Hemorrhagic Shock

First aid: stop the bleeding

Following the American College of Surgeons Stop the Bleed program:

1. Call 911 or your local emergency number. Make sure the scene is safe.
2. Find the source of bleeding. Remove or cut clothing if needed.
3. Apply firm, direct pressure with both hands on the wound using a clean cloth or gauze. Do not lift it to check; add more cloth on top if it soaks through.
4. Pack deep wounds (for example in the groin or armpit) tightly with gauze or cloth, then hold firm pressure.
5. Use a tourniquet for life-threatening bleeding from an arm or leg that does not stop with pressure. Place it 5 to 8 cm (2 to 3 inches) above the wound, not over a joint, and tighten until bleeding stops. Note the time it was applied. Do not remove it.
6. Keep the person lying down and warm. Cover them with a blanket; cold worsens bleeding.
7. Do not give food or drink.

How hemorrhagic shock develops

When blood is lost, the body first compensates: the heart beats faster, blood vessels in the skin and gut constrict to send blood to the brain and heart, and breathing quickens. Blood pressure may stay normal until a large amount has been lost, particularly in young, fit people and children, which is why a normal blood pressure can be falsely reassuring.

As loss continues, organs receive too little oxygen, cells switch to anaerobic metabolism, and acid builds up (lactic acidosis). Body temperature falls and blood loses its ability to clot. This "lethal triad" of acidosis, hypothermia and coagulopathy makes bleeding worse and can become irreversible.

Stages of hemorrhagic shock

ATLS describes four classes in adults (approximate):

An adult has about 5 liters of blood. Children and pregnant women compensate well and may look stable until they suddenly deteriorate.

Causes

• Trauma: penetrating wounds, crashes, falls, crush injuries; bleeding into the chest, abdomen, pelvis, thighs or externally. See multiple trauma.
• Gastrointestinal bleeding: bleeding ulcers, esophageal varices, diverticular bleeding
• Vascular: ruptured aortic aneurysm, aortic dissection
• Obstetric: ectopic pregnancy, placental abruption, postpartum hemorrhage
• Surgical bleeding and complications of blood thinners

Symptoms and signs

• fast heart rate (rapid pulse)
• pale, cold, sweaty, mottled skin
• fast, shallow breathing
• anxiety, restlessness, then confusion
• thirst and dry mouth
• dizziness or fainting when sitting up
• weak or absent pulses
• little or no urine
• visible bleeding, or signs of internal bleeding: abdominal swelling or pain, bruising over the flank, black stools, vomiting blood

Diagnosis

Diagnosis is clinical and rapid. In the emergency department:

• vital signs, including pulse, blood pressure and shock index (heart rate divided by systolic pressure; above about 0.9 to 1 suggests significant bleeding)
• FAST ultrasound to look for blood in the abdomen and around the heart
• chest and pelvic X-rays, and CT scanning in stable patients
• blood tests: hemoglobin (may be normal early), lactate and base deficit, clotting tests, blood type and crossmatch
• endoscopy for GI bleeding

Treatment

Control the bleeding

• direct pressure, tourniquets and wound packing
• pelvic binder for pelvic fractures
• emergency surgery (damage control laparotomy)
• interventional radiology to block bleeding vessels (embolization)
• endoscopic treatment for GI bleeding
• REBOA, a balloon placed in the aorta, in some trauma centers

Restore blood volume

• Massive transfusion protocols: red cells, plasma and platelets in balanced ratios (often 1:1:1), or whole blood in some centers.
• Limited crystalloid fluids: large amounts of saline dilute clotting factors and worsen outcomes.
• Permissive hypotension: in trauma without head injury, accepting lower blood pressure until bleeding is controlled.
• Tranexamic acid: given within 3 hours of injury reduces death from bleeding in trauma and postpartum hemorrhage.
• Correct clotting with targeted factor replacement and calcium.
• Prevent hypothermia with warmed fluids and blankets.

Complications

• kidney failure
• multi-organ failure
• disseminated intravascular coagulation
• brain injury from low oxygen
• death; outcomes depend heavily on how quickly bleeding is controlled

Frequently asked questions

What are the first signs of hemorrhagic shock?

Early signs include a fast pulse, pale, cool and clammy skin, rapid breathing, anxiety and thirst. Blood pressure often stays normal until a large amount of blood has been lost, so these early signs are important warnings.

How much blood loss causes shock?

Signs of shock usually appear after losing about 15 to 30% of blood volume, roughly 750 to 1,500 ml in an average adult. Losing more than 30 to 40% causes low blood pressure, confusion and life-threatening shock.

How do you stop severe bleeding?

Apply firm, continuous direct pressure to the wound with a cloth or gauze, pack deep wounds, and use a tourniquet above the wound on a limb if pressure does not stop life-threatening bleeding. Call 911 immediately and keep the person warm and lying down.

Can you survive hemorrhagic shock?

Yes, many people survive when bleeding is controlled quickly and blood is replaced. Survival falls the longer shock lasts, which is why bystander bleeding control and rapid transport to a trauma center are so important.