Chapter 29: Fluids and Electrolytes

Vocabulary practice flashcards covering crystalloid and colloid solutions, blood products, electrolyte balance (potassium and sodium), and related pharmacology from Chapter 29.

Total Body Water (TBW)

The total volume of fluid within the body, comprised of intracellular fluid (ICF), extracellular fluid (ECF), interstitial fluid (ISF), and intravascular fluid (IVF), which accounts for approximately $60\%$ of an adult human's body weight.

Colloid Oncotic Pressure (COP)

The osmotic pressure exerted by plasma proteins that pulls fluid into the intravascular compartment, with a normal physiological value of $24\,\text{mm Hg}$.

Interstitial Fluid Hydrostatic Pressure

The pressure exerted by the interstitial fluid (ISF) against cells and vessel walls, with a normal physiological value of $17\,\text{mm Hg}$.

Crystalloids

Intravenous solutions containing fluids and electrolytes naturally present in the body that maintain osmotic gradients between compartments without proteins, carrying no risk for viral transmission, anaphylaxis, or alteration of coagulation profiles.

Normal Saline (NS)

An isotonic crystalloid solution of $0.9\%$ sodium chloride that matches physiological extracellular fluid osmolality, commonly indicated for fluid replacement, volume resuscitation, and acute kidney injury.

Half-Normal Saline

A hypotonic crystalloid solution containing $0.45\%$ sodium chloride, used for maintenance fluid therapy, diabetic ketoacidosis (DKA), and cellular dehydration.

Hypertonic Saline (3% Sodium Chloride)

A high-osmolality crystalloid solution indicated primarily for severe symptomatic hyponatremia accompanied by neurological signs, as well as for reducing increased intracranial pressure (ICP).

Lactated Ringer's (LR)

An isotonic electrolyte crystalloid solution used for fluid resuscitation in burns, trauma, and hypotension; contraindicated in severe renal/liver failure, metabolic alkalosis ($\text{pH} > 7.5$), hyperkalemia, and co-administration with blood transfusions.

Dextrose 5% in Water (D5W)

A crystalloid solution containing $50\,\text{g/L}$ of glucose ($\sim 200\,\text{calories}$) that is isotonic in the intravenous bag ($275\text{--}295\,\text{mOsm/kg}$) but acts as a hypotonic fluid in the body once dextrose is metabolized.

Tonicity

The operational ability of an extracellular solution to exert an osmotic gradient that causes net movement of water into or out of cells.

Osmolarity

The total concentration of solute particles dissolved within a solution; fluids with higher solute concentrations possess higher osmolarity.

Hypotonic IV Fluids

Intravenous fluids with an osmolality lower than $275\,\text{mOsm/kg}$ that shift water into cells, risking cellular edema and worsening conditions such as severe head injury or elevated intracranial pressure.

Hypertonic IV Fluids

Intravenous solutions with an osmolality exceeding $295\,\text{mOsm/kg}$ that draw water out of the cells into the extracellular space, causing cellular dehydration and shrinkage.

Osmotic Demyelination Syndrome (ODS)

A severe, potentially irreversible neurological disorder caused by overly rapid elevation of serum sodium levels when administering hypertonic saline.

Colloids

Protein or carbohydrate-based macromolecular substances that remain in the vascular bed, increasing colloid oncotic pressure to pull fluid from the interstitial space into the intravascular compartment.

Albumin

A naturally occurring plasma protein synthesized by the liver that generates approximately $70\%$ of physiological colloid oncotic pressure; supplied as pasteurized $5\%$ and $25\%$ solutions prepared from human donors.

Dextran

A glucose polymer solution acting as a volume expander by pulling fluid into the vascular system; contraindicated in hypersensitivity, heart failure, renal insufficiency, and extreme dehydration.

Packed Red Blood Cells (PRBCs)

A blood component product indicated to enhance oxygen-carrying capacity in patients with anemia, substantial hemoglobin deficits, or blood volume loss up to $25\%$.

Whole Blood

A blood product containing cellular components and plasma proteins, specifically indicated for massive acute hemorrhage where blood loss exceeds $25\%$ of total blood volume.

Fresh Frozen Plasma (FFP)

A liquid blood product derived from centrifuged whole blood, indicated to replenish multiple clotting factor levels in patients with demonstrated coagulation deficiencies or massive transfusion needs.

Cryoprecipitate

A specialized blood derivative rich in clotting elements, indicated for acute massive bleeding, hypofibrinogenemia, Factor XIII deficiency, and Hemophilia A.

Hypokalemia

A deficient serum potassium level below $3.5\,\text{mEq/L}$, frequently caused by loop or thiazide diuretics, corticosteroid use, vomiting, diarrhea, or alkalosis.

Hyperkalemia

An excessive serum potassium level greater than $5.5\,\text{mEq/L}$, presenting with muscle weakness, paresthesias, paralysis, and life-threatening ventricular dysrhythmias.

Intravenous Potassium Infusion Safety Limit

A strict parenteral safety parameter limiting potassium administration to a maximum of $10\,\text{mEq/hour}$ in unmonitored patients, up to $20\,\text{mEq/hour}$ or more with continuous cardiac monitoring, and prohibiting IV bolus or push administration.

Sodium Polystyrene Sulfonate (Kayexalate)

A cation-exchange resin administered orally, via nasogastric tube, or as a rectal enema to eliminate potassium through the intestine; contraindicated in individuals without normal bowel motility.

Patiromer (Veltassa)

An oral, non-absorbed cation exchange polymer that binds potassium in the gastrointestinal tract to treat hyperkalemia; has a delayed onset of action and must be spaced at least $6\,\text{hours}$ apart from other oral medications.

Sodium Zirconium Cyclosilicate (Lokelma)

An oral inorganic cation-exchange agent that captures potassium ions in the gastrointestinal tract for hyperkalemia management; not suitable for emergency treatment due to its delayed onset.

Hyponatremia

A serum sodium deficit characterized by levels below $135\,\text{mEq/L}$, causing symptoms such as lethargy, stomach cramps, hypotension, vomiting, diarrhea, and seizures.

Hypernatremia

A serum sodium level greater than $145\,\text{mEq/L}$, typically resulting from poor renal excretion or dehydration, manifesting as edema, hypertension, flushed skin, dry sticky mucous membranes, fever, and oliguria.

Conivaptan (Vaprisol)

An intravenous vasopressin receptor antagonist indicated for the inpatient treatment of euvolemic hyponatremia that requires strict monitoring to prevent overly rapid sodium elevation.

Tolvaptan (Samsca)

An oral vasopressin receptor antagonist used to treat hyponatremia that must be initiated and closely monitored in a hospital environment to avoid rapid sodium shifts.

Hemolytic Transfusion Reaction

A life-threatening systemic reaction caused by donor-recipient blood incompatibility, marked by fever, chills, low back pain, tachycardia, hypotension, dyspnea, and hemoglobinuria.