NUR 252: EXAM 5 TERMS/CONCEPTS

Fluid and Electrolyte Balance

the various body fluids and electrolytes (intracellular, extracellular, intravascular, and transcellular) that when in balance promote homeostasis

Total Body Water Adult

Approximately 60% of body weight

Total Body Water Newborn

Approximately 70% of body weight

Intracellular Fluid (ICF)

Fluid inside cells representing about 40% of body weight

Primary Electrolyte in ICF

Potassium (K+)

Extracellular Fluid (ECF)

Fluid outside cells representing about 20% of body weight

Primary Electrolyte in ECF

Sodium (Na+)

Intravascular Fluid (plasma)

Plasma component of extracellular fluid within blood vessels

Primary Electrolytes in Intravascular Fluid

Potassium (K+), Magnesium (Mg++), Phosphate (PO4), and proteins

Interstitial Fluid

Fluid in tissues and surrounding (in-between) cells

Transcellular Fluid

Fluid is contained in specific body spaces, such as cerebrospinal fluid and joints

Primary Electrolytes in Transcellular Fluid

High in Sodium (Na+), Chlorine (Cl-), and Bicarbonate (HCO3-)

Infant Fluid Balance Risk

Inability to communicate thirst and a higher percentage of body weight as water; more ECF and ICF

Older Adult Fluid Balance Risk

Decreased thirst sensation, decreased lean body mass, decreased percentage of body weight as water, and reduced renal reserve

Fluid

Water and substances dissolved or suspended in it

Volume

Amount of fluid present

Osmolality

Degree of solute concentration in fluid

pH

Measure of hydrogen ion concentration

Electrolytes

Charged particles, when placed in water

Balance

Body keeps all elements in normal ranges

Fluid Intake

Fluid consumed orally or intravenously, triggered through thirst mechanisms

Fluid Absorption

Movement of fluid and electrolytes in the bloodstream

Fluid Distribution

Movement of fluid between various body fluid compartments

Fluid Output

Elimination of fluid from body

Filtration

Movement of fluid out of capillaries

Reabsorption

Movement of fluid back into capillaries

Capillary Hydrostatic Pressure

Force pushing fluid out of capillaries

Capillary Osmotic Pressure

Force pulling fluid into capillaries

Interstitial Hydrostatic Pressure

Force pushing fluid from the interstitial space into the capillaries

Interstitial Osmotic Pressure

Force pulling fluid into the interstitial space

How does the movement of fluids work?

Whichever force is stronger causes movement

Arterial end of capillaries

Filters some ECF from capillaries to the interstitial compartment to bring nutrients to cells (capillary hydrostatic pressure higher)

venous end of capillaries

Some interstitial fluid goes back to the capillaries to excrete waste due to higher osmotic pressure, resorption (colloidal osmotic pressure is higher)

Osmosis

Movement of water from an area of lower concentration of solute to an area of higher concentration of solute across a semipermeable membrane in an effort to create the same concentration on both sides of the membrane

Osmolaity

Total solute concentration within a fluid compartment; sodium is the greatest determinant of this in ECF; potassium in ICF: normal serum (ECF) is 275-295 mOsm/kg

Normal Serum (ECF) Osmolality

275-295 mOsm/kg

Diffusion

Movement of molecules/electrolytes from higher to lower concentration across a semipermeable membrane

Active Transport

Movement of large substances between ICF and ECF; these substances are too large to cross by diffusion and are transported out using ATP (proteins)

Fluid Output/Elimination Routes

Urine, stool, skin, and lungs

Sensible Fluid Loss

Fluid loss that can be measured

Insensible Fluid Loss

Fluid loss that cannot be measured directly

Extracellular Volume Imbalance

Abnormal amount of fluid in the extracellular compartment (vascular and interstitial spaces); osmolarity is the same

Fluid Volume Deficit (FVD) (Hypovolemia)

Hypovolemia caused by loss of fluid and electrolytes

Fluid Volume Deficit (FVD) / Hypovolemia Clinical Manifestations

Increased heart rate, decreased blood pressure

Fluid Volume Deficit (FVD) / Hypovolemia Urine Findings

Decreased and concentrated urine output

Fluid Volume Deficit (FVD) / Hypovolemia Laboratory Findings

Increased hematocrit due to hemoconcentration and Na+ level normal

Fluid Volume Deficit (FVD) / Hypovolemia Weight Change

Weight loss

Fluid Volume Excess (FVE) / Hypervolemia

Hypervolemia caused by excess fluid retention

Fluid Volume Excess (FVE) / Hypervolemia Clinical Manifestations

Increased blood pressure and heart rate

Fluid Volume Excess (FVE) / Hypervolemia Lung Findings

Crackles

Fluid Volume Excess (FVE) / Hypervolemia Vascular Findings

Jugular venous distention and edema

Fluid Volume Excess (FVE) / Hypervolemia Urine Findings

Dilute urine output

Fluid Volume Excess (FVE) / Hypervolemia Weight Change

Weight gain

Fluid Volume Excess (FVE) / Hypervolemia Laboratory Findings

Decreased hematocrit due to dilution, Na+ levels are normal

Isotonic

Same concentration as normal body fluid; same concentration between water and sodium as in normal body fluid

