F/E & A/B LECTURE 3

Fluid Replacement Agents

• Categories of IV Solutions

  • Crystalloids:

    • Crystalloids are solutions that contain small molecules, usually salts, that can freely cross cell membranes. They mainly consist of electrolytes and mimic the body’s extracellular fluid.

    • These solutions are commonly used for replacing depleted fluids and promoting urine output, especially in cases of dehydration.

    • Crystalloids are suitable for short-term maintenance of fluid balance and can rapidly diffuse across membranes, distributing into both interstitial and intracellular compartments.

    • However, they can lead to cellular movement between compartments (plasma, interstitial, intracellular), which can necessitate further monitoring and adjustments of fluid therapy.

    • Types of Crystalloids:

      • Isotonic Solutions:

        • These solutions have the same osmotic pressure as extracellular fluid (280-300 osmoles), expanding circulating intravascular volume without causing significant fluid shifts.

        • Isotonic solutions are often used in clinical scenarios of fluid loss due to conditions such as vomiting, diarrhea, and surgical hydration.

        • Examples include:

          • Lactated Ringer's Solution: contains electrolytes and buffers to help with metabolic acidosis.

          • Normal Saline: a standard for fluid resuscitation, especially in emergencies.

          • D5W (5% Dextrose in Water): provides calories and can also be used for hydration.

      • Hypertonic Solutions:

        • These solutions have a higher osmolarity than 300 osmoles, drawing water out of cells and into the plasma, which can result in cellular shrinkage.

        • Hypertonic solutions are typically utilized in cases of cellular edema, particularly cerebral edema, as they help reduce intracranial pressure.

        • Example: D5 half normal saline, which is used selectively under specific medical guidance.

      • Hypotonic Solutions:

        • These solutions have a lower osmolarity than 280 osmoles, facilitating the movement of water into cells and potentially causing them to swell.

        • Hypotonic solutions are indicated for the treatment of hypernatremia and in cases where cellular hydration is critically needed.

        • Example: Half normal saline, utilized cautiously to avoid rapid shifts in fluid balance.

  • Colloids (Plasma Expanders):

    • Colloids are solutions that contain larger molecules, such as proteins and starches, which remain in the vascular system longer than crystalloids.

    • These larger molecules draw water into the plasma, which increases osmolarity and oncotic pressure, making colloids effective for treating hypovolemic shock, which can occur due to burns, hemorrhages, or major surgical losses.

    • Example: Dextran, which can improve blood volume but carries risks such as hypersensitivity reactions, fluid overload, and hypertension in vulnerable populations.

  • Blood and Blood Products:

    • This category includes essential components like Packed Red Blood Cells (PRBC), plasma, platelets, and albumin meant for restoring blood volume and improving oxygen-carrying capacity.

    • When administering blood products, use a large bore IV (19 gauge or larger), and adhere strictly to blood transfusion protocols.

    • Key administration protocols include:

      • Proper tubing and administration protocols to minimize contamination risk.

      • Maximum transfusion time should not exceed 4 hours to reduce the risk of bacterial growth.

      • Never add medications to blood units, as this can alter the blood product's effectiveness and safety.

Nursing Considerations for Fluid Replacement

• Perform a thorough health history assessment to identify patient risks for fluid status alterations.

• It is imperative to monitor the following:

  • Vital signs to detect any abnormalities in blood pressure or heart rate, which may indicate fluid overload or deficit.

  • Look for signs of allergic reactions or hypersensitivity during and after administration of fluids.

  • Continuous assessment of fluid volume status through physical exams and patient-reported outputs.

  • Neuro status to ensure adequate cerebral perfusion, especially in cases of hypertonic solutions used.

  • Urinary output, which is a critical indicator of renal function and fluid balance.

Electrolyte Replacement

• Potassium Chloride:

  • This electrolyte is crucial for treating hypokalemia and preventing complications related to alkalosis.

  • Available in multiple forms including tablets and IV solutions; oral forms should be diluted and taken with food to minimize gastrointestinal irritation.

  • Intravenous administration of potassium chloride should be done slowly (typically 5-10 mEq/hour) to avoid hyperkalemia and associated cardiac issues.

  • Close monitoring of IV sites is necessary to prevent complications such as thrombophlebitis.

• Sodium Chloride:

  • Sodium chloride is essential for treating hyponatremia and is available in various forms such as IV solutions, tablets, and sprays.

  • Care must be taken to avoid excessive administration, as this can lead to hypernatremia; monitoring symptoms of over-administration is crucial.

• Calcium Gluconate:

  • Administered for hypocalcemia, it is available in both IV and oral forms.

  • Monitoring is critical for adverse effects, particularly potential cardiac issues that can arise with rapid administration.

• Magnesium:

  • Magnesium supplementation, particularly via IV administration, is key in managing hypomagnesemia.

  • IV administration should be done slowly under care due to the risk for hypermagnesemia with overuse, emphasizing the importance of appropriate dosing.

Acid-Base Correction

• Sodium Bicarbonate:

  • Often used in the treatment of metabolic acidosis, it can be administered either intravenously or orally.

  • Care should be taken not to mix with calcium solutions due to potential adverse chemical reactions.

  • Excessive use can lead to metabolic alkalosis, necessitating close monitoring for symptoms like muscle twitching or irritability.

• Ammonium Chloride:

  • Ammonium chloride is used to treat metabolic alkalosis when administered slowly via IV or orally; careful monitoring for signs of acidosis is essential during this treatment.

• Ion Exchange Resin (K-exelate):

  • This is utilized for managing hyperkalemia, taking advantage of its mechanism of exchanging sodium for potassium.

  • Administration can be done orally or via enema, but side effects, including constipation and gastrointestinal irritation, must be monitored closely.