8- Fluid balance and IV fluid therapy (n) copy

Fluid Therapy in Emergency Medicine

Fluid Requirements

Daily Fluid Requirement:

The average daily fluid requirement for a normal adult weighing approximately 70kg is about 2 to 2.5 liters. The breakdown of fluid losses is as follows:

  • Urine: 1500 mL

  • Insensible losses: 800 mL

  • Stool: 200 mL

The total fluid intake typically comes from the following sources:

  • Food: 1000 mL

  • Drinks: 1500 mL

Intravenous Fluids

Intravenous fluids are necessary when oral intake isn't sufficient to meet these requirements. On average, patients require approximately 2–2.5L of fluids containing roughly 70mmol of sodium (Na+) and potassium (K+) daily to maintain proper electrolyte balance.

  • Venous Access Options:

    • Peripheral IV line or central line can be used; however, the risk of infection is higher with central lines. esp MRSA

    • Preferred order of venous access: femoral > jugular > subclavian > peripheral.

      RESUME ORAL FLUID INTAKE ASAP

    • Considerations for Fluid Loss:

    • Be mindful of additional fluid loss factors such as drains, fever, diarrhea, or conditions that might increase metabolic demands.

    • Regular patient assessments are critical to monitoring fluid balance, especially in dynamically changing clinical situations.

Fluid Compartments

The total bodily fluid for a 70kg individual is approximately 42 liters, constituting about 60% of body weight. This fluid is distributed as follows:

  • Intracellular Fluid: 28L (approximately 2/3 of total fluid)

  • Extracellular Fluid: 14L (approximately 1/3 of total fluid), which includes:

    • Intravascular Fluid: 5L (constituting 1/3 of the extracellular fluid).

    • The different types of IV fluids will distribute among these compartments based on their osmotic content, thereby influencing patient hydration status and electrolyte balance.

Types of IV Fluids

  1. 5% Glucose (Dextrose):

    • Isotonic solution containing minimal glucose (50g/L).

    • Provides roughly 10% of daily energy needs per liter

    • it is rapidly metabolized by the liver, making it unsuitable for resuscitation but effective for hydration.

    • Potential risk: Excess can lead to water overload and hyponatremia.

  2. 0.9% Saline (Normal Saline):

    • Isotonic solution with sodium content matching plasma (150mmol/L).

    • Rapidly equilibrates in the extracellular space

    • is effective for fluid resuscitation and maintaining hydration.

    • Less effective in affecting intracellular fluid when compared to glucose-based fluids.

  3. Glucose with NaCl (Dextrose Saline):

    • Isotonic solution composed of 0.18% saline (30mmol/L Na+) and 4% glucose (222mmol/L).

    • Provides essential Na+ for fluid maintenance when given every 10hrs

    • commonly used in pediatric patients to balance fluids and electrolytes effectively.

  4. Ringer’s Lactate Solution (Hartmann’s Solution):

    • Complex composition: Na+ 131mmol, Cl- 111mmol, lactate 29mmol, K+ 5mmol, HCO3- 29mmol, Ca2+ 2mmol/L.

    • Often considered more physiological than 0.9% saline, as it better mimics plasma composition and helps in maintaining the acid-base balance during resuscitation.

  5. Hypertonic Glucose:

    • Available in various concentrations (10%, 50%, etc.).

    • Used primarily in emergencies to treat hypoglycemia

    • caution is necessary as hypertonic solutions can irritate veins.

    • Regular inspection and flushing of infusion sites with 0.9% saline is essential post-use to prevent phlebitis.

Assessing Fluid Balance

Signs of an Underfilled State (Hypovolaemia):

  • Tachycardia.

  • Low Jugular Venous Pressure (JVP).

  • Postural drop in blood pressure.

  • Non-specific physical signs: dry mucous membranes, decreased skin turgor, sunken eyes, and altered mental status.

Signs of an Overfilled State (Hypervolemia):

  • Pitting edema in extremities and abdominal swelling.

  • Bibasal crepitations audible on lung examination, indicative of pulmonary edema.

  • Cool peripheries; hypervolemia can be further visualized via chest X-ray (CXR).

The Jugular Venous Pressure (JVP) serves as a crucial marker for assessing central venous pressure