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Detailed Overview of Hypovolemic Shock

Apr 23, 2025

Lecture on Hypovolemic Shock

Presented by: Orion Colin, Registered Nurse

This lecture is part of a series on shock, focusing specifically on hypovolemic shock, its causes, pathophysiology, stages, signs and symptoms, as well as nursing interventions and treatments.

Definition of Hypovolemic Shock

  • Hypovolemic Shock: Low fluid volume in the blood (hypo = low, vol = volume, emic = blood).
  • Affected Area: Blood volume in the intravascular space (circulatory system).
  • Consequences: Decreased cardiac output, reduced oxygen supply to cells, cell death, and signs of shock.

Fluid Volume Loss and Effects

  • Volume Loss Threshold: Symptoms occur after losing 15% or more of blood volume.
  • Average Adult: 5 liters of blood; losing 1 liter equals 20% volume loss.

Causes of Hypovolemic Shock

  • External Fluid Loss: Major injury causing bleeding.
  • Internal Fluid Shift: Conditions causing fluid shift within the body.

Types of Hypovolemic Shock

  1. Relative Hypovolemic Shock:
    • Internal fluid shift from the intravascular system.
    • Causes: Internal bleeding, third spacing (e.g., severe burns), long bone fractures, acute pancreatitis, massive vasodilation (e.g., sepsis).
  2. Absolute Hypovolemic Shock:
    • External fluid loss from the body.
    • Causes: Massive bleeding, vomiting, diarrhea, urination, sweating due to illness or endocrine disorder.

Pathophysiology of Hypovolemic Shock

  • Decreased Cardiac Preload: Low venous return to the heart.
  • Stroke Volume and Cardiac Output: Decreased due to reduced fluid volume.
  • Tissue Perfusion: Reduced, leading to decreased oxygen supply and cell distress.
  • Compensation Mechanisms: Sympathetic nervous system and renin-angiotensin system activation.

Signs and Symptoms

  • Affected by fluid volume loss percentage.
  • Classes of Hypovolemic Shock:
    • Class 1: < 15% fluid loss, asymptomatic.
    • Class 2: 15-30% fluid loss, mild symptoms, compensation active.
    • Class 3: 30-40% fluid loss, decompensation, severe symptoms.
    • Class 4: > 40% fluid loss, critical condition, near death.

Class-specific Symptoms

  • Class 1: Normal vitals, asymptomatic.
  • Class 2: Tachycardia, decreased blood pressure, mild respiratory and mental changes.
  • Class 3: Severe tachycardia, hypotension, respiratory failure, oliguria, mental status changes.
  • Class 4: Extreme vital sign changes, coma, anuria.

Nursing Interventions and Treatment

  • Primary Goals: Fluid replacement, correct underlying cause.
  • Monitoring: Oxygenation, circulation, perfusion status.
  • Fluid Access: IV access for fluid and medication administration.
  • Positioning: Modified Trendelenburg to improve venous return.
  • Lab Monitoring: Hemoglobin, hematocrit, ABGs, lactate levels.

Fluid Types for Treatment

  1. Crystalloids:
    • Examples: Normal saline, lactated ringers.
    • Function: Volume expanders, increase preload.
    • Risk: Monitor for fluid overload.
  2. Colloids:
    • Examples: Albumin, hetastarch.
    • Function: Long-term intravascular volume retention.
    • Risk: Anaphylactic reactions, cost.

Blood Products

  • Uses: Severe bleeding, unresponsive to crystalloid fluids.
  • Types: Packed RBCs, platelets, fresh frozen plasma.
  • Monitoring: Watch for transfusion reactions.

Conclusion

Understanding hypovolemic shock involves recognizing the signs, knowing the causes, and implementing effective treatment strategies to manage and restore blood volume and cardiac output.

For more detailed explanations and a quiz on this topic, please visit our YouTube channel.

Full transcript