United States Department of Transportation

National Highway Traffic Safety Administration

Paramedic: National Standard Curriculum

(Reprinted with permission)

http://www.nhtsa.dot.gov/people/injury/ems/

Trauma: 4

Trauma Systems and Mechanism of Injury: 1

UNIT TERMINAL OBJECTIVE

4-1 At the completion of this unit, the Paramedic student will be able to integrate the principles of kinematics to enhance the patient assessment and predict the likelihood of injuries based on the patient’s mechanism of injury.

COGNITIVE OBJECTIVES

At the completion of this unit, the Paramedic student will be able to:

4-1.1 List and describe the components of a comprehensive trauma system. (C-1)

4-1.2 Describe the role of and differences between levels of trauma centers. (C-3)

4-1.3 Describe the criteria for transport to a trauma center. (C-1)

4-1.4 Describe the criteria and procedure for air medical transport. (C-1)

4-1.5 Define energy and force as they relate to trauma. (C-1)

4-1.6 Define laws of motion and energy and understand the role that increased speed has on injuries. (C-1)

4-1.7 Describe each type of impact and its effect on unrestrained victims (e.g., “down and under,” “up and over,” compression, deceleration). (C-1)

4-1.8 Describe the pathophysiology of the head, spine, thorax, and abdomen that result from the above forces. (C-1)

4-1.9 List specific injuries and their causes as related to interior and exterior vehicle damage. (C-1)

4-1.10 Describe the kinematics of penetrating injuries. (C-1)

4-1.11 List the motion and energy considerations of mechanisms other than motor vehicle crashes. (C-1)

4-1.12 Define the role of kinematics as an additional tool for patient assessment. (C-1)

AFFECTIVE OBJECTIVES

None identified for this unit.

PSYCHOMOTOR OBJECTIVES

None identified for this unit.

DECLARATIVE

I. Introduction

A. Epidemiology of trauma

1. A leading cause of death for people 1- 44 years of age

2. 140,000 unexpected deaths per year

3. Automobile related deaths are > 40,000

4. Penetrating trauma may exceed blunt in near future

5. Pre-incident, incident, post-incident phase

B. History

1. Complete and accurate history of incident will identify possibility for 95% of the injuries present

2. Incident site

a. Indications of severity of injury

3. Major factors of tissue injury

4. Amount of energy exchanged

5. Anatomical structures potentially involved

II. Trauma systems

A. Components

1. Injury prevention

2. Prehospital care

a. Treatment

b. Transportation

c. Trauma triage guidelines

3. Emergency department care

4. Interfacility transportation - if necessary

5. Definitive care

6. Trauma critical care

7. Rehabilitation

8. Data collection/ trauma registry

B. Trauma centers

1. Levels

2. Qualifications

a. Essential

b. Desired

3. Role

C. Transport considerations

1. Level of receiving facility

2. Mode of transport

a. Ground transport

(1) If appropriate facility can be reached within reasonable time

(2) To a more accessible landing zone for air medical transport

b. Air medical transport

(1) Indications

(2) Contraindications

(3) Procedure

III. Energy

A. Physical laws

1. Newton’s first law of motion

a. A body at rest or a body in motion will remain in that state until acted upon by an outside force

b. In a vehicle traveling at 50 mph, the occupant is also traveling at 50 mph

c. When the car stops, the occupant continues to travel at 50 mph until some force acts on the occupant

2. Conservation of energy

a. Energy cannot be created nor destroyed

b. It can be changed in form

c. Energy can be absorbed producing deformation of substance

3. Kinetic energy (KE)

a. KE = ½ the mass of the object multiplied by the velocity (speed) of the object squared (Mass/2 x V²)

b. Velocity (V) influences KE more than mass

c. Greater speed means more energy generated

4. Force

a. Force = Mass x Acceleration

b. Force = Mass x Deceleration

c. Mass x Acceleration = Force = Mass x Deceleration

d. Simply put, to accelerate a bullet from a the muzzle of a weapon requires the force from the explosion of the gunpowder; once the bullet is set in motion by this explosion, an equal amount of tissue destruction must occur inside the body to stop it as was used to start it

