12 ago • Diagnosis: Costochondritis

  5. Background PE • Incidence: 23/100000/yr • Mortality 30% at 1 yr untreated, 2-8% treated • 50% undiagnosed pre mortem • Wide differential diagnosis • Poor clinical signs • Myriad of diagnostic strategies • No consensus

  6. Massive PEBTS 2003 • Highly Likely If • Collapse / hypotension and • Unexplained hypoxia and • Engorged neck veins and • RV Gallop • Bedside echocardiogram or CTPA <1hr

  7. Non-massive PEThe Literature • Using a pre-investigation clinical score is useful • Defines a group of low risk patients that it is safe to use D-Dimer as a ‘rule out’ test • Use Bayes’ theorem to calculate post test probability • The Se and Sp of each test needs to be known, these used to determine likelihood of PE given + or - test • Post test probability of <2% accepted as sufficient to stop investigating for PE and look for other cause • Post test probability >80% treat

  8. Bayes’ TheoremEssay Towards Solving a Problem in the Doctrine of ChancesPhilosophical Transactions of the Royal Society of London (1764). • Bayes theorem • Take pre test probability • Calculate odds • Multiply by test Likelihood Ratio to get post test odds • Calculate post test probability Thomas Bayes 1702-1761

  9. PE Clinical Scores 1. Empiric (Best guess - Auckland) 2. Derived from logistic regression analysis of known risk factors, clinical and investigation findings - complex derivation • Wells et al. (Canada) • Wicki et al. (Switzerland) • Kline et al. (USA)

  10. Wells et al. Clinical Model SimplifiedThrombosis Haemostasis 2000; 83:416-20 976 patients, prevalence PE 17% 3 Clinical Sn/Sx DVT Minimum leg swelling + pain on palpation deep veins 3 Alternative diagnosis less likely than PE 1.5 HR >100 1.5 Immobilisation or surgery previous 4 weeks 1.5 Previous VTE 1 Haemoptysis 1 Malignancy Treated in last 6/12 or palliative

  11. Score %Pts %PE <2 Low 40 3.6 2-6 Mod 53 20.5 >6 High 7 66.7 <=4 Unlikely 71 7.8 >4 Likely 29 40.7 Wells et al. >2500 patients several studies

  12. Wicki et al. Arch. Int. Med. 2001:161, 92-98986 ED patients prevalence 27% Score Risk %Pts %PE <4 Low 49 10 4-8 Int. 44 38 >8 High 6 81

  13. Category %Pts %PE Safe 79 13.3 Unsafe 21 42 HR/SBP >1 or Age > 50 sO2 < 95% (normal lungs) Unilateral leg swelling Recent surgery Haemoptysis Kline et al Ann Emerg. Med. 2002:39:2, 144-152934 ED patients, prevalence of PE 19% If yes to any of the above, asked in this order, then ‘unsafe’ to test with D-Dimer

  14. PE Clinical Scores

  15. PE InvestigationsD-Dimer Assays use an antibody directed against the D-dimer peptide, which is a product of fibrin breakdown • Currently using latex agglutination test • Sufficiently inaccurate so that post test probability 9% in low risk patients, 60% in high risk (empiric score) • Negative LR 0.38, Positive LR 3.5 • Rapid ELISA test now available (Vidas) • Negative LR 0.07, Positive LR 1.6 • Post test probability <2% in low risk group, 23% in high risk group

  16. PE Investigations CTPA • Multitude of papers • Modern multi-slice scanners accurate • Probably as good as pulmonary angiography • Sn 95%, Sp95% • -ve LR 0.06, +ve LR 19 • Can reveal other diagnosis • Some scans will be equivocal • Relative contraindications • Renal impairment • Young women • Absolute contraindication • Contrast Allergy

  17. NO LEG SIGNS 3 studies Approx 2000 patients NLR 0.39-0.73 LEG SIGNS 5 Studies >2000 patients NLR 0.02-0.16 PE InvestigationsCompression Ultrasound

  18. Investigations • Pulmonary Angiography • ?Consigned to history • VQ scan • May have a place if CTPA contraindicated • NRL 0.1 • only 14% have normal/near normal scans • 9% of these had PE in PIOPED

  19. Algorithms • Plethora of published algorithms with various strategies • Aim to rule out PE with post test probability <2% • Recently published (2003) • British Thoracic Society • Emergency Medicine

  20. Currently at Auckland Applying Bayes’ Theorem to the presented cases, using our current tests

  21. A Very Safe Algorithm SCGH Perth WA

  22. BTS guidelinesThorax 2003, 58:470-484 2.5-10%

  23. RMO Handbook 4% 6%

  24. Ignoring the Pretest Probability • Parallel stream in the literature • Assumptions • “A negative Vidas D-Dimer rules out PE” • “A negative CTPA rules out PE” • Problems • Vidas D-Dimer will miss PE • Sensitivity 90-100%, NLR 0.05-0.22 • 50-85% of patients require CTPA, 5-23% have PE • CTPA will miss PE / be equivocal • Sensitivity 95%, specificity 95%, NLR 0.06

  25. Proposed Algorithm Well’s Score 4 or less Unlikely PE Well’s Score >4 Likely PE CTPA / VQ Vidas D-Dimer + - Well’s likely Well’s Unlikely Compression US + - - + 2.2% CTPA 3.6% VQ Other cause Post test prob > 75% Treat

  26. Algorithm Implications Regardless of chosen algorithm, imaging for PE will increase markedly (diagnosis of PE will also increase)

  27. Thomas Bayes 1736 “..why, therefore, if I am half blind, must I take for my guide one that cannot see at all?”

  28. Selected References • Clinical Score PE • Wells PS et Al. Thromb. Haemost. 2000: 83;416-20 • Wicki et Al Arch. Int. Med. 2001:161, 92-98 • Kline et al Ann Emerg. Med. 2002:39:2, 144-152 DVT • Wells PS et al. Thromb. Haemost. 1999 81 493-7 • D-Dimer • Kline paper above (good summary of the issues) • Sijens PE et al. Thromb. Haemost. 2000: 84; 156-9 • CTPA vs Pulmonary Angio • Wells PS et al. Clin Chest Med 24 2003 13-28 Chapter ‘Diagnosis of PE: When is imaging needed?’ • Kline et al. Ann Emerg Med 35 (2) 2000; 168-80 • Compression Ultrasound • Turkstra et al. Ann Int med 1997 126(10) 775-781 • Heijboer H et al. NEJM 1993 329 (19) 1365-1369 • Perrier A et Al Lancet 1999 353 190-195 • Strategies PE • Perrier A et al Lancet 1999 353 190-195 • Musset et al. Lancet 2002 360 1914-1920 • Chagnon et al. Am J Med 2002 113: 269-275 • BTS Standards of care committee Thorax 2003 58 470-83 • British Thoracic Society Guidelines • Mountain D. emergency medicine 2003 15 (3); 250-62 • Fedullo PF et al. NEJM 2003 349 (13); 1247-56 • Kline JA and Wells PS: Ann Emerg Med August 2003 42:2 266-276 DVT • Wells et al NEJM 2003 349 (13); 1227-35 (and many others)

More Related