Hypovolemic Shock

First aid for shock

1. Call 911 or your local emergency number.
2. Stop any visible bleeding with firm, direct pressure. Use a tourniquet for life-threatening limb bleeding if trained.
3. Lay the person flat on their back. Do not raise the legs if there is a head, neck, back or leg injury.
4. Keep them warm with a blanket or coat. Shock worsens with cold.
5. Do not give food or drink, as surgery may be needed.
6. Loosen tight clothing and reassure them.
7. Monitor breathing. Start CPR if they stop breathing normally.
8. If they vomit, roll them onto their side, supporting the head and neck.

What happens in hypovolemic shock

Blood volume carries oxygen to the organs. When it falls, the body compensates:

• the heart beats faster
• blood vessels in the skin, gut and kidneys tighten to redirect blood to the brain and heart
• breathing speeds up

These responses keep blood pressure normal at first, which is why low blood pressure is a late sign. When compensation fails, organs become starved of oxygen, lactic acid builds up, and organ damage, cardiac arrest and death can follow.

Causes

Blood loss (hemorrhagic shock)

• trauma: car crashes, falls, stabbings, gunshot wounds
• internal bleeding from a ruptured spleen or liver, pelvic or femur fractures
• gastrointestinal bleeding from ulcers or varices
• ruptured ectopic pregnancy or abdominal aortic aneurysm
• bleeding during or after childbirth or surgery

See hemorrhagic shock.

Fluid loss

• severe vomiting and diarrhea, especially cholera and other infections in children and older adults
• burns over large areas
• heat stroke and extreme sweating
• uncontrolled diabetes with very high blood sugar (excess urination)
• fluid shifting out of the blood in pancreatitis or bowel obstruction

Stages of hemorrhagic shock

Trauma teams estimate blood loss using four classes (for an average adult with about 5 liters of blood):

Children and fit young adults can compensate well until sudden collapse. Older people and those on beta-blockers may not develop a fast pulse.

Diagnosis

Shock is recognized clinically from pulse, blood pressure, skin, breathing, mental state and urine output. Tests guide treatment:

• blood count, blood group and crossmatch
• lactate and blood gases to measure oxygen debt
• kidney function and electrolytes
• clotting tests
• bedside ultrasound (FAST scan) to find internal bleeding
• CT scans and endoscopy to find the source when stable

Treatment

• Stopping the loss: pressure, tourniquets, surgery, endoscopic treatment of GI bleeding, or embolization by interventional radiology.
• Blood transfusion: red cells, plasma and platelets in balanced ratios for major bleeding.
• Tranexamic acid: reduces death from bleeding in trauma when given early, within 3 hours.
• IV fluids: for fluid-loss shock. In bleeding, fluids are given cautiously to avoid diluting clotting factors.
• Oxygen.
• Warming: to prevent hypothermia, which worsens bleeding.
• Treating the cause: antibiotics for infection, insulin for diabetic emergencies, burn care.
• Monitoring in intensive care.

For dehydration from diarrhea in children, oral rehydration solution prevents shock when started early, but children in shock need IV fluids.

Complications

• kidney failure
• brain damage
• heart attack and arrhythmias
• liver and gut injury
• multiple organ failure
• death

Outlook

Outcomes depend on the cause, how much fluid or blood was lost, how quickly treatment starts, and the person's age and health. Early recognition and rapid treatment save lives.

Frequently asked questions

What are the signs of hypovolemic shock?

Signs include a fast, weak pulse, fast breathing, pale, cold, clammy or mottled skin, thirst, dizziness, confusion or agitation, and little or no urine. Low blood pressure appears later. These signs after bleeding or fluid loss need a 911 call.

What causes hypovolemic shock?

It is caused by losing a large amount of blood, such as from trauma or internal or GI bleeding, or a large amount of body fluid, such as from severe vomiting, diarrhea, burns or extreme dehydration.

Is hypovolemic shock the same as hemorrhagic shock?

Hemorrhagic shock is a type of hypovolemic shock caused specifically by blood loss. Hypovolemic shock also includes shock caused by losing other body fluids, such as from diarrhea, vomiting or burns.

Can you recover from hypovolemic shock?

Yes, many people recover fully when shock is recognized early and the cause is treated quickly. Prolonged or severe shock can cause lasting organ damage and can be fatal.