Kinematics & MOI

Week 4

Trauma

Result of energy/force applied to body. Top causes are MVCs, falls and burns.

Mechanical Energy

Kinetic (movement), Potential (falling)

Chemical Energy

Explosives

Thermal Energy

Heat, friction

Electrical Energy

Lightening strike, electrocution

Barometric

SCUBA diving

Velocity (v)

Speed per time

Acceleration (a)

Change in velocity

Gravity (g)

Downward acceleration

Kinetic Energy (KE)

Energy associated with objects in motion (KE = 1/2mv2)

Mass (m)

Measure amount of matter

Newton’s 1st Law

Body in motion/rest will remain in motion/rest unless acted on by an external force

Newton’s 2nd Law

Force an object can exert is m x a

Newton’s 3rd Law

Every action has an equal and opposite reaction (what comes forwards comes backwards)

Other Factors Affecting Injury Type

1. Appropriate restraint

2. Appropriate PPE

3. Position at time of trauma

4. Impact resistance of body

MVCs (cars)

1. Deceleration of vehicle (strike object)

2. Deceleration of occupant (impact with vehicle structures)

3. Deceleration of internal organs (impact of organs with body)

4. Secondary impacts

5. Additional collisions

Directional Forces (vehicles)

1. Rear End (whiplash and seatbelt injuries)

2. Head-On Collisions (x both velocity of vehicles) (50×50 = 100km accident)

3. Side Impact (A + B post are weaker than front to absorb energy

4. Rotational Collision (twisting of body, steering wheel is going to whip, arms broken)

5. Rollover Collision (high risk of c-spine injury)

Directional Forces (patient)

1. Up and Over (risk for those that sit close to steering wheel, head, neck, chest)

2. Down and Under (risk for those that sit far from steering wheel, knee, femur, hip fracture)

3. Rotational (spine, ribs, lower back injuries)

MVCs (motorcycles)

1. Low side (minor injuries)

2. High side (unpredictable)

3. Leathers vs Regular Clothes

4. Full Face vs Open Face Helmet

5. Take helmet to hospital!

MVCs (pedestrian struck)

1. Adult: Knee, leg, pelvic and head injuries

2. Pediatric: Waddell’s Triad (take a face forward impact), intra-thoarcic or abdominal injury, femur fracture and head injury

Sporting Injuries

1. Axial Loading

2. Pressure Changes (SCUBA diving)

Blast Injuries

1. Primary: Damaged caused by pressure wave (burst air filled organs; ears, lungs, brain, abdomen, eyes)

2. Secondary: Damage caused by flying debris

3. Tertiary: Thrown into stationary object

4. Burns, inhalation and crush injuries 

GSWs

• Small entry wounds (doesn’t look like what you think it looks like)

• Large exit wound (if present, explodes due to shock wave)

• If no exit wound, energy transferred to internal bone (shattered)

• Regardless of dispatch be aware of surroundings!

Stab Wounds

• Small and easy to miss

• Low energy - not as much blood loss but can be

• Ask the length of the knife!

• Not usually isolated wounds (defense wounds)

Deceleration Injuries

• Won’t see or feel, based on MOI and vital signs, watch patient!

• Aortic Shear (when heart moves abruptly and aorta is torn completely or a little

• Cardiac Contusion (bruise that limits stroke volume, pressure on heart)

• Cardiac Tamponade (leaks fluid, fluid presses on heart, high speed, looks pale and BP dropping like no tomorrow)

• Coup-Contre Coup (brain hits front and back of skull)

• Whiplash (hyperextension (worse, backwards) and hyperflexion (forwards))

Crush/Compression Injuries

• Compartment Syndrome (bleeding and swelling of muscle that can cut off circulation)

• Crush Syndrome (hyperkalemia) (K leaking out of cells, heart can’t contract) (toxin gets released after removing crush, myoglobin (block kidney circulation), over longer duration) 

Closed Head Injuries

• Compression (intracranial haemorrhage, pressure on brain)

• Increasing ICP (Monroe-Kellie Hypothesis/Doctrine)

• Herniation

Monroe-Kellie Hypothesis/Doctrine

• Skull is a container

• 80% brain, 10% blood, 10% CSF

• Swelling resulting in taking away CSF (extra 10%)

• If continues blood vessels constrict

• If continues brain loses blood circulation

• Pushes brain through foramen magnum, blood goes down spine