Module 2 Fluids & Electrolytes - 300 Vocabulary Flashcards

300 vocabulary-style flashcards drawn from the Fluids & Electrolytes lecture notes, covering TBW, compartments, tonicity, IV fluids, regulatory hormones, pathophysiology of hypo-/hypervolemia, electrolytes, and pharmacologic interventions.

Total Body Water (TBW)

The total amount of water in the body; about 60% of body weight in adults (higher in infants, lower in elderly/obese).

Intracellular Fluid (ICF)

Fluid inside cells; contains most intracellular electrolytes such as K+, Mg2+, and phosphate.

Extracellular Fluid (ECF)

Fluid outside cells; includes interstitial fluid, plasma, and transcellular fluid; rich in Na+, Cl−, and HCO3−.

Interstitial Fluid

Part of the extracellular fluid that bathes tissue cells between capillaries and cells.

Plasma

Intravascular fluid, part of ECF; high in proteins like albumin.

Transcellular Fluid

Specialized fluids in distinct compartments (CSF, synovial, pleural, peritoneal, etc.).

Electrolytes

Charged minerals in body fluids that regulate nerve/muscle function, fluid balance, and acid-base status.

Intracellular Potassium (K+)

Major intracellular cation; essential for cellular function and electrical activity.

Intracellular Magnesium (Mg2+)

Intracellular cation important for enzyme activity and stability.

Intracellular Phosphate (PO4^3-)

Intracellular anion important for energy (ATP) and signaling.

Sodium (Na+) in ECF

Major extracellular cation that governs osmolarity and volume status.

Chloride (Cl−)

Major extracellular anion that aids in acid-base and osmotic balance.

Bicarbonate (HCO3−)

Extracellular buffer that helps maintain acid-base homeostasis.

Potassium Regulation (K+)

Renal excretion and cellular shifts (e.g., insulin) regulate serum K+. വക

Osmolarity

Concentration of solute particles per liter of solution that affects water movement.

Effective Osmoles

Osmotically active particles (eg, Na+, glucose) that influence water movement across membranes.

Tonicity

Ability of a solution to cause a change in cell size via osmotic water movement.

Isotonic Solution

Tonicity that does not cause net water movement; same osmolality as plasma.

Hypotonic Solution

Causes water to move into cells, leading to cell swelling.

Hypertonic Solution

Causes water to move out of cells, leading to cell shrinkage.

Isotonic Crystalloids

Crystalloid fluids that stay primarily in the extracellular space (eg, 0.9% NS, LR).

Hypotonic Crystalloids

Crystalloids that draw water into cells (eg, 0.45% NS).

Hypertonic Crystalloids

Crystalloids that draw water out of cells (eg, 3% NS, D5NS, D5LR).

Crystalloids

Solutions with small molecules that move between intravascular and interstitial spaces.

Colloids

Solutions with large molecules that stay primarily in the intravascular space (eg, albumin).

0.9% NaCl (Normal Saline)

Isotonic crystalloid; expands extracellular fluid; may cause overload if overused.

Lactated Ringer’s (LR)

Isotonic crystalloid with electrolyte composition similar to plasma; used for resuscitation.

0.45% NaCl

Hypotonic crystalloid; shifts water into cells.

3% NaCl

Hypertonic crystalloid; pulls water from cells; used for severe hyponatremia.

Dextrose 5% in Water (D5W)

D5W; isotonic solution that becomes hypotonic as glucose is metabolized.

Dextrose 10% in Water (D10W)

Hypertonic dextrose solution used in certain clinical scenarios.

D5NS

Dextrose 5% in normal saline; hypertonic combination solution.

D5LR

Dextrose 5% in lactated Ringer’s; hypertonic mix depending on glucose.

D5W vs D5NS vs D5LR

Different tonicity and electrolyte content; used based on clinical need.

Albumin (Colloid)

Colloid solution that expands intravascular volume via oncotic pressure.

Dextran

Colloid used to expand plasma volume; less common today.

ADH (Antidiuretic Hormone)

Hormone that increases water reabsorption in the kidney; reduces urine output.

Aldosterone

Hormone that increases Na+ reabsorption in the distal nephron; water follows; increases volume.

ANP/BNP

Natriuretic peptides that promote Na+ and water excretion; reduce volume.

Thirst Mechanism

Hypothalamic-driven drive to drink water in response to osmolality/blood volume changes.

Hypothalamus

Brain region controlling thirst and ADH release.

SIADH

Syndrome of inappropriate antidiuretic hormone; excess water retention and hyponatremia risk.

Diabetes Insipidus (DI)

Insufficient ADH leading to free water loss and hypernatremia risk.

NGN Micro-Case Scenario

Case framework: recognize cues, analyze cues, prioritize hypotheses, generate solutions, take action, evaluate outcomes.

Hypovolemia

ECF volume loss causing decreased circulating blood volume.

Dehydration

Water deficit leading to increased serum osmolality and sodium.

Third Spacing

Fluid moves from intravascular space to interstitial or third-space compartments.

GI Losses

Vomiting, diarrhea, NG suction causing fluid and electrolyte loss.

Renal Losses

Diuretics or osmotic diuresis causing fluid loss.

Skin Losses

Burns or sweating causing fluid loss.

Hemorrhage

Significant blood loss contributing to hypovolemia.

Clinical Cues of Hypovolemia

Low blood pressure, tachycardia, dry mucous membranes, poor skin turgor.

Laboratory Cues for Hypovolemia

↑ Hct, ↑ BUN/Cr (prerenal), ↑Na+ with dehydration, USG >1.030.

