Fluid Balance and Electrolytes Practice Flashcards

Comprehensive practice flashcards covering fluid volume imbalances, IV solution types, and major electrolytes for nursing exam preparation.

Fluid Volume Deficit (FVD)

Also known as dehydration or hypovolemia, characterized by tachycardia (earliest sign), hypotension, poor skin turgor (tenting), and a $Urine\ Specific\ Gravity > 1.030$.

Fluid Volume Excess (FVE)

Hypervolemia often caused by heart or renal failure, presenting with bounding pulses, distended neck veins (JVD), crackles in the lungs, and sudden weight gain where $1\text{ kg} \approx 1\text{ L}$ of fluid.

Isotonic IV Fluids

Solutions like $0.9\%\ \text{NaCl}$ (Normal Saline) and Lactated Ringer's (LR) that expand extracellular space with no shift across cell membranes; used for shock and fluid resuscitation.

Hypotonic IV Fluids

Solutions such as $0.45\%\ \text{NaCl}$ that move fluid into cells (causing them to swell like a hippo); used for intracellular dehydration but never given with increased ICP or cerebral edema.

Hypertonic IV Fluids

High-risk solutions like $3\%\ \text{NaCl}$, $5\%\ \text{NaCl}$, or $\text{D}_{10}\text{W}$ that pull fluid out of cells into the vascular space, used for severe hyponatremia and cerebral edema.

Normal Sodium (Na+) Range

$135\text{--}145\text{ mEq/L}$; primary focus is the neurological system.

Normal Potassium (K+) Range

$3.5\text{--}5.0\text{ mEq/L}$; primary focus is the cardiac system.

Normal Calcium (Ca2+) Range

$9.0\text{--}10.5\text{ mg/dL}$; primary focus is the neuromuscular system.

Normal Magnesium (Mg2+) Range

$1.3\text{--}2.1\text{ mEq/L}$; primary focus is reflexes and the neuromuscular junction.

Hyperkalemia ECG Changes

Tall peaked T-waves, widened QRS, and prolonged PR interval; associated with renal failure and potassium-sparing diuretics.

Hypokalemia ECG Changes

Presence of U-waves, flattened or inverted T-waves, and ST depression; common with loop diuretics like Furosemide.

Potassium IV Safety Rule

NEVER administer IV Push; maximum infusion rate is $10\text{ mEq/hr}$ on med-surg floors and always check for urine output $> 30\text{ mL/hr}$ before administration.

Central Pontine Myelinolysis

Irreversible brain stem damage caused by the rapid correction of hyponatremia.

Chvostek’s Sign

Facial twitching induced by tapping the facial nerve (cheek), indicating hypocalcemia ($< 9.0\text{ mg/dL}$).

Trousseau’s Sign

Carpal spasm induced by inflating a BP cuff above systolic pressure for $3\text{ minutes}$, indicating hypocalcemia.

Hypercalcemia (Groans, Moans, Bones, Stones)

A state caused by hyperparathyroidism or malignancy characterized by bone pain, kidney stones, constipation, and decreased deep tendon reflexes.

Golden Rule of Magnesium

Magnesium acts as a sedative on the central nervous system and neuromuscular junction.

Hypermagnesemia Toxicity Sign

Hypoactive or absent Deep Tendon Reflexes (DTRs), which is the earliest warning sign of toxicity ($> 2.1\text{ mEq/L}$).

Magnesium Antidote

Calcium Gluconate; must be kept at the bedside when administering IV $\text{MgSO}_4$.

Torsades de Pointes

A dangerous ventricular dysrhythmia associated with hypomagnesemia ($< 1.3\text{ mEq/L}$).

Kayexalate (Sodium Polystyrene Sulfonate)

A medication that excretes potassium ($K^+$) via the stool; ensure bowel sounds are present before administration.