approach to the mediastinum in trauma: density vs. width tammy washut ms4

Approach to the Approach to the Mediastinum in Mediastinum in

Trauma:Trauma:

Density vs. WidthDensity vs. Width

Tammy Washut MS4Tammy Washut MS4

Traumatic Injuries to Worry Traumatic Injuries to Worry AboutAbout

Mediastinal hematomaMediastinal hematoma

– Aorta/great vessel injuryAorta/great vessel injury

– Spinal hematomaSpinal hematoma

MechanismMechanism

Rapid deceleration Rapid deceleration injuryinjury

Blunt chest Blunt chest trauma- MVA, fallstrauma- MVA, falls

Sudden decelerationas sternum hits steeringwheel.

The sudden stop causes the blood filled descendingaorta to “snap”. The aortic arch isfixed in position by branches from the arch.

As the aortic tube “snaps”, the intima is torn just distal to left sub-clavian artery.

External signsExternal signs ““Seat belt sign”Seat belt sign” Chest ecchymosisChest ecchymosis Sternal/Rib fracturesSternal/Rib fractures

Chest X-rayChest X-ray

Classically taught to look for widened Classically taught to look for widened mediastinummediastinum

Wide mediastinum = 8 cmWide mediastinum = 8 cm

What is the problem with this???What is the problem with this???

• Wide mediastinum has a broader differential than paratracheal density

Causes of Wide Causes of Wide MediastinumMediastinum

MagnificationMagnification RotationRotation Mediastinal hematomaMediastinal hematoma Spinal hematomaSpinal hematoma LymphadenopathyLymphadenopathy Long intravascular volumeLong intravascular volume Obese patientsObese patients

MagnificationMagnification

MagnificationMagnification• Film placed directly behind the patient

• Initially used to determine the 8 cm criteria for wide mediastinum

MagnificationMagnification• Film placed under the backboard

• 17% enlargement

MagnificationMagnification• Film placed in trauma bed

• 25% enlargement

RotationRotation

Rotated Right Rotated Left

7 cm 4 cm

Intravascular VolumeIntravascular Volume

4 cm7 cm

Pre-Dialysis Post-Dialysis

LymphadenopathyLymphadenopathy

Right Paratracheal Right Paratracheal DensityDensity

Composed of Composed of azygous vein and azygous vein and SVCSVC

Density normally less Density normally less than aortic archthan aortic arch

Increased = Increased = hematomahematoma

Why?Why?– Not affected by Not affected by

technical factorstechnical factors– SimpleSimple

Right Paratracheal Right Paratracheal DensityDensity

Normal Increased Density

Mediastinal HematomaMediastinal Hematoma Other Signs:Other Signs:

– PT stripePT stripe– Apical capApical cap– Aortic ArchAortic Arch– NG deviationNG deviation– Tracheal Tracheal

deviationdeviation

Mediastinal HematomaMediastinal Hematoma Other SignsOther Signs::


deviationdeviation

Mediastinal HematomaMediastinal Hematoma Other Signs:Other Signs:


deviationdeviation

Hypothesis:Hypothesis:

Right paratracheal density is Right paratracheal density is discriminatory sign in trauma discriminatory sign in trauma

patients with widened patients with widened mediastinummediastinum

OHSU DATA

MethodsMethods

122 Trauma patients (2001-2003)122 Trauma patients (2001-2003)– Screening Trauma chest radiographScreening Trauma chest radiograph– Mediastinal width > 8.0 cmMediastinal width > 8.0 cm– CT Chest w/contrast within 24 hoursCT Chest w/contrast within 24 hours

Four readers of different levels of Four readers of different levels of training training

R paratracheal region evaluatedR paratracheal region evaluated

MethodsMethods

Patients categorized by ISSPatients categorized by ISS– AIS by body regionAIS by body region– Chest: 1-6Chest: 1-6– Low risk: 0-2 (80 patients)Low risk: 0-2 (80 patients)– High risk: >2 (42 patients)High risk: >2 (42 patients)

ResultsResults 19 mediastinal hematomas (15.6%)19 mediastinal hematomas (15.6%)

– 13 high-risk13 high-risk– 6 low-risk6 low-risk

5 aortic injuries (4.1%)5 aortic injuries (4.1%) 4 deceased (3.3%)4 deceased (3.3%)

