The heart cannot pump blood around the body unless a certain volume is present.
Hypovolemic shock can be caused by a number of things. A doctor will diagnose the condition once an individual loses 15 percent or more of their blood volume.
The condition is a medical emergency that is difficult to diagnose and treat. It can result in organ failure.
Stages and symptoms
Hypovolemic shock progresses in stages. Heavy sweating and intermittent loss of consciousness can occur at its most severe stage.
There are four stages of hypovolemic shock based on how much blood volume has been lost. All stages require early treatment, but it is helpful to recognize the stage of hypovolemia a person is in, so they receive appropriate treatment quickly.
During the earliest stage of hypovolemic shock, a person with will have lost up to 15 percent, or 750 ml, of their blood volume. This stage can be difficult to diagnose. 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 has lost up to 30 percent, or 1500 ml, 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 and feeling more anxious and restless.
By stage 3, a person with hypovolemic shock will have 30 to 40 percent, or 1500 to 2000 ml, blood loss.
The top number or systolic pressure of their blood pressure will be 100 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 over 30 breaths per minute.
They will begin to experience mental distress, including anxiety and agitation. The skin will be pale and cold, and they will begin sweating.
A person with stage-4 hypovolemia faces a critical situation.
They will have experienced a loss of blood volume greater than 40 percent, or 2,000 ml. They will have a weak pulse but extremely rapid heart rate.
Breathing will become be very fast and difficult. Systolic blood pressure will be under 70 millimeters of mercury (mm/Hg). They may experience the following symptoms:
- drifting in and out of consciousness
- sweating heavily
- feeling cool to the touch
- looking extremely pale
Blood loss from an external wound is observable and a person can often control the bleeding. Uncontrolled blood loss can lead to hypovolemia.
However, it is not the only cause.
The loss of blood volume can also occur due to internal bleeding as a result of illness or injury. Hypovolemic shock will often develop as a complication of an underlying condition. Internal bleeding is usually not 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 these signs so that they can get help for themselves and others as quickly as possible.
Since this type of shock occurs as a result of either an illness or an injury, the specific risk factors are difficult to determine.
They are the risk factors associated with the getting the condition that leads to hypovolemic shock, such as being severely injured in a car crash or having an aneurysm rupture.
Dehydration may be a contributing factor in some cases of hypovolemic shock. This occurs when the body loses only water.
Hypovolemia occurs when the body loses both water and salt. During dehydration, continuing to drink water is very important, especially when a person's illness is causing them to experience vomiting or diarrhea. These can lead to further loss of fluids.
It is not always possible 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 or not the person has low blood pressure, increased heart and breathing rates, and a low body temperature.
Several blood tests that can also 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, also called a CBC, can tell you how much blood has been lost.
The following tests can help determine if shock is due to hypovolemia or another cause and then locate a source of internal bleeding or find the underlying cause:
- a CT scan to look at the organs in the body
- echocardiogram to assess how well the heart is working
- endoscopy to look for a bleeding source in the gastrointestinal tract
- a right heart catheter to show how well the heart is pumping blood
Doctors will attempt to treat hypovolemic shock with a liquid solution containing salt and water. However, treatment can be difficult.
The treatment for the underlying cause of hypovolemic shock can difficult.
However, the initial goal of treatment is always to stop fluid loss and stabilize blood volume levels before complications develop.
Research from 2006 shows that developments in intensive care have reduced deaths from hypovolemic shock in children more than tenfold.
The doctor usually replaces lost blood volume with intravenous (IV) fluids called crystalloids. These are liquids with a thin consistency, such as saline solution. The doctor may use thicker solutions called colloids.
If a high volume of blood was lost, the doctor may provide transfusions of plasma, the fluid component of blood, or red blood cells (RBCs).
In the most severe cases, the remaining blood becomes diluted, resulting in low levels of platelets and other blood components that help form clots to stop bleeding. The medical team will replace these components when necessary, especially if the person is still bleeding.
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.
The outlook depends heavily on which complications develop while a person is in shock, such as damage to the kidneys or brain. It is therefore critical that an emergency doctor increases 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
- underlying medical conditions, such as heart disease or taking blood thinners
Hypovolemic shock and older adults
Hypovolemic shock is especially dangerous for older adults because they often do not tolerate having a low blood volume.
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 even more important that older adults receive prompt treatment as soon as they or an individual near them recognizes 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 can range from stages 1 to 4. At stage 4, the condition becomes critical.
This type of shock is treatable by 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 seek medical treatment.
What is the likelihood I will die from shock?
Hypovolemia is only one of several factors that cause shock, but no matter what causes it, being in shock is serious and life-threatening. Without treatment, shock is almost always fatal. The likelihood of dying from shock depends on several factors including:
- When treatment starts: The sooner treatment begins, the more likely you are to survive.
- Age: Older people are less likely to be able to tolerate the effects of shock on their body and may not respond as well to treatment as their younger counterparts.
- The cause of shock: Causes that tend to respond well to early treatment, such as blood loss that can be stopped as treatment starts, are less likely to be fatal than causes that don’t respond well, such as a massive heart attack.
- Underlying medical condition: An individual with no prior medical history is more likely to survive than a person with one or more medical conditions, such as heart failure or a bleeding disorder.
- The extent of organ failure: If the organs, such as the kidneys, liver, or brain, have started to fail before or during treatment of shock, the chances of survival are lower than in a person who is in shock but has functional organs.
It is essential that a person in shock seeks medical attention immediately.Nancy Moyer, MD Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.