Lesson  3 Kinematics of Trauma
Objectives <ul><li>As a result of active participation in this lesson you should be able to: </li></ul><ul><ul><li>Apply p...
Introduction <ul><li>Applying principles of kinematics to patient assessment helps predict injuries that might otherwise b...
Overview <ul><li>General principles of kinematics </li></ul><ul><li>Mechanical components of energy exchange </li></ul><ul...
General Principles of Kinematics <ul><li>A crash is any impact between the body and an object </li></ul><ul><li>Assessment...
General Principles of Kinematics <ul><li>Precrash factors must be considered in the assessment and management of the traum...
General Principles of Kinematics <ul><li>Crash </li></ul><ul><ul><li>Three impacts occur in an automobile crash </li></ul>...
General Principles of Kinematics <ul><li>Postcrash </li></ul><ul><ul><li>Patient outcome is affected by conditions after  ...
General Principles of Kinematics <ul><li>Energy </li></ul><ul><ul><li>What were the crash phase factors? </li></ul></ul><u...
General Principles of Kinematics <ul><li>Newton’s first law of motion </li></ul><ul><ul><li>A body at rest will remain at ...
General Principles of Kinematics <ul><li>The law of conservation of energy </li></ul><ul><ul><li>Energy can be neither cre...
General Principles of Kinematics <ul><li>Kinetic energy </li></ul><ul><li>½ (mass) (velocity 2 ) </li></ul><ul><li>150-lb ...
General Principles of Kinematics <ul><li>Mass vs. velocity </li></ul><ul><li>KE = (160/2) (30 2 ) = 72,000 units </li></ul...
General Principles of Kinematics <ul><li>Force </li></ul><ul><li>Mass  ×  acceleration = force  </li></ul><ul><li>= mass  ...
General Principles of Kinematics <ul><li>Acceleration = (v final  −  v original )/time, expressed as m/sec 2  or km/hr 2 <...
General Principles of Kinematics <ul><li>Force (in Newtons) = mass  ×  acceleration </li></ul><ul><li>Example: </li></ul><...
General Principles of Kinematics <ul><li>Energy exchange </li></ul><ul><ul><li>The greater the density of an object or bod...
General Principles of Kinematics <ul><li>Energy exchange </li></ul><ul><ul><li>Body tissue densities </li></ul></ul><ul><u...
General Principles of Kinematics <ul><li>Energy exchange: Cavitation </li></ul><ul><ul><li>Transfer of kinetic energy to t...
General Principles of Kinematics <ul><li>Energy exchange: Object surface area </li></ul><ul><ul><li>Blunt trauma: energy a...
Scenario <ul><li>Your patient is a 37-year-old construction worker who fell 25 ft (7.6 m) from a scaffold onto packed, dry...
Mechanical Principles <ul><li>Blunt trauma </li></ul><ul><li>Severity and pattern depend on </li></ul><ul><ul><li>Directio...
Mechanical Principles <ul><li>Blunt trauma forces </li></ul><ul><ul><li>Compression </li></ul></ul><ul><ul><ul><li>Example...
Mechanical Principles <ul><li>Blunt trauma forces </li></ul><ul><ul><li>Shear </li></ul></ul><ul><ul><ul><li>One part of a...
Mechanical Principles <ul><li>Motor vehicle crashes </li></ul><ul><ul><li>Frontal impact </li></ul></ul><ul><ul><li>Rear i...
Mechanical Principles <ul><li>General principles of rapid deceleration mechanisms (MVCs, falls, etc.) </li></ul><ul><ul><l...
Mechanical Principles <ul><li>General principles of rapid deceleration mechanisms (MVCs, falls, etc.) </li></ul><ul><ul><l...
Mechanical Principles <ul><li>General principles of rapid deceleration mechanisms (MVCs, falls, etc.) </li></ul><ul><ul><l...
Mechanical Principles <ul><li>Motor vehicle crashes: frontal impact </li></ul><ul><ul><li>Damage indicates speed of vehicl...
Mechanical Principles <ul><li>Motor vehicle crashes: frontal impact </li></ul><ul><ul><li>Two pathways of the unrestrained...
Mechanical Principles <ul><li>Up and over </li></ul><ul><ul><li>Head leads </li></ul></ul><ul><ul><li>Compression of cervi...
Mechanical Principles <ul><li>Down and under </li></ul><ul><ul><li>Force is transmitted to lower extremities </li></ul></u...
Mechanical Principles:  Rear Impact
Mechanical Principles <ul><li>Motor vehicle crashes: rear impact </li></ul><ul><ul><li>“Bullet vehicle” and target vehicle...
Mechanical Principles: Lateral Impact
Mechanical Principles <ul><li>Motor vehicle crashes: lateral impact </li></ul><ul><ul><li>Intersection collisions </li></u...
Mechanical Principles:  Rotational Impact Click to play video
Mechanical Principles <ul><li>Motor vehicle crashes: rotational impact </li></ul><ul><ul><li>A corner of the vehicle stops...
Mechanical Principles: Rollover Click to play video
Mechanical Principles <ul><li>Motor vehicle crashes: rollover impact </li></ul><ul><ul><li>Multiple impacts at various ang...
Mechanical Principles <ul><li>Motor vehicle crashes </li></ul><ul><ul><li>Unrestrained occupants </li></ul></ul><ul><ul><u...
Mechanical Principles: Restraints
Mechanical Principles <ul><li>Motor vehicle crashes </li></ul><ul><ul><li>Restrained occupants </li></ul></ul><ul><ul><ul>...
Scenario <ul><li>Your patient is a 52-year-old motorcyclist who struck a guard rail nearly head-on as he was rounding a cu...
