Fluid and Electrolyte Balance and Imbalances

Vocabulary practice flashcards covering fluid compartments, fluid dynamics, intake and output, intravenous solutions, and electrolyte imbalances based on nursing lecture notes.

Intracellular Fluid (ICF)

The fluid contained within body cells, comprising approximately two-thirds ($\frac{2}{3}$) of total body water.

Extracellular Fluid (ECF)

The fluid outside of body cells, representing one-third ($\frac{1}{3}$) of total body water; composed of interstitial fluid (80%) and intravascular fluid or plasma (20%).

Interstitial Fluid

The portion of the extracellular fluid located in the spaces between tissue cells, making up approximately 80% of total ECF volume.

Total Body Water Distribution (Male vs. Female)

Fluids constitute approximately 60% of total body mass in adult males (40% solids) and approximately 55% in adult females (45% solids).

Diffusion

The passive movement of solute particles from an area of higher concentration to an area of lower concentration across a semipermeable membrane or gradient.

Osmosis

The movement of water across a semipermeable membrane from a region of lower solute concentration (higher water concentration) to a region of higher solute concentration.

Osmolality

The concentration of dissolved solute particles per unit of water, which establishes osmotic pressure and regulates fluid shifts between fluid compartments.

Isotonic IV Solution

An intravenous solution with an osmolality equivalent to normal body fluids that causes no net fluid shift across cell membranes; examples include 0.9% NaCl (NS), Lactated Ringer's (LR), and 5% Dextrose in Water (D5W).

Hypotonic IV Solution

An intravenous fluid with a lower solute concentration and osmolality than plasma (such as 0.45% NaCl / $\frac{1}{2}$ NS), which causes water to shift into tissue cells, potentially leading to cellular swelling or cytolysis.

Hypertonic IV Solution

An intravenous fluid with a higher solute concentration and osmolality than plasma (such as 3% NaCl or 10% Dextrose), which pulls fluid out of cells into the intravascular space, resulting in cellular shrinkage or plasmolysis.

Normal Daily Fluid Intake

An expected daily intake of $2400-2700\,\text{mL/day}$, consisting of oral fluids ($1200-1500\,\text{mL/day}$), moisture from food ($1000\,\text{mL/day}$), and metabolic water production ($200\,\text{mL/day}$).

Normal Daily Fluid Output

An expected daily elimination of $2300-2500\,\text{mL/day}$, consisting of urine from kidneys ($1400-1500\,\text{mL/day}$), sweat ($100\,\text{mL/day}$), feces ($100-200\,\text{mL/day}$), and insensible skin and lung losses ($350-400\,\text{mL/day}$ each).

Minimum Urine Output

The minimum acceptable urinary excretion rate, which must exceed $30\,\text{mL/hr}$ in a normal adult to maintain renal clearance and organ perfusion.

Net Fluid Volume

The physiological balance between fluid gains and losses, calculated as $\text{Intake} - \text{Output}$, which should remain equal in a healthy individual.

Hypervolemia (ECV Excess)

Extracellular fluid volume excess manifested by rapid weight gain ($\ge 2\,\text{lbs}$ in a day), dependent pitting edema, vascular overload (bounding pulses, JVD, hypertension), dyspnea, pulmonary crackles, and cool skin; managed with fluid restriction, diuretics, and low-sodium diets.

Hypovolemia (ECV Deficit)

Extracellular fluid volume deficit manifested by weight loss, dry mucous membranes, poor skin turgor (tenting), sunken eyeballs, flat fontanels, oliguria, thready pulse, and orthostatic hypotension; treated with oral or IV fluids and treating the underlying cause.

Orthostatic Hypotension

A sign of intravascular volume depletion marked by a drop in blood pressure accompanied by a compensatory increase in heart rate when moving from lying to standing positions.

Third Spacing

The shift and accumulation of extracellular fluid into physiological compartments where it is nonfunctional, such as ascites; often managed with intravenous albumin to draw fluid back into the vascular space.

Hyponatremia

A serum sodium level $< 135$; manifested by altered mental status, headache, confusion, seizures, coma, nausea/vomiting, and orthostatic hypotension; treated with fluid restriction and gradual sodium replacement.

