Fluid & Electrolyte, & Acid-base Balance

FLUID & Electrolyte & Acid-base Balance Notes

Introduction

  • Focus on the care for clients with fluid, electrolyte, and acid-base imbalances based on the provided chapter material from GateWay Community College NUR160PN.

Body Fluids Components

  • Main Components:
    • Water and Chemicals: Essential for various physiological functions.
    • Electrolytes: Substances that carry an electrical charge when dissolved in fluids.
    • Acids: Release hydrogen ions into fluids.
    • Bases: Substances that bind with hydrogen ions.
  • Purpose:
    • Regulate fluid volume.
    • Buffer blood to maintain a neutral pH.

Body Fluid Compartments

  • Total Water Composition:
    • Approximately 60% of the body is water.
  • Fluid Types:
    • Intracellular Fluid (ICF): Fluid located within the cells.
    • Extracellular Fluid (ECF): Fluid located outside of cells.
    • Interstitial Fluid: Fluid found between the cells.
    • Intravascular Fluid: Plasma that circulates within blood vessels.

Intake and Output

  • Average Fluid Intake:
    • Adults require approximately 2500 mL/day (normal range: 1800 to 3600 mL/day).
    • Sources include food and liquids.
  • Fluid Elimination:
    • Sources: Urination, bowel elimination, perspiration, and breathing.
    • Insensible Losses: Losses that occur through sweat and exhaled air.

Distribution of Fluids and Electrolytes

  • Physiological Processes: Continuous translocation of fluid and exchange of electrolytes, acids, and bases through five key mechanisms:
    • Osmosis: Movement of water through a semipermeable membrane; connected to tonicity.
    • Filtration: Movement of fluid based on pressure differences, particularly in the kidneys.
    • Passive Diffusion: Movement of substances across membranes without energy, with examples including insulin facilitating glucose transport into cells.
    • Facilitated Diffusion: Similar to passive diffusion but involves a carrier protein for transport.
    • Active Transport: Requires energy (ATP), exemplified by the sodium–potassium pump, which regulates sodium and potassium levels across cell membranes.

Mechanisms of Fluid and Electrolyte Regulation

  • Osmoreceptors: Neurons that detect blood concentration and stimulate the release of Antidiuretic Hormone (ADH).
  • Baroreceptors: Monitor blood pressure changes.
  • Renin-Angiotensin-Aldosterone System (RAAS): A hormone system that regulates blood pressure and fluid balance through chemical release.
  • Natriuretic Peptides: Such as ANP and BNP, which are released to increase urine production.

Fluid Imbalances

Hypovolemia

  • Definition: Reduced volume of extracellular fluid.
  • Causes:
    • Vomiting, diarrhea, wounds, profuse urination, hemoconcentration.
  • Assessment Findings: Increased thirst.
  • Diagnostic Findings:
    • Elevated Hematocrit (Hct) and blood cell counts.
    • Elevated urine specific gravity.
  • Medical Management: Replenishing fluid deficits through oral or IV methods.
  • Nursing Management: Encourage 8 to 10 glasses of water per day, avoid caffeine, restrict sodium.

Hypervolemia

  • Definition: Increased volume of water in the intravascular fluid compartment.
  • Causes:
    • Excessive oral intake, IV fluids, heart failure, kidney disease, adrenal gland dysfunction, circulatory overload.
  • Assessment Findings:
    • Weight gain, elevated blood pressure, pitting or nonpitting edema, dependent edema, moist lung sounds.
  • Diagnostic Findings:
    • Low Hematocrit (Hct) and blood cell count, low specific gravity indicating hemodilution.
  • Medical Management: Restricting oral or parenteral fluid intake; use diuretics; limit sodium.

Fluid Imbalances and Edema Classification

  • Pitting Edema:
    • 1+ Pitting: Slight indentation (2 mm); normal contours; indicates interstitial fluid volume 30% above normal.
    • 2+ Pitting: Deeper pit (4 mm), lasts longer than 1+.
    • 3+ Pitting: Deep pit (6 mm).
    • 4+ Pitting: Very deep pit (8 mm), remains for several seconds; skin swelling is obvious.
  • Brawny Edema: Fluid can no longer be displaced due to excessive interstitial fluid accumulation; no pitting, skin feels firm or hard.