Mechanical Principles <ul><li>Motorcycle crashes </li></ul><ul><ul><li>Laws of physics don’t change, but interaction of th...
Motorcycle: Ejection
Mechanical Principles <ul><li>Motorcycle crashes: head-on </li></ul><ul><ul><li>Impact stops the vehicle </li></ul></ul><u...
Motorcycle: Angular Impact
Mechanical Principles <ul><li>Motorcycle crashes: angular </li></ul><ul><ul><li>Motorcycle strikes an object (vehicle, gua...
Motorcycle: Laying Down the Bike
Mechanical Principles <ul><li>Motorcycle crashes: ejection </li></ul><ul><ul><li>Injury occurs at point of impact and radi...
Mechanical Principles <ul><li>Motorcycle crashes: injury prevention </li></ul><ul><ul><li>Helmets save lives </li></ul></u...
Mechanical Principles <ul><li>Pedestrians </li></ul><ul><li>Crash phases vary by height relative to vehicle </li></ul><ul>...
Adult Pattern
Mechanical Principles <ul><li>Pedestrians: pediatric </li></ul><ul><ul><li>May turn toward vehicle </li></ul></ul><ul><ul>...
Pediatric Pattern
Mechanical Principles <ul><li>Falls </li></ul><ul><ul><li>Falls from more than 3 ×  patient height are severe </li></ul></...
Mechanical Principles <ul><li>Falls </li></ul><ul><ul><li>Feet-first </li></ul></ul><ul><ul><ul><li>Energy absorption occu...
Sports Injuries
Mechanical Principles <ul><li>Sports injuries </li></ul><ul><ul><li>Deceleration </li></ul></ul><ul><ul><li>Torsion </li><...
Mechanical Principles <ul><li>Sports injuries </li></ul><ul><ul><li>Boating </li></ul></ul><ul><ul><li>ATVs, snowmobiles <...
Mechanical Principles <ul><li>Sports injuries </li></ul><ul><ul><li>What forces acted on the victim and how? </li></ul></u...
Blast Injuries
Mechanical Principles <ul><li>Blast injuries </li></ul><ul><ul><li>Warfare </li></ul></ul><ul><ul><li>Terrorism </li></ul>...
Mechanical Principles <ul><li>Blast injuries </li></ul><ul><ul><li>Three initial phases </li></ul></ul><ul><ul><ul><li>Pri...
Mechanical Principles <ul><li>Primary phase </li></ul><ul><ul><li>Pressure wave moves at up to 10,000 ft/sec (3048 m/sec) ...
Mechanical Principles <ul><li>Secondary phase </li></ul><ul><ul><li>Fragmentation injuries (shrapnel) </li></ul></ul><ul><...
Mechanical Principles <ul><li>Tertiary phase (blunt force injuries) </li></ul><ul><ul><li>Contact with ground/stationary o...
Mechanical Principles <ul><li>Quarternary phase   </li></ul><ul><ul><li>Heat and fumes </li></ul></ul><ul><li>Quinary (bom...
Regional Effects: Blunt Trauma <ul><li>Head </li></ul><ul><ul><li>External injury should increase suspicion of brain traum...
Regional Effects: Blunt Trauma <ul><li>Neck </li></ul><ul><ul><li>Compression </li></ul></ul><ul><ul><ul><li>Range of moti...
Regional Effects: Blunt Trauma <ul><li>Thorax </li></ul><ul><ul><li>Compression </li></ul></ul><ul><ul><ul><li>May exceed ...
Regional Effects: Blunt Trauma <ul><li>Abdomen </li></ul><ul><ul><li>Compression </li></ul></ul><ul><ul><ul><li>Damage to ...
Penetrating Trauma <ul><li>Same laws of physics and kinetic energy apply </li></ul><ul><li>The energy of a projectile is e...
Penetrating Trauma <ul><li>Larger projectile frontal area = more tissue particles impacted = greater damage </li></ul><ul>...
Penetrating Trauma <ul><li>Weapon energy </li></ul><ul><ul><li>Low velocity </li></ul></ul><ul><ul><ul><li>Usually causes ...
Penetrating Trauma <ul><li>Weapon energy </li></ul><ul><ul><li>Medium velocity </li></ul></ul><ul><ul><ul><li>Most handgun...
Penetrating Trauma
Penetrating Trauma <ul><li>Weapon energy </li></ul><ul><ul><li>Consider the range </li></ul></ul><ul><ul><ul><li>Air resis...
Regional Effects: Penetrating Trauma <ul><li>Head </li></ul><ul><ul><li>Low velocity may not penetrate skull </li></ul></u...
Regional Effects: Penetrating Trauma <ul><li>Thorax </li></ul><ul><ul><li>Lung tissue is less dense, fewer tissue particle...
Regional Effects: Penetrating Trauma <ul><li>Abdomen </li></ul><ul><ul><li>Gas/liquid-filled structures </li></ul></ul><ul...
Regional Effects: Penetrating Trauma <ul><li>Extremities </li></ul><ul><ul><li>Bone fragments become secondary projectiles...
Using Kinematics in Assessment <ul><li>With significant impact in blunt trauma, a bruise is not just a bruise </li></ul><u...
Summary <ul><li>Kinematics predicts up to 90% of injuries </li></ul><ul><li>Knowledge of anatomy and energy exchange is ne...
<ul><li>QUESTIONS? </li></ul>
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Lesson 03

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  • Instructor Notes: Emphasize that this formula is for illustrative purposes only to demonstrate the effect of stopping time on force.
  • Instructor Notes: Emphasize that this formula is for illustrative purposes only to demonstrate the effect of stopping time on force.
