Fluid and Sodium Disorders Flashcards

These vocabulary flashcards cover fluid physiology, hypervolemia, hypovolemia, and the etiologies and treatments for sodium disorders (hyponatremia and hypernatremia) as discussed in the lecture.

OsmoLALity

The number of osmoles of solute per kg of solvent, expressed as $Osm/kg$.

OsmoLARity

The number of osmoles of solute per L of solution, expressed as $Osm/L$.

Daily Fluid Requirement

A standard requirement for adults estimated at $25-30 \text{ ml/kg/day}$.

Total Body Water (TBW) - Infants

Estimated at $0.7 \text{ L/kg}$.

Total Body Water (TBW) - Males

Estimated at $0.6 \text{ L/kg}$.

Total Body Water (TBW) - Females

Estimated at $0.5 \text{ L/kg}$.

Hypervolemia

Too much volume in the body characterized by symptoms like SOB, chest heaviness, edema, crackles in lungs, and JVD.

Edema

Palpable swelling caused by the expansion of interstitial fluid; can be classified as pitting or non-pitting.

Loop Diuretics MOA

Inhibit sodium reabsorption at the ascending limb of the loop of Henle.

Furosemide (Lasix) IV to PO Dosing Ratio

The ratio is $1:2$, where $40 \text{ mg}$ IV is equivalent to $80 \text{ mg}$ PO.

Torsemide (Demadex)

A loop diuretic with a $1:1$ IV to PO dosing ratio, good bioavailability, and a long $t_{1/2}$ allowing for once-daily dosing.

Ethacrynic Acid (Edecrin)

A loop diuretic reserved specifically for patients with a true sulfa allergy.

Bumetanide (Bumex)

A loop diuretic with a $1:1$ IV to PO dosing ratio and an equivalent IV dose of $1 \text{ mg}$.

Hypovolemia

A state of volume depletion characterized by thirst, dizziness, hypotension, tachycardia, and decreased skin turgor.

Crystalloids

IV fluids containing water, sodium, chloride, and dextrose that pass freely through semipermeable membranes and are less expensive than colloids.

Colloids

Large molecules like albumin, dextran, or hetastarch that primarily remain in the intravascular space and increase oncotic pressure.

Lactated Ringers (LR)

An isotonic balanced crystalloid containing sodium, chloride, potassium, calcium, and lactate; it mimics plasma fluid and is preferred in surgery/trauma.

Hyponatremia

Defined as a serum sodium level of less than $136 \text{ mEq/L}$.

Severe Hyponatremia

Defined as a serum sodium level of less than $125 \text{ mEq/L}$.

Osmotic Demyelination Syndrome (ODS)

A serious condition caused by rapid correction of sodium; manifestations include mutism, dysphasia, quadriparesis, delirium, and coma.

Urea (Ure-Na)

A medical food that causes osmotic diuresis for the management of hyponatremia; typically dosed at $30-60 \text{ g/day}$.

Conivaptan (Vaprisol)

A mixed $V1a/V2$ vasopressin receptor antagonist used for euvolemic or hypervolemic hyponatremia; available only as IV therapy.

Tolvaptan (Samsca)

A selective $V2$ vasopressin receptor antagonist used for hyponatremia in HF and SIAD; limited to 30 days of use due to hepatotoxicity risks.

Hypernatremia

Defined as a serum sodium level of greater than $145 \text{ mEq/L}$.

Arginine Vasopressin Disorder (AVP-D)

Previously known as Central Diabetes Insipidus, it is caused by decreased AVP secretion and is treated with desmopressin.

Arginine Vasopressin Resistance (AVP-R)

Previously known as Nephrogenic Diabetes Insipidus, it is caused by decreased kidney response to ADH and may be drug-induced by lithium.

Desmopressin (dDAVP)

An ADH analog used to treat central DI; can be administered intranasally ($10 \text{ mcg}$), orally, or IV/SubQ.

Water Deficit Formula

Calculation used for hypernatremia: $Water \text{ deficit (L)} = TBW \text{ percent} \times \text{weight in kg} \times \frac{serum \text{ Na} - 140}{140}$.