1. Shock is a life-threatening condition defined as inadequate delivery of oxygen and nutrients to tissues due to acute circulatory failure, leading to cellular injury and death if untreated.
2. The document classifies and describes the pathophysiology and stages of different types of shock, including hypovolemic, cardiogenic, septic, and neurogenic shock.
3. Left untreated, the stages of shock progress from initial compensated shock to decompensated shock and finally irreversible shock, with multi-organ failure potentially leading to death.