SLIDE 1:
Crash Assessment for Field Triage
“Rules and Exceptions”

Stewart Wang, M.D., Ph.D.
University of Michigan 
Trauma Burn Center

Joel MacWilliams
University of Michigan
Transportation Research Institute


[presented]
University of Maryland
Baltimore, Maryland
November 4, 20004


SLIDE 2:
[CIREN map]


SLIDE 3:
[unidentified photo of trauma copters landing]


SLIDE 4:
University of Michigan
Transportation Research Institute
[photos of crash test dummies/ sleds/ building exterior UMTRI


SLIDE 5:
Motor Vehicle Crashes
 * 1,000,000 deaths per year worldwide
 * No. 4 global health problem by the year 2020 – W.H.O.   


SLIDE 6:
Crashes in the USA

 ~40,000 killed (115/day, 1/13 minutes)
 ~3,000,000 injured
 ~$230 Billion


SLIDE 7:
Riding in a car continues to be the most dangerous thing you do on a daily basis


SLIDE 8:
ABC’s of Vehicle Assessment


SLIDE 9:
ABC’s of Vehicle Assessment

•A is for “Angle” or more precisely Principle Direction of Force (PDOF)


SLIDE 10:
ABC’s of Vehicle Assessment

•A is for “Angle” or more precisely Principle Direction of Force (PDOF)

• Why is PDOF important?



SLIDE 11:
PDOF and Occupant Response
Occupant Response is equal and opposite to the PDOF


SLIDE 12:

ABC’s of Vehicle Assessment

Newton’s Third Law of Motion…..
For every action (force) in nature, there is an equal and opposite reaction



SLIDE 13:
ABC’s of Vehicle Assessment
….which tells us the patient’s 

– likely path of travel, 
– side of body likely injured, 
– the parts of the vehicle that are likely injury sources, and 
– the direction from which unsecured cargo and/or unrestrained occupants may have struck the patient from the “backside” of the PDOF


SLIDE 14:
ABC’s of Vehicle Assessment

Remember
– The other occupants in the vehicle (injured or not) often interact during the crash sequence and can be the source of a patients injury 


SLIDE 15:
ABC’s of Vehicle Assessment

Remember
– The other occupants in the vehicle (injured or not) often interact during the crash sequence and can be the source of a patients injury 

– Unsecured cargo is also a potential injury source - e.g. text books, portable DVD players, 
golf clubs, softball equipment, water heaters, 
laptops, bowling balls, etc. 


SLIDE 16:
ABC’s of Vehicle Assessment
• How to quickly assess the PDOF of a given vehicle


SLIDE 17:
Quick Assessment of PDOF
The “Superman” technique
- if you could grab a piece of the vehicle with one finger and pull in one direction, what direction would you pull in order to restore the car to its original shape


SLIDES 18-20:
[post-crash overhead shots of exterior crushed vehicles. arrows indicates likely direction of PDOF]


SLIDE 21:
ABC’s of Vehicle Assessment

• Precision is not required
• An “o’clock” interpretation is sufficient



SLIDE 22:
O’CLOCK / PDOF

[clock-face diagram illustrating the "o'clock" interpretation of a PDOF]


SLIDE 23:
ABC’s of Vehicle Assessment

•B is for “Belts & Bags”


SLIDE 24:
Field Assessment of Belt Use
• Seatbelt D-rings
• Seatbelt “Continuous Loops”
• Seatbelt webbing
• Seatbelt load limiters
• Seatbelt post-crash modes
  – Locked in extended or retracted position
  – Webbing cut with tongue in buckle
  – Webbing cut without tongue in buckle
• Steering-wheel rim deformation


SLIDE 25:
D-rings
[photo close-ups]


SLIDE 26:
Continuous Loops
[photo close-up]


SLIDE 27:
Webbing Marks 
[photo close-ups]


SLIDE 28-29:
Load Limiters 
[photo close-ups]


SLIDE 30:
Post-Crash Belt Mode 
- Belt “locked” in extended mode post-crash - will not retract


SLIDE 31:
Post-Crash Belt Mode 
- Belt “locked” in retracted mode post-crash - will not extend


SLIDES 32-34:
Post-Crash Webbing Cut 
[photo close-up]


SLIDE 35:
ABC’s of Vehicle Assessment
• Loading evidence of belt systems is not always so grossly obvious


SLIDE 36:
[post-crash interior close-up of steering wheel deformation]

Lower SW rim deformation is “usually” indicative of an unbelted driver


SLIDE 37:
[post-crash interior close-up of steering wheel deformation]

Upper SW rim deformation is “usually” indicative of a belted driver


SLIDE 38:
[post-crash interior close-up of steering wheel deformation]

Upper AND lowerSW rim deformation tends to occur in higher severity crashes and can be a belted or unbelted driver