ResultsResults

Mechanism of Injury

44%

25%16%

7%8%

MVCFallMCAAuto vs. PedsOther

ResultsResults

Hematomas

57%

11%

32%

MVCFallMCA

ResultsResults

1.8 1.7

3.1

0

0.5

1

1.5

2

2.5

3

3.5

All Patients No Hematoma Hematoma

Average Injury Score

ResultsResults

9.8

9.6

9.9

9.4

9.5

9.6

9.7

9.8

9.9

cm

All Patients Hematoma No Hematoma

Average Mediastinal Width

ResultsResults

0

20

40

60

80

100

%

Sensitivity Specificity PPV NPV

Right Paratracheal Density Low-Risk Patients

ResultsResults

0

20

40

60

80

100

%

R PT Density vs. Other Signs

R PT Stripe

Apical Cap

Azygous

Arch

AP Window

Trach Dev

L Bronchus

L PV Stripe

R PT Density

Sensitivity

LimitationsLimitations Single institutionSingle institution Presented to readers in artificial Presented to readers in artificial

settingsetting Relatively few hematomasRelatively few hematomas AIS/ISS scoring not useful as triage AIS/ISS scoring not useful as triage

tooltool

StrengthsStrengths

Trauma patients with widened Trauma patients with widened mediastinummediastinum

Confirmed by CT w/in 24 hoursConfirmed by CT w/in 24 hours Blinded analysisBlinded analysis Clinical information available on all Clinical information available on all

patientspatients

ConclusionsConclusions

Screening chest radiograph valuable Screening chest radiograph valuable in low/moderate risk trauma patientsin low/moderate risk trauma patients

Right paratracheal density valuableRight paratracheal density valuable Avoid CT in low-risk patientsAvoid CT in low-risk patients 7.3% normal mediastinum7.3% normal mediastinum High risk patients should have CTHigh risk patients should have CT

RecommendationsRecommendations

Low risk patients with or without a Low risk patients with or without a wide mediastinum but no wide mediastinum but no paratracheal density do not need to paratracheal density do not need to have CT of the chesthave CT of the chest

High risk patients with mechanism of High risk patients with mechanism of injury (i.e. seatbelt sign) should go to injury (i.e. seatbelt sign) should go to CT regardlessCT regardless

Paratracheal density, not width, Paratracheal density, not width, should direct further managementshould direct further management

ExamplesExamples

Possible Hematoma?Possible Hematoma?

• Yes- aortic rupture

• Paratracheal density on right and loss of aortic arch definition


• Yes, but in this case it is lymphadenopathy in a high risk trauma patient

• This patient should get a chest CT


• No- mediastinum is wide, but no paratracheal density

• Patient is rotated to right

ExamplesExamples

ReferencesReferences1.1. Melton SM et al., Melton SM et al., J TraumaJ Trauma 2004; 56:243-250 2004; 56:243-250

2.2. Mirvis SE et al., Mirvis SE et al., RadiologyRadiology 1987; 13:487-493 1987; 13:487-493

3.3. Baker SP et al., Baker SP et al., J TraumaJ Trauma 1974; 14:187-196 1974; 14:187-196

4.4. Woodring JH et al., Woodring JH et al., RadiologyRadiology 1984; 151:15-21 1984; 151:15-21

5.5. Parmley LF et al., Parmley LF et al., CirculationCirculation 1953; 17:1086-1101 1953; 17:1086-1101

6.6. Woodring JH et al., Woodring JH et al., J Emerg MedJ Emerg Med 1990; 8:467-476 1990; 8:467-476

7.7. Woodring D et al., Woodring D et al., Ann Thor SurgAnn Thor Surg 1984; 37:171-178 1984; 37:171-178

8.8. Blackmore CC et al., Blackmore CC et al., Emerg RadiologyEmerg Radiology 2000; 7:142-148 2000; 7:142-148

9.9. Patel NH et al., Patel NH et al., RadiologyRadiology 1998; 209:335-348 1998; 209:335-348

10.10. Milne EN et al., Milne EN et al., Radiology Radiology 1984; 153:25-311984; 153:25-31

11.11. Demetriades D et al., Demetriades D et al., Arch SurgArch Surg 1998; 133:1084-1088 1998; 133:1084-1088

12.12. O’Connor CE et al., O’Connor CE et al., Emerg Med JEmerg Med J 2004; 21:414-419 2004; 21:414-419

• Special thanks to Dr. Marc Gosselin and Dr Peter Verhey for references,

images and study data and slides.

approach to the mediastinum in trauma: density vs. width tammy washut ms4

Documents

chesthigh risk patients

trauma bed

patientshigh risk

lowrisk patients7

cmct chest

aortic archincreased

widened mediastinumconfirmed

enlargementmagnification