Hypovolemic Shock

Hypovolemic shock is a dangerous condition that happens when you suddenly lose a lot of blood or fluids from your body. This drops your blood volume, the amount of blood circulating in your body. That’s why it’s also known as low-volume shock.

Hypovolemic shock is a life-threatening emergency. Blood helps hold your body temperature steady, forms blood clots, and moves oxygen and nutrients to all of your cells. If your blood volume gets too low, your organs won't be able to keep working.

The most common cause of hypovolemic shock is blood loss when a major blood vessel bursts or when you’re seriously injured. This is called hemorrhagic shock.

You can also get it from heavy bleeding related to pregnancy, from burns, or even from severe vomiting and diarrhea.

What are the stages of hypovolemic shock?

Stage I hemorrhage (loss of 0-15%)

In the absence of complications, only minimal tachycardia is seen. Usually, no changes in BP, pulse pressure, or respiratory rate occur.

A delay in capillary refill of longer than 3 seconds corresponds to a volume loss of approximately 10%.

Stage II hemorrhage (loss of 15-30%)

Clinical symptoms include tachycardia (rate >100 beats per minute), tachypnea, decrease in pulse pressure, cool clammy skin, delayed capillary refill, and slight anxiety.

The decrease in pulse pressure is a result of increased catecholamine levels, which causes an increase in peripheral vascular resistance and a subsequent increase in the diastolic BP.

Stage III hemorrhage (loss of 30-40%)

By this point, patients usually have marked tachypnea and tachycardia, decreased systolic BP, oliguria, and significant changes in mental status, such as confusion or agitation.

In patients without other injuries or fluid losses, 30-40% is the smallest amount of blood loss that consistently causes a decrease in systolic BP.

Most of these patients require blood transfusions, but the decision to administer blood should be based on the initial response to fluids.

Stage IV hemorrhage (loss of >40%)

Symptoms include the following: marked tachycardia, decreased systolic BP, narrowed pulse pressure (or immeasurable diastolic pressure), markedly decreased (or no) urinary output, depressed mental status (or loss of consciousness), and cold and pale skin.

This amount of hemorrhage is immediately life threatening.