  • Instructor Notes: Example, if you strike a pillow with your fist, the pillow, which is less dense, will be deformed. If you strike a brick wall with your fist, your fist, which is less dense, will be deformed.
  • Instructor Notes: Example: What would be the relative effects on each of these tissues if it received low-velocity penetrating trauma from a knife?
  • {Insert video clip: frontal collision “crashdum3.wmv”}
  • Instructor Notes: Make sure participants understand that tibial impact can lead to knee dislocation and damage of the popliteal artery.
  • Instructor Notes: Point out how differences in lap and shoulder belt placement can lead to abdominal and spinal injuries.
  • Instructor Notes: Discuss cavitation, entry and exit wound patterns, and fragmentation
  • Lesson 03

    1. 1. Lesson 3 Kinematics of Trauma
    2. 2. Objectives <ul><li>As a result of active participation in this lesson you should be able to: </li></ul><ul><ul><li>Apply principles of kinematics to create an index of suspicion for blunt and penetrating trauma </li></ul></ul><ul><ul><li>Incorporate principles of kinematics into an overall impression of the patient’s needs for intervention and transport </li></ul></ul><ul><ul><li>Consider the interaction of age and health </li></ul></ul><ul><ul><li>status with kinematics to modify the index </li></ul></ul><ul><ul><li>of suspicion for injury </li></ul></ul>
    3. 3. Introduction <ul><li>Applying principles of kinematics to patient assessment helps predict injuries that might otherwise be missed </li></ul><ul><li>Failure to suspect injuries based on kinematics can have dire impact on a patient’s outcome </li></ul>
    4. 4. Overview <ul><li>General principles of kinematics </li></ul><ul><li>Mechanical components of energy exchange </li></ul><ul><ul><li>Blunt and penetrating mechanisms </li></ul></ul><ul><li>Regional injury pathophysiology </li></ul><ul><ul><li>Blunt and penetrating mechanisms </li></ul></ul>
    5. 5. General Principles of Kinematics <ul><li>A crash is any impact between the body and an object </li></ul><ul><li>Assessment and management of the injured patient must consider three phases </li></ul><ul><ul><li>Precrash </li></ul></ul><ul><ul><li>Crash </li></ul></ul><ul><ul><li>Postcrash </li></ul></ul>
    6. 6. General Principles of Kinematics <ul><li>Precrash factors must be considered in the assessment and management of the trauma patient </li></ul><ul><ul><li>Patient age and size </li></ul></ul><ul><ul><li>Drugs/alcohol </li></ul></ul><ul><ul><li>Preexisting medical conditions and medications </li></ul></ul>
    7. 7. General Principles of Kinematics <ul><li>Crash </li></ul><ul><ul><li>Three impacts occur in an automobile crash </li></ul></ul><ul><ul><li>In falls and other mechanisms, only two crashes are involved </li></ul></ul><ul><ul><li>Consideration of: </li></ul></ul><ul><ul><ul><li>Direction of energy exchange </li></ul></ul></ul><ul><ul><ul><li>Amount of energy exchange </li></ul></ul></ul><ul><ul><ul><li>Effect on the body </li></ul></ul></ul>
    8. 8. General Principles of Kinematics <ul><li>Postcrash </li></ul><ul><ul><li>Patient outcome is affected by conditions after </li></ul></ul><ul><ul><li>the crash </li></ul></ul><ul><ul><ul><li>Response time and resources available </li></ul></ul></ul><ul><ul><ul><li>Providers’ knowledge of kinematics, assessment, and management </li></ul></ul></ul><ul><ul><li>Providers’ response depends on knowledge of energy and anatomy </li></ul></ul>
    9. 9. General Principles of Kinematics <ul><li>Energy </li></ul><ul><ul><li>What were the crash phase factors? </li></ul></ul><ul><ul><ul><li>Direction </li></ul></ul></ul><ul><ul><ul><li>Speed </li></ul></ul></ul><ul><ul><ul><li>Stopping time </li></ul></ul></ul><ul><ul><ul><li>Restraint systems and protective gear </li></ul></ul></ul><ul><ul><ul><li>Ejection </li></ul></ul></ul><ul><ul><li>Surveying the scene to predict injury patterns produced by crash factors is called kinematics </li></ul></ul>
    10. 10. General Principles of Kinematics <ul><li>Newton’s first law of motion </li></ul><ul><ul><li>A body at rest will remain at rest and a body in motion will remain in motion unless acted upon by an outside force </li></ul></ul><ul><ul><li>Three impacts in MVCs revisited </li></ul></ul>
    11. 11. General Principles of Kinematics <ul><li>The law of conservation of energy </li></ul><ul><ul><li>Energy can be neither created nor destroyed — only changed in form </li></ul></ul><ul><ul><li>Heat, noise, vehicle deformation, tissue damage </li></ul></ul>
    12. 12. General Principles of Kinematics <ul><li>Kinetic energy </li></ul><ul><li>½ (mass) (velocity 2 ) </li></ul><ul><li>150-lb (68-kg) person travels </li></ul><ul><li>at 30 mph (48 kph) </li></ul><ul><li>KE units = (150/2) (30 2 ) = 67,500 </li></ul>
    13. 13. General Principles of Kinematics <ul><li>Mass vs. velocity </li></ul><ul><li>KE = (160/2) (30 2 ) = 72,000 units </li></ul><ul><li>KE = (150/2) (40 2 ) = 120,000 units </li></ul>
