Trauma is the leading cause of death in people under 45, and the deaths cluster in a predictable pattern. A first group dies at the scene from injuries no system can reverse. A second group dies within the first hours from airway obstruction, tension pneumothorax, massive haemorrhage and expanding intracranial bleeding — and these are precisely the injuries a structured assessment finds and treats. A third group dies days later from sepsis and multi-organ failure, which is often determined by how well the first hours went. That middle group is why trauma care is protocolized. The discipline of the approach is the intervention: a systematic primary survey performed the same way every time, with each life threat treated at the moment it is found rather than after the assessment is complete. This is the single most important habit to carry into both the exam and the resuscitation room. You do not finish the assessment and then act. If you find an obstructed airway at A, you manage it before you look at breathing. If you find a tension pneumothorax at...