An ED Approach to Blunt Aortic Injury and Myocardial Confusion

1. An ED Approach to Blunt Aortic Injury and Myocardial Confusion Steven Issley, MD, CCFP Emergency Medicine McGill University September 12, 2001

2. Overview • Blunt aortic injury (BAI) • Myocardial contusion • Focus: • which investigations • when should these investigations be done • how sensitive are these investigations

4. Case One • Sunday, 1600h.

5. Case One • Sunday, 1600h. • On the way home from an afternoon of bongos in the park. • 20 yo healthy, but not-so-smart male • Trying to beat the light @ 80 km/h...

6. Case One • Sunday, 1600h. • On the way home from an afternoon of bongos in the park. • 20 yo healthy, but not-so-smart male • Trying to beat the light @ 80 km/h... • T-boned to passenger’s side…

7. Case One • Sunday, 1600h. • On the way home from an afternoon of bongos in the park. • 20 yo healthy, but not-so-smart male • Trying to beat the light @ 80 km/h... • T-boned to passenger’s side… • As usual, being drunk, he walks out of his car without a scratch. (...except for scratching his head in disbelief!)

8. Case One • Sunday, 1600h. • On the way home from an afternoon of bongos in the park. • 20 yo healthy, but not-so-smart male • Trying to beat the light @ 80 km/h... • T-boned to passenger’s side… • As usual, being drunk, he walks out of his car without a scratch. (...except for scratching his head in disbelief!) • He’s all yours!

9. Case One • Normal CXR • Is this patient at risk for aortic dissection? • What Next? • A) discharge: no injuries and CXR is reassuring • B) hCT chest; if normal discharge. • C) angio, as high risk, despite negative studies

10. BAI: stats • Aorta & great vessel injury 1-4% of blunt chest traumas • 20% incidence when BAI suspected (mechanism or wide mediastinum) • 75-90% ruprured thoracic aorta --> immediate death • If untreated: • 30% die within 1 day • 60% die within 1 week • 90% die within 1 month • 71-84% survive with prompt intervention

11. Deceleration: vertical (>30 ft / 10 m) horizontal (>30 mph / 50 km/h) Mediastinum and diaphragm compression Traction Dissection, thrombosis, pseudoaneurism, hemorrhage BAI: pathophysiology

12. BAI: associated risks • High speed head on or T-bone (>30 mph / 50 km/h) • Ejection • Other passengers dead • Steering wheel deformity • Fall from height (>30 ft / 10 m) • NB: seat belt does not affect incidence

13. BAI: clinical findings • Physical exam not sens or spec • 50% hypotension • pseudocoarctation syndrome • 30% harsh systolic murmur

14. BAI: associated injuries • Closed head injury (39%) • Other significant chest pathology (67%) • pelvic # (33%) • Femur, tibia # (51%) • T1-8 # • liver & spleen injury • 1st & 2nd rib # • Sternum #

15. BAI: associated injuries • 30-50% have no associated external injury!

16. 7 clinical predictors: age > 50: OR 12.1 (1.8-84) unrestrained: OR 5.9 (1.1-31) hypotension (sys<90): OR 9.9 (1.8-54) head injury: OR 4.9 (1.2-20) thoracic injury: OR 12.1 (2.7-54) abdomino-pelvic injury: OR 4.5 (1.1-19) extremity fracture: OR 8.4 (1.3-55) composite predictor: 0  0% 1  0.2% 2  0.5% 3  4.5 % 4 to 7  30% BAI: clinical prediction ruleBlackmore, et al. Am J Rad 2000

18. Wide mediastinumMS ration >0.25-0.4 Blurred aortic knob Pleural effusion Apical Capping NG deviation 1st or 2nd rib # Depressed left mainstem bronchus Blunted AP window HTX, PTX Enlargement of the paratracheal stripe BAI: investigations - CXR

19. Why do we screen with CXR? • Cheap • Readily available • Can be done in the trauma bay • non-invasive

20. BAI: investigations - CXR • Sensitivity:75-90% (Pretre’95, Fabian ‘98, Scaletta’00) • CXR completely normal up to 25% pt’s w/ aortic injury! • Specificity: 5-10% • PPV: 10-20% (low prevalence)

21. Wide mediastinum (67-85%) MS ration >0.25-0.38 Blurred aortic knob (24%) Pleural effusion (7-19%) Apical Capping (4-19%) NG deviation (3-11%) Depressed left mainstem bronchus (5%) Blunted AP window HTX, PTX Enlargement of the paratracheal stripe BAI: investigations - CXR

22. BAI: investigations - CXR • MW dependent on pt position and depth of inspiration • Erect PA view better than supine AP • Schwab, ‘89

23. BAI: recommendation • CXR is good screening tool, but variably sensitive • Require further investigation: • WM or other cxr abnormality (not skeletal) OR • clinical suspicion OR • high risk mechanism

25. Gold standard 73-100% sensitive 1% false positive Specificity 99% contrast time consuming invasive done in non-critical care environment BAI: investigations - angio