    14. 14. General Principles of Kinematics <ul><li>Force </li></ul><ul><li>Mass × acceleration = force </li></ul><ul><li>= mass × deceleration </li></ul><ul><li>Stopping distance matters! </li></ul>
    15. 15. General Principles of Kinematics <ul><li>Acceleration = (v final − v original )/time, expressed as m/sec 2 or km/hr 2 </li></ul><ul><li>Example: </li></ul><ul><li>A vehicle traveling 70 kph (1167 m/sec or 43 mph) brakes and comes to a stop over 7 sec. </li></ul><ul><li>(0 – 1167)/7 = − 167 m/sec 2 </li></ul><ul><li>A vehicle traveling 70 kph strikes a bridge abutment and comes to a stop over 0.5 sec. </li></ul><ul><li>(0 – 1167)/0.5 = − 2334 m/sec 2 </li></ul>
    16. 16. General Principles of Kinematics <ul><li>Force (in Newtons) = mass × acceleration </li></ul><ul><li>Example: </li></ul><ul><li>907-kg (2000-lb) vehicle traveling at 70 kph </li></ul><ul><li>with a stopping time of 7 sec. </li></ul><ul><li>907 × − 167 = − 151,469 </li></ul><ul><li>907-kg (2000-lb) vehicle traveling at 70 kph </li></ul><ul><li>with a stopping time of 0.5 sec. </li></ul><ul><li>907 × − 2334 = − 2,116,938 </li></ul>
    17. 17. General Principles of Kinematics <ul><li>Energy exchange </li></ul><ul><ul><li>The greater the density of an object or body tissue, the greater the number of particles impacted by a force </li></ul></ul><ul><ul><ul><li>The less dense of 2 objects will receive more damage (deformation) </li></ul></ul></ul><ul><ul><li>The greater the contact area, the greater the number of particles impacted by a force </li></ul></ul>
    18. 18. General Principles of Kinematics <ul><li>Energy exchange </li></ul><ul><ul><li>Body tissue densities </li></ul></ul><ul><ul><ul><li>Air (lung) </li></ul></ul></ul><ul><ul><ul><li>Water (muscles, organs) </li></ul></ul></ul><ul><ul><ul><li>Solid (bone) </li></ul></ul></ul><ul><ul><li>How would each of these tissues be affected by the same force? </li></ul></ul>
    19. 19. General Principles of Kinematics <ul><li>Energy exchange: Cavitation </li></ul><ul><ul><li>Transfer of kinetic energy to the tissues causes tissue particles to accelerate away from the impact, leaving a cavity </li></ul></ul><ul><ul><ul><li>Temporary cavity (elasticity) </li></ul></ul></ul><ul><ul><ul><li>Permanent cavity (force exceeds tensile strength) </li></ul></ul></ul>
    20. 20. General Principles of Kinematics <ul><li>Energy exchange: Object surface area </li></ul><ul><ul><li>Blunt trauma: energy applied over a larger surface of the body results in less localized energy exchange </li></ul></ul><ul><ul><li>Penetrating trauma: energy concentrated to small area of tissue with greater destructive force to one area </li></ul></ul>
    21. 21. Scenario <ul><li>Your patient is a 37-year-old construction worker who fell 25 ft (7.6 m) from a scaffold onto packed, dry, bare earth, making first contact with outstretched arms. </li></ul><ul><ul><li>What factors impact the transfer of energy? </li></ul></ul><ul><ul><li>What injuries do you suspect? </li></ul></ul><ul><ul><li>What is the expected severity of injuries? </li></ul></ul>
    22. 22. Mechanical Principles <ul><li>Blunt trauma </li></ul><ul><li>Severity and pattern depend on </li></ul><ul><ul><li>Direction of impact </li></ul></ul><ul><ul><li>For vehicle crashes — energy absorbed by vehicle </li></ul></ul><ul><ul><li>Part(s) of body to which energy is transmitted </li></ul></ul><ul><ul><li>Use of protective equipment </li></ul></ul><ul><ul><li>Compression, deceleration, acceleration </li></ul></ul><ul><ul><li>Density and contact area of object </li></ul></ul><ul><ul><li>Velocity at impact </li></ul></ul>
    23. 23. Mechanical Principles <ul><li>Blunt trauma forces </li></ul><ul><ul><li>Compression </li></ul></ul><ul><ul><ul><li>Example: The heart is compressed between the sternum and spine upon sudden frontal impact </li></ul></ul></ul>
    24. 24. Mechanical Principles <ul><li>Blunt trauma forces </li></ul><ul><ul><li>Shear </li></ul></ul><ul><ul><ul><li>One part of a structure changes speed faster than another part of the structure </li></ul></ul></ul><ul><ul><ul><li>Examples: </li></ul></ul></ul><ul><ul><ul><ul><li>Aortic arch at ligamentum arteriosum </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Kidneys at renal artery </li></ul></ul></ul></ul>
    25. 25. Mechanical Principles <ul><li>Motor vehicle crashes </li></ul><ul><ul><li>Frontal impact </li></ul></ul><ul><ul><li>Rear impact </li></ul></ul><ul><ul><li>Lateral impact </li></ul></ul><ul><ul><li>Rotational impact </li></ul></ul><ul><ul><li>Rollover </li></ul></ul><ul><ul><li>Motorcycle crashes </li></ul></ul><ul><ul><li>Pedestrian – motor vehicle crashes </li></ul></ul>Click to play video
    26. 26. Mechanical Principles <ul><li>General principles of rapid deceleration mechanisms (MVCs, falls, etc.) </li></ul><ul><ul><li>Three collisions </li></ul></ul><ul><ul><ul><li>Vehicle collides with object (MVCs only) </li></ul></ul></ul><ul><ul><ul><li>Occupant strikes a surface </li></ul></ul></ul><ul><ul><ul><li>Occupant’s internal organs collide with each other or the wall of a body cavity </li></ul></ul></ul>
