Vol.4-Ch.2 "Mechanism of Injury" Flashcards
What are the 2 fundamental causes of trauma?
Impacts and collisions
Kinetics is ?
Branch of physics dealing with objects in motion and energy exchanges that occur as these objects collide
Kinematics is ?
Branch of physics that studies the motion of a body or system of bodies WITHOUT consideration given to its mass or the acting forces
What are the 2 basic principals to kinetics?
Law of Inertia
Law of Energy Conservation
The law of Inertia is Newtons ____ Law?
First
The first part of Newtons Law of Inertia is?
“A body in MOTION will remain in motion unless acted upon by an outside force”
The second part of Newtons Law of Inertia is?
“A body at REST will remain at rest unless acted upon by an outside force”
What is Energy defined as?
What is the Law of Energy? (Energy Conservation)
Energy = the ability to do work
“Energy can be neither created nor destroyed. It can only be changes from one form to another”
What is Newtons second Law of Motion about?
How is it calculated?
Force = (Mass x Acceleration (or Decceleration)) / 2
What is Kinetic Energy?
How is is calculated?
Kinetic Energy = (Mass x Velocity^2) / 2
What is the definition of “kinetics of impact”?
The study of energy exchange with human body and the effects applied to the body (not only the damages on the body like “biomechanics of trauma”)
What is the definition of “biomechanics of trauma”
The manner of which the energy exchange damages the human body tissues.
What are the 3 Laws of physics used in biomechanics of trauma?
- Inertia
- Force
- Energy Conservation
What are the 3 types of forces that can damage the body when applied?
- Compression
- Stretch
- Shear
What is a compression injury?
Injury that occurs from impact that abruptly stops a portion of the body while inertia causes the reaming structures to continue in motion
What is a stretch injury?
Injury that occurs from part of the body being pulled away abruptly, specifically from tissues stretching too far
What is a shear injury?
Injury occurring along the edges of the impacting force or at organ attachments
(bascically the closest two points of partial tissue being stopped, while the other wants to keep moving because of inertia)
What are the 5 events that occur in a vehicle collision and when does each one start?
- Vehicle Collision - when the vehicle hits something
- Body Collision - when the body his the vehicle
- Organ Collision - when organs hit the inside of body
- Secondary Collision - any other loose objects that hit Pt in the vehicle
- Additional Impacts - when the vehicles gets struck again after the first impact
What is the correct way for a child safety seat to be positioned in a vehicle (under and above 2 years)
If under 2 years old (infant/small child):
Put in back seat facing backwards, held securely to seat with lap belt or lower anchors/tethers
If older than 2:
Place in back seat, facing forward, with the lab belt now going over the child at waist with 4 point restraint system holding kid in place
What are the 4 types of restraints in a vehicle?
- Seat belts
- Supplemental Restraint System (SRS)
- Child Safety Seats
- Head rests
What are the 5 types of auto impact?
- Frontal (most common)
- Lateral
- Oblique
- Rear-end
- Rollover
Frontal Impact, the most common, can cause what 4 types of pathways for a Pt?
- Restrained Pathway
- Up and Over Pathway
- Down and Under Pathway
- Ejection
In the frontal impact’s Restrained pathway, what can occur?
This implies that the lap belt and shoulder straps were used properly.
If lap belt not used: intraabdominal injury, lumbar spine injury, or hip dislocation are possible
If shoulder strap not used: contusions and rib fractures are possible
In the frontal impact’s Up and Over pathway, what can occur?
What is Axial Loading? When does it occur here?
W/out use of restraints, the body moves upward and forward (typically when Pt stiffens legs before impact); MOST DEATHS occur in the Up and Over Pathway
The legs usually get impinged on the steering wheel causing possible fractures of both femurs
The abdomen and or low chest strike the steering wheel causing possible hollow organ damage, liver laceration, if diaphragm is torn then organs can enter the wrong cavities, thoracic spine damage.
The head will trike the windshield causing AXIAL LOADING (compression force on the cervical spine) as trying to push through the windshield
In the frontal impact’s Down and Under pathway, what can occur?
What is “paper bag” syndrome
The knees bend first here (driver did not straiten legs before like in up and over) and are the first to strike the vehicle at the firewall. This COMMONLY ends in knee, femur, and hip dislocations.
Then the upper body bends at waste to hit steering wheel but this occurs HIGHER on the body than in up and over. Therefore can lead to flail chest, aortic tears, tracheal damage, or “Paper Bag” Syndrome (when Pt takes big breath in before impact and closes his glottis, impact overload lungs and alveoli with air and can rupture causing pneumothorax)
In the frontal impact’s Ejection pathway, what can occur?
With up and over, a Pt may be ejected from vehicle which causes 2 impacts:
- contact with vehicle windshield
- contact with ground, tree, or other object
This accounts for 27% of vehicular fatalities (mostly with frontal impact)
Why is a frontal impact safer than other angles of impact? (3)
- vehicles have CRUMPLE ZONES in the front (region of vehicle designed to absorb impact forces)
- Most air bags and seat belts are best utilized by a frontal impact
- Most space between the colliding object and the person (as opposed to say just a car door from lateral)
Oblique impact occurs when _____?
What are the 4 subcategories?
Occurs when vehicle is hit from any other angle than directly from front, side or rear.
Subcategories include:
- Left front
- Right front
- Left rear
- Right rear
Rollovers are commonly caused by _____?
What is a common result of a rollover?
Normally caused by a change in elevation or affects a vehicle with a high center of gravity.
