Trauma Physiology

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🩸 Trauma physiology examines how the body responds to severe injury. Understanding these responses is crucial for effective trauma care: stabilising vital functions, preventing secondary injury, and optimising recovery.

⚡ Physiological Responses to Trauma

• Haemodynamic Changes:
  • 🩸 Hypovolemic Shock: Severe blood loss ↓ circulating volume → inadequate perfusion and oxygen delivery.
  • 🫀 Vasoconstriction: Peripheral vasoconstriction maintains cerebral and coronary perfusion.
  • 💓 Tachycardia: Compensatory mechanism to sustain cardiac output, though may fail with prolonged bleeding.
• Inflammatory Response:
  • 🔥 Cytokine Release: TNF-α, IL-1, and IL-6 drive systemic inflammatory response (SIRS).
  • 🦠 Leukocyte Activation: Migration to injured tissues for repair and infection control.
  • 🧬 Coagulation Cascade: Activation of clotting pathways; risk of trauma-induced coagulopathy if dysregulated.
• Metabolic Response:
  • ⚡ Hypermetabolism: Catecholamine surge ↑ resting energy expenditure.
  • 🍖 Catabolism: Muscle and fat breakdown → energy substrate but worsens muscle wasting.
  • 🩺 Insulin Resistance: Stress response causes hyperglycaemia, which can impair wound healing.

🕑 Phases of Trauma Response

• Immediate Phase (Minutes–Hours):
  • 🩹 Control bleeding, maintain perfusion (Airway, Breathing, Circulation).
  • Shock response: catecholamines and vasoconstriction dominate.
• Acute Phase (Hours–Days):
  • Ongoing resuscitation, stabilisation, and correction of metabolic derangements.
  • Systemic inflammatory response peaks, risk of sepsis and coagulopathy.
• Chronic Phase (Days–Weeks):
  • Focus shifts to wound healing, rehabilitation, and psychological recovery.
  • Risk of malnutrition, sarcopenia, PTSD.

🫁 Key Organ Systems Affected

• Cardiovascular: Maintain perfusion, prevent exsanguination. Uncorrected shock → MODS.
• Respiratory: Risk of pneumothorax, pulmonary contusion, ARDS. Prioritise oxygenation.
• Renal: Trauma + hypoperfusion → prerenal AKI. Beware rhabdomyolysis releasing myoglobin.
• Nervous: Traumatic brain injury (TBI), spinal cord injury. Raised ICP → secondary brain injury if untreated.

🛠️ Trauma Assessment & Management

• Primary Survey (ABCDE):
  • 🅰️ Airway: With c-spine protection.
  • 🅱️ Breathing: Ventilation, chest drains for pneumothorax/haemothorax.
  • 🅲️ Circulation: Control haemorrhage, restore volume (balanced resuscitation with blood products).
  • 🅳️ Disability: Neuro assessment (AVPU, GCS).
  • 🅴️ Exposure: Full exposure to find injuries, prevent hypothermia.
• Secondary Survey: Head-to-toe exam, imaging, history (AMPLE: Allergies, Meds, Past history, Last meal, Events).
• Resuscitation: Blood transfusion, TXA (within 3 hours), vasopressors if refractory shock.

⚠️ Complications

• ARDS: Inflammatory lung damage → impaired oxygenation.
• Sepsis & MODS: Secondary infections worsen outcomes.
• Trauma-Induced Coagulopathy: “Lethal triad” of hypothermia, acidosis, coagulopathy.
• Compartment Syndrome: 🚨 Orthopaedic emergency → requires fasciotomy.

💪 Recovery & Rehabilitation

• 🏃 Physiotherapy: Regain strength and mobility.
• 🧠 Psychological Support: PTSD, anxiety, and depression common after major trauma.
• 🧑‍🦽 Occupational Therapy: Assist return to independence and work.
• 📅 Follow-up: Ongoing monitoring for renal, neuro, and cardiac sequelae.

📌 Summary

Trauma physiology integrates shock, inflammation, and metabolic stress. Effective care requires rapid resuscitation, vigilant monitoring of organ systems, and multidisciplinary rehabilitation. A trauma team must anticipate complications early — survival depends on recognising patterns of physiology as much as on treating the injuries themselves.