PHTLS Kinematics of Trauma

Question 1

According to Newton's first law as it applies to trauma, what happens to an unrestrained occupant when a vehicle suddenly stops?

Accepted Answer

The occupant continues moving at the same speed until acted upon by another force

Answer

Newton's first law states that an object in motion stays in motion; an unrestrained occupant continues forward at the pre-impact speed until struck by the dashboard, steering wheel, or windshield.

Question 2

The kinetic energy formula used in PHTLS to estimate energy transfer during trauma is:

Accepted Answer

KE = ½ × mass × velocity²

Answer

KE = ½mv² demonstrates that velocity has a squared effect on kinetic energy, meaning doubling speed quadruples the energy that must be absorbed by body tissues.

Question 3

In a frontal-impact motor vehicle collision, which injury pattern is associated with an unbelted driver who travels 'up-and-over' the steering wheel?

Accepted Answer

Head, neck, thorax, and face injuries

Answer

The up-and-over pathway directs the body toward the steering wheel and windshield, commonly causing head, facial, cervical spine, and thoracic injuries.

Question 4

Which injury pattern is most characteristic of the 'down-and-under' pathway in a frontal motor vehicle collision?

Accepted Answer

Knee, femur, hip, and posterior acetabulum fractures

Answer

In the down-and-under pathway the knees impact the dashboard, transmitting force up the femur to the hip and posterior acetabulum, producing a predictable lower-extremity and pelvic injury pattern.

Question 5

A patient was a restrained driver in a rear-impact collision. Which injury is most predictable based on kinematics alone?

Accepted Answer

Hyperextension cervical spine injury

Answer

Rear impacts cause rapid forward acceleration of the torso while the unsupported head lags behind, producing hyperextension stress on the cervical spine.

PHTLS - Prehospital Trauma Life Support Practice Test

PHTLS - Prehospital Trauma Life Support Practice Test

PHTLS Kinematics of Trauma