Hypovolemic shock happens when a drop in blood volume — usually due to bleeding — leads to severe complications, including organ failure. Symptoms include a rapid heart rate and breathing difficulty.

The heart cannot pump blood around the body unless a certain volume of blood is present. Blood volume describes the total amount of blood in the body. If a person’s blood volume drops significantly, then a person can go into hypovolemic shock.

Many health problems can lead to hypovolemic shock. A doctor will diagnose a patient with the issue once an individual loses 20% or more of their blood volume. Hypovolemic shock is a medical emergency that is difficult to diagnose and treat. It can result in organ failure.

In a study, more than 82% of patients who died from hypovolemic shock died within the first 24 hours.

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There are approximately three stages of hypovolemic shock based on the level of blood volume loss. All the stages require fast treatment. The earlier doctors can recognize the stage of shock a person is in, the faster they can give the patient the appropriate treatment.


During the earliest stage of hypovolemic shock, a person loses less than 20% of their blood volume. This stage can be difficult to diagnose because blood pressure and breathing will still be normal.

The most noticeable symptom at this stage is skin that appears pale. The person may also experience sudden anxiety.


In the second stage, the body loses 20-40% of blood. The individual may experience increased heart and breathing rates.

Blood pressure may still be within normal range. However, the diastolic pressure, or bottom number, of their blood pressure may be high. The person may begin sweating, as well as feeling more anxious and restless.


By stage 3, a person with hypovolemic shock will have lost more than 40% of their blood.

The systolic pressure, or top number, of their blood pressure, will be 100 millimeters of mercury (mm Hg) or lower. Their heart rate will increase to over 120 beats per minute (bpm). They will also have a rapid breathing rate of more than 30 breaths per minute.

They will begin to experience mental distress, including anxiety and agitation. Their skin will be pale and cold, and they will begin sweating. They will have a weak pulse but an extremely rapid heart rate.

Breathing will become be very fast and difficult. Systolic blood pressure will be under 70 mm/Hg. They may experience the following symptoms:

  • drifting in and out of consciousness
  • sweating heavily
  • feeling cool to the touch
  • looking extremely pale

A major cause of hypovolemic shock can be acute blood loss. The term hemorrhagic shock refers specifically to this type of hypovolemic shock. This can occur as a result of an acute tissue injury or because of conditions like internal bleeding or illness.

But, hypovolemic shock can also refer to any major loss of bodily fluid that also results in significant blood loss. Blood plasma is the liquid part of blood that holds red blood cells, white blood cells, and blood platelets. Water makes up 92% of plasma. If a person loses a significant volume of fluid, the plasma part of blood will deplete too.

For this reason, many conditions that are not acute blood loss can lead to a critical reduction in blood volume. Severe burns, persistent diarrhea, vomiting, and even excessive sweating could all be potential causes of hypovolemic shock.

Doctors can identify hypovolemic shock more easily when they can see significant blood loss from an external wound. However, hypovolemic shock often develops as a complication of an underlying medical condition. Internal bleeding may not be obvious from observation and is often hard to control without surgery.

Medical professionals and first responders are trained to recognize the signs of blood loss. However, people should educate themselves on its signs so that they can get help for themselves and others as quickly as possible.

Hypovolemic shock usually occurs as a result of either an illness, injury, or other medical condition. As a result, doctors may find it hard to predetermine specific risk factors. Any risk factors would be the risk of getting a condition that can cause the shock, such as the risk of being severely injured in a car crash or having an aneurysm rupture.

When a person is dehydrated, they lose a significant amount of water volume. People who are dehydrated can become hypovolemic if they are also losing salt, which can lead to a loss in blood volume.

For this reason, people who are dehydrated, or at risk of becoming dehydrated, should continue to drink fluids, especially if their illness is causing them to experience vomiting or diarrhea. These can lead to further loss of fluids.

A person may not be able to prevent the injuries or illnesses that cause hypovolemic shock. However, a person may be able to prevent further complications by rehydrating.

The easiest way for a medical professional to diagnose hypovolemic shock is through observation and examination. A physical exam will show whether the person has low blood pressure, increased heart and breathing rates, and a low body temperature.

Doctors can use blood tests to help support this diagnosis. A blood chemistry test can give some additional clues about the level of salt and electrolytes in the body as well as how the kidneys and liver are functioning. A complete blood count (CBC) can tell how much blood a person has lost.

The following tests or devices can help determine the underlying cause of the hypovolemia or locate a source of internal bleeding:

  • a CT scan can give a view of the organs in the body
  • an echocardiogram can assess how well the heart fills up with and squeezes blood
  • an endoscopy can help find a bleeding source in the gastrointestinal tract

Treating hypovolemic shock means treating the underlying medical cause. Physicians first will try to stop fluid loss and stabilize blood volume levels before more complications develop.

Doctors usually replace lost blood volume with intravenous (IV) fluids called crystalloids. These are liquids with a thin consistency, such as a saline solution. The doctor may also use thicker solutions called colloids.

In the most severe cases, the remaining blood becomes diluted. This can result in low levels of platelets and other blood components that help form clots that stop bleeding. The medical team will replace these components when necessary, especially if the person is still bleeding, through plasma or red blood cell (RBC) transfusions.

After the shock is under control and the blood volume stabilizes, the doctor can treat the underlying illness or injury.

Hypovolemic shock is a life-threatening emergency. A person’s outlook depends heavily on which complications develop while a person is in shock. This can include damage to the kidneys or brain. It is critical that an emergency doctor increases the person’s blood volume quickly to restore blood supply to all organs.

The amount of time it takes to increase the blood volume can depend on:

  • the stage of shock
  • the rate of blood loss
  • the extent of blood loss
  • any underlying medical conditions, such as heart disease or taking blood thinners

Hypovolemic shock and older adults

Older adults are particularly at risk of getting hypovolemic shock because they can be more susceptible to dehydration, which can trigger hypovolemia. They also do not tolerate having a low blood volume well.

The risk of complications increases with age, especially if other conditions have already caused organ damage such as kidney failure or a heart attack.

It is especially important that older adults receive prompt treatment as soon as they, or individuals near them, recognize any signs of hypovolemic shock.

Hypovolemic shock is a medical emergency in which blood volume drops to a dangerous level. It occurs when the body loses excessive amounts of water and salt. The condition has four stages. By the fourth stage, a person’s condition becomes critical.

Treatment for this type of shock involves replacing fluids in the body, usually with a saline solution. However, treatment is difficult and the condition usually carries a high risk of death. The best way to stabilize the condition is to spot symptoms as early as possible and to seek prompt medical treatment.