Thoracic Injury

Question 1

What principle lf physics explains why airbags and seatbelts are effective at preventing injuries?

Answer 1

Momentum:

Impulse-momentum principles
- increase time to decrease force applied on body

Work-energy principle:
- increase distance to decrease force applied on body

Question 2

What are the injuries associated with seatbelt use? (5)

Answer 2

1. Rupture of abdominal and pelvic organs
   –> highest occurrence in “lap belt only”
2. Aortic and other major vessel injuries
3. cardiac injuries and pulmonary contusions
4. brachial plexus injuries
5. fractures of thoracic and lumbar spine, clavile, ribs and sternum
   –> highest occurrence in “lap and shoulder belt only”

Question 3

What is the significance of thoracic injuries in automotive accidents?

Answer 3

Ranks 2nd only to head injury in terms of serious / fatal injuries

(skeletal injury is most common which is followed by pulmonary, liver, and heart injuries)

Question 4

What are injury scales and why are they important?

Answer 4

Standardized system to classify and quantify injury severity

Why?
- helps researchers and engineers improve safety measures!!!
- better comparison and data analysis
- aid in medical decision-making

Question 5

What is Flail Chest? (Causes and Mechanism)

Answer 5

3 or more adjacent ribs break in 2 places –> unstable chest segment

Causes:
paradoxical breathing
- flail segmetn moves opp to normal respiraiton –> impaired ventilation and high risk of respiratory failure

Mechanism:
- blunt trauma –> ribs fail in bending w/ failure on tensile side of ribs
- rib fracture occurs at max compression of chest (bone is stronger in compression than tension)

Question 6

What is Pulmonary Contusion? (Mechanism)

Answer 6

“bruised lung” –> lung parenchymal injury w/o lung or vascular lacerations

Effect:
- disrupts gas exchange, reduces lung compliance, leads to respiratory failure (death)

Mechanism:
- Pulmonary contusion is rate dependent (visoelastic)
–> at high speeds, pressure wave passes through chest walls and dmgs alveolar capillaries in lungs

Question 7

What is Pneumothorax?

Answer 7

Air enters pleural cavity due to pleural perforation
- (visceral from lung injury)
- (parietal form truma / external punctures)

Effect:
- disrupts neg pressure —> lung collapse

(Tension pneumothroax)
- trapped air increases pressure –> compresses lung, heart, and vessels (life threatening)

Mechanism:
- pneumo/hemothorax appear to depend on chest deflection

Question 8

What is aortic rupture / laceration?

Answer 8

• severe direct chest impact / compression
• 90% occurs at aortic isthmus (just beyond left subclavian artery

Mechanism:
1. shear forces at mobile vs fixed pts
2. direct compression againts vertebrae
3. suddent intraluminal pressure surge

(lacerations are usually transverse)

Question 9

What is Commotio Codis

Answer 9

major heart contusion

• most prevalent for 20 year old males (said to have flexible chests)

88% mortality (due to decreased rates of CPR and defribrillation compared to sport-related commotio cordis)

Mechanism
- incomplete repolarization –> causes firbrillation of heart

Question 10

Where in the ECG waveform is the heart most vulnerable?

Answer 10

T-wave (repolarization of ventricle)