Ejection (or partial ejection) can be common or having a head, limb, or torso being trapped under the vehicle
Lateral impacts differ in what 2 major ways from frontal?
Lateral Impacts account for ____% of all auto collisions but account for a _____% of vehicular fatalities?
- Occupants are moved on a 90 degree angle
- There is less crumple zone
Lateral Impacts account for 25% of all auto collisions but account for a HIGHER% of vehicular fatalities?
What 2 hazards do electric or hybrid vehicles present?
- danger of electrocution
- unexpected movement (vehicle may be on without realizing, make sure to take out key)
What 5 regions of the body should be emphasized in a rapid trauma assessment in a MVC?
- Head
- Neck
- Chest
- Abdomen
- Pelvis
What are the 4 types of impacts for a motorcycle collision?
- Frontal
- Angular
- Sliding
- Ejection
For adults hit by a car (not suv or truck) what is usually the first thing hit?
What tends to happen with children or short people when hit?
The knee or tibia/fibula
They usually go under the vehicle
What are the main 3 types of off road collision vehicles?
What generally makes these difficult?
- snowmobiles
- watercraft
- All terrain vehicles (ATVs)
They are difficult because collision usually occurs somewhere hard to get to with an ambulance
_____ are the most common mechanism for blunt trauma.
Falls
The most at risk for fall injuries are the _____ and the _____.
Old and very young
Trauma from a fall depeonds on the _____ _____ and the __________.
Contact Area and the Pathway of Energy Transmission
What is the most common energy path through the body in a fall scenario?
From the Calcaneus, to the leg, thigh, and then the lumbar spine.
The lumbar spine is especially prone to compression because it is the only thing supporting the upper body
In a fall scenario where someone falls on an outstretched arm, what is most often fractured?
The clavicle because it can support the least weight of the bones taking energy
What constitutes a severe fall?
What should you look for on a severe fall that you might not on a small fall?
Falls from a height 3x that of the Pt (20ft for adult or 10ft for children roughly)
Organ damage, if fall is bad enough the heart can drop down, tearing from the aorta and cause EXSANGUINATION (a draining of the blood severe enough to cause death)
What 5 things should you try to identify about the circumstances of a fall?
- Fall height
- Anatomical point of impact
- Suspected force
- Nature of impact surface
- Energy pathway through skeleton
What is an explosion?
A rapid increase in volume and release of energy in an extreme manner.
What are the 6 different mechanisms of injury from an explosion?
- Pressure Wave
- Blast Wind
- Projectiles
- Personnel Displacement
- Confined Space Explosions/Structural Collapses
- Burns
What is Pressure Wave (aka over pressure wave) and what would it injure and how?
The pressure wave is a wave of super compressed air formed by the severe heat of the explosion.
Because this wave compresses then decompresses very quickly through the body, all the open space organs can be effected, this normally includes:
- Eardrum
- middle ear
- sinuses
- bowel
- lungs
Does an explosion in water increase or decrease the effect?
Since water is not compressible like air, it makes the pressure wave range up to 3x greater
What is the blast wind?
Outward movement of heated gases just behind the Pressure wave. It is not as strong but lasts longer.
What are flechettes?
arrow shaped missiles used in military ordinances
What is a “dirty bomb”?
A bomb that spreads radiation
What is personal displacement?
When the overpressure wave is strong enough to physically move the Pt
The most lethal blasts are those that cause _____?
Structural Collapses
What are the 4 blast injury types?
- Primary - caused by heat of explosion and overpressure wave
- Secondary - caused by blast projectiles
- Tertiary - caused by personnel displacement and structural collapse
- Quaternary - other injuries associated with or exacerbated by a blast
When you suspect a bomb may be of terrorism, what should you watch out for?
Secondary bombs left to hurt rescuers, and watch for signs of radiation
What is the most common life threatening trauma associated with explosions?
Pulmonary Injury
What are the main causes of injury in sports? (3)
- extreme exertion
- fatigue
- direct trauma
If an athlete experiences any of the following 3 things then they should be examined at a medical center?
- period of unconsciousness
- neurological deficit
- altered mental status
What is perforating trauma?
When an object enters AND exists the body
What is the most common cause of penetrating trauma? (2)
Gunshot and knife wounds
What are the 3 levels of penetrating trauma and what can general cause each one?
- Low velocity trauma: knives/ pointed objects
- Medium velocity trauma: handguns
- High velocity trauma: rifles
What is the definition of ballistics?
the study of projectiles in motion and their effects on objects they impact
What 7 factors can change a projectiles effect on the body?
- VELOCITY
- PROFILE (portion of object you would see if it were coming straight at you; ex. bullet is diameter (caliber)
- SHAPE
- STABILITY (if bullet tumbles if creates larger profile and more damage but slows much faster; the spinning effect from a barrels rifling is what fights this tumbling)
- EXPANSION / FRAGMENTATION (when a bullet mushrooms or fragments when it hits something, causing more damage)
- SECONDARY IMPACTS
What 3 types of injury processes are caused by gun wounds?
- Direct Injury (direct tissue damage from bullet)
- Pressure Wave (the outward and forward wave of
pressure created by bullet velocity) - Cavitation
A. Temporary (much larger cavity formed by the
immediate penetration of the bullet and the
pressure wave pushing tissue out, stretching and
tearing it)
B. Permanent (Once pressure wave has disbursed,
this is the cavity that remains)
C. Zone of Injury (total area of affected tissue)
(handguns usually only cause direct injury)
