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Andrew Pollack-Gray

Nursing Notes

Blood Loss

3 min read

What is it?

Blood loss is a reduction in circulating blood volume caused by bleeding.

  • Acute blood loss: Occurs over a short period, such as after trauma or surgery.
  • Chronic blood loss: Develops gradually through repeated or ongoing bleeding.
  • Hemorrhage: The escape of blood from damaged blood vessels; can be external or internal.

Hemorrhage

Hemorrhage means bleeding due to blood escaping from the circulatory system.

  • External hemorrhage: Blood leaves the body through a wound or opening.
  • Internal hemorrhage: Blood accumulates within the body.
  • Acute hemorrhage: Bleeding occurs over a relatively short period.
  • Chronic blood loss: Smaller or repeated episodes of bleeding over time.
    Clinical Connection: Severe hemorrhage can reduce circulating blood volume, decrease cardiac output, and cause hypovolemic shock.
    For emergency response, see Bleeding, Shock & Injury Response.

How does it work?

Effects on Circulation

  1. Blood is lost from the circulatory system.
  2. Circulating blood volume decreases.
  3. Venous return to the heart may decrease.
  4. Reduced ventricular filling can decrease Cardiac Output.
  5. Blood pressure may fall if compensatory mechanisms are insufficient.

Compensation

The body initially attempts to maintain circulation through:

  • Increasing heart rate.
  • Constricting blood vessels.
  • Redirecting blood flow toward vital organs.
    Important: Blood pressure may remain near normal during early significant blood loss because the body compensates.

Severe Blood Loss

  • Can result in hypovolemic shock.
  • Reduces oxygen delivery to tissues.
  • May impair brain, kidney, and other organ function.

Why does it matter clinically?

Blood loss can cause:

  • Reduced tissue perfusion.
  • Dizziness, weakness, and fainting.
  • Rapid pulse and breathing.
  • Shock and organ damage when severe.
  • Anemia with chronic or repeated blood loss.

What should I look for?

External Bleeding:

  • Visible bleeding from wounds or injuries.
  • Blood-soaked dressings or linens.
    Possible Internal Bleeding:
  • Unexplained bruising or swelling.
  • Abdominal pain or distention.
  • Black, tarry stool.
  • Blood in urine or stool.
    Signs of Significant Blood Loss:
  • Rapid or weak pulse.
  • Pale, cool, or clammy skin.
  • Dizziness or fainting.
  • Unusual weakness.
  • Confusion or decreased responsiveness.
  • Low blood pressure, which may be a later finding.

What should I do?

  • Recognize and report unexpected bleeding promptly.
  • Activate emergency response for severe bleeding or signs of shock.
  • Follow trained first-aid procedures and facility emergency protocols.
  • Observe and communicate changes in pulse, breathing, consciousness, and skin appearance.
  • Use appropriate PPE when contact with blood is anticipated.
  • Document objective findings according to facility policy.
    CNA Scope: Recognize, provide authorized emergency assistance, and report. Determining the cause and medical treatment of bleeding are responsibilities of qualified clinicians.

Sources

  • CNA Module 12 — Emergency Procedures
  • Cardiovascular physiology — circulating blood volume and perfusion

Flashcards

Why can blood pressure be near normal during early serious blood loss?02-mechanisms / diseases-conditions
Answer

Compensatory increased heart rate and vasoconstriction.

What is a possible late consequence of severe blood loss?02-mechanisms / diseases-conditions
Answer

Hypovolemic shock from reduced circulating volume.

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