Chapter 1-7 Fluids and Electrolytes: Practice Flashcards

A set of concise Q&A flashcards covering hypovolemia, hypervolemia, electrolyte balance (sodium, potassium, calcium, magnesium), fluid management strategies, and critical treatments referenced in the lecture notes.

What is the difference between hypovolemia and dehydration?

Hypovolemia is a deficit in extracellular fluid with decreased circulating blood volume. Dehydration is fluid loss that specifically increases solute concentration in the blood; they often occur together but can occur separately.

Where is extracellular fluid located, and how is it different from intracellular fluid?

Extracellular fluid is the fluid outside cells (including intravascular/plasma and interstitial spaces). Intracellular fluid is the fluid inside cells.

List common etiologies of hypovolemia.

Loss of fluid via the GI tract, kidneys, and skin; third-spacing (fluid shifts into interstitial spaces); and hemorrhage (external or internal bleeding).

What is third spacing?

Third spacing is fluid accumulation in the interstitial space where it is not within cells or in blood vessels, effectively sequestered away from circulation.

What are important clinical cues for hypovolemia related to vital signs and examination?

Weak peripheral pulses, delayed capillary refill, decreased urine output, and concentrated urine. Blood pressure may be low due to reduced circulating volume.

What laboratory findings are commonly seen with hypovolemia?

Hemoconcentration (elevated hematocrit), elevated BUN and creatinine (slower kidney function), increased serum osmolality (often driven by sodium), and concentrated urine with high urine specific gravity.

Why are isotonic fluids typically chosen for initial volume replacement?

Isotonic fluids increase intravascular volume without creating an osmotic gradient that pulls water into or out of cells, effectively expanding the circulating volume.

When might colloid solutions be preferred in fluid resuscitation?

Colloids may be used if hypoalbuminemia is present; simply giving crystalloids won’t retain fluid in the vasculature because fluid can leak out; colloids help restore intravascular volume by maintaining oncotic pressure.

What is the general plan if initial fluid resuscitation does not maintain blood pressure?

Consider additional interventions such as vasopressors to constrict blood vessels and raise pressure, after optimizing fluid volume; address electrolyte abnormalities if present.

What are typical signs of hypervolemia (fluid overload)?

Edema, weight gain, crackles in the lungs, elevated blood pressure, and sometimes a high central venous pressure; can lead to dyspnea and hypoxia if not managed.

What does hemodilution mean in the context of hypervolemia?

Hemodilution is the dilution of blood due to excess fluid, leading to a lower hematocrit and sometimes dilution of serum sodium.

How does heart rate typically change with hypovolemia and with hypervolemia?

Hypovolemia usually causes an increased heart rate (tachycardia) to maintain cardiac output. Hypervolemia may have a normal or lower heart rate; a combination of high BP and high HR is a critical sign.

What is the nurse’s first priority when a patient has fluid overload with pulmonary edema?

Ensure adequate oxygenation (address dyspnea and hypoxia) as the first priority, then diuresis and volume management as appropriate.

Name the four key electrolytes highlighted and why they’re emphasized.

Potassium, Sodium, Magnesium, and Calcium; these electrolytes have the most clinical impact on cell function and electrical activity, especially in the heart and nervous system.

Where is potassium primarily located, and where is sodium primarily located?

Potassium is primarily intracellular (inside cells). Sodium is primarily extracellular (outside cells).

Which hormones regulate electrolytes and how do they influence them?

Aldosterone helps regulate sodium (and thus fluid balance); Parathyroid hormone (PTH) and calcitonin regulate calcium; these hormones influence electrolyte homeostasis in kidneys and bones.

What is the role of insulin in potassium balance?

Insulin drives potassium from the extracellular space into cells, helping to lower serum potassium levels during hyperkalemia or during treatment of hyperkalemia.

What is a common risk when giving potassium replacement therapy, and how is it mitigated?

Potassium replacement can be dangerous and cause life-threatening arrhythmias if misdosed. It requires careful monitoring (often with cardiac monitoring) and appropriate dosing, sometimes using potassium chloride intravenously or orally depending on severity.

What is the normal range for sodium, and what conditions result from its imbalance?

Normal sodium is approximately 135-145 mEq/L. Hyponatremia (low sodium) can cause confusion, seizures, and weakness (often seen with SIADH or water intoxication). Hypernatremia (high sodium) can cause dehydration and neurologic symptoms.

What is SIADH and how is it treated?

Syndrome of inappropriate antidiuretic hormone secretion; causes water retention and hyponatremia. Treatment may include hypertonic saline for severe hyponatremia and vasopressin antagonists to block ADH; fluid restriction is also used.

What is diabetes insipidus and how does it relate to sodium balance?

Diabetes insipidus is the opposite of SIADH—low ADH leading to excessive water loss (polyuria) and potential hypernatremia; fluids and electrolyte management are used to correct the imbalance.

What is half-normal saline and when might it be used?

0.45% saline (half-normal saline) is a hypotonic IV fluid used to dilute the blood and reduce sodium concentration when there is excess sodium relative to water; it helps adjust osmolar balance more gradually.

What is the role of albumin and other colloids in fluid management?

Colloids like albumin increase oncotic pressure in the vasculature, helping to pull fluid from interstitial spaces back into the intravascular compartment, particularly when there is hypoalbuminemia.

What is the sequence of treatment for severe hyperkalemia with ECG changes?

1) Calcium gluconate (to stabilize cardiac membranes), 2) Insulin with glucose to drive potassium into cells, 3) Potassium-binding agents like sodium polystyrene sulfonate (Kayexalate) to remove potassium from the body, 4) Dialysis if needed as a last resort.

What are common signs of calcium imbalance, and what is a primary cause of hypocalcemia?

Tetany (muscle spasms) is a key sign of hypocalcemia; hormonal imbalances (such as hypoparathyroidism) and vitamin D deficiency reduce calcium absorption and cause low calcium levels.