Hypovolemic shock is a particular form of shock in which the heart is unable to supply enough blood to the body. It is caused by blood loss or inadequate blood volume.
Causes, incidence, and risk factors
Loss of approximately one-fifth or more of the normal blood volume produces hypovolemic shock. The loss can be from any cause, including external bleeding (from cuts or injury), gastrointestinal tract bleeding, other internal bleeding, or from diminished blood volume resulting from excessive loss of other body fluids (such as can occur with diarrhea, vomiting, burns, and so on). In general, larger and more rapid blood volume losses result in more severe shock symptoms.
In another form of shock called cardiogenic shock, there is adequate blood volume, but the heart is unable to pump the blood effectively.
- rapid pulse
- pulse may be weak (thready)
- rapid breathing
- anxiety or agitation
- cool, clammy skin
- pale skin color (pallor)
- sweating, moist skin
- decreased or no urine output
- low blood pressure
Signs and tests
An examination indicates the presence of shock. There is usually low blood pressure, rapid pulse, and body temperature may drop.
- Laboratory tests include a CBC; other tests may be performed depending on the suspected cause of the loss of volume.
- Tests may be required to determine site and cause of volume depletion, and could include a CT scan or an X-Ray of suspected areas.
- Endoscopy may be performed in cases of bleeding from the gastrointestinal tract.
- An echocardiogram (heart ultrasound) or right heart (Swan-Ganz) catheterization may show low cardiac output (pumping action), confirming shock, and may also help to differentiate between hypovolemic versus cardiogenic shock.
Obtain professional medical care immediately! Limited measures to help include:
- Keep the victim comfortable and warm (to avoid hypothermia).
- Have the victim lie flat with the feet elevated about 12 inches to increase circulation. However, if the victim suffers from a head, neck, back, or leg injury, leave the victim in the position in which they were found unless doing so poses other immediate danger.
- Do not give fluids by mouth.
- If victim is stung or suffering an allergic reaction, treat the allergic reaction.
- If the victim must be carried, try to maintain the flat, head down, feet elevated position. Stabilize the head and neck before moving a victim with a suspected spinal injury.
Hospital treatment focuses on replacing blood and fluid volume. Treatment may also include determination of the cause of blood loss and control of bleeding to prevent recurrence of hypovolemic shock.
Intravenous fluids, which may include blood or blood products, are used to maintain volume in the circulatory system.
Dopamine, dobutamine, epinephrine, norepinephrine, and other medications may be required to increase blood pressure and cardiac output.
Other interventions that may be used to manage shock include:
- cardiac monitoring, including Swan-Ganz (used to guide treatment)
- placement of a urinary catheter to monitor urine output
Hypovolemic shock is always a medical emergency, but there is wide variation in both symptoms and outcomes depending upon the amount of blood volume lost, the rate of loss, the underlying illness or injury causing the loss, and other factors.
In general, patients with milder degrees of shock tend to do better than those with more severe shock. However, in cases of severe hypovolemic shock, death is possible even with immediate medical attention. The elderly are at increased risk of having poor outcomes from shock.
- kidney damage
- brain damage
Calling your health care provider
Hypovolemic shock is a medical emergency! Call the local emergency number
(such as 911) or take the victim to the emergency room if symptoms indicate hypovolemic shock.
Preventing shock is easier than trying to treat it once it happens. Prompt treatment of the underlying cause will reduce the risk of developing severe shock. Early first aid can help control shock.
by David A. Scott, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.