Isotonic Fluid Imbalance

Fluid imbalance where sodium concentration remains normal

Extracellular Isotonic Excess Causes

Commonly caused by heart failure, renal failure, liver failure, or excessive IV fluids, and increased secretion of aldosterone

Extracellular Fluid Isotonic Excess Pathophysiology

Sodium and water increase at equal rate

Extracellular Fluid Isotonic Excess Extreme Case

Fluid moves into cells, causing them to swell and lyse due to osmosis

Extracellular Fluid Isotonic Deficit Causes

Commonly caused by hemorrhage, vomiting, diarrhea, burns, or fever

Extracellular Fluid Isotonic Deficit Pathophysiology

Sodium and water decrease at an equal rate

Dehydration

Frequently used terms to describe water deficit often involve the loss of both sodium and water

Extracellular Fluid Isotonic Deficit Extreme Cases

Fluid moves out of the cell; cells ultimately shrink due to osmosis

Normal Sodium (Na+)

135-145 mEq/L

Isotonic Fluid Deficit or Excess

gains and losses are equivalent

Hypertonic Fluid Imbalance

Net result leads to increased extracellular osmolality, causing cell shrinkage

Hypotonic Fluid Imbalance

Net result leads to decreased extracellular osmolality, causing cell swelling

Hypernatremia

Body fluids are too concentrated (hypertonic)

Hypernatremia Sodium Concentration

Elevated sodium concentration greater than 145 mEq/L

Hypernatremia Imbalance Classification

Hypertonic fluid imbalance

Hypernatremia Pathophysiology

Water shifts from the intracellular to the extracellular compartment, causing cellular dehydration and cell shrinkage

Hypernatremia Causes

Increased output, increased sodium (Na+) intake, decreased water intake, diarrhea, burns, heat stroke, fever, infection, and lack of antidiuretic hormone (ADH)

Hypernatremia Clinical Manifestations

Thirst, restlessness, confusion, polydipsia, hyperchloremia, muscle weakness, decreased BP, and decreased urine output

Hypernatremia Urine Findings

Decreased urine output and increased urine specific gravity

Hypernatremia Severe Complication

Seizures

Hyponatremia

Body fluids are too diluted (hypotonic)

Hyponatremia Sodium Concentration

Low sodium concentration less than 135 mEq/L

Hyponatremia Imbalance Classification

Hypotonic fluid imbalance

Hyponatremia Pathophysiology

Water shifts into the ICF/cell, causing cellular swelling

Hyponatremia Causes

Gastrointestinal fluid loss, medications, adrenal insufficiency, burns

Hyponatremia Clinical Manifestations

Headache, cramps/weakness, nausea, hypochloremia, anxiety, lethargy, decreased BP

Hyponatremia Severe Complication

Cell swelling can lead to cerebral edema, shock, and seizures

Isotonic Solution

Fluid with same osmolality as body fluids such as 0.9% normal saline

Hypertonic Solution

Fluid with higher osmolality than body fluids, such as 3% sodium chloride (NaCl), is given when Na+ is low

Hypotonic Solution

Fluid with lower osmolality than body fluids, such as 0.45% or 0.3% sodium chloride or D5W, which is given when Na+ is high

Edema

Excess fluid accumulation in the interstitial space

Edema Causes

Increased capillary hydrostatic pressure from venous obstruction (clots) or increased venous pressure leading to Na+ and H2O retention

Edema Inflammatory Cause

Increased capillary permeability from inflammation or trauma

Edema Protein Cause

Decreased plasma proteins, reducing colloid osmotic pressure

Edema Lymphatic Cause

Obstruction of the lymphatic system, such as surgical removal of lymph nodes

Edema Volume Cause

Excess sodium and water retention, typically due to heart failure or renal failure

Localized Edema

Fluid accumulation at site of injury

Generalized Edema (Anasarca)

Fluid accumulation throughout body

Dependent Edema

Fluid accumulation in gravity-dependent areas such as lower extremities

Electrolyte Imbalance

Abnormal plasma concentration of electrolytes

What are the different electrolytes?

Sodium, potassium, calcium, magnesium, chloride, and phosphorus

Chloride (Cl-) Normal Range

95-105 mEq/L

Chloride Function

The main extracellular anion that is proportional to Na+, as it typically follows sodium concentration

Chloride Location

Found in the stomach as a component of hydrochloric acid

Hypochloremia

Chloride level less than 95 mEq/L