Nursing Care Plan for Hypervolemia

  • Nursing Diagnosis: Excess Fluid Volume related to intake that exceeds fluid loss.
  • Monitoring Requirements:
    • Baseline and daily weights (weight gain of 2 lb/24 hours raises concern).
    • Accurate intake and output.
    • Auscultate lung sounds.
    • Measure vital signs including blood pressure and heart rate.
    • Inspect skin for edema, cracks, and breakdown.

Third-Spacing

  • Definition: Translocation of fluid from intravascular to tissue compartments where it becomes unusable.
  • Causes: Hypoalbuminemia, burns, severe allergic reactions.
  • Assessment Findings: Ascites and generalized edema.
  • Diagnostic Findings:
    • Hemoconcentration, CVP normal, borderline blood counts.
  • Medical Management: Albumin infusion, IV diuretic, paracentesis to relieve pressure.

Electrolyte Imbalances

  • General Concept: Electrolyte imbalances can occur as deficits or excesses and are typically accompanied by fluid changes.

Causes of Deficits

  • Administration of IV fluids, vomiting, diarrhea, use of diuretics.

Causes of Excess

  • Over-consumption orally, parenteral administration, kidney failure, endocrine dysfunction, crushing injuries, burns.

Priority Electrolyte Imbalances

  • Sodium, potassium, calcium, magnesium.

Sodium Imbalances

Normal Range: 135-145 mEq/L
  • Function:
    • Maintains normal nerve and muscle activity, regulates osmotic pressure, and preserves acid-base balance.
  • Imbalance Definitions:
    • Hyponatremia: Serum sodium level below 135 mEq/L.
    • Causes: Profuse sweating, diuretic use, gastrointestinal fluid losses, Addison Disease.
    • Assessment Findings: Mental confusion, muscular weakness, anorexia, elevated body temperature, tachycardia.
    • Medical Management: Encourage foods high in sodium, administer IV sodium chloride.
    • Hypernatremia: Serum sodium level above 145 mEq/L.
    • Causes: Diarrhea, excessive salt intake, high fever, excessive water loss, reduced water intake.
    • Assessment Findings: Thirst, dry mucous membranes, decreased urine output, fever.
    • Diagnostic Findings: Serum levels >145 mEq/L.
    • Medical Management: Encourage water intake, administer hypotonic IV solution (0.45% NaCl or 5% dextrose), monitor intake and output, assess vital signs, dietary restrictions/supplements.

Potassium Imbalances

Normal Range: 3.5-5 mEq/L
  • Function: Maintains normal nerve and muscle activity, especially in the cardiac context.
  • Hypokalemia: Serum potassium below 3.0 mEq/L.
    • Causes: Potassium-wasting diuretics, GI losses, corticosteroid use, IV insulin.
    • Assessment Findings: Fatigue, weakness, nausea, cardiac dysrhythmias, paresthesias.
    • Medical Management: Potassium-sparing diuretics, dietary potassium intake, oral/IV potassium supplementation.
  • Hyperkalemia: Serum potassium above 5.5 mEq/L.
    • Causes: Renal failure, potassium-sparing diuretics, overconsumption of potassium, Addison's disease.
    • Assessment Findings: Diarrhea, nausea, muscle weakness, cardiac dysrhythmias.
    • Medical Management: Restrict potassium intake, administer insulin and glucose, use of Kayexalate, dialysis.

Calcium Imbalances

Normal Range: 8.8-10 mg/dL
  • Function: Essential for blood clotting, nerve impulse transmission, regulated by the parathyroid gland.
  • Hypocalcemia: Serum calcium below 8.8 mg/dL.
    • Causes: Vitamin D deficiency, hypoparathyroidism, pancreatitis.
    • Assessment Findings: Tingling, muscle cramps, Chvostek's and Trousseau's signs, bleeding.
    • Medical Management: Administer calcium and vitamin D supplementation, IV calcium infusions.
  • Hypercalcemia: Serum calcium above 10 mg/dL.
    • Causes: Parathyroid tumors, prolonged immobilization.
    • Assessment Findings: Deep bone pain, kidney stones, constipation.
    • Medical Management: Treat underlying cause, IV sodium chloride, diuretics.

