Ch. 41 Fluids and Electrolytes Study Guide Questions

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Extracellular body fluids

Is the fluid outside the cell (interstitial, intravascular, and transcellular fluid)

Intracellular body fluids

Comprises all fluid within the cells of the body (42% of body weight)

Cations

Positively charged electrolytes (sodium, potassium, and calcium)

Anions

Negatively charged electrolytes (chloride, bicarbonate, and sulfate)

meg/L

Represents the number of grams of the specific electrolyte dissolved in a liter of plasma

Solute

Is an electrolyte; oxygen, carbon dioxide, glucose, and proteins

Osmosis

Involves the movement of a pure solvent across a semipermeable membrane from an area of lesser solute concentration to an area of greater solute concentration

Osmols

The concentration of a solution is measured in osmols, which reflects the amount of a substance in the form of molecules, ions, or both

Osmotic pressure

Is the drawing power of water and depends on the number of molecules in solution

Osmolality

The osmotic pressure of a solution

Osmolarity

Another term that describes the concentration of solution

Isotonic solution

The solutions on both sides of the semipermeable membrane are equal in concentration (expand the body's fluid volume without causing a fluid shift from one compartment to another).

Hypertonic solution

A solution of higher osmotic pressure (pulls fluid from cells, causing them to shrink)

Hypotonic solution

A solution of lower osmotic pressure (moves fluids into the cells, causing them to enlarge)

Diffusion

Random movement of a solute in a solution across a semipermeable membrane from an area of higher concentration to an area of lower concentration

Concentration gradient

The difference between two concentrations

Filtration

Is the process by which water and diffusible substances move together across a membrane, in response to fluid pressure, moving from an area of higher pressure to one of lower pressure

Active transport

Requires metabolic activity and expenditure of energy to move substances across the cell membrane

Three ways that body fluids are regulated

a. Fluid intake
b. Hormonal controls
c. Fluid output

Osmoreceptors

Continually monitor the serum osmotic pressure

Hypovolemia

Excess fluid is lost

Dehydration

Risk for clients who are unable to perceive or respond to the thirst mechanism

Antidiuretic hormone

Is stored in the pituitary gland and is released in response to changes in the blood osmolarity

Angiotension I

Causes vasoconstriction

Angiotension II

Causes massive selective vasoconstriction of blood vessels and relocates blood flow to kidneys and stimulates the release of aldosterone (when the sodium is low)

Aldosterone

Adrenal cortex releases in response to increased plasma potassium levels

atrial natriuetic peptide

Plays a critical role in the balance of fluid and electrolytes and the maintenance of vascular tone

Four organs of water loss

a. Kidneys
b. Skin
c. Lungs
d. Gastrointestinal tract

Insensible water loss

Is continuous and occurs through the skin and lungs, not perceived by the person

Sensible water loss

Occurs through excess perspiration and can be perceived by the client

Values of Sodium

135-145 mEq/L

Values of Potassium

3.5-5.0 mEq/L

Values of Calcium

4.5-5.5 mg/dL

Values of Magnesium

1.5-2.5 mEq/L

Values of Chloride

95-105 mEq/L

Values of Bicarbonate

22-26 (arterial) mEq/L
24-30 (venous) mEq/L

Values of Phosphate

2.8-4.5 mg/dL

Function of Sodium

Major contributor to maintain water balance

Function of Potassium

Is necessary for glycogen deposits in the liver and skeletal muscle, transmission and conduction of nerve impulses, normal cardiac conduction, and skeletal and smooth muscle contraction

Function of Calcium

Bone and teeth formation, blood clotting, hormone secretion, cell membrane integrity, cardiac conduction, transmission of nerve impulses, and muscle contraction

Function of Magnesium

Essential for enzyme activities, neurochemical activities, and cardiac and skeletal muscle excitability

Function of Chloride

Chloride is the major anion in extracellular fluid (ECF). The transport of _______ follows sodium.

Function of Bicarbonate

The ________ ion is an essential component of the carbonic acid-bicarbonate buffering system essential to acid-base balance.

Function of Phosphate

It assists in acid-base regulation. ______ and calcium help to develop and maintain bones and teeth. ________ also promotes normal neuromuscular action and participates in carbohydrate metabolism.

