Fluid and Electrolyte Balance

Fluid and Electrolytes

Introduction to Fluid Balance

• The body is primarily composed of water and electrolytes.

• Electrolytes include sodium, potassium, calcium, etc.

• Losing water often results in electrolyte loss as well.

• Salt follows water; therefore, volume loss (vomiting, diarrhea) usually involves salt loss.

• Pedialyte is recommended for electrolyte replacement with less sugar than Gatorade.

Electrolytes

• Electrolytes are minerals or salts dissolved in body fluid.

• Also known as ions with electrical charges.

• Cations: Positive charge (remember "cats" and petting them)

• Anions: Negative charge (A in medical terminology means "without" – without positive charge).

• Ions must be balanced (cation balanced with anion).

• Imbalances cause various problems.

Special Considerations

• Infants and elderly are more affected by fluid balance changes.

• Infants have more water in their systems, making them more vulnerable.

• Elderly individuals often experience dehydration.

Water in the Body

• Water is a major component of the circulatory system (plasma, red blood cells).

• Facilitates the transport of electrolytes.

• Water intake is dependent on external sources; the body doesn't produce it.

• Adequate water intake helps prevent swelling and improves kidney function.

• Aids in digestion; lack of water leads to constipation.

• Intake depends on physical health, age, and gender.

Sources of Water

• Main source: Drinking water.

• Foods with high water content (e.g., melons).

• Metabolism produces some water.

• Oral intake of water is measurable.

• Clear liquids also count as water intake (e.g., coffee).

Water Output

• Urine.

• Sweating.

• Feces.

• Exhalation.

• Output is slightly more than intake due to additional routes of water loss.

• Only specific outputs (urine) are typically measured.

• Survival without water is approximately three days.

Electrolytes Explained

• Minerals and salts dissolved in body fluids, also known as ions.

• Ions have positive (cations) or negative (anions) charges.

• Main source: Diet.

• Key electrolytes: Sodium, potassium, calcium, magnesium, chloride, and phosphate.

Sodium

• Water regulation and balance.

• Minor role in heart rhythm.

• Water follows sodium concentration (osmosis).

• Excess sodium leads to swelling.

• Insufficient sodium affects heart rhythm.

Potassium

• Critical for heart rhythm.

• Nerve impulse transmission (signals to the brain).

• Muscle contraction.

• Too high or too low potassium can cause arrhythmias and cardiac arrest.

Calcium

• Affects muscle activity.

• Blood coagulation.

• Bone and teeth development.

• Insufficient calcium can lead to osteoporosis.

Magnesium

• Nerve impulse transmission.

• Muscle contraction.

• Blood coagulation.

• Used for sleep and muscle pain.

• Excess intake can cause serious problems, particularly affecting glycogen.

Chloride

• Maintains acid-base balance.

• More in-depth study in med-surg courses.

Phosphate

• ATP production (energy).

Normal Electrolyte Ranges

• Sodium: 135-145

• Ranges may vary; use the book's values for tests.

• NCLEX will provide values significantly outside the normal range.

• Memorization, especially of sodium and potassium, is essential.

Non-Electrolytes

• Amino acids (complete with all 11, incomplete with less).

• Glucose (sugar).

• Fatty acids.

Blood

• Normal volume: 4 to 6 liters.

• Composed of:

  • Erythrocytes (red cells, erythro- meaning red).

  • Leukocytes (white cells, leuko- meaning white).

  • Platelets (thrombocytes).

  • Plasma (liquid part).

• Plasma volume affects circulation.

Fluid Compartments

• Intracellular: Inside the cell (most water is here).

• Extracellular: Outside the cell.

  • Vascular system (blood products).

  • Interstitial (spaces between cells, e.g., pleural space).

  • Transcellular.

Extracellular Fluid

• 1/3 of total body water.

• Transports nutrients and hemoglobin to and from cells.

• High in sodium content.