    27. 27. Mechanical Principles <ul><li>General principles of rapid deceleration mechanisms (MVCs, falls, etc.) </li></ul><ul><ul><li>Car strikes tree, stopping at the point of impact, but the rest of the car continues forward, causing deformation until the energy is dissipated by deforming the car </li></ul></ul>
    28. 28. Mechanical Principles <ul><li>General principles of rapid deceleration mechanisms (MVCs, falls, etc.) </li></ul><ul><ul><li>The damage to a vehicle mirrors the injury pattern to the body </li></ul></ul><ul><ul><li>The unrestrained driver’s chest strikes the steering wheel, stopping it at the point of impact </li></ul></ul><ul><ul><li>The rest of the body continues forward </li></ul></ul><ul><ul><li>Cavitation of the body is temporary </li></ul></ul>
    29. 29. Mechanical Principles <ul><li>Motor vehicle crashes: frontal impact </li></ul><ul><ul><li>Damage indicates speed of vehicle </li></ul></ul><ul><ul><li>The greater the speed at impact, the greater the intrusion into the body of the vehicle </li></ul></ul><ul><ul><li>Occupants move at the same speed as the vehicle </li></ul></ul>
    30. 30. Mechanical Principles <ul><li>Motor vehicle crashes: frontal impact </li></ul><ul><ul><li>Two pathways of the unrestrained/improperly restrained occupant </li></ul></ul><ul><ul><ul><li>Up and over </li></ul></ul></ul><ul><ul><ul><li>Down and under </li></ul></ul></ul>National Highway Traffic Safety Administration Video Click to play video
    31. 31. Mechanical Principles <ul><li>Up and over </li></ul><ul><ul><li>Head leads </li></ul></ul><ul><ul><li>Compression of cervical spine </li></ul></ul><ul><ul><li>Chest/abdomen impacts steering wheel </li></ul></ul><ul><ul><ul><li>Compression of hollow and solid organs </li></ul></ul></ul><ul><ul><ul><li>Shearing </li></ul></ul></ul>
    32. 32. Mechanical Principles <ul><li>Down and under </li></ul><ul><ul><li>Force is transmitted to lower extremities </li></ul></ul><ul><ul><ul><li>Tibial impact </li></ul></ul></ul><ul><ul><ul><li>Femoral impact </li></ul></ul></ul><ul><ul><li>Upper body rotates forward and strikes dash or steering wheel </li></ul></ul>
    33. 33. Mechanical Principles: Rear Impact
    34. 34. Mechanical Principles <ul><li>Motor vehicle crashes: rear impact </li></ul><ul><ul><li>“Bullet vehicle” and target vehicle </li></ul></ul><ul><ul><li>Energy of bullet vehicle is converted to damage and acceleration of target vehicle </li></ul></ul><ul><ul><li>Hyperextension of the neck may occur with improperly placed/absent headrest </li></ul></ul><ul><ul><li>Rapid deceleration may follow if the target car strikes another object or brakes </li></ul></ul>
    35. 35. Mechanical Principles: Lateral Impact
    36. 36. Mechanical Principles <ul><li>Motor vehicle crashes: lateral impact </li></ul><ul><ul><li>Intersection collisions </li></ul></ul><ul><ul><li>Rapid lateral acceleration and impact of door against occupant </li></ul></ul><ul><ul><ul><li>Compression of thorax and thoracic organs, including overpressure injuries </li></ul></ul></ul><ul><ul><ul><li>Shear injury to aorta </li></ul></ul></ul><ul><ul><ul><li>Abdominal (spleen/liver) and pelvic injuries </li></ul></ul></ul><ul><ul><ul><li>Cervical spine lateral flexion and rotation </li></ul></ul></ul><ul><ul><ul><li>Head </li></ul></ul></ul>National Highway Traffic Safety Administration Video Click to play video
    37. 37. Mechanical Principles: Rotational Impact Click to play video
    38. 38. Mechanical Principles <ul><li>Motor vehicle crashes: rotational impact </li></ul><ul><ul><li>A corner of the vehicle stops, the rest of the vehicle continues in forward motion until energy </li></ul></ul><ul><ul><li>is transformed </li></ul></ul><ul><ul><li>Combination of frontal and lateral patterns </li></ul></ul><ul><ul><li>More severe injuries to victim closest to the point of impact </li></ul></ul>
    39. 39. Mechanical Principles: Rollover Click to play video
    40. 40. Mechanical Principles <ul><li>Motor vehicle crashes: rollover impact </li></ul><ul><ul><li>Multiple impacts at various angles </li></ul></ul><ul><ul><li>Energy is exchanged at each impact </li></ul></ul><ul><ul><li>Restrained driver </li></ul></ul><ul><ul><ul><li>Body is fixed, but organs move (shearing) </li></ul></ul></ul><ul><ul><li>Unrestrained driver </li></ul></ul><ul><ul><ul><li>Partial or full ejection </li></ul></ul></ul><ul><ul><ul><li>Direct impact with ground, tree, etc. </li></ul></ul></ul><ul><ul><ul><li>Crushed by vehicle </li></ul></ul></ul>
    41. 41. Mechanical Principles <ul><li>Motor vehicle crashes </li></ul><ul><ul><li>Unrestrained occupants </li></ul></ul><ul><ul><ul><li>Rollovers account for a small proportion of crashes but a high proportion of ejection and death </li></ul></ul></ul><ul><ul><ul><li>75% of totally ejected occupants die </li></ul></ul></ul><ul><ul><ul><li>Risk of death is 6 times greater for ejected occupants </li></ul></ul></ul>
