What are the types of hypovolemic shock?

Types of Hypovolemic Shock

Hypovolemic shock is classified into four major categories based on the source of volume loss: hemorrhagic, non-hemorrhagic external fluid loss, third-space losses, and traumatic shock. 1

Classification of Hypovolemic Shock Types

1. Hemorrhagic Shock

• Caused by acute blood loss from:
  • Gastrointestinal bleeding
  • Trauma with external or internal bleeding
  • Obstetric/gynecological bleeding
  • Ruptured aneurysms
  • Surgical complications

2. Non-Hemorrhagic External Fluid Loss

• Results from excessive loss of body fluids:
  • Severe vomiting or diarrhea
  • Excessive sweating
  • Burns with plasma loss
  • Diabetic ketoacidosis with polyuria
  • Inadequate fluid intake

3. Third-Space Losses

• Fluid shifts from intravascular to interstitial space:
  • Peritonitis
  • Pancreatitis
  • Intestinal obstruction
  • Severe sepsis with capillary leak
  • Post-surgical fluid sequestration

4. Traumatic Shock

• Combined mechanisms including:
  • Blood loss
  • Tissue damage
  • Inflammatory responses
  • Potential neurogenic components

Pathophysiologic Features

Hypovolemic shock is characterized by a critical decrease in intravascular volume resulting in:

• Diminished venous return (preload)
• Decreased ventricular filling
• Reduced stroke volume
• Decreased cardiac output
• Tissue hypoperfusion and cellular hypoxia 2, 3

Diagnostic Features

Echocardiographic Findings

• Small hyperdynamic unloaded ventricle
• Reduced left ventricular end-diastolic area
• Small inferior vena cava diameter (<10 mm) with inspiratory collapse in spontaneously breathing patients
• In mechanically ventilated patients: small IVC diameter at end expiration with variable respiratory changes 2

Clinical Presentation (Progressive Stages)

1. Compensated shock:

   • Tachycardia
   • Normal blood pressure
   • Preserved mental status
   • Mild peripheral vasoconstriction

2. Decompensated shock:

   • Persistent tachycardia
   • Hypotension
   • Altered mental status
   • Poor peripheral perfusion
   • Decreased urine output

3. Irreversible shock:

   • End-organ damage
   • Metabolic acidosis
   • Multiple organ dysfunction

Management Principles

Initial Resuscitation

• Administer isotonic crystalloids (preferably balanced/buffered solutions)
• For adults: Boluses titrated to clinical response
• For children: 10-20 mL/kg boluses over 5-10 minutes, up to 40-60 mL/kg in first hour 2, 4
• Monitor for signs of fluid overload (hepatomegaly, rales)
• Consider blood products for hemorrhagic shock 4

Special Considerations

• In children with severe hemolytic anemia who are not hypotensive, blood transfusion is superior to crystalloid or albumin bolusing 2
• In resource-limited settings without ICU availability, limit fluid boluses to 40 mL/kg in the first hour if hypotension is present 4

Monitoring Response

• Clinical markers: Heart rate, blood pressure, capillary refill, level of consciousness, urine output
• Advanced hemodynamic variables when available: Cardiac output/index, systemic vascular resistance, central venous oxygen saturation
• Trends in blood lactate levels 4

Common Pitfalls

• Relying solely on blood pressure as an endpoint for resuscitation
• Delayed recognition of fluid overload
• Inappropriate fluid choice
• Inadequate monitoring
• Failure to consider specific disease states 4

Early recognition and prompt, appropriate fluid resuscitation are critical to preventing progression to irreversible shock and multi-organ failure.