Fluid and Electrolyte Imbalances

Body fluid compartments

Intracellular Fluid (ICF) and Extracellular Fluid (ECF)

ICF

Fluid inside cells; about 2/3 of total body water

ECF

Fluid outside cells

ECF components

Plasma, interstitial, lymph, transcellular

Examples of transcellular fluid

CSF, pleural, peritoneal, synovial, pericardial

How does fluid move

Diffusion, osmosis, filtration, active transport

Diffusion

High to low concentration

Osmosis

Water moves toward higher solute concentration

Filtration

Fluid moves from high to low pressure

Active transport

Moves substances against gradient using ATP

Main fluid imbalances

Dehydration

Loss of water from the body

Hypovolemia

Loss of water and sodium; decreased blood volume

Another name for hypovolemia

Isotonic dehydration or FVD

Compensation for hypovolemia

Thirst, SNS activation, ADH release

ADH function

Increases water reabsorption by kidneys

Severe dehydration complication

Seizures

FVD complication

Hypovolemic shock

Causes of FVD

Vomiting, diarrhea, NG suction, excessive diaphoresis, diuretics, kidney disease, adrenal insufficiency, burns, hemorrhage or plasma loss, NPO, anorexia, nausea, dysphagia, confusion

Causes of dehydration

Fever, hyperventilation, DKA, DI, osmotic diuresis, poor water intake, excess salt, hypertonic IV fluids

Vital signs with FVD

Tachycardia, hypotension, orthostatic hypotension, tachypnea

Temperature changes

Hypothermia (FVD), hyperthermia (dehydration)

Findings of FVD

Dizziness, weakness, confusion, syncope, seizures, thirst, dry mouth, dry tongue, nausea, weight loss, oliguria, poor turgor, cool clammy skin, delayed cap refill, sunken eyes, flat neck veins, no tears

Hematocrit with dehydration

Increased

Serum osmolarity with dehydration

Increased (>295 mOsm/kg)

Urine specific gravity with dehydration

Increased (>1.030)

Sodium level with dehydration

Increased (>145 mEq/L)

BUN with dehydration

Increased (>25 mg/dL)

Other lab changes with dehydration

Increased protein, glucose, electrolytes

Overhydration

Too much fluid in the body

Fluid overload

Excess water causing hemodilution

Hemodilution

Blood components appear decreased due to excess fluid

Hypervolemia

Excess water and electrolytes (FVE)

Severe FVE complications

Pulmonary edema and heart failure

Compensation for FVE

↑ Natriuretic peptides, ↓ aldosterone

Natriuretic peptides

Increase sodium and water excretion

Causes of hypervolemia

Heart failure, cirrhosis, kidney failure, burns, hypertonic fluids, aging

High sodium sources

IV fluids, diet, sodium bicarbonate, hypertonic enemas

Causes of overhydration

Excess water intake, SIADH, excess D5W, hypotonic fluids

SIADH

Excess ADH causing water retention

Vital signs with FVE

Tachycardia, bounding pulse, hypertension, tachypnea

Findings with FVE

Confusion, weakness, paresthesias, visual changes, seizures from sudden hyponatremia, increased motility, ascites, dyspnea, orthopnea, crackles, pitting edema, JVD, weight gain, cool pale skin

Hematocrit with FVE

Decreased (hemodilution)

Serum osmolarity with FVE

Decreased (<280 mOsm/kg)

Sodium level with FVE

Decreased

BUN with FVE

Decreased

ABG finding with FVE

Respiratory alkalosis

Respiratory alkalosis values

PaCO₂

Urine specific gravity with FVE

<1.010 (unless SIADH)

Chest x-ray finding with FVE

Pulmonary congestion

Diet for FVE

Restrict sodium

Medication for FVE

Loop or osmotic diuretics

Reposition frequency

At least every 2 hours

What are electrolytes?