    42. 42. Mechanical Principles: Restraints
    43. 43. Mechanical Principles <ul><li>Motor vehicle crashes </li></ul><ul><ul><li>Restrained occupants </li></ul></ul><ul><ul><ul><li>Properly placed restraints allow absorption of energy by skeletal structures resulting in few serious injuries </li></ul></ul></ul><ul><ul><ul><li>Force of body is transmitted to restraint systems </li></ul></ul></ul><ul><ul><ul><li>Injury is produced by improperly placed restraints/occupants </li></ul></ul></ul><ul><ul><ul><ul><li>Compression </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Overpressure </li></ul></ul></ul></ul>National Highway Traffic Safety Administration Video Click to play video
    44. 44. Scenario <ul><li>Your patient is a 52-year-old motorcyclist who struck a guard rail nearly head-on as he was rounding a curve at a high rate of speed and was ejected from the bike, landing in a grassy area beyond the guardrail. He was not wearing a helmet. </li></ul><ul><ul><li>What injury patterns do you suspect? </li></ul></ul>
    45. 45. Mechanical Principles <ul><li>Motorcycle crashes </li></ul><ul><ul><li>Laws of physics don’t change, but interaction of the vehicle and occupant differs </li></ul></ul>
    46. 46. Motorcycle: Ejection
    47. 47. Mechanical Principles <ul><li>Motorcycle crashes: head-on </li></ul><ul><ul><li>Impact stops the vehicle </li></ul></ul><ul><ul><li>Center of gravity is above and behind the front axle, making it the pivot point </li></ul></ul><ul><ul><li>Rider is ejected over the handlebars; impacting thighs </li></ul></ul><ul><ul><li>Bilateral femur fractures are common </li></ul></ul><ul><ul><li>Secondary impact with stationary object </li></ul></ul><ul><ul><li>or ground </li></ul></ul>
    48. 48. Motorcycle: Angular Impact
    49. 49. Mechanical Principles <ul><li>Motorcycle crashes: angular </li></ul><ul><ul><li>Motorcycle strikes an object (vehicle, guardrail, etc.) at an angle </li></ul></ul><ul><ul><li>Motorcycle falls on occupant or occupant is crushed between the motorcycle and object struck </li></ul></ul><ul><ul><li>Extensive injuries to extremities </li></ul></ul><ul><ul><li>Abdominal injuries </li></ul></ul>
    50. 50. Motorcycle: Laying Down the Bike
    51. 51. Mechanical Principles <ul><li>Motorcycle crashes: ejection </li></ul><ul><ul><li>Injury occurs at point of impact and radiates throughout body as energy is transformed </li></ul></ul><ul><ul><li>Laying down the bike can result in extensive skin damage in unprotected riders </li></ul></ul>
    52. 52. Mechanical Principles <ul><li>Motorcycle crashes: injury prevention </li></ul><ul><ul><li>Helmets save lives </li></ul></ul><ul><ul><li>Incidence of head injuries is 300% higher without helmets </li></ul></ul><ul><ul><li>Helmets neither prevent nor contribute to neck injuries </li></ul></ul><ul><ul><li>Other protection includes boots and leather clothing </li></ul></ul>
    53. 53. Mechanical Principles <ul><li>Pedestrians </li></ul><ul><li>Crash phases vary by height relative to vehicle </li></ul><ul><ul><li>Adults </li></ul></ul><ul><ul><ul><li>Initial impact to lower extremities/hips </li></ul></ul></ul><ul><ul><ul><li>Torso rolls onto hood </li></ul></ul></ul><ul><ul><ul><li>Victim falls to ground, often head-first </li></ul></ul></ul>
    54. 54. Adult Pattern
    55. 55. Mechanical Principles <ul><li>Pedestrians: pediatric </li></ul><ul><ul><li>May turn toward vehicle </li></ul></ul><ul><ul><li>Impact to thighs or pelvis </li></ul></ul><ul><ul><li>Impact to thorax </li></ul></ul><ul><ul><li>Head and face strike front or hood of vehicle </li></ul></ul><ul><ul><li>May not be thrown clear and may be drug by or run over by vehicle </li></ul></ul>
    56. 56. Pediatric Pattern
    57. 57. Mechanical Principles <ul><li>Falls </li></ul><ul><ul><li>Falls from more than 3 × patient height are severe </li></ul></ul><ul><ul><li>Velocity increases with height </li></ul></ul><ul><ul><li>Landing surface affects stopping distance (deceleration) </li></ul></ul>
    58. 58. Mechanical Principles <ul><li>Falls </li></ul><ul><ul><li>Feet-first </li></ul></ul><ul><ul><ul><li>Energy absorption occurs vertically through lower extremities to spine </li></ul></ul></ul><ul><ul><ul><li>Compression occurs because of continued downward movement of torso and head </li></ul></ul></ul><ul><ul><ul><li>Hyperflexion and compression injuries of spine </li></ul></ul></ul><ul><ul><li>Outstretched arms </li></ul></ul><ul><ul><ul><li>Colles’ fractures, clavicle fractures, shoulder </li></ul></ul></ul><ul><ul><ul><li>dislocation </li></ul></ul></ul><ul><ul><li>Other patterns: consider pathway of energy exchange </li></ul></ul>
    59. 59. Sports Injuries
    60. 60. Mechanical Principles <ul><li>Sports injuries </li></ul><ul><ul><li>Deceleration </li></ul></ul><ul><ul><li>Torsion </li></ul></ul><ul><ul><li>Exceeding range of motion </li></ul></ul><ul><ul><li>Shear </li></ul></ul><ul><ul><li>Compression </li></ul></ul>