26. BAI: angio - recommendations • Even though CT and TEE can often obviate need for this invasive test • Still gold standard • Still needed to delineate injury • Still best at picking up proximal arch and arch branches

28. Relatively widely available non-invasive fast alternate diagnoses Requires dye costly BAI: investigations - hCT

29. hCT - Fabian ‘98

30. BAI: hCT - recommendations • hCT has very high sensitivity, and can be used to exclude aortic injury if low clinical probability • Specificity only moderate • Aortography, still the gold standard • define non-specific CT abnormalities • negative CT scan but high clinical probability • As technology improves hCT may become the diagnostic modalities of choice [Greenberg ‘99]

32. Less time consuming than angio no contrast bedside serial exams other info about heart Invasive may reqire intubation need specific expertise contraindicated if esophageal, c-spine or maxillo-facial injury BAI: investigations - TEE

33. BAI: investigations - TEE • accurate for isthmus, but misses arch and arch branches. • complications: • respiratory distress • hypotension • cardiac dysrhythmias

34. BAI: TEE vs. angio • Smith, NEJM ‘95 • TEE: sens 100%, spec 98% • Kearney, J Trauma ‘93 • TEE: sens 100%, spec 100% • aortography: sens 63%, spec 98% • Buckmaster J Trauma ‘94 • TEE: sens 100%, spec 100% • aortography: sens 73%, spec 99%

35. BAI: TEE vs. angio (cont’d) • Chirillo, Heart ‘96 • sens 93%, spec 98% • suggested a positive test could be used to take patients directly to OR, significantly decreasing time to definitive therapy. • Goarin, J Trauma ‘00 • angio less sens than TEE, because did not Dx minor injuries (eg: intramural hematoma, limited intimal flap) • However, these did not require surgery • For clinically significant injuries, both angio and TEE had sens 97% and spec 100%

36. BAI: TEE vs. angio (cont’d) • Ahrar ‘97: • 1% injury to proximal ascending aorta • 9% injury to arch branches (14/17 intact aorta) • missed if TEE alone • retrospective • only 20 cases

37. BAI: algorithm (Greenberg ‘99)

38. BAI: beta blockade • Short acting BB (eg Esmolol, labetalol) • decrease wall stress with upstroke • titrate to sys BP < 100 mmHg and HR < 100 bpm • Systolic 110-120 mmHg tolerable if necessary, particularly in the elderly

40. Case Two • 2nd passenger in the car • Our patient’s 70 year-old grandfather, who decided to join his grandson at the Tam Tam’s for the Sunday afternoon festivities. • Like his grandson, Gramps also seems well: • normal CXR • No chest pain • Mild sternal tenderness

41. Case Two • You consider the Dx of myocardial contusion. What next? • Discharge home • ECG: treatment plan based on results • ECG and enzymes • ECG and echo

42. MC: stats • Incidence: 3-75% • Depends on definition • On autopsy: well demarcated hemorrhagic area of anterior wall of right ventricle • lack of clinical gold standard makes it difficult to consistently define and difficult to interpret literature

43. MC: pathophysiology • Anterior force causing chest compression • sudden decel: heart moves freely and hits sternum • traction or torsion • fractured sternum

44. MC: associated risks • Age > 60 • high speed decelerations • unrestrained • steering column damage • 73% MC assoc’d with signs of external chest trauma: • multiple rib fractures / flail chest • pulmonary contusion • major vascular injury

45. MC: complications • 3% develop comp’s requiring treatment • dysrhythmias acount for 77% of comp’s • pump failure • MI • valve, cardiac rupture (rare) • tamponade, ventricular aneurism

46. MC: diagnosis • No gold standard short of autopsy • screening test: • clinical symptoms and signs • ECG • cardiac enzymes • radionucleotide scans • echo

47. MC: clinical presentation • Non-specific and inconsistent. • Cannot be relied upon to make Dx. • Findings: • chest wall tenderness, ecchymosis • dysrhythmias • chest pain (sharp or angina-like) • cardiac dysfunction similar to MI • sternal # NOT predictive

48. MC: ECG • Best screening test available in the ED • Sens 54% • sinus tachy is most sensitive • non-spec ST depression and T changes most specific • dysrhythmias, condction delay, axis deviation • Primary research inconsistent, small number of cases • Most agree that asymptomatic, stable patients with normal ECG can be safely discharged from ED

49. MC: ECG - Meta-analysis:Maenza, Am J Emerg Med ‘96 • All English retrospective, prospective and reviews from 1967-1993 • N= almost 5000 patients • ECG abnormalities correlated with complications • prospective: OR 9.18 (4.31-19.57) • retrospective: OR 26 (18.5-36.5) • combined: OR 19.9 (1.92-25.77)

50. MC: cardiac enzymes • Main problem: no gold standard to define MC. • CK-MB • Numerous prospective trials poor correlation • 40-50% sensitive • Troponin • few, very small studies • sens variable (30%-100%) • seems more specific than CK-MB • does not change management: patients with documented elevation in Trops all had ECG abnormailities