SLIDE 39:
ABC’s of Vehicle Assessment


SLIDE 40:
ABC’s of Vehicle Assessment

[interior post-crash photo showing driver & front passenger frontal airbag deployment


SLIDE 41:
ABC’s of Vehicle Assessment

[interior post-crash photo showing driver side airbag deployment]


SLIDE 42:
ABC’s of Vehicle Assessment

[interior post-crash photo showing driver's curtain style side airbag deployment]


SLIDE 43:
ABC’s of Vehicle Assessment

[interior post-crash photo showing driver's airbag not completely deployed]


SLIDE 44:
ABC’s of Vehicle Assessment

• Rule - belted occupants may still contact interior components in higher severity crashes


SLIDE 45:
ABC’s of Vehicle Assessment

• Rule - belted occupants may still contact interior components in higher severity crashes

• Rule - in general, belt restrained occupants fare well in most crashes



SLIDE 46:
ABC’s of Vehicle Assessment

• Rule - belted occupants may still contact interior components in higher severity crashes

• Rule - in general, belt restrained occupants fare well in most crashes

• Exceptions - improperly belted, inappropriately belted, very young and the very old 


SLIDE 47:
ABC’s of Vehicle Assessment

• Rule - airbag restrained occupants generally enjoy good protection from head to abdomen



SLIDE 48:
ABC’s of Vehicle Assessment

• Rule - airbag restrained occupants generally enjoy good protection from head to abdomen

• Exception - unbelted occupants can often miss or skip off the airbag (angled PDOFs)


SLIDE 49:
ABC’s of Vehicle Assessment

• Rule - airbag restrained occupants generally enjoy good protection from head to abdomen

• Exception - unbelted occupants can often miss or skip off the airbag (angled PDOFs)

• Exception - occupants who are out-of-position (OOP) can sustain “inflation injuries” - eg flail chest, A-O separation, forearm fractures, brain injuries (angular acceleration)


SLIDE 50:
ABC’s of Vehicle Assessment
•C is for “Crash Severity”


SLIDE 51:

ABC’s of Vehicle Assessment
Minor - Frontal
 * Minimal hood deformation
 * No wheelbase reduction
 * Appears “driveable”
SLIDE 52:


SLIDE 53:
ABC’s of Vehicle Assessment
Moderate - Frontal

* Moderate hood deformation
* Typically not driveable
* Minimal or no wheelbase reduction
* Minimal intrusion; typically limited to floor/toepan


SLIDE 54:
ABC’s of Vehicle Assessment
Moderate - Side

* 4-6 inches of door intrusion
* Minimal or no wheelbase  reduction
* Doors may be jammed but no entrapment (physically pinned by vehicle component)


SLIDE 55:
ABC’s of Vehicle Assessment
Severe - Frontal
[post-crash exterior photo vehicle make/model unclear]

* Significant hood deformation
* Obvious wheelbase reduction
* Remote buckling of roof due to A-pillar movement
* Dash, floor, & steering column intrusion common


SLIDE 56:
ABC’s of Vehicle Assessment
Severe - Side 
[post crash exterior photo saturn sedan, impact to driver side]

* More than 6 inches of door intrusion
* Roof buckling
* Obvious wheelbase reduction 
* Vehicle may bow (banana shape)
* Seat cushion & seat backrest deformation common
* Occupant entrapment (physically pinned) more common



SLIDE 57:
Vehicle Incompatibility/Aggressivity
Fatality Ratios from FARS
Car Front to Vehicle-X Left Side

Vehicle X / Fatality Ratio (Veh. XCar)

* car / 5.6
* SUV / 1.4
* Van / 1.1
* Pickup Truck / 1.1


SLIDE 58:
Vehicle Incompatibility/Aggressivity
Fatality Ratios from FARS
Vehicle-X Front to Passenger Car Left Side

Vehicle X / Fatality Ratio (Car/Veh. X)

* SUV / 30
* Van / 13
* Pickup Truck / 25




SLIDE 59:
ABC’s of Vehicle Assessment

• Rule - injury probability increases as crash severity increases


SLIDE 60:
ABC’s of Vehicle Assessment

• Rule - injury probability increases as crash severity increases

• Rule - near-side impacts have higher probability of injury than other crash modes (front, rear)



SLIDE 61:
ABC’s of Vehicle Assessment

• Rule - injury probability increases as crash severity increases

• Rule - near-side impacts have higher probability of injury than other crash modes (front, rear)

• Exceptions - OOP, ejections, cargo, collision partner (mass or geometric incompatibility)



SLIDE 62:

ABC’s of Vehicle Assessment

•A is for “Angle” or more precisely Principle Direction of Force (PDOF)

•B is for “Belts & Bags”

•C is for “Crash Severity”



SLIDE 63:
ABCs of Occupant Assessment

Age
 – Rule:  The extremes of age are more vulnerable to injury (and have decreased physiologic reserve)



SLIDES 64-65:

