Hypovolemic shock

Hypovolemic shock is a form of shock caused by severe hypovolemia (insufficient blood volume or fluid outside of cells in the body). It can be caused by severe dehydration or blood loss. Hypovolemic shock is a medical emergency; if left untreated, the insufficient blood flow can cause damage to organs, leading to multiple organ failures.

In treating hypovolemic shock, it is important to determine the cause of the underlying hypovolemia, which may be the result of bleeding or other fluid loss. To minimize damage to tissues from insufficient blood flow, treatment involves quickly replacing lost blood or fluids, with consideration of both rate and the type of fluids used.

Tachycardia, a fast heart rate, is typically the first abnormal vital sign. When resulting from blood loss, trauma is the most common root cause, but severe blood loss can also happen in various body systems without clear traumatic injury. The body in hypovolemic shock prioritizes getting oxygen to the brain and heart, which reduces blood flow to nonvital organs and the limbs, causing them to grow cold, look mottled, and exhibit delayed capillary refill. The lack of adequate oxygen delivery causes the blood to become more acidic (acidosis). The "lethal triad" of ways trauma can lead to death is acidosis, hypothermia, and coagulopathy. It is possible for trauma to cause clotting problems even without resuscitation efforts.

Damage control resuscitation is based on three principles:

• permissive hypotension: tries to balance temporary suboptimal perfusion to organs with conditions for halting blood loss by setting a goal of 90 mmHg systolic blood pressure
• hemostatic resuscitation: restoring blood volume in ways (with whole blood or equivalent) that interfere minimally with the natural process of stopping bleeding.
• damage control surgery.