Fluid Balance, Osmolarity, and Fluid Volume Management

Introduction

• Key topics: fluid balance, osmolarity, calculating intake & output, fluid volume excess, and deficit.
• Reference: Nursing Fundamentals flashcards (starting at card 90).

Solution Osmolarity

Types

• Hypertonic: Higher tonicity than body fluid.
  • Causes fluid to move out of cells (cells shrink).
  • Examples: D10W (dextrose 10% in water), 3% Sodium Chloride, 5% Sodium Chloride.
• Isotonic: Same tonicity as body fluid.
  • No change in intracellular volume.
  • Examples: Normal Saline, Lactated Ringers.
• Hypotonic: Lower tonicity than body fluid.
  • Causes fluid to move into cells (cells swell and may burst).
  • Examples: 0.45% Normal Saline, 0.225% Normal Saline.

Intake and Output Calculation

• Intake: All fluids entering the body (oral, IV, medications, etc.).
• Output: All fluids exiting the body (urine, emesis, blood, etc.).
  • Sensible losses: Measurable (e.g., urine, blood).
  • Insensible losses: Not measurable (e.g., sweat, respiration).
• Key Conversion: 1 fluid ounce = 30 mLs.
• Ice Chips: Recorded at half volume (100 mLs of ice chips = 50 mLs of water).

Fluid Volume Deficit

Signs and Symptoms

• Hypotension & Tachycardia (compensatory mechanism).
• Pulse: Fast but weak and thready.

Labs and Diagnostics

• Elevated Hematocrit, Blood Osmolality, BUN, Urine Specific Gravity, Urine Osmolality.

Treatment

• IV fluids (usually isotonic).
• Notify provider if urine output <30 mLs/hour.

Fluid Volume Excess

Signs and Symptoms

• Weight gain, Edema, Hypertension, Tachycardia.
• Dyspnea, Crackles in lungs, Jugular vein distension, Bounding pulses.

Labs and Diagnostics

• Decreased Hematocrit, Hemoglobin, Serum Osmolality, Urine Specific Gravity.

Treatment

• Diuretics, Procedures to remove excess fluid (e.g., paracentesis).
• Report weight gain of 1-2 lbs in 24 hours or 3 lbs in a week.

Conclusion

• Understanding these concepts is crucial for nursing exams and NCLEX.
• Encourage engagement through comments and video interactions.
• Upcoming content: Electrolytes and electrolyte imbalances.