1. Injuries: definition and classification

1. Definition

• Injury (trauma) → damage to tissues or organs by an external agent whose force exceeds tissue resistance
• Causes a local reaction (tissue damage, inflammation) and a general reaction (pain, shock, metabolic response)
• Traumatism → total of injuries in a population group over a set period
• Trauma → leading cause of death under 45 years

2. Classification

By agent

• Mechanical → blunt, sharp, penetrating, blast
• Thermal → burns, frostbite
• Chemical → acids, alkalis
• Electrical → technical current, lightning
• Radiation → ionising radiation
• Biological → bites, venoms
• Psychological → acute stress
• Combined injury → 2 or more different agents (burn + fracture)

By skin and mucosa integrity

• Closed → skin intact: contusion, haematoma, sprain, dislocation, closed fracture, organ rupture
• Open → skin or mucosa breached: wounds, open fractures

By relation to a body cavity

• Non-penetrating → serous lining of the cavity intact
• Penetrating → peritoneum, pleura or dura breached
  • Without organ injury
  • With organ injury

By number and distribution

• Isolated → 1 injury in 1 body region
• Multiple → several injuries in 1 body region (multiple rib fractures)
• Associated → injuries in 2 or more body regions (head + abdomen)
• Polytrauma → associated injuries where at least 1, or the combination, is life-threatening

By mechanism

• Direct → injury at the point of impact
• Indirect → injury away from the point of impact (fall on the hand → clavicle fracture)

By severity

• Minor, moderate, severe, critical
• Injury Severity Score (ISS) → sum of squares of the highest Abbreviated Injury Scale (AIS) grade in the 3 most injured body regions
• ISS range → 1–75
• Major trauma → ISS > 15

3. Types of trauma (traumatism)

• Industrial
• Agricultural
• Road traffic (transport)
• Domestic
• Sports
• Street (assault, falls in public places)
• Military
• Intentional → assault, self-harm
• Iatrogenic → caused by medical care

4. Body response to injury

Local

• Tissue destruction
• Haemorrhage
• Inflammation → repair and healing

General

• Pain
• Haemorrhagic or traumatic shock
• Metabolic response to trauma:
  1. Ebb phase → first 24–48 h, reduced metabolic rate
  2. Flow phase → catabolism, then anabolism
• Systemic inflammatory response syndrome (SIRS) → multi-organ dysfunction

5. Trimodal distribution of trauma deaths

1. Immediate → seconds to minutes; brain, brainstem, heart, great vessels
2. Early → minutes to hours (golden hour); haemothorax, ruptured spleen or liver, epidural haematoma
3. Late → days to weeks; sepsis, multi-organ failure

6. Clinical and surgical significance

• Assessment of every injured patient → Advanced Trauma Life Support (ATLS) primary survey:
  1. Airway with cervical spine control
  2. Breathing
  3. Circulation with haemorrhage control
  4. Disability (neurological status)
  5. Exposure
• Secondary survey → head-to-toe examination once the patient is stable