    61. 61. Mechanical Principles <ul><li>Sports injuries </li></ul><ul><ul><li>Boating </li></ul></ul><ul><ul><li>ATVs, snowmobiles </li></ul></ul><ul><ul><li>Contact sports </li></ul></ul><ul><ul><li>Skiing, skateboarding </li></ul></ul><ul><ul><li>Bicycling </li></ul></ul><ul><ul><li>Collision between participants </li></ul></ul>
    62. 62. Mechanical Principles <ul><li>Sports injuries </li></ul><ul><ul><li>What forces acted on the victim and how? </li></ul></ul><ul><ul><li>Apparent injuries may indicate related, but unapparent injuries </li></ul></ul><ul><ul><li>What were points of contact and energy exchange? </li></ul></ul><ul><ul><li>Protective equipment? </li></ul></ul><ul><ul><li>Damaged protective equipment? </li></ul></ul><ul><ul><li>Reconstruct impact from eyewitness </li></ul></ul><ul><ul><li>accounts if possible </li></ul></ul>
    63. 63. Blast Injuries
    64. 64. Mechanical Principles <ul><li>Blast injuries </li></ul><ul><ul><li>Warfare </li></ul></ul><ul><ul><li>Terrorism </li></ul></ul><ul><ul><li>Industry </li></ul></ul><ul><ul><ul><li>Mines </li></ul></ul></ul><ul><ul><ul><li>Chemical plants </li></ul></ul></ul><ul><ul><ul><li>Fireworks plants </li></ul></ul></ul><ul><ul><ul><li>Factories </li></ul></ul></ul><ul><ul><ul><li>Grain elevators </li></ul></ul></ul><ul><ul><ul><li>Transportation </li></ul></ul></ul><ul><ul><li>Gas leaks </li></ul></ul>Click to play video
    65. 65. Mechanical Principles <ul><li>Blast injuries </li></ul><ul><ul><li>Three initial phases </li></ul></ul><ul><ul><ul><li>Primary </li></ul></ul></ul><ul><ul><ul><li>Secondary </li></ul></ul></ul><ul><ul><ul><li>Tertiary </li></ul></ul></ul><ul><ul><li>Two subsequent phases </li></ul></ul><ul><ul><ul><li>Quarternary </li></ul></ul></ul><ul><ul><ul><li>Quinary </li></ul></ul></ul>
    66. 66. Mechanical Principles <ul><li>Primary phase </li></ul><ul><ul><li>Pressure wave moves at up to 10,000 ft/sec (3048 m/sec) </li></ul></ul><ul><ul><ul><li>Dismemberment </li></ul></ul></ul><ul><ul><ul><li>Pulmonary contusion </li></ul></ul></ul><ul><ul><ul><li>Pneumothorax </li></ul></ul></ul><ul><ul><ul><li>Air emboli </li></ul></ul></ul><ul><ul><ul><li>Tympanic rupture </li></ul></ul></ul><ul><ul><li>Pulmonary manifestations may be immediate or delayed </li></ul></ul>
    67. 67. Mechanical Principles <ul><li>Secondary phase </li></ul><ul><ul><li>Fragmentation injuries (shrapnel) </li></ul></ul><ul><ul><ul><li>Glass </li></ul></ul></ul><ul><ul><ul><li>Auto parts </li></ul></ul></ul><ul><ul><ul><li>Metal </li></ul></ul></ul><ul><ul><ul><li>Building materials </li></ul></ul></ul>
    68. 68. Mechanical Principles <ul><li>Tertiary phase (blunt force injuries) </li></ul><ul><ul><li>Contact with ground/stationary object </li></ul></ul><ul><ul><li>Crushed by structural collapse </li></ul></ul><ul><li>Secondary and tertiary injuries are more obvious, but primary injuries can be more severe </li></ul>
    69. 69. Mechanical Principles <ul><li>Quarternary phase </li></ul><ul><ul><li>Heat and fumes </li></ul></ul><ul><li>Quinary (bomb-related injuries) </li></ul><ul><ul><li>Dirty bombs (bacteria, radiation, chemicals) </li></ul></ul><ul><ul><li>Fragments of human (suicide bomber) remains can be embedded in victims </li></ul></ul>
    70. 70. Regional Effects: Blunt Trauma <ul><li>Head </li></ul><ul><ul><li>External injury should increase suspicion of brain trauma </li></ul></ul><ul><ul><li>Compression may lead to scalp laceration/hematoma and/or skull fracture </li></ul></ul><ul><ul><li>Shearing injuries result from continued forward motion of the brain after the skull comes to a stop </li></ul></ul>
    71. 71. Regional Effects: Blunt Trauma <ul><li>Neck </li></ul><ul><ul><li>Compression </li></ul></ul><ul><ul><ul><li>Range of motion exceeded </li></ul></ul></ul><ul><ul><ul><li>Axial loading </li></ul></ul></ul><ul><ul><li>Shear </li></ul></ul><ul><ul><ul><li>In a lateral impact to the torso, the torso accelerates away from the head, stretching the soft tissues and vertebral column (distraction injury) </li></ul></ul></ul>
    72. 72. Regional Effects: Blunt Trauma <ul><li>Thorax </li></ul><ul><ul><li>Compression </li></ul></ul><ul><ul><ul><li>May exceed tensile strength of ribs </li></ul></ul></ul><ul><ul><ul><li>Pulmonary overpressure injuries </li></ul></ul></ul><ul><ul><ul><li>Compression of organs </li></ul></ul></ul><ul><ul><ul><ul><li>Pulmonary contusion </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Cardiac contusion </li></ul></ul></ul></ul><ul><ul><li>Shear </li></ul></ul><ul><ul><ul><li>Aortic transection </li></ul></ul></ul><ul><ul><ul><li>Traumatic aortic aneurysm </li></ul></ul></ul>
