Hypovolemic Shock

Overview

Hypovolemic shock is a dangerous condition that happens when the body loses a large amount of blood or other fluids, so there is not enough volume in the bloodstream for the heart to pump to vital organs. When organs do not receive enough blood and oxygen, they begin to fail.

This is a medical emergency. Without rapid treatment, hypovolemic shock can be fatal. If you suspect someone is going into shock from heavy bleeding, severe vomiting or diarrhea, burns, or another major fluid loss, call emergency services immediately.

Symptoms

Signs depend on how much volume has been lost and how quickly. They may include:

• Rapid, weak pulse and rapid breathing
• Cool, pale, clammy, or bluish skin
• Low blood pressure
• Feeling weak, dizzy, lightheaded, or faint
• Confusion, agitation, or reduced alertness
• Little or no urine output
• Intense thirst

These are emergency warning signs. As shock worsens, the person may become unresponsive. Do not wait for all signs to appear before seeking help.

Causes

Hypovolemic shock results from a major loss of blood or fluids. Causes include:

• Severe bleeding: From trauma, internal bleeding, gastrointestinal bleeding, ruptured blood vessels, or complications of pregnancy and childbirth. This form is called hemorrhagic shock.
• Severe fluid loss: From prolonged vomiting or diarrhea, extensive burns, or excessive sweating without replacement.

In all cases, the amount of fluid in the circulation drops too low for the heart to maintain adequate blood flow to the organs.

Risk Factors

• Major injuries or trauma
• Conditions that can cause internal or gastrointestinal bleeding, such as ulcers or ruptured aneurysms
• Severe infections of the gut causing heavy vomiting or diarrhea
• Large burns
• Pregnancy and childbirth complications
• Use of blood-thinning medications, which can worsen bleeding

Diagnosis

Hypovolemic shock is recognized clinically as an emergency, and treatment begins immediately. In the hospital, evaluation may include:

• Vital signs: Heart rate, blood pressure, breathing, and oxygen levels.
• Blood tests: To check blood counts, signs of organ stress, and the body's chemistry.
• Imaging: Ultrasound, CT, or other tests to find the source of bleeding or fluid loss.

Finding and stopping the source of loss is a key part of both diagnosis and treatment.

Treatment

Treatment must be rapid and is carried out by emergency and hospital teams.

• Restoring volume: Intravenous fluids and, for major blood loss, blood transfusions to refill the circulation.
• Stopping the loss: Controlling bleeding through pressure, procedures, or surgery, or treating the cause of fluid loss.
• Supporting organs: Oxygen, medications to support blood pressure, and intensive monitoring.

While waiting for emergency help with severe bleeding, apply firm, direct pressure to the wound, keep the person lying down and warm, and do not give them anything to eat or drink. Follow the instructions of emergency dispatchers.

Prevention

Hypovolemic shock is prevented mainly by avoiding and promptly treating major fluid and blood loss:

• Seek prompt care for heavy bleeding, severe vomiting or diarrhea, or large burns
• Stay hydrated during illness, replacing fluids with oral rehydration solutions when needed
• Control bleeding quickly after injuries with firm pressure
• Manage conditions that can bleed, such as ulcers, and use blood thinners carefully as directed
• Wear seatbelts and protective gear to reduce the severity of injuries

When to See a Doctor

Call emergency services immediately if you suspect hypovolemic shock. Warning signs include rapid weak pulse, fast breathing, cool pale clammy skin, confusion, severe weakness or fainting, and very low urine output, especially after heavy bleeding, severe vomiting or diarrhea, or major burns.

Do not attempt to manage suspected shock at home. While awaiting help, lay the person down, control any bleeding with firm pressure, keep them warm, and avoid giving food or drink.

Related Topics

Frequently Asked Questions

References

1. MedlinePlus, U.S. National Library of Medicine. Shock.
2. Merck Manual Consumer Version. Shock.
3. American Heart Association. Bleeding and shock first aid.
4. National Heart, Lung, and Blood Institute (NHLBI). Blood and circulation.