Body Fluid Compartments, Osmosis, and IV Fluids

Introduction

• Presented by Sarah from RegisteredNurseRN.com
• Focus on body fluid compartments, osmosis, and types of IV fluids.

IV Fluids

• Definition: Special fluids administered to the intravascular space (extracellular compartment).
• Common Uses:
  • Treat dehydration
  • Correct electrolyte imbalances
  • Address acid-base imbalances
• Nurse's Role: Administer fluids as per healthcare provider's orders and monitor patients.

Body Fluid Compartments

• Total Body Water: Average adult body is about 60-70% water.
• Main Compartments:
  • Intracellular Compartment:
    • Fluid inside the cell.
    • Accounts for 2/3 of body water.
  • Extracellular Compartment:
    • Fluid outside the cell (1/3 of body water).
    • Contains:
      • Intravascular Fluid: Plasma found in blood vessels.
      • Interstitial Fluid: Surrounds the cells.
      • Transcellular Fluid: Found in certain body cavities (e.g., spinal fluid, joint fluid).

Interconnection of Compartments

• Compartments are interconnected and work together to maintain homeostasis by shifting water, electrolytes, and nutrients via osmosis.

Osmosis

• Definition: Movement of water from a higher concentration of water (lower solute concentration) to a lower concentration of water (higher solute concentration) across a semi-permeable membrane.
• Key Concept: Solute concentration influences the movement of water between intracellular and extracellular compartments.
• Solute Definition: Solid dissolved in a liquid (e.g., sodium, chloride).
• Osmolarity: The total solute concentration per liter of solution.
  • High Osmolarity: High solute concentration (less water).
  • Low Osmolarity: Low solute concentration (more water).

Types of IV Fluids

Isotonic IV Solutions

• Definition: Same osmolarity as blood plasma (equal solute concentrations).
• Function: Expands extracellular fluid volume without altering cell size.
• Uses:
  • Fluid loss from vomiting, diarrhea, hypovolemic shock, or surgery.
• Examples:
  • Normal saline (only solution used with blood).
  • Lactated Ringer's (LR).
  • 5% Dextrose in Water (D5W) - starts isotonic but becomes hypotonic after metabolism.
• Monitoring: Watch for fluid overload, especially in patients with kidney or heart issues.

Hypertonic IV Solutions

• Definition: Higher osmolarity than blood (higher solute concentrations).
• Function: Causes water to move from intracellular to extracellular space (can shrink cells).
• Uses: Treat severe hyponatremia or cerebral edema.
• Examples:
  • 3% saline
  • Dextrose 10% in water
  • Dextrose 5% in normal saline
• Monitoring: Risk of fluid overload and hypernatremia; may require central line administration.

Hypotonic IV Solutions

• Definition: Lower osmolarity than blood (lower solute concentrations).
• Function: Causes water to move from extracellular to intracellular space (can swell cells).
• Uses: Treat hypernatremia and provide free water for kidney function.
• Examples:
  • Half normal saline (0.45% saline)
  • 0.225% saline
  • 5% Dextrose in water (starts isotonic, becomes hypotonic in the body)
• Monitoring: Watch for brain swelling, low blood pressure, and hyponatremia, especially in fluid-sensitive patients.

Conclusion

• Understanding body fluid compartments, osmosis, and IV fluids is essential for effective patient care.
• For more information, watch additional videos linked in the YouTube description.