Regulatory Mechanism of Sodium

Dietary intake and aldosterone secretion

Regulatory Mechanism of Potassium

Dietary intake and renal excretion regulate this

Regulatory Mechanism of Calcium

Absorbed from intestine, excreted by the kidneys and reabsorbed or deposited in bone Regulated by parathyroid hormone, vitamin D, and calcitonin

Regulatory Mechanism of Magnesium

regulated by dietary intake, renal mechanisms, and actions of the parathyroid hormone (PTH).

Regulatory Mechanism of Chloride

regulated by dietary intake and the kidneys

Regulatory Mechanism of Bicarbonate

The kidneys regulate this

Regulatory Mechanism of Phosphate

normally absorbed through the gastrointestinal (GI) tract. It is regulated by dietary intake, renal excretion, intestinal absorption, and PTH

Three types of acid-base regulators in the body

a. Chemical
b. Biological
c. Physiological buffering

Hyponatremia Lab Finding

Serum sodium level below 135 mEq/L, serum osmolality 280 mOsm/kg, and urine specific gravity below 1.010 (if not caused by syndrome of inappropriate antidiuretic hormone [SIADH])

Hyponatremia Signs and Symptoms

Apprehension, personality change, postural hypotension, postural dizziness, abdominal cramping, nausea and vomiting, diarrhea, tachycardia, dry mucous membranes, convulsions, and coma

Hypernatremia Lab Finding

Serum sodium levels above 145 mEq/L, serum osmolality 300 mOsm/kg, and urine specific gravity 1.030 (if not caused by diabetes insipidus

Hypernatremia Signs and Symptoms

Extreme thirst, dry and flushed skin, dry and sticky tongue and mucous membranes, postural hypotension, fever, agitation, convulsions, restlessness, and irritability

Hypokalemia Lab Finding

Serum potassium level below 3.5 mEq/L and electrocardiogram (ECG) abnormalities: flattened T wave; ST segment depression; U wave; potentiated digoxin effects (e.g., ventricular dysrhythmias)

Hypokalemia Signs and Symptoms

Weakness and fatigue, muscle weakness, nausea and vomiting, intestinal distention, decreased bowel sounds, decreased deep tendon reflexes, ventricular dysrhythmias, paresthesias, and weak, irregular pulse

Hyperkalemia Lab Finding

Serum potassium level above 5.0 mEq/L and ECG abnormalities: peaked T wave and widened QRS complex (bradycardia, heart block, dysrhythmias); eventually QRS pattern widens and cardiac arrest occurs

Hyperkalemia Signs and Symptoms

Anxiety, dysrhythmias, paresthesia, weakness, abdominal cramps, and diarrhea

Hypocalcemia Lab Finding

Serum ionized calcium level below 4.5 mEq/L or total serum calcium below 8.5 mg/dL and ECG abnormalities: ventricular tachycardia

Hypocalcemia Signs and Symptoms

Numbness and tingling of fingers and circumoral (around mouth) region, hyperactive reflexes, positive Trousseau's sign (carpopedal spasm with hypoxia), positive Chvostek's sign (contraction of facial muscles when facial nerve is tapped), tetany, muscle cramps, and pathological fractures (chronic hypocalcemia)

Hypercalcemia Lab Finding

Serum ionized calcium level above 5.5 mEq/L or total serum calcium level above 10.5 mg/dL; x-ray examination showing generalized osteoporosis, widespread bone cavitation, radiopaque urinary stones; and elevated blood urea nitrogen (BUN) level 25 mg/100 mL and elevated creatinine level 1.5 mg/100 mL caused by fluid volume deficit (FVD) or renal damage caused by urolithiasis; ECG abnormalities: heart block

Hypercalcemia Signs and Symptoms

Anorexia, nausea and vomiting, weakness, hypoactive reflexes, lethargy, flank pain (from kidney stones), decreased level of consciousness, personality changes, and cardiac arrest

Hypomagnesemia Lab Finding

Serum magnesium level below 1.5 mEq/L

Hypomagnesemia Signs and Symptoms

Muscular tremors, hyperactive deep tendon reflexes, confusion and disorientation, tachycardia, hypertension, dysrhythmias, and positive Chvostek's sign and Trousseau's sign