5. Energy law summary

a. Motion is created by force (energy exchange)

b. Force (energy exchange) must stop this motion

c. If such energy exchange occurs inside the body tissue damage is produced

B. Energy exchange

1. Cavitation

a. Energy exchange produces particle motion

b. Temporary cavity

(1) Short lived

(2) Produced by stretching

(3) Dependent on the elasticity of the object involved

(4) Produces particle compression at the limits of the cavity

c. Permanent cavity

(1) Visible when the energy exchange has been completed

(2) Produced by compression and destruction

2. Interaction between two bodies

a. At least one must be in motion

b. Both can be in motion

3. Dependent on number of particles involved in the interface of the interaction

a. Density of the interacting bodies

(1) Air density (few particles)

(a) Lung

(b) Intestinal tract

(2) Water density ( more particles)

(a) Vascular system

(b) Liver

(d) Muscle

(3) Solid density (thick particles)

(a) Bone

(b) Asphalt

b. Area on interaction

(1) Shape of object

(2) Position of object

(3) Fragmentation of object

C. Types on trauma based on ingress

1. Blunt

a. Tissue not penetrated

b. Cavitation away from site of impact

c. Cavitation in direction of impact

2. Penetrating

a. Tissue penetrated

b. Cavitation at 90^o to bullet pathway

(1) Tissue inline to penetration is crushed

IV. Blunt trauma

A. Vehicle collisions

1. Frontal

2. Lateral

3. Rear

4. Rotational

5. Roll over

B. Occupant collisions

1. Frontal impacts

a. Down and under

(1) Feet impact floor pan

(2) Knees impact dash

(a) Tibia impact

i) Knee dislocation

ii) Popliteal artery disruption

iii) Knee support disruption

(b) Femur impact

i) Femur fracture

ii) Acetabular posterior fracture dislocation

(3) Torso rotates

(a) Steering column

(b) Dash

b. Up and over

(1) Head impact

(a) Windshield

(b) Roof

(2) Chest impact

(a) Steering column

(b) Dash

(3) Abdominal impact

(a) Steering column

(b) Dash

2. Lateral impacts

a. Vehicle moves into and impacts body

(1) Chest

(2) Pelvis

(3) Body moves laterally

(a) Neck

i) Rotates

ii) Lateral flexion

iii) Combination

3. Rear impacts

a. Vehicle seat pushes body

(1) All body parts in contact with seat move

(2) Body parts not in contact dragged along with torso

b. Secondary impact if vehicle hits another object

(1) Similar to frontal impact

4. Rotational impacts

a. Part of vehicle stops; the rest remains in motion

b. Combination of frontal and lateral impacts

5. Roll over

a. Difficult to predict the body impacts

C. Organ collisions

1. Two types of injury from blunt trauma

a. Compression

b. Change in velocity

(1) Acceleration

(a) Shear

(b) Avulsion

(2) Deceleration

(a) Shear

(b) Avulsion

2. Organ collisions with different vehicular collisions

a. Frontal impacts

(1) Head

(a) Compression

i) Skull fractures

ii) Cerebral contusion

(b) Deceleration

i) Opposite end separation

ii) Hemorrhage

iii) Brain stem stretch

(2) Neck

(a) Compression

i) Vertebral body

a) Compression fracture

b) Hyperextension injury

- Posterior element compression

- Anterior body separation

c) Hyperflexion injury

- Anterior body compression

- Posterior element separation

(b) Shear

i) Not significant

(3) Thorax

(a) Chest wall

i) Compression

a) Fracture rib(s) - producing single rib fractures, flail chest, and/or pneumothorax

ii) Shear

a) Fracture thoracic spine

(b) Heart

i) Compression

a) Contusion

b) Rupture

ii) Shear

a) Not significant

i) Compression

a) Not significant

ii) Shear

a) Junction arch and descending portions

b) Aortic origin at the aortic valve

c) A t the diaphragm

(d) Lung

i) Compression

a) Pneumothorax

b) Rib fracture and penetration

ii) Shear

a) Not significant

(4) Abdomen

(a) Abdominal cavity

i) Diaphragm

a) Compression tears

b) Shear - not significant

ii) Abdominal wall

a) Compression tears

b) Shear - not significant

(b) Liver

i) Compression

a) Burst type injuries

ii) Shear

a) Tears from Ligamentum Teres

b) Avulsion of liver from inferior vena cava at the hepatic veins

i) Compression

a) Burst

ii) Shear

a) Avulsion of pedicle

(d) Gastrointestines

i) Compression

a) Rupture

ii) Shear

a) Avulsion of mesenteric vessels from aorta or vena cava

b) Tears along mesenteric vessels

c) Avulsion of vessels from intestine

(e) Gall bladder

i) Compression

a) Rupture

ii) Shear

a) Avulsion from liver

b) Avulsion of cystic duct

b. Lateral impacts

(1) Head

(a) Compression

i) Similar to frontal except lateral head and on the side of the impact to the vehicle

