Approach to the
Mediastinum in Trauma:
Density vs. Width
Tammy Washut MS4
Traumatic Injuries to Worry About

Mediastinal hematoma
– Aorta/great vessel injury
– Spinal hematoma
Mechanism

Rapid deceleration
injury

Blunt chest traumaMVA, falls
Sudden
deceleration
as sternum
hits steering
wheel.
The sudden stop
causes the blood
filled descending
aorta to “snap”.
The aortic arch is
fixed in position
by
branches from the
arch.
As the aortic tube
“snaps”, the intima
is torn just distal
to left subclavian artery.
External signs
“Seat belt sign”
 Chest ecchymosis
 Sternal/Rib fractures

Chest X-ray

Classically taught to look for widened
mediastinum

Wide mediastinum = 8 cm

What is the problem with this???
• Wide mediastinum has a broader differential than paratracheal density
Causes of Wide Mediastinum
Magnification
 Rotation
 Mediastinal hematoma
 Spinal hematoma
 Lymphadenopathy
 Long intravascular volume
 Obese patients

Magnification
Magnification
• Film placed directly behind the patient
• Initially used to determine the 8 cm criteria for wide mediastinum
Magnification
• Film placed under the backboard
• 17% enlargement
Magnification
• Film placed in trauma bed
• 25% enlargement
Rotation
7 cm
Rotated Right
4 cm
Rotated Left
Intravascular Volume
7 cm
Pre-Dialysis
4 cm
Post-Dialysis
Lymphadenopathy
Right Paratracheal Density
Composed of azygous
vein and SVC
 Density normally less
than aortic arch
 Increased = hematoma
 Why?

– Not affected by
technical factors
– Simple
Right Paratracheal Density
Normal
Increased Density
Mediastinal Hematoma

Other Signs:
–
–
–
–
–
PT stripe
Apical cap
Aortic Arch
NG deviation
Tracheal deviation
Mediastinal Hematoma

Other Signs:
–
–
–
–
–
PT stripe
Apical cap
Aortic Arch
NG deviation
Tracheal deviation
Mediastinal Hematoma

Other Signs:
–
–
–
–
–
PT stripe
Apical cap
Aortic Arch
NG deviation
Tracheal deviation
Mediastinal Hematoma

Other Signs:
–
–
–
–
–
PT stripe
Apical cap
Aortic Arch
NG deviation
Tracheal deviation
Mediastinal Hematoma

Other Signs:
–
–
–
–
–
PT stripe
Apical cap
Aortic Arch
NG deviation
Tracheal deviation
OHSU DATA
Hypothesis:
Right paratracheal density is
discriminatory sign in trauma
patients with widened mediastinum
Methods

122 Trauma patients (2001-2003)
– Screening Trauma chest radiograph
– Mediastinal width > 8.0 cm
– CT Chest w/contrast within 24 hours
Four readers of different levels of training
 R paratracheal region evaluated

Methods

Patients categorized by ISS
– AIS by body region
– Chest: 1-6
– Low risk: 0-2 (80 patients)
– High risk: >2 (42 patients)
Results

19 mediastinal hematomas (15.6%)
– 13 high-risk
– 6 low-risk
5 aortic injuries (4.1%)
 4 deceased (3.3%)

Results
Mechanism of Injury
25%
16%
44%
7%
8%
MVC
Fall
MCA
Auto vs. Peds
Other
Results
Hematomas
11%
57%
32%
MVC
Fall
MCA
Results
Average Injury Score
3.1
3.5
3
2.5
2
1.8
1.7
1.5
1
0.5
0
All Patients
No Hematoma
Hematoma
Results
Average Mediastinal Width
9.9
9.9
9.8
9.8
cm
9.7
9.6
9.6
9.5
9.4
All Patients
Hematoma
No Hematoma
Results
Right Paratracheal Density
Low-Risk Patients
100
80
% 60
40
20
0
Sensitivity Specificity
PPV
NPV
Results
R PT Density vs. Other Signs
R PT Stripe
100
Apical Cap
80
Azygous
Arch
60
AP Window
%
Trach Dev
40
L Bronchus
20
0
L PV Stripe
R PT Density
Sensitivity
Limitations
Single institution
 Presented to readers in artificial setting
 Relatively few hematomas
 AIS/ISS scoring not useful as triage tool

Strengths
Trauma patients with widened mediastinum
 Confirmed by CT w/in 24 hours
 Blinded analysis
 Clinical information available on all patients

Conclusions
Screening chest radiograph valuable in
low/moderate risk trauma patients
 Right paratracheal density valuable
 Avoid CT in low-risk patients
 7.3% normal mediastinum
 High risk patients should have CT

Recommendations
Low risk patients with or without a wide
mediastinum but no paratracheal density
do not need to have CT of the chest
 High risk patients with mechanism of
injury (i.e. seatbelt sign) should go to CT
regardless
 Paratracheal density, not width, should
direct further management

Examples
Possible Hematoma?
• Yes- aortic rupture
• Paratracheal density on right and loss of aortic arch definition
Possible Hematoma?
• Yes, but in this case it is lymphadenopathy in a high risk trauma patient
• This patient should get a chest CT
Possible Hematoma?
• No- mediastinum is wide, but no paratracheal density
• Patient is rotated to right
Examples
Examples
Examples
References
1.
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9.
10.
11.
12.
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Baker SP et al., J Trauma 1974; 14:187-196
Woodring JH et al., Radiology 1984; 151:15-21
Parmley LF et al., Circulation 1953; 17:1086-1101
Woodring JH et al., J Emerg Med 1990; 8:467-476
Woodring D et al., Ann Thor Surg 1984; 37:171-178
Blackmore CC et al., Emerg Radiology 2000; 7:142-148
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• Special thanks to Dr. Marc Gosselin and Dr Peter Verhey for references,
images and study data and slides.