Nursing Priorities in Hypovolemia

Assess vitals and mental status; restore volume; monitor for overload; educate.

Hypovolemia Pharmacologic Management

Isotonic crystalloids (0.9% NS or LR); colloids if significant hypoalbuminemia; vaso­pressors after resuscitation.

Hypervolemia

Excess extracellular fluid volume; often with Na+ retention and edema.

Hypervolemia Etiologies

Excess IV fluids, heart failure, renal/liver failure, high-sodium intake.

Hypervolemia Clinical Cues

Weight gain, edema, JVD, crackles, pulmonary edema; elevated BP.

Pulmonary Congestion

Fluid accumulation in lungs seen with hypervolemia.

BNP in HF

Elevated BNP suggests heart-failure-related fluid overload.

Hypervolemia Nursing Priorities

Restrict fluids and Na+, daily weights and I&O, diuretics, monitor respiration.

Electrolyte Disturbances & Pharmacologic Management

Recognize and correct Na+, K+, Ca2+, Mg2+ imbalances; use specific antagonists/ replacements.

ICF vs ECF Regulation

ICF contains K+, Mg2+, phosphate; ECF contains Na+, Cl−, HCO3−; regulated by GI intake, renal excretion, aldosterone, PTH, calcitonin.

Regulatory Hormones - ADH

Increases water reabsorption in renal collecting ducts; concentrates urine.

Regulatory Hormones - Aldosterone

Promotes Na+ reabsorption (water follows); expands extracellular volume.

Regulatory Hormones - ANP/BNP

Promotes Na+ and water excretion; reduces circulating volume.

Thirst Sensitivity in Older Adults

Decreased thirst sensation increases dehydration risk.

USG (Urine Specific Gravity)

Indicator of urine concentration; elevated in dehydration.

Hematocrit (Hct)

Proportion of blood volume occupied by red cells; rises with dehydration, falls with hemodilution.

BUN/Cr in Hypovolemia

Elevated BUN and creatinine with prerenal azotemia due to reduced renal perfusion.

Isotonic Resuscitation First-Line

0.9% NS or LR used to restore circulating volume in hypovolemia.

Vasopressors after Resuscitation

Norepinephrine or dopamine used only after adequate fluid resuscitation.

Isotonic Crystalloids - Uses

Go-to fluids for hypovolemia/resuscitation; monitor for overload.

Hypovolemia Lab Clues - Increased Na+

Can occur with dehydration due to concentrated urine.

Hypernatremia

Serum Na+ >145 mEq/L; causes include water loss, DI, high Na intake; signs include thirst and seizures.

Hyponatremia

Serum Na+ <135 mEq/L; causes include GI loss, SIADH, water intoxication; signs include confusion, seizures.

Hyperkalemia

Serum K+ >5.0 mEq/L; causes include renal failure, acidosis, burns; signs include weakness and arrhythmias.

Hypokalemia

Serum K+ <3.5 mEq/L; causes include GI loss, diuretics, insulin; signs include weakness and arrhythmias.

Potassium Treatment - Hyperkalemia

Calcium gluconate for ECG changes; IV insulin + glucose; sodium polystyrene sulfonate; dialysis if needed.

Potassium Treatment - Hypokalemia

Potassium chloride replacement (PO/IV); monitor for arrhythmias.

Hypercalcemia

Serum Ca2+ >10.2 mg/dL; causes include hyperparathyroidism, malignancy; signs include weakness and stones.

Hypocalcemia

Serum Ca2+ <8.6 mg/dL; signs include tetany, Chvostek/Trousseau signs.

Calcium Therapies

IV calcium gluconate; PO calcium carbonate; vitamin D analogs.

Hypermagnesemia

Mg2+ >2.1 mEq/L; causes include renal failure; signs include hypotension and respiratory depression.

Hypomagnesemia

Mg2+ <1.3 mEq/L; signs include tremors, seizures; treatment with magnesium sulfate.

Mg2+ Repletion

Magnesium sulfate IV/PO as prescribed.

Sodium Homeostasis in SIADH

Hyponatremia due to excess ADH; treated with hypertonic saline in severe cases.

Hypertonic Saline Indication

3% NaCl used for severe symptomatic hyponatremia.

Desmopressin (DDAVP)

Synthetic ADH used in central DI or certain bleeding disorders.

Tolivantin (tolvaptan)

Vasopressin receptor antagonist used to treat SIADH; promotes aquaresis.

Vasopressors

Drugs like norepinephrine or dopamine used to raise blood pressure after volume restoration.

Renal Replacement Therapy (Dialysis)

Used for refractory electrolyte disturbances or fluid overload.

Diuretic Classes - Loop

Loop diuretics (e.g., furosemide) promote rapid fluid removal; monitor electrolyte loss.

Diuretic Classes - Thiazide

Thiazide diuretics promote Na+ and water excretion; commonly used for hypertension and edema.

Diuretic Classes - K+-Sparing

Spironolactone; reduces K+ loss in exchange for Na+; used in hyperaldosteronism.

Dialysis Indication

Used to manage severe electrolyte disturbances or fluid overload not responsive to diuretics.

Chvostek Sign

Facial muscle contraction in response to tapping along the facial nerve; sign of hypocalcemia.

Trousseau Sign

Carpal spasm with blood pressure cuff; sign of hypocalcemia.

Oxygen Therapy in Hypervolemia

Supplemental oxygen for dyspnea or hypoxemia; monitor respiratory status.

1 kg ≈ 1 L

Rough rule: one kilogram weight gain reflects about one liter of fluid retained.