Central Pontine Myelinolysis (CPM)

A severe neurological complication resulting from overly rapid correction of chronic hyponatremia with sodium-containing solutions.

Hypernatremia

A serum sodium level $> 145$; manifested by excessive thirst, dry red swollen tongue, hyperthermia, restlessness, disorientation, decreased LOC, and seizures; treated by lowering sodium gradually with hypotonic fluids, diuretics, and fluid restriction.

Hypokalemia

A serum potassium level $< 3.5$; manifested by muscle weakness, muscle cramps, hyporeflexia, paralytic ileus, constipation, and ECG abnormalities (flattened/inverted T waves, prominent U waves, ST depression); treated with dietary potassium and oral or slow IV potassium infusions.

Hyperkalemia

A serum potassium level $> 5.5$; manifested by peaked T waves, widened PR and QRS intervals, bradycardia, flaccid paralysis, diarrhea, and asystole; treated with IV regular insulin with dextrose (D5W / D5 $\frac{1}{2}$ NS), Kayexalate (sodium polystyrene sulfonate), IV calcium, albuterol, loop diuretics, or hemodialysis.

Hypocalcemia

A serum calcium level $< 8.4$; characterized by increased neuromuscular excitability, positive Chvostek's and Trousseau's signs, tetany, hyperactive DTRs, laryngospasms, and prolonged QT/ST intervals; managed with oral or IV calcium and vitamin D.

Hypercalcemia

A serum calcium level $> 10.2$; characterized by decreased neuromuscular excitability, muscle weakness, diminished reflexes, bone pain, anorexia, constipation, dysrhythmias (shortened QT/ST), and nephrolithiasis risk; managed by encouraging ambulation, increasing fluid intake, and restricting calcium.

Chvostek's Sign

A clinical manifestation of neuromuscular excitability in hypocalcemia and hypomagnesemia elicited by tapping the facial nerve anterior to the ear, producing an involuntary ipsilateral facial muscle twitch.

Trousseau's Sign

A sign of latent tetany occurring in hypocalcemia and hypomagnesemia characterized by carpopedal spasm induced by inflating a blood pressure cuff above systolic pressure for several minutes.

Hypomagnesemia

A serum magnesium level $< 1.6$; manifests with increased neuromuscular transmission (+ Chvostek's/Trousseau's signs, hyperactive DTRs, muscle tetany, tremors, seizures), tachycardia, hypertension, and paralytic ileus; treated with magnesium salts and high-magnesium foods.

Hypermagnesemia

A serum magnesium level $> 2.6$; manifests with decreased neuromuscular excitability, diminished or absent deep tendon reflexes (DTRs), facial flushing, muscle weakness, bradycardia, AV block, hypotension, and respiratory depression; treated with normal saline and hemodialysis.

Hypophosphatemia

A serum phosphorus level $< 3.0$; caused by refeeding malnourished patients, alcohol withdrawal, DKA, or respiratory alkalosis; presents with muscle weakness, diplopia, irritability, confusion, seizures, and increased respiratory rate; treated with gradual phosphorus replacement.

Hyperphosphatemia

A serum phosphorus level $> 4.5$; caused by renal failure, hypoparathyroidism, chemotherapy, or DKA; presents with metastatic soft tissue and arterial calcification and signs of hypocalcemia (tetany, hyperreflexia, + Chvostek's/Trousseau's); treated with phosphate-binding medications and dietary phosphate restriction.

Hypochloremia

A serum chloride level $< 96$; caused by DKA, metabolic alkalosis, fever, or vomiting; presents with hyper-excitable muscles, hyperactive deep tendon reflexes, irritability, and coma; treated with IV chloride replacement and discontinuation of diuretics.

Hyperchloremia

A serum chloride level $> 108$; associated with hypernatremia, SIADH, hypervolemia, and adrenal insufficiency; manifested by tachypnea, lethargy, decreased LOC, hypertension, and dysrhythmias; managed with hypotonic IV solutions, diuretics, and fluid restriction.

Aldosterone

A mineralocorticoid hormone that acts on the kidneys to increase renal reabsorption of sodium and water while promoting potassium excretion.