Inadequate blood flow to the body that results in tissue damage.

Tissue damage is due to lack of oxygen and nutrients.

1. Non-prograssive stage (compensated stage):Can heal without treatment.
2. Progressive stage: need to interfere/treat for it to heal.
3. Irreversible stage

Up until 10% loss, nothing really changes.  CO is the first to start decreasing.

1. Baroreceptors reflexes
2. CNS ischemic response
3. Reverse stress-relaxation of the circulatory system.
4. Angiotensin formation by the kidney
5. Vasopressin (ADH) secretion by posterior pituitary gland
6. Blood volume compensatory

0-3hrs it decreases slowly.

4+ hrs it decreases very quickly

• Severe hemorrhage or large burn→ Loss of  blood volume
• Excessive vomiting or diarrhea→ Loss of fluids derived from plasma→ Loss of blood volume
• Loss of blood volume→ ↓Cardiac output→ ↓MAP(Circulatory shock)

• Weakened heart→ ↓CO→ ↓MAP(Circulatory shock)

Part of Vasogenic shock category

• bacteria release vasodilator toxins→ widespread vasodilation→ ↓TPR→ ↓MAP (circulatory shock)

Vasogenic shock category

• Histamine released because of allergies→ widespread vasodilation→ ↓TPR→ ↓MAP(Circulatory shock)

can be caused by anesthesia

• ↓Sympathetic nerve activity→ Loss of vascular tone→ widespread vasodilation→ ↓TPR→ ↓MAP(circulatory shock)

1. Fluid replacement therapy: Blood and plasma transfusion. Plasma substitute (dextran) transfusion.

2. Sympathomimetic drugs:(vasoconstric vessels, bring CO and MAP back to normal) Epi and Norepinephrine. Mainly used in neurogenic and anaphylactic shock.

3. Other measures:

-Head down position

-Oxygen therapy(not very useful)

-Glucorticoid(steroids)