Fluid and Electrolyte Balance Quiz

Fluid and Electrolyte Balance Control

• Kidneys are the primary regulators of fluid and electrolyte balance
• Antidiuretic Hormone (ADH) from the pituitary gland promotes water retention
• Aldosterone, produced by the adrenal glands, promotes sodium retention and potassium excretion (part of the renin-angiotensin-aldosterone system)

Fluid Gains and Losses

• Average daily fluid intake: 1500ml
• Fluid intake sources:
  • Beverages: ~700ml
  • Food: ~250ml
  • Cellular respiration: ~25ml
• Fluid losses:
  • Kidneys: ~100ml
  • Insensible loss: through skin, lungs, and bowels
  • Sweat

Risk Factors for Fluid Imbalances

• Elderly and infants
• Illnesses affecting the kidneys or circulation
• Hospitalized patients

Fluid and Electrolyte Therapy

• Intravenous (IV) Fluids:
  • 25ml - 1000ml bags
  • Used for:
    • Maintaining fluid balance
    • Replacing fluid losses
    • Treating electrolyte imbalances
• Glass Bottles: Used for medications unstable in plastic (e.g., nitroglycerin)
• Vented tubing: Required for use with glass bottles to allow air into the bottle

Types of IV Solutions

• Isotonic Solutions: Same osmolality as body fluids (no fluid shift)
  • Used for: replacing extracellular fluid losses and expanding intravascular volume
  • Examples: Normal saline (0.9% sodium chloride), Lactated Ringer's (LR), D5W (5% dextrose in water), D5 1/4 NS (5% dextrose in 1/4 normal saline)
• Hypotonic Solutions: Lower osmolality than body fluids (expand intracellular space)
  • Used for: hydration and cellular rehydration
  • Examples: 1/2 NS (0.45% normal saline), 1/3 NS (0.33% sodium chloride)
• Hypertonic Solutions: Higher osmolality than body fluids (pull fluid from intracellular space)
  • Used for: treating severe hyponatremia
  • Examples: D10W (10% dextrose in water), D5NS (5% dextrose in normal saline), D5 1/2 NS (5% dextrose in 1/2 normal saline), D5LR (5% dextrose in Lactated Ringer's), D10LR (10% dextrose in Lactated Ringer's)

Specific IV Solutions

• D5W (5% dextrose in water): Treats hypoglycemia, provides calories, and is used for shock
• Normal Saline (NS): Replaces extracellular fluid, treats metabolic acidosis, sodium depletion, and is used for initiating blood transfusions
• D5 1/4 NS (5% dextrose in 1/4 normal saline): Isotonic solution
• Lactated Ringer’s (LR): Isotonic solution used to replace fluids and electrolytes

Fluid Volume Deficit (Dehydration)

• Signs and Symptoms:
  • Sunken eyeballs
  • Dry mucous membranes
  • Weight loss
  • Tachycardia
  • Tachypnea (increased respiratory rate)
  • Decreased skin turgor
  • Flattened neck veins
  • Hypotension
• Nursing Actions/Treatment:
  • Replace fluids (oral if not acute, IV if acute)
  • Treat underlying cause
  • Daily weight monitoring
  • Strict I&Os (intake and output)

Fluid Volume Excess (Overhydration)

• Signs and Symptoms:
  • Neck vein distension
  • Crackles/rales in lungs (pulmonary edema)
  • Weight gain
  • Full, bounding pulses
  • Hypertension
  • Peripheral edema
• Nursing Actions/Treatment:
  • Treat underlying cause
  • Daily weight monitoring
  • Diuretics
  • Fluid and sodium restriction
  • Positioning and skincare to prevent skin breakdown

Fluid Compartments

• Extracellular Fluid (ECF): Fluid outside the cells (one-third of total body fluid)
  • Interstitial fluid: between cells and tissues
  • Intravascular fluid: plasma portion of the blood
• Intracellular Fluid (ICF): Fluid inside cells (two-thirds of total body fluid)

Transport of Fluids and Electrolytes

• Passive transport: Does not require energy
  • Diffusion: Movement of solutes from high to low concentration
  • Osmosis: Movement of water across a semipermeable membrane from low to high solute concentration
  • Filtration: Movement of solutes and water across a membrane from high to low pressure
• Active transport: Requires energy (ATP)
  • Sodium-potassium pump: Moves sodium out of the cell and potassium into the cell
• Colloid Osmotic Pressure: Pulling pressure exerted by large molecules in vascular fluid (e.g., albumin)
• Hydrostatic Pressure: Force exerted by fluid against a membrane

Osmolality and Cell Response

• Hypertonic Solution: Causes cell to shrink; pulls fluid out of cell
• Hypotonic Solution: Causes cell to swell; pulls fluid into cell
• Isotonic Solution: No fluid shift

Electrolytes

• Electrolytes: Minerals that carry electrical charges
• Intracellular Electrolytes: Higher concentration inside the cell
  • Potassium: Most important intracellular electrolyte
  • Magnesium
  • Phosphate
• Extracellular Electrolytes: Higher concentration outside the cell
  • Sodium: Most important extracellular electrolyte
  • Chloride
  • Bicarbonate

Sodium (Na+)

• Normal serum level: 135-145 mEq/L
• Functions:
  • Main extracellular cation
  • Fluid balance (water follows sodium)
  • Nerve impulse conduction
  • Heart rhythm
  • Muscle contraction
  • Regulation of osmotic pressure
  • Cell membrane permeability
• Regulation: Aldosterone (retains sodium)
• Hypernatremia (High Sodium):
  • Causes: excessive sodium intake, dehydration, fever, hypertonic IV solutions, glucocorticoid administration, diabetes
  • Signs and symptoms: thirst, dry mucous membranes, oliguria, restlessness, confusion, agitation, seizures, coma
  • Treatment: hypotonic IV solutions, increased IV fluid intake, monitoring of vital signs and electrolytes
  • Nursing Interventions:
    • Monitor for signs and symptoms
    • Offer fluids
    • Monitor lab values (sodium, urine specific gravity)
    • Watch for fluid overload
• Hyponatremia (Low Sodium):
  • Causes: diuretics, diaphoresis, GI suction, water intoxication, tap water enemas, cerebral injuries
  • Signs and symptoms: headache, weakness, confusion, lethargy, cramps, seizures, coma
  • Treatment: isotonic or hypertonic IV solutions, sodium supplements, monitor vital signs and electrolytes
  • Nursing Interventions:
    • Caution with administering sodium solutions
    • Monitor closely for signs and symptoms
    • Monitor lab values
    • Watch for fluid overload