(b) Shear

i) Shear of brain and vessels opposite side of the impact

(2) Cervical spine

(a) Compression

i) Minimal unless head hits the top of the passenger compartment or the support for the windows

(b) Shear

i) Two fold mechanism

ii) Rotation

a) Center of gravity of the head is anterior to the pivot point of the head and the spine at the odontoid process; as lateral impact occurs the torso and then the C-spine is pushed under the head; the head rotates in relative position to the body, toward the impact

b) The center of gravity of the head is also cephalad to the point of support at the cervical spine; as the lateral forces push the torso away from the point of impact the motion of the head produces lateral flexion of the head

c) The combination of these two forces is lateral flexion of the neck opening the facets opposite the side of impact and rotation of the vertebral bodies in relation to each other; the result is jumped facets and if the force is great enough significant torsion of the spinal cord

(3) Thorax

(a) Compression

i) Impact of the door into the thorax

a) Lateral ribs - fractures and flail chest

b) Lung - pneumothorax

c) Spleen or liver - lacerations and hemorrhage

(b) Shear

i) Lateral motion of the thoracic spine as the torso is pushed away from the impact

ii) Thoracic aorta moves with the spine

iii) Arch and heart do not move until traction on the arch

iv) Shear forces tear the aorta at the junction of the movable arch and the descending aorta that is attached to the thoracic spine

(4) Abdomen

(a) Compression

i) Liver or spleen depending of the side of the impact

ii) Kidneys depending of the side of the impact

iii) Diaphragm similar to frontal impact

(b) Shear

i) Abdominal aorta moves with the lumbar spine

a65535 Shear of the renal vessels

b65535 Shear of the splenic vessels

(5) Pelvis

(a) Compression

i Impact on the femur

a65535 Femoral head driven through the acetabulum

b65535 Fracture of the ileum

c65535 Sacro-iliac joint fracture

d65535 Fracture of the other bones of the pelvis

(6) Extremities

(a) Compression

i Clavicle compressed between the humerus and the sternum

ii Lateral compression of the humerus

c0 Rear impact

(1) Physics

(a) Energy (velocity) imparted to the rear

i Moves all attached parts of the vehicle

ii) Occupants in direct contact with vehicle move also

iii Parts of the occupants not in direct contact do not move until pulled along

a65535 Newton’s first law of motion

b65535 Unrestricted body parts will be separated or at least stretched by this differential velocity

iv The force of the energy exchange depends on the differential energy of the two vehicles and the exchange of energy between the two

(2) Head

(a) Compression

i Into structures behind the seat

ii Energy of compression depends on the force of the change of energy between the vehicle and the impact into the head

(b) Shear

i Separation of the brain and skull in front

(3) Neck

(a) Compression

i Unrestrained occupant into the top of the passenger compartment or into the rear seat

(b) Shear

i Head restraint not in the correct position to move the head forward with the motion of the vehicle

ii Neck hyperextended over the malpositioned head restraint; usually only ligamentous and tendon stretch and no fractures

(4) Torso

(a) As most of the torso is in contact with the seat and springs of the seat only minimal differential energy is exchanged onto the body parts

(b) Unless there is rebound when the vehicle hits another vehicle there is little injury to the torso in the rear impact collision

(5) Extremities

(a) The extremities move with the torso and receive very little differential exchange with rear impacts

d0 Rotational impacts

(1) In the pure rotational impact, one part of the vehicle hits an immovable object, while the rest continues in motion (Newton’s first law of motion)

(2) As the one part stops and the rest of the vehicle continues to move the vehicle moves around the fixed point