Hypermagnesemia Lab Finding

Serum magnesium level above 2.5 mEq/L; ECG abnormalities: prolonged QT interval, AV block

Hypermagnesemia Signs and Symptoms

Acute elevations in magnesium levels: hypoactive deep tendon reflexes, decreased depth and rate of respirations, hypotension, and flushing

pH

Measures the hydrogen ion concentration in the body fluids (7.35 to 7.45)

PaCO2

Is the partial pressure of carbon dioxide in arterial blood (35 to 45 mm Hg)

PaO2

Is the partial pressure of oxygen in the blood (80 to 100 mm Hg)

Oxygen saturation

Is the point at which hemoglobin is saturated by oxygen (95% to 99%)

Base excess

Is the amount of blood buffer (hemoglobin and bicarbonate) that exists (+/- 2 mEq/L)

Bicarbonate

Is the major renal component of acid-base balance (22 to 26 mEq/L)

Respiratory acidosis Lab Findings

Arterial blood gas alterations: pH < 7.35, PaCO2 > 45 mm Hg, PaO2 < 80 mm Hg, and bicarbonate level normal (if uncompensated) or >26 mEq/L (if compensated)

Respiratory acidosis Signs and Symptoms

Confusion, dizziness, lethargy, headache, ventricular dysrhythmias, warm and flushed skin, muscular twitching, convulsions, and coma

Metabolic acidosis Lab Findings

Arterial blood gas alterations: pH < 7.35, PaCO2 normal (if uncompensated) or < 35 mm Hg (if compensated), PaO2 normal or increased (with rapid, deep respirations), bicarbonate level < 22 mEq/L, and oxygen saturation normal

Metabolic acidosis Signs and Symptoms

Headache, lethargy, confusion, dysrhythmias, tachypnea with deep respirations, abdominal cramps, and flushed skin

Respiratory alkalosis Lab Findings

Arterial blood gas alterations: pH > 7.45, PaCO2 < 35 mm Hg, PaO2 normal, and bicarbonate level normal (if short lived or uncompensated) or < 22 mEq/L (if compensated)

Respiratory alkalosis Signs and Symptoms

Dizziness, confusion, dysrhythmias, tachypnea, numbness and tingling of extremities, convulsions, and coma

Metabolic alkalosis Lab Findings

Arterial blood gas alterations: pH > 7.45, PaCO2 normal (if uncompensated) or > 45 mm Hg (if compensated), PaO2 normal, and bicarbonate level > 26 mEq/L

Metabolic alkalosis Signs and Symptoms

Dizziness; dysrhythmias; numbness and tingling of fingers, toes, and circumoral region; muscle cramps; tetany

Risk factors for fluid, electrolyte and acid-base imbalances

a. Age—Very young; very old
b. Gender—Women
c. Environment—Diet, exercise, and hot weather and sweating
d. Chronic diseases—Cancer; cardiovascular disease, such as congestive heart failure; endocrine disease, such as Cushing's disease and diabetes mellitus; malnutrition; chronic obstructive pulmonary disease; and renal disease
e. Trauma—Crush injuries, head injuries, burns
f. Therapies—Diuretics, steroids, intravenous (IV) therapy, and total parenteral nutrition (TPN)
g. Gastrointestinal losses - Gastroenteritis; nasogastric suctioning; fistulas

How can age affect fluid, electrolyte, and acid-base balances?

Infants and children have greater water needs and are more vulnerable to fluid volume alterations; fever in children creates an increase in the rate of insensible water loss; adolescents have increased metabolic processes; older adults have decreased thirst sensation, which often causes electrolyte imbalances

How can acute illness affect fluid, electrolyte, and acid-base balances?

Surgery, head and chest trauma, shock, and second- and third-degree burns place the clients at risk.

How can surgery affect fluid, electrolyte, and acid-base balances?

The more extensive the surgery and fluid loss, the greater the body's response

How can burns affect fluid, electrolyte, and acid-base balances?

The greater the body surface burned, the greater the fluid loss

How can respiratory disorders affect fluid, electrolyte, and acid-base balances?

Predispose to respiratory acidosis and/or respiratory alkalosis

How can head injury affect fluid, electrolyte, and acid-base balances?