Magnesium Imbalances

Normal Range: 1.3-2.1 mEq/L
  • Function: Transmits nerve impulses, activates enzyme systems.
  • Hypomagnesemia: Serum magnesium below 1.3 mEq/L.
    • Causes: Alcoholism, renal disease, malnutrition.
    • Assessment Findings: Tachycardia, neuromuscular irritability.
    • Medical Management: Administer oral or IV magnesium, dietary supplements.
  • Hypermagnesemia: Serum magnesium above 2.1 mEq/L.
    • Causes: Renal failure, excessive antacid use.
    • Assessment Findings: Flushing, lethargy, muscle weakness.
    • Medical Management: Limit oral magnesium, potential mechanical ventilation.

Acid–Base Imbalances

  • Regulation of Plasma pH: Normal plasma pH should range from 7.35 to 7.45; critical death occurs if it falls outside 6.8 to 7.8.
  • Key Terms:
    • Carbonic Acid (H2CO3): Regulates pH through respiration by altering carbonic acid levels.
    • Bicarbonate (HCO3): Regulates pH via retention or excretion by the kidneys.
  • Types of Imbalance:
    • Acidosis: Excess acidity due to acid accumulation or bicarbonate loss.
    • Alkalosis: Excess alkalinity due to base accumulation or acid loss.

Normal Values to Remember

  • pH: 7.35-7.45
  • PaCO2: 35-45 mmHg
  • HCO3: 22-26 mEq/L

Steps to ABG Analysis

  1. Analyze pH:
    • pH < 7.35 = Acidic
    • pH > 7.45 = Alkalotic
  2. Analyze CO2:
    • If PaCO2 isn't in range, indicates respiratory issue.
    • PaCO2 < 35 = Alkalosis
    • PaCO2 > 45 = Acidosis
  3. Analyze HCO3:
    • HCO3 < 22 = Acidosis
    • HCO3 > 26 = Alkalosis

Acid-Base Balance Classification

  • ROME:
    • Respiratory: Opposite (in respiratory imbalances, pH and CO2 move inversely).
    • Metabolic: Equal (in metabolic imbalances, pH and HCO3 move in the same direction).
  • Regulatory Organs:
    • Lungs: Control carbonic acid levels via respiration.
    • Kidneys: Regulate bicarbonate retention/excretion.

Sample Cases of Acid-Base Disturbances

  1. Respiratory Alkalosis: pH 7.49, CO2 32, HCO3 24.
  2. Metabolic Alkalosis: pH 7.49, CO2 40, HCO3 30.
  3. Metabolic Acidosis: pH 7.32, CO2 40, HCO3 18.

Common Causes of Metabolic Acidosis

  • Causes include shock, cardiac arrest, starvation, and renal failure; assessment findings include Kussmaul breathing, nausea, and abdominal pain.

Common Causes of Metabolic Alkalosis

  • Causes include excessive vomiting, diuretic therapy; assessment findings include confusion, paresthesias, decreased respirations.

Common Causes of Respiratory Acidosis

  • Causes include COPD, airway obstruction; assessment findings include hypoventilation, cyanosis.

Common Causes of Respiratory Alkalosis

  • Causes include anxiety, fever, mechanical ventilation; assessment findings include light-headedness, numbness, and tingling.

Practice Question Responses

  1. Acid-base disturbance in narcotic overdose: B) Respiratory Acidosis - because narcotic overdose can slow respiration rates and lead to CO2 retention.
  2. Interventions for hypercalcemia: A) Encourage fluids - helps promote calcium excretion.

Additional Resources

  • Video segments: Consciousness on Electrolyte Imbalances and Acid-Base Balance.
  • Further practice sessions recommended for retention of acid-base balance analysis.

Concluding Remarks

  • Continual education on fluid, electrolyte, and acid-base management is vital in nursing practice to ensure effective client care and to uphold patient safety.