(3) The motion to the occupant is a combination of two motions

(a) Frontal and lateral

(b) Rear and lateral

(4) The injuries are combinations of the two motions with emphasis on the initial impact motion

e0 Roll over

(1) In a roll over the pattern of injuries is very difficult as the unrestrained occupant can hit all parts of the vehicle

f0 Ejection

(1) If the force is such and the occupant is unrestrained then ejection is possible

(2) The major injuries occur inside of the vehicle and on the way out rather than afterward on impact the ground or some other object

(3) Since the major part of the injuries occur on the way out, the Paramedic can better predict the injuries by thinking of the first part of the collision rather than the latter portion

D0 Restraints

1 Restraints are systems for absorbing the energy of the impact before the occupant hits something hard and limiting the distance the body has to travel thus helping to decrease velocity (speed)

2 Belt restraint

a0 Contrary to popular belief the belt restraints work on lateral impacts as we as in frontal impacts (they are not quite as effective in lateral impacts because the hard parts of the passenger compartment is closer on the sides than in the front therefore the belt systems do not have as much distance to be effective)

b0 The benefit of the belt restraint can be seen on any Sunday at the automobile race track

c0 Lap belts

(1) Benefits

(a) Hold the lower torso in close approximation to the seat and away from the dash or steering column

(b) Prevent

i Forward motion of the lower torso in frontal collisions

ii Moves the torso with the vehicle and away from the impact in lateral impact collisions

iii Prevents multiple impacts in rollover collisions

iv Prevents ejection

(d) Prevent forward motion of the pelvis by supporting the anterior part of the pelvis

(e) No impingement on the soft intra-abdominal contents

(2) Limitations

(a) Upper torso is not supported

(b) If positioned above the anterior iliac spine, the belt stops the forward motion of the body against the lumbar spine with the intra-abdominal organs crushed between the belt and the spine

(d) Increased intra-abdominal pressure can rupture the diaphragm

d0 Shoulder restraints

(1) Benefits

(a) Prevents

i Forward motion of the upper torso in frontal impact collisions

ii Hyper flexion of the upper torso around the lap belts preventing spinal injuries

(b) Moves the upper torso with the vehicle in lateral impact collisions

(2) Limitations

(a) If worn without the lap belt neck injuries can occur

(b) Lessened benefit if the seat is very close to the dash or steering column

e0 Air bags

(1) Benefits

(a) Supplemental protection

(b) Frontal impact protection only with frontal bags

(2) Limitations

(a) Minimally effective alone

(b) Can produce significant injuries if too close to the occupant

i Bag expansion

ii Protective cover into the face or chest

(d) Facial and forearm abrasions

(e) Deployed air bag may hide structural damage to the vehicle that may aid in assessment

f0 Child safety seats

(1) Age and types

(2) Proper use

(3) Injury patterns

(4) Proper use with airbags

E0 Motorcycle collisions

1 Frontal impact

a0 Bike stops

b0 Occupant continues forward

(1) Impacts parts of the bike

(a) Face

(b) Chest

(d) Upper legs (femur)

(2) Ejected over the bike

(a) Into vehicle

(b) Onto ground

(3) Injuries

(a) C-spine fractures

(b) Torso

i Compression injuries

a65535 Solid organ crush

b65535 Hollow organ rupture (e.g. lungs)

ii Deceleration (sheer injuries)

a65535 Aorta

b65535 Pedicled organs

2 Angular impact

a0 Collapse of bike onto vehicle

(1) Legs trapped between bike and vehicle

(2) Open fracture and/or dislocations

b0 Lateral motion of torso into vehicle

c0 Injuries

(1) Cervical spine

(a) Similar to lateral impact in vehicle

(2) Torso

(a) Compression

i Lateral chest

ii Lateral abdomen

(b) Deceleration

i Aorta

ii Pedicled organs

3 Protection

a0 Head

(1) Helmet

(a) 300% increase brain injury without helmet

(b) Spine

i Small protection

ii No increase

b0 Skin

(1) Leathers

(2) Very protective during slides on asphalt

c0 Ankles and feet

(1) Strong boots

F0 Pedestrian verses motor vehicle

1 Injuries patterns depends on

a0 Height

b0 Body area facing impact

2 Three phases

a0 Vehicle pedestrian impact

(1) Legs

(a) Feet stay in place on asphalt

(b) Legs pushed by bumper

(2) Torso

(a) Pelvis

(b) Crushed by front of vehicle

i Lumbar fractures

ii Thoracic fractures

b0 Pedestrian rotates onto hood

(1) Impact onto torso

(a) Compression injuries

(b) Acceleration (shear) injures

(2) Cervical spine

(a) Severe flexion or lateral flexion

(b) Torsion

c0 Pedestrian rolls off onto the ground (asphalt)

