Fluids & electrolytes

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Fluid, Electrolyte, and Acid-Base Regulation

Electrolytes

• Electrolytes are minerals in the body that conduct electricity.

  • Found in urine, blood, tissues, and other body fluids.

  • Include potassium (K+), sodium (Na+), calcium (Ca2+), magnesium (Mg2+).

  • Naturally occurring in the body; found in food, drinks, and supplements.

Functions of Electrolytes

• Responsible for balancing the body’s:

  • Water content.

  • pH (acid/base) levels.

  • Waste removal from body cells.

  • Nutrient intake into body cells.

  • Proper functioning of muscles, heart, nerves, and brain.

Dehydration

• The average person's weight composition is 50-66% water.

• Dehydration occurs when fluid intake is insufficient to meet bodily needs, leading to fluid loss.

Thirst Mechanism

• Thirst is triggered by nerve centers in the brain when water is needed.

• The pituitary gland secretes vasopressin (antidiuretic hormone) to:

  • Stimulate kidneys to conserve water by reducing urine output.

Electrolyte Imbalance Causes

• May result from:

  • Dehydration and overhydration.

  • Certain medications and disorders (heart, kidney, liver).

  • Incorrect intravenous fluids or feedings.

Normal Electrolyte Values

• Potassium (K+): 3.5-5.1 mEq/L

• Sodium (Na+): 135-145 mEq/L

• Calcium (Ca2+): 8.5-10.5 mg/dL

• Magnesium (Mg2+): 1.8-2.2 mg/dL

Potassium and Sodium Levels

Potassium (K+) Function

• Crucial for nerve and muscle cell function, particularly in heart muscle.

• Low potassium = hypokalemia; high potassium = hyperkalemia.

Sodium (Na+) Function

• Supports nerve and muscle functions, maintains blood pressure, regulates fluid balance.

• Low sodium = hyponatremia; high sodium = hypernatremia.

Calcium (Ca2+) Function

• Maintains strong bones; stored in teeth and bones to support hardness.

• Assists muscle movement, nerve messaging, and blood vessel function.

• Low calcium = hypocalcemia; high calcium = hypercalcemia; linked to parathyroid gland disorders.

Magnesium (Mg2+) Function

• Regulates nerve and muscle function, blood pressure, and blood sugar levels.

• Vital for bone, protein, and DNA production.

• Low magnesium = hypomagnesemia; high magnesium = hypermagnesemia.

Hypovolemia

• Caused by a decrease in blood volume due to fluid or blood losses.

• Potential causes:

  • Excessive sweating, burns, diuretics, inadequate fluid intake, increased urination.

• Early signs:

  • Dry mucous membranes, decreased skin elasticity, reduced urine output.

• Body compensatory responses include:

  • Increased heart rate and contraction strength, vasoconstriction in extremities.

Untreated Hypovolemia

• Serious symptoms may develop without treatment:

  • Cyanosis (blue discoloration of lips/nail beds).

  • Altered consciousness, chest pain, palpitations, anuria (no urine production).

  • Tachycardia (increased heart rate), tachypnea (rapid breathing), low blood pressure, weak pulse.

Hypovolemic Shock

• Occurs when 20% or one-fifth of blood volume is lost.

• Treatment focuses on controlling fluid/blood loss and restoring circulation.

Hypervolemia

• Also known as fluid overload; occurs with excess water in the body, often due to kidney issues.

• Treatment goal is fluid excess removal.

Intravenous Rehydration

• Crystalloids: Small particles passing into cells/tissues from the bloodstream, categorized by tonicity:

  • Hypotonic: Move water into cells.

  • Hypertonic: Move water out of cells.

  • Isotonic: No movement between fluids.

Blood Transfusions

• Packed red blood cells (RBCs) restore blood levels without significantly increasing blood volume.

• Whole blood contains all cellular elements and is used in significant blood loss scenarios.

• Plasma is the liquid part of blood carrying platelets alongside red and white blood cells.

Intake and Output

• Intake: Amount taken in by the client through food, IV, or feeding tubes.

• Output: Amount produced by the body, including urine, bowel movements, and vomit.

• Should be recorded at least every 8 hours as per facility protocol.

Acid-Base Balance

• The balance of acidic and basic compounds in the blood.

• Acidosis: Too much acid in the blood.

• Alkalosis: Blood becomes too alkaline.

Common Causes of Metabolic Acidosis

• Kidney disease.

• Lactic acidosis.

• Diabetic acidosis (uncontrolled diabetes).

• Severe dehydration.

• Severe diarrhea (excess sodium bicarbonate loss).

Common Causes of Metabolic Alkalosis

• Diuretic overuse.

• Excessive vomiting.

• Ingestion of antacids.

• Rapid loss of potassium or sodium.

• Alcohol abuse and laxative use.

• Heart, kidney, or liver failure.

Respiratory Alkalosis

• Develops when carbon dioxide levels drop due to excessive breathing (hyperventilation).

Respiratory Acidosis

• Results when the lungs cannot remove enough carbon dioxide.

• Common causes include:

  • Airway diseases (COPD, asthma).

  • Chest and breathing impairments (scoliosis, lung tissue diseases).

  • Medications suppressing breathing (narcotics).

  • Severe obesity and obstructive sleep apnea.