Intravascular Fluid

• Blood cells.

• High in protein and electrolytes.

• Maintains volume.

Transcellular Fluid

• Fluid in cavities (peritoneal, pericardial).

• Gastrointestinal secretions.

• Fluids in the urinary tract, eyes, and saliva.

• Testing can reveal abnormal contents (e.g., glucose or protein in urine).

Fluid Output: Urinary System

• Kidneys and bladder are primary.

• Other losses: Feces, sweating, breathing, crying.

• Thirst indicates existing dehydration.

• The thirst signal comes from the hypothalamus in the brain.

Hormonal Regulation of Fluid Balance

Antidiuretic Hormone (ADH)

• Released when dehydrated or with low fluid volume.

• Causes fluid retention.

• Issues with ADH can lead to dehydration.

Aldosterone

• Affects water amount in the body.

Atrial Natriuretic Peptide (ANP)

• Protects from fluid overload.

• Electrolyte balance is tied to fluid balance.

• Excessive fluid dilutes electrolytes.

Factors Affecting Fluid and Electrolyte Balance

• Kidney function.

• Illness (vomiting, diarrhea).

• Heart conditions (congestive heart failure causes fluid retention).

• Fluid deficit concentrates electrolytes; fluid excess dilutes them.

Fluid Volume Deficit (Hypovolemia)

• Inability to take in enough fluid.

• Excessive fluid loss (blood loss, vomiting, diarrhea, sweating, wound drainage).

• Inability to take in fluid due to weakness or coma.

• Hemorrhage, excessive wound drainage (burns), and vomiting/diarrhea can cause excessive fluid loss.

• Dehydration: Too little water in the plasma; cells start drawing water out of cells, which can lead to cell death.

• Treatment: Fluids (orally or IV).

• Rapid fluid replacement can shock the system due to electrolyte imbalances.

Signs and Symptoms of Dehydration

• Thirst.

• Poor skin turgor.

• Fatigue.

• Dizziness.

• Concentrated, dark urine with a strong odor.

• Low blood pressure (orthostatic).

• Decreased urine production.

• Dry or cracked lips.

• Dry mucous membranes.

• Thick saliva.

• Flat neck veins.

• Increased, weak, and thready pulse.

• Elevated temperature.

• Headache.

Symptoms are triggered by

• Less volume in plasma.

• Increased ADH production, leading to decreased urine volume.

Fluid Volume Excess (Hypervolemia)

• Excessive fluid.

• Risk: Circulatory issues, rapid IV fluids (bolus), high-volume enemas, drinking too much water, overproduction of ADH.

Neurological Changes Include

• Headaches.

• Confusion.

• Changes in level of consciousness.

Cardiovascular Changes Include

• Bounding pulse.

• Distended jugular vein.

• Increased blood pressure.

• Possible extra heart sound (S3).

• Tachycardia.

Gastrointestinal Changes Include

• Anorexia.

• Nausea.

• Pulmonary congestion.

• Edema (pitting or non-pitting).

• Electrolyte concentrations and osmolality can be decreased due to water excess.

Other Symptoms Include

• Weight gain.

• Crackles in the lungs.

• Slow bounding pulse.

• Elevated blood pressure.

• Edema.

Assessment and Interventions

• Tracking intake and output.

• Vital signs.

• Urine analysis.

• Complete Metabolic Panel (CMP) for electrolytes.

• Physical assessment.

• Nursing diagnoses: Fluid volume deficit or excess.

Interventions Depend on the Side of the Spectrum:

• Assess eyes and nose.

Fluid Excess:

• Limit fluids (fluid restriction).

Fluid Deficit

• Administer fluids.

• Monitor electrolyte values (daily CMP).

• Daily weights.

• Diuretics (monitor sodium and potassium levels).

Review Questions

• Minimum urine output: 30 mL/hour.

• Fluid intake should be slightly more than total output because of water loss from other mechanisms.