    73. 73. Regional Effects: Blunt Trauma <ul><li>Abdomen </li></ul><ul><ul><li>Compression </li></ul></ul><ul><ul><ul><li>Damage to solid organs </li></ul></ul></ul><ul><ul><ul><li>Overpressure </li></ul></ul></ul><ul><ul><ul><ul><li>Ruptured diaphragm </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Hollow organs </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Retrograde aortic flow ruptures aortic semilunar valve </li></ul></ul></ul></ul><ul><ul><li>Shearing </li></ul></ul><ul><ul><ul><li>Occurs at points of attachment/fixation of organs </li></ul></ul></ul><ul><ul><ul><ul><li>Kidneys, liver, spleen, intestines, (full) bladder </li></ul></ul></ul></ul>
    74. 74. Penetrating Trauma <ul><li>Same laws of physics and kinetic energy apply </li></ul><ul><li>The energy of a projectile is exchanged with individual tissue cells </li></ul><ul><ul><li>Cells are crushed and destroyed, leaving a permanent cavity </li></ul></ul><ul><ul><li>Cells of elastic tissue accelerate away from </li></ul></ul><ul><ul><li>the impact leaving a temporary cavity that disappears when tissues rebound </li></ul></ul>
    75. 75. Penetrating Trauma <ul><li>Larger projectile frontal area = more tissue particles impacted = greater damage </li></ul><ul><ul><li>Profile </li></ul></ul><ul><ul><ul><li>Initial size and change of size on impact </li></ul></ul></ul><ul><ul><li>Tumble </li></ul></ul><ul><ul><ul><li>Center of gravity of a projectile seeks to become the leading edge </li></ul></ul></ul><ul><ul><li>Fragmentation </li></ul></ul><ul><ul><ul><li>More fragments create a greater total surface </li></ul></ul></ul><ul><ul><ul><li>area and more tissue damage </li></ul></ul></ul>
    76. 76. Penetrating Trauma <ul><li>Weapon energy </li></ul><ul><ul><li>Low velocity </li></ul></ul><ul><ul><ul><li>Usually causes injury only with a sharp point or edge </li></ul></ul></ul><ul><ul><ul><li>Less secondary trauma (cavitation due to dissipation of energy) </li></ul></ul></ul><ul><ul><ul><li>Cone of injury </li></ul></ul></ul>
    77. 77. Penetrating Trauma <ul><li>Weapon energy </li></ul><ul><ul><li>Medium velocity </li></ul></ul><ul><ul><ul><li>Most handguns and some rifles </li></ul></ul></ul><ul><ul><li>High velocity </li></ul></ul><ul><ul><ul><li>Hunting and assault rifles </li></ul></ul></ul><ul><ul><ul><li>Creates a vacuum that pulls debris into its track </li></ul></ul></ul>
    78. 78. Penetrating Trauma
    79. 79. Penetrating Trauma <ul><li>Weapon energy </li></ul><ul><ul><li>Consider the range </li></ul></ul><ul><ul><ul><li>Air resistance (drag) slows velocity </li></ul></ul></ul><ul><ul><ul><li>Greater distance = decreased velocity </li></ul></ul></ul>
    80. 80. Regional Effects: Penetrating Trauma <ul><li>Head </li></ul><ul><ul><li>Low velocity may not penetrate skull </li></ul></ul><ul><ul><li>Medium velocity missile may penetrate the skull, dissipating enough energy that it cannot exit, but follows the curve of the skull or is deflected off it </li></ul></ul><ul><ul><li>High velocity missiles transmit tremendous energy through the inelastic brain tissue, greatly increasing intracranial pressure and may cause skull to “explode” </li></ul></ul>
    81. 81. Regional Effects: Penetrating Trauma <ul><li>Thorax </li></ul><ul><ul><li>Lung tissue is less dense, fewer tissue particles are impacted, less energy is transferred to the tissue, yet these injuries are still clinically significant </li></ul></ul><ul><ul><li>Vascular system </li></ul></ul><ul><ul><ul><li>Pericardial tamponade </li></ul></ul></ul><ul><ul><ul><li>Exsanguination </li></ul></ul></ul><ul><ul><li>Esophageal perforation may not be detected </li></ul></ul><ul><ul><li>for several days but is a significant injury </li></ul></ul>
    82. 82. Regional Effects: Penetrating Trauma <ul><li>Abdomen </li></ul><ul><ul><li>Gas/liquid-filled structures </li></ul></ul><ul><ul><li>Solid structures </li></ul></ul><ul><ul><li>30% of knife wounds require surgical intervention </li></ul></ul><ul><ul><li>85% to 90% of medium-velocity wounds require surgical intervention </li></ul></ul>
    83. 83. Regional Effects: Penetrating Trauma <ul><li>Extremities </li></ul><ul><ul><li>Bone fragments become secondary projectiles </li></ul></ul><ul><ul><li>Stretch on muscles may tear blood vessels </li></ul></ul><ul><ul><li>Adjacent blood vessels sustain intimal damage, leading to thrombosis </li></ul></ul>
    84. 84. Using Kinematics in Assessment <ul><li>With significant impact in blunt trauma, a bruise is not just a bruise </li></ul><ul><ul><li>Consider the compression and shearing forces applied due to absorption of kinetic energy </li></ul></ul><ul><li>The damage due to medium- and high-velocity missiles greatly exceeds the circumference </li></ul>
    85. 85. Summary <ul><li>Kinematics predicts up to 90% of injuries </li></ul><ul><li>Knowledge of anatomy and energy exchange is needed to understand kinematics </li></ul><ul><li>The same laws of physics apply to blunt and penetrating trauma </li></ul><ul><li>Velocity is more important than mass in determining kinetic energy </li></ul>
    86. 86. <ul><li>QUESTIONS? </li></ul>

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