(1) Beside vehicle

(a) Impact into the ground as fall from height

(2) In front of vehicle

(a) Run over by the vehicle

(b) Dragged by the vehicle

G0 Falls

1 Factors

a0 Height of fall

b0 Surface of the impact

c0 Objects struck during the fall

d0 Body part of first impact

2 Feet first

a0 Impact onto calcaneus

b0 Continued motion of the torso

(1) Ankles, knees, femur

(2) Acetabulum, pelvis

(3) Spine

(a) Break the “S”

(b) Arch

i Convexity stretched & opened

ii Concavity compressed

(4) Torso

(a) Deceleration (shear)

i Liver

ii Kidney

iii Spleen

iv Aorta

3. Head first

a0 Compression

(1) Skull fracture

(2) Brain

(a) Contusion

(b) Laceration

(3) Spine

b0 Deceleration (shear)

(1) Aorta

(2) Kidney

(3) Other

4 Parallel to ground

a0 Compression

(1) All parts of the impact

Penetrating injuries

A0 Energy exchange

1 Number of particles involved

a0 Density of tissue

(1) Gas

(a) Lung

(b) Gastrointestinal tract

(2) Liquid

(a) Blood vessels

(b) Muscle

i Spleen

ii Liver

iii Kidney

iv Other

(3) Solid

(a) Bone

b0 Area of interaction

(1) Deformation of bullet

(2) Tumble

(3) Fragmentation

2 Cavitation

a0 Permanent

(1) Visible when examined

(2) Crushed tissue

b0 Temporary

(1) Compression wave of tissue particles

(2) Away from the pathway of the bullet

(3) Lasts only a few microseconds

(4) Tissue damage produced by stretch

3 Available energy

a0 KE = M/2 x V²

(1) Velocity more important than the mass

b0 Mass x acceleration = FORCE = mass x deceleration

(1) Then energy used to place the mass in motion must be completely exchanged into the body tissues to stop the mass

c0 Energy potential

(1) Continuum of energy increase

(2) Can be broken down into artificial but workable groups

(3) Energy

(a) Low energy objects

i) Hand driven

a65535 Knife

b65535 Ice pick

c65535 Ax

d65535 Other

ii Minimal cavitation

iii Damage only by cutting edge

(b) Medium energy

i Muzzle velocity > 1500 feet/ second

ii Hand guns, low power rifle

iii Small projectile

iv Cavitation 6-10 x bullet frontal area

i Muzzle velocity < 1500 feet/ second

ii Military high velocity small caliber weapons

a65535 Examples (M16, AK 47/74)

b65535 Other

iii Cavitation 20-30 x frontal area of missile

(d) Implications of soft body armor

B0 Anatomy

1 Organs injured

2 Pathway of missile

a0 Entrance wound

(1) Hole is crushed inward

(2) Round or oval shaped

(3) Rim

(a) Dark

(b) 1-2 mm width

(4) Abrasion

(a) Produced by spinning of the bullet

(b) Largest with greatest contact of skin

i Larger when impact is at an angle

(5) Burn

(a) Flame from barrel

(b) End of weapon 4-6 inches from the skin

b0 Exit wound

(1) Pushed outward

(2) Stellate or slit

Blast

A0 Introduction

1 The blast effect is broken down in to three phases depending on the type of force that occurs during that phase

2 Each phase has a different energy pattern

B0 Phases

1 Primary

a0 Pressure wave of the blast

(1) Major effect on gas containing organs

(a) Organ systems

i Lungs

ii Intestinal tract

(b) Pathology

i Rupture of the organ

b0 Heat wave

(1) Burns on unprotected part of body

(2) Skin burns

(3) Eye burns

2 Secondary

a0 Struck by flying particles

(1) Glass

(2) Bricks

(3) Wood

(4) Metal

b0 Pathology

(1) Compression

(2) Lacerations

3 Tertiary

a0 Patient becomes flying object

(1) Impact into other objects

(2) Similar to falls