Lecture Notes: Hypovolemia vs Hypervolemia

Introduction

• Presenter: Christine from Nurse in the Making
• Topic: Differences between Hypovolemia and Hypervolemia

Hypovolemia

• Definition: Low fluid volume in the vessels
  • Also known as dehydration, fluid volume deficit, fluid depletion
  • Can lead to hypovolemic shock if untreated
• Causes:
  • Loss of fluids from various sources (thoracentesis, paracentesis, hemorrhage, NG tube, trauma, GI losses)
  • Polyuria (e.g., diabetes, diabetes insipidus, diuretics)
  • Third spacing (burns, ascites) – fluid shifts from the intravascular space to the interstitial space
• Signs and Symptoms:
  • Decreased weight (loss of water weight)
  • Increased heart rate (weak and thready pulse)
  • Decreased blood pressure
  • Decreased CVP (Central Venous Pressure)
  • Increased respirations
  • Decreased urine output
  • Decreased skin turgor (tenting)
  • Dry mucous membranes, thirst
  • Flat neck veins
• Laboratory Findings:
  • Increased serum osmolality
  • Increased urine-specific gravity
  • Increased hematocrit
  • Increased serum sodium
  • Increased BUN
• Treatment:
  • Replace fluid loss (PO or IV)
  • Monitor for fluid overload when giving IV fluids
  • Safety precautions: prevent orthostatic hypotension, educate to rise slowly
  • Daily I's and O's, daily weights (same time, scale, clothes)

Hypervolemia

• Definition: High fluid volume in the vessels
  • Also known as fluid volume excess, overhydration
• Causes:
  • Heart failure (backflow of blood)
  • Kidney dysfunction (inability to excrete excess volume)
  • Cirrhosis
  • Increased sodium intake (sodium retention leads to fluid retention)
• Signs and Symptoms:
  • Increased weight (water weight)
  • Increased heart rate (bounding pulse)
  • Increased blood pressure
  • Increased CVP
  • Wet lung sounds (crackles, pulmonary edema)
  • Polyuria (large amounts of dilute urine)
  • Edema
  • Distended neck veins (JVD)
• Laboratory Findings:
  • Decreased serum osmolality
  • Decreased urine-specific gravity
  • Decreased hematocrit
  • Decreased serum sodium
  • Decreased BUN
• Treatment:
  • Low sodium diet
  • Daily I's and O's, daily weights (same time, scale, clothes)
  • Diuretics to remove excess fluid
  • Position patient in high to semi-fowler’s to ease breathing

Conclusion

• Key differences between hypovolemia (deficit) and hypervolemia (excess) in terms of causes, symptoms, labs, and treatments.
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