CASE #2
[post crash photo vehicle exterior]
3 Child Occupants: Ages 3,6 & 7



SLIDE 66:
Outcome
7 year-old right front passenger
  • Bruises
  • Atlanto-occipital dissociation


SLIDE 67:
[post crash photo - vehicle interior]
6 year old right rear passenger
  Shoulder belt behind back
  Lap belt slack


SLIDE 68:
Outcome
6 year-old right rear passenger
  • Skull fracture and brain injuries
  • Lumbar (L2,3,4) spine fractures
  • Multiple intestinal injuries
  • Atlanto-occipital dissociation (more severe)


SLIDE 69:
[post crash photo - vehicle interior]
3 year old right front passenger 
Shoulder belt behind back
SLIDE 70:
Outcome
3 year-old left rear passenger
  • Multiple intestinal injuries
  • Pelvic fractures
  • Atlanto-occipital dissociation (most severe)

SLIDE 71:
CASE II

1. Adult Driver
   No significant injuries

2. 7 year-old right front passenger
   Atlanto-occipital dissociation

3. 6 year-old right rear passenger
   Atlanto-occipital dissociation (more severe)
   Other injuries deleted


4. 3 year-old left rear passenger
   Atlanto-occipital dissociation (most severe)
   Other injuries deleted


SLIDE 72:
Risk of Injury to Children in Crashes
[bar chart]

Injury Risk:

Unrestrained -38% - Seat belt 59% - Booster seat

SLIDE 73:
[photo] Children Don’t Fit Adult Seats

SLIDE 74:
Seat Belt Mispositioning
[graphics]


SLIDE 75:
Risk of Abdominal Injury for Child Occupants in Crashes 1999-2002
[bar chart]


SLIDE 76:
Involvement, Injury, and Fatality Rates (rates per vehicle miles of travel) [line chart]

SLIDE 77:
ABCs of Occupant Assessment

Age
 – Rule:  The extremes of age are more vulnerable to injury (and have decreased physiologic reserve)
 - Exception: Children 3 – 8 fare poorly if not in belt-positioning booster seats.

Body Habitus
– Rule:  Size does matter – fat is protective.



SLIDES 78-88:
Obesity Trends* Among U.S. Adults
BRFSS, 1991 through 2001
BMI >/=30 or ~ 30lbs overweight for 5'4" woman
[US map]

SLIDE 89:
[CAD - driver impact to airbag at time of deployment

2 side view CTs - one normal body weight male, one heavy bodyweight male


SLIDE 90:
Study Methods
2 inch slab selected at L3

SLIDE 91:
Study Methods

SubQ and Visceral Fat selected and volumes measured

SLIDE 92:
All subjects: Correlation between fat volume and physical and outcome factors

[table]

SLIDE 93:
Increased Subcutaneous Fat Volume Is Associated With Decreased Abdominal Injury Severity



SLIDE 94:
[scattercharts]

Effect of SubQ FAT on Injury Severity in Frontal Crashes

Overall - Head - lower Extremity - Abdomin


SLIDE 95:
ABCs of Occupant Assessment

Age
 – Rule:  The extremes of age are more vulnerable to injury (and have decreased physiologic reserve)
 - Exception: Children 3 – 8 fare poorly if not in belt-positioning booster seats.

Body Habitus
– Rule:  Size does matter – fat is protective.
– Exception:  Side impacts and LEX injuries

Complaints
– Rule:  Respiratory, neurologic, torso pain
– Exception:  Unable to complain

SLIDE 96:
Complaints

Respiratory
– Airway compromise, pneumothorax, hemothorax, flail chest, diaphragm rupture
– Secure airway and ventilation

Neurologic 
– Spine, intracranial, cerebral-vascular
– Spine stabilization, 

Torso pain
– Internal visceral injuries
– Chest decompression, access/volume, pelvic stabilization.



SLIDE 97:
Frontal Collisions- Torso Injuries

Lateral rib fractures
• Visceral Injuries evenly distributed
• Lung, liver, spleen

– Intestinal - seatbelt

– Pelvic fractures 
• open book, posterior hip dislocation

SLIDE 98:
Side Impact Collisions- Torso Injuries

 Greater risk of injury than frontal
– Posterior rib fractures 
– Struck side visceral injuries <lung, liver, spleen, kidney>
– Diaphragm and aortic injuries common  (Left)
– Pelvic fractures - central acetabular

Risk of chest, neck and head injuries increases with height of striking object


SLIDE 99:
ABCs of Occupant Assessment

Age
 – Rule:  The extremes of age are more vulnerable to injury (and have decreased physiologic reserve)
 - Exception: Children 3 – 8 fare poorly if not in belt-positioning booster seats.

Body Habitus
– Rule:  Size does matter – fat is protective.
– Exception:  Side impacts and LEX injuries

Complaints
– Rule:  Respiratory, neurologic, torso pain
– Exception:  Unable to complain