Can result in cerebral edema and diabetes insipidus

How can chronic illness affect fluid, electrolyte, and acid-base balances?

Cancer, congestive heart failure (CHF), or renal disease

How can cancer affect fluid, electrolyte, and acid-base balances?

Depends on the type and progression of the cancer and its treatment (diarrhea and anorexia)

How can cardiovascular disease affect fluid, electrolyte, and acid-base balances?

Diminished cardiac output, which reduces kidney perfusion and decreases urine output

How can renal disorders affect fluid, electrolyte, and acid-base balances?

Causes an abnormal retention of sodium, chloride, potassium, and water (metabolic acidosis)

How can gastrointestinal disturbances affect fluid, electrolyte, and acid-base balances?

Gastroenteritis and nasogastric suctioning result in the loss of fluid, potassium, and chloride ions.

How can environmental factors affect fluid, electrolyte, and acid-base balances?

Vigorous exercise or exposure to extreme temperatures

How can diet affect fluid, electrolyte, and acid-base balances?

Recent changes in appetite or the ability to chew and swallow (breakdown of glycogen and fat stores, metabolic acidosis, hypoalbuminemia, edema)

How can lifestyle affect fluid, electrolyte, and acid-base balances?

History of smoking or alcohol consumption (respiratory acidosis)

How can medication affect fluid, electrolyte, and acid-base balances?

Diuretics—Metabolic alkalosis, hyperkalemia, and hypokalemia
Steroids—Metabolic alkalosis
Potassium supplements—GI disturbances, including intestinal and gastric ulcers and diarrhea
Respiratory center depressants (e.g., opioid analgesics)—Decreased rate and depth of respirations, resulting in respiratory acidosis
Antibiotics—Nephrotoxicity (e.g., vancomycin, methicillin, or aminoglycosides); hyperkalemia and/or hypernatremia (e.g., azlocillin, carbenicillin, piperacillin, ticarcillin, or Unasyn)
Calcium carbonate (Tums)—Mild metabolic alkalosis with nausea and vomiting
Magnesium hydroxide (Milk of Magnesia)—Hypokalemia
Nonsteroidal antiinflammatory drugs—Nephrotoxicity

Imbalances associated with Weight loss of 5% to 8%:

Mild to moderate fluid volume deficit (FVD)

Imbalances associated with Irritability

Metabolic or respiratory alkalosis, hyperosmolar imbalance, hypernatremia, hypokalemia

Imbalances associated with Lethargy

FVD, metabolic acidosis or alkalosis, respiratory acidosis, hypercalcemia

Imbalances associated with Periorbital edema

Fluid volume excess (FVE)

Imbalances associated with Sticky, dry mucous membranes

FVD, hypernatremia

Imbalances associated with Chvostek's sign

Hypocalcemia

Imbalances associated with Distended neck veins

FVE

Imbalances associated with Dysrhythmias

Metabolic acidosis, respiratory alkalosis and acidosis, potassium imbalance, hypomagnesemia

Imbalances associated with Weak pulse

FVD, hypokalemia

Imbalances associated with Low blood pressure

FVD, hyponatremia, hyperkalemia, hypermagnesemia

Imbalances associated with Third heart sound

FVE

Imbalances associated with Increased respiratory rate

FVE, respiratory alkalosis, metabolic acidosis

Imbalances associated with Crackles

FVE

Imbalances associated with Anorexia

Metabolic acidosis

Imbalances associated with Abdominal cramps

Metabolic acidosis

Imbalances associated with Poor skin turgor

FVD

Imbalances associated with Oliguria or anuria

FVD, FVE

Imbalances associated with Increased specific gravity

FVD

Imbalances associated with Muscle cramps, tetany

: Hypocalcemia, metabolic or respiratory alkalosis

Imbalances associated with Hypertonicity of muscles on palpation

Hypocalcemia, hypomagnesemia, metabolic alkalosis

Imbalances associated with Decreased or absent deep tendon reflexes

Hypokalemia, hypercalcemia

Imbalances associated with Increased temperature

Hypernatremia, hyperosmolar imbalance, metabolic acidosis

Imbalances associated with Distended abdomen

Third-space syndrome

Imbalances associated with Cold, clammy skin

FVD

Imbalances associated with 2+ edema

FVE

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