TRAUMA: MECHANISM OF INJURY

KEY CONCEPTS

The following section provides information and space for notes on the key concepts provided by the instructor.

TRAUMA STATISTICS

· Causes 125,000 deaths per year

· Leading cause of death (ages 1 through 44)

· Responsible for 80% of teenage deaths

· Responsible for 60% of childhood deaths

IMPACT ON HEALTHCARE

· 60 million injuries each year

· 30 million require hospitalization

· 300,000 permanently disabled

· 8.7 million temporarily disabled

· Responsible for 40% of U.S. health care costs

EFFECTS OF FORCES ON THE BODY

· BASIC LAW OF MOTION: "Energy cannot be created or destroyed, but it can change in form or be absorbed"

· Motion injury is basically caused by the body's absorption of energy

MAJOR MECHANISMS OF MOTION INJURY

Rapid Forward Deceleration

· To appreciate the forces involved in this mechanism, consider another BASIC LAW OF MOTION: "A body in motion, remains in motion unless acted upon by an outside force."

· Motor vehicle accidents are the most common form of rapid forward deceleration

MOTOR VEHICLE ACCIDENTS

Impacts

MOTOR VEHICLE ACCIDENTS (MVAs) - can be broken down into 3 separate impacts. For example, if a car is traveling 40 mph and hits a tree head on,

· The first, vehicle impact, will occur when the car hits the tree;

· The second, body impact, will occur when the occupant hits some structure inside the car (eg., windshield, steering wheel, or dashboard);

· The third, organ impact, will occur within the body of the occupant, when movable organs (i.e., brain, heart, liver, spleen, or intestines) impact with the supporting structures i.e., the skull, sternum, ribs, spine, or pelvis)

Looking for signs of these types of impacts will assist the EMT-1 or EMT-P in predicting the injuries that the patient may have.

Head-On Collision

When arriving on scene, the EMT-1 should look for the following clues:

· Vehicle Impact

· extent of front end damage

· Body Impact

· windshield damage (spider web pattern)

· steering wheel damage

· dashboard damage

· Organ Impact

· obvious soft tissue injury (lacerations abrasions, bruising, and contusions) or fractures to the head, neck, chest and abdomen

Windshield Damage

·          Major indication that victim was unrestrained and that the skull has impacted the windshield

·          Injuries may include:

     head injury - soft tissue injury, fractures, coup and contrecoup            injury to the brain

     scalp, face, or neck injury

           hyperextension or flexion of C-spine

Steering Wheel Damage

·          Major indication that victim was unrestrained and the body has impacted with the steering wheel

·          Note any obvious bruising to area of impact; a primary consideration should be the deeper structures and organs that are susceptible to shearing and compression forces generated by this type of impact

·          Injuries may include:

·          soft tissue neck injuries

·          larynx and tracheal injuries

·          fractured sternum

·          myocardial contusion

·          pericardial tamponade

·          pneumothorax

·          hemothorax

·          flail chest

·          intraabdominal injuries (ruptured spleen, liver or bowel)

Dashboard Damage

· Major indication that victim was unrestrained and the body has impacted with the dashboard

· Injuries may include:

· knee injuries

· femur, hip, or pelvis injuries (if energy is transferred proximally from the knee)

· head, face, and C-spine injuries

Lateral-Impact or T-Bone Collision

When arriving on scene, the EMT-1 should look for the following clues:

Vehicle Impact

• damage to the driver's or passenger's side

Body Impact

• intrusion of the door, arm rests, window, or other parts of the car into the victim's space

Organ Impact

• head injury

• C-spine injury (the combination of the flexion and rotation of the spine that occurs with lateral impact produces more frequent and severe cervical injuries; fractures of the spine are more common with this type of collision than with rear-end collisions)

• chest and abdominal injuries to the side of impact (same as in head-on collisions)

• upper arm, shoulder and clavicle injuries on the side of impact

• pelvic, hip, or femur injuries on the side of impact

Rear-Impact Collision

· Most common type of rear-end collision is when a stationary car is hit from behind by another car

· Injuries occur as the torso and seat shoot forward; if the headrest is too low, the neck will end up hyperextended over the top of the headrest (this is how strains, torn ligaments, and more serious cervical injuries often occur)