Charged minerals that regulate fluid balance, nerve function, muscle contraction, and metabolism

Major electrolytes

Sodium, potassium, calcium, magnesium, chloride, phosphorus

Cations

Sodium, potassium, calcium, magnesium

Anions

Chloride, phosphate, bicarbonate

Who is at greatest risk for electrolyte imbalances

Infants, children, older adults, clients with chronic illness or cognitive disorders

Normal sodium

136-145 mEq/L

Normal potassium

3.5-5.0 mEq/L

Normal calcium

9-10.5 mg/dL

Normal magnesium

1.3-2.1 mEq/L

Normal chloride

98-106 mEq/L

Normal phosphorus

3-4.5 mg/dL

Main extracellular electrolyte

Sodium (Na+)

Functions of sodium

Maintains fluid balance, acid-base balance, nerve and muscle function

Hyponatremia

Sodium <136 mEq/L

Causes of hyponatremia

Excess water or sodium loss, vomiting, diarrhea, diuretics, SIADH, heart failure, excess water

What happens to cells in hyponatremia

Water moves into cells causing swelling

Brain effect of hyponatremia

Brain cell swelling causing neurologic symptoms

Older adults and hyponatremia

Higher risk due to chronic illness and diuretics

Vital signs with hyponatremia

Tachycardia, hypotension, orthostatic hypotension

Findings of hyponatremia

Headache, confusion, lethargy, weakness, seizures, coma, nausea, vomiting, anorexia

Treatment for severe hyponatremia

Hypertonic saline (3% or 5% NaCl)

Hypernatremia

Sodium >145 mEq/L

What happens to cells in hypernatremia

Water moves out of cells causing dehydration

Main causes of hypernatremia

Water loss or excess sodium intake

Common causes of hypernatremia

Fever, burns, DI, heat stroke, hypertonic IV fluids

Vital signs with hypernatremia

Hyperthermia, tachycardia, orthostatic hypotension

Findings of hypernatremia

Restlessness, confusion, irritability, seizures, coma, thirst, dry sticky mucous membranes, nausea, vomiting, warm flushed skin, oliguria

IV fluids for fluid-loss hypernatremia

Hypotonic or isotonic fluids as prescribed

Hypotonic IV fluid examples

0.225% NaCl, 0.45% NaCl

Isotonic IV fluid examples

D5W, 0.9% NaCl, Lactated Ringer's

Treatment for excess sodium

Increase water intake and give loop diuretics if indicated

Main intracellular cation

Potassium (K+)

Functions of potassium

Nerve impulses, muscle contraction, cardiac function, acid-base balance

Hypokalemia

Potassium

Risk factors for hypokalemia

Diuretics, vomiting, diarrhea, insulin, alkalosis, Cushing syndrome

Causes of hypokalemia

Losses, low intake, potassium shifts into cells, vomiting, diarrhea, NG suction, laxatives, loop diuretics, corticosteroids, renal disorders, diaphoresis, wound drainage

Vital signs with hypokalemia

Weak irregular pulse, hypotension, respiratory distress

Findings of hypokalemia

Fatigue, weakness, cramps, paresthesias, confusion, respiratory paralysis, constipation, ileus, abdominal distention, nausea, vomiting, flat T waves, U waves, ST depression, prolonged QT, PVCs, bradycardia, VT, VF, heart blocks

Foods high in potassium

Bananas, oranges, potatoes, spinach, avocados, fish

How is IV potassium given

Diluted and slowly by infusion (10-20 mEq/hr)

Why is IV potassium never given IV push?

High risk for cardiac arrest

What should be monitored in hypokalemia?

Adequate urine output, monitor for shallow respirations, monitor ECG continuously

Effects of hypokalemia and digoxin

Increases risk of digoxin toxicity

Hyperkalemia

Potassium >5.0 mEq/L

Causes of hyperkalemia

Excess intake, potassium shifts out of cells, decreased excretion

Who is most at risk for hyperkalemia?

Clients with kidney failure

Why is hyperkalemia dangerous?

Can cause fatal cardiac dysrhythmias