· The vehicle may be involved in double impacts - front and rear; the EMT-1 and the EMT-P should be looking for two sets of injuries

Rollover Collision

· Occupant can be tossed around and injured from all directions

· Difficult to predict all the injuries that could result, however, the EMT-I should be prepared to perform a thorough primary and secondary survey

· Greater chance of occupants being ejected from the vehicle

Restraint Systems

Seat Belts

· Should be worn correctly (should be positioned across the pelvis above the femur and should be pulled tight enough to remain in this position)

· Protect the occupants from impacting with the inside of the car

· Prevent occupants from being ejected from the vehicle

Victims Ejected From Vehicle

· 25 times more likely to be killed

· Injuries that result after the second impact when the body hits the ground outside the car are even more severe than the initial impact

· Distance between the victim and the vehicle usually indicates how fast the car was traveling and, therefore, how much energy was absorbed by the patient

· One out of 13 ejected victims sustain spinal injuries

SEAT BELTS WORN IMPROPERLY - may be a source of trauma; the following injuries may occur:

If worn too high,

· Compression injuries to abdominal organs

· Burst injuries to the small intestine and colon

· Rupture of the diaphragm due to increased intrabdominal pressure

· Compression fractures to the lumbar spine

If the lap belt is worn alone,

· Severe trauma to the head, face, and neck (since there is no shoulder strap to stop the forward momentum of the upper body)

If the shoulder belt is worn alone,

· Severe C-spine injuries

· Decapitation

Air Bags

· Provide maximum protection during head-on collisions when used in addition to seat belts

· Deflate immediately after impact so they provide no further protection with multiple-impact collisions

· Not effective with lateral or rear-impact collisions

· Not recommended in children, since its use may cause death even in low impact collisions

Motorcycle Accidents

· 75% of motorcycle deaths are due to severe head trauma

· Helmets help to prevent head trauma, but do not protect against spinal injury

· Injuries are similar to victims that are ejected from vehicles; high frequency of head, neck, and extremity trauma

Auto vs. Pedestrian Collisions

Two common injury patterns occur, one for the adult and another for the child; because of the difference in height, they will contact the vehicle at different levels of the body.

· With an adult, the first impact is made by the bumper to the lower extremities; in children contact is usually to the upper legs or pelvis

· As the victim folds forward, the second impact occurs when the adult's upper legs and trunk hit the hood of the car; for the child, it is usually the abdomen and thorax (if the victim continues forward, their head may strike the hood or the windshield of the car)

· Finally, the third impact occurs when the victim falls off the car and hits the pavement usually head first

Multi-system trauma should be assumed, even if they are asymptomatic initially.

RAPID VERTICAL DECELERATION (FALLS)

Injury Patterns

· Injury pattern that results with this mechanism is dependent upon three factors:

· distance of the fall

· body part that impacts first

· type of landing surface

· Falling from greater heights increases the incidence of trauma because velocity increases as they fall

· Falls are considered severe if greater than three times the height of the victim

· If the landing surface is more resilient, thereby increasing the stopping distance, the kinetic energy will be absorbed by the surface instead of the victim's body

Injury Pattern For Children

· Associated with head injury, since their head is the heaviest part of their body and usually impacts first

Injury Pattern For Adults

· Feet or leg fractures

· Hip or pelvic fractures

· Lumbar/sacral spine fractures

· Wrists fractures

PENETRATING TRAUMA

Stab Wounds

· Severity of wound depends on the following:

· location penetrated

· blade length

· angle of penetration

· Location:

· stab wounds that have entered the upper abdomen may have reached organs in the thoracic cavity

· Stab wounds that have entered the chest wall below the 4th intercostal space may have injured abdominal organs, since this is the highest level of the diaphragm.

Do not underestimate the internal damage of simple entrance wounds, since the attacker may have moved the blade around inside after stabbing his victim, causing extensive internal injury.

Firearms

Severity of injury affected by the following factors:

· Type of weapon

· low velocity weapons are less destructive than high velocity weapons

· Caliber or size of bullet

· larger bullets cause more resistance and therefore a larger area of damage

· Distance from which the weapon was fired

· with increased distance, the bullet will decrease in velocity by the time it reaches the victim

· Bullet deformity

· hollow point and soft nose bullets flatten out when they impact the victim, so the area damaged is greater