Chapter 16 Fluid, Electrolyte, and Acid-Base Imbalances study guide Flashcards
A patient with consistent dietary intake who loses 1 kg of weight in 1 day has lost ____ mL
1000
Which statements about fluid in the human body are true. Select all that apply.
a. The primary hypothalamic mechanism of water intake is thirst
b. Third spacing refers to the abnormal movement of fluid into interstitial spaces.
c. A cell surrounded by hypoosmolar fluid will shrink and die as water moves out of the cell
d. A cell surrounded by hyperosmolar fluid will shrink and die as water moves out of the cell
e. Concentrations of Na and K in intertitial and intracellular fluids are maintained by the sodium potassium pump
a, d, e
Rational: With fluid volume deficit, the osmoreceptors stimulate thirst. Hyperosmolar extracellular fluid (ECF) draws fluid out of the cells. The sodium potassium pump maintains the fluid balance between the intracellular fluid (ICF) and ECF. Third spacing is when fluid will swell and burst as water moves into the cell
Force exerted by a fluid
Hydrostatic pressure
Uses a protein carrier molecule
Facilitated diffusion
Pressure exerted by plasma proteins
Oncotic pressure
Adenosine triphosphate (ATP) required
Active transport
Force determined by osmoality of a fluid
Osmotic pressure
Flow of water from low solute concentration to a high solute concentration
Osmosis
Passive movement of molecules from a high concentration to lower concentration
Diffusion
As fluid circulates through the capillaries, there is movement of fluid between the capillaries and interstitium. What describes the fluid movement that would cause edema (select all that apply)
a. Plasma hydrostatic pressure is less than plasma oncotic pressure
b. Plasma oncotic pressure is higher than interstitial oncotic pressure
c. Plasma hydrostatic pressure is higher than plasma oncotic pressure
d. Plasma hydrostatic pressure is less than interstitial hydrostatic pressure
e. Interstitial hydrostatic pressure is lower than plasma hydrostatic pressure.
c. Plasma hydrostatic pressure is higher than plasma oncotic pressure
e. Interstitial hydrostatic pressure is lower than plasma hydrostatic pressure.
Rational: At the arterial end of the capillary, capillary hydrostatic pressure exceeds plasma oncotic pressure and fluid moves into the interstitial space. At the capillary level, hydrostatic pressure is the major force causing fluid to shift from vascular to the interstitial space. The other options would not cause edema
Burns
Direction of fluid shift
Mechanism of fluid movement involved
Direction of fluid shift: From blood vessels to interstitium
Mechanism of fluid movement involved: Plasma hydrostatic pressure
Dehydration
Direction of fluid shift
Mechanism of fluid movement involved
Direction of fluid shift: From extracellular compartment to cell
Mechanism of fluid movement involved: Interstitial hydrostatic pressure
Fluid overload
Direction of fluid shift
Mechanism of fluid movement involved
Direction of fluid shift: From cell to extracellular compartment & from interstitium to vessels
Mechanism of fluid movement involved: Tissue oncotic pressure
Hyonatremia
Direction of fluid shift
Mechanism of fluid movement involved
Direction of fluid shift: From interstitium to vessels
Mechanism of fluid movement involved: Osmosis
Low serum albumin
Direction of fluid shift:
Mechanism of fluid movement involved:
Direction of fluid shift: From blood vessels to interstitium
Mechanism of fluid movement involved: Oncotic pressure
Administration of 10% Glucose
Direction of fluid shift:
Mechanism of fluid movement involved:
Direction of fluid shift: From blood vessels to interstitium
Mechanism of fluid movement involved: Osmosis
Application of elastic bandages
Direction of fluid shift:
Mechanism of fluid movement involved:
Direction of fluid shift: From interstitium to vessels
Mechanism of fluid movement involved: Interstitial hydrostatic pressure
A woman has ham with gravy and green beans cooked with salt pork for dinner.
a. What could happen to the woman’s serum osmolality as a result of this meal?
b. What fluid regulation mechanisms are stimulated by the intake of these foods?
a. Serum osmolality increases as a large amount of sodium is absorbed.
b. Stimulates antidiuretic hormone (ADH) release from the posterior pituitary, which increases water reabsorption from the kidney, lowering the sodium concentration but increasing vascular volume and hydrostatic pressure, perhaps causing fluid shift into interstitial spaces.
While caring for an 84-year-old patient, the nurse monitors the patient’s fluid and electrolyte balance, recognizing that normal changes of aging are likely to cause:
a: Hyperkalemia
b. Hyponatremia
c. Decreased insensible fluid loss
d. Increased plasma oncotic pressure
b. Hyponatremia
Hyponatremia. A decrease in renin and aldosterone and an increase in ADH and atrial natriuretic peptide (ANP) lead to decreased sodium reabsorption and increased water retention by the kidney, both of which lead to hyponatremia. Skin changes lead to increased insensible water loss, and plasma oncotic pressure is more often decreased because of lack of protein intake.
The nurse is admitting a patient to the clinical unit from surgery. Being alert to potential fluid volume alterations, what assessment data will be important for the nurse to monitor to identify early changes in the patient’s postoperative fluid volume? (Select all that apply)
a. Intake and output
b. Skin turgor
c. Lung sounds
d. Respiratory rate
e. Level of consciousness
a, b, c, d, e
All of these are important in assessing fluid balance in a postop patient. Daily weight along with these assessments will provide data about potential fluid volume abnormalities
Which patient is a risk of hypernatremia?
a. Has a deficiency of aldosterone
b. Has prolonged vomiting and diarrhea
c. Receives excessive IV 5% dextrose solution
d. Has impaired consciousness and decreased thirst sensitivity
d. Has impaired consciousness and decreased thirst sensitivity
A major cause of hypernatremia is a water deficit, which can occur in those with a decreased sensitivity to thirst, the major protection against hyperosmolality. All other conditions lead to hyponatremia
In a patient with sodium imbalances, the primary clinical manifestations are related to alterations in what body system?
a. Kidneys
b. Cardiovascular system
c. Musculoskeletal system
d. Central nervous system
d. Central nervous system
Rational: As water shifts into and out of cells in response to the osmoality of the blood, the cells that are most sensitive to shrinking or swelling are those of the brain, resulting in neurologic symptoms
A patient is taking diuretic drugs. Which fluid or electrolyte imbalance can occur in this patient (select all that apply)?
a. Hyperkalemia
b. Hyponatremia
c. Hypocalcemia
d. Hypotonic fluid loss
e. Hypertonic fluid loss
b, c
Rational: Because of the osmotic pressure of sodium, water will be excreted with the sodium lost with the diuretic. A change in the relative concentration of sodium will not be seen, but an isotonic fluid loss will occur. Diuretics can also cause a loss of calcium in the urine.
With which disorder is hyperkalemia frequently associated with?
a. Hypoglycemia
b. Metabolic acidosis
c. Respiratory alkalosis
d. Decreased urine potassium levels
Metabolic acidosis
In metabolic acidosis, hydrogen ions in the blood are taken into the cell in exchange for potassium ions as a means of buffering excess acids. This results in an increase in serum potassium until the kidneys have time to excrete the potassium
In a patient with a positive Chvostek’s sign, the nurse would anticipate the IV administration of which medication?
a. Calcitonin
b. Vitamin D
c. Loop diuretics
d. Calcium gluconate
d. Calcium gluconate
Chvostek’s sign is a contraction of facial muscles in response to a tap over the facial nerve. This indicates the neuromuscular irritability of low calcium levels and IV calcium is the treatment used to prevent laryngeal spasms and respiratory arrest. Calcitonin is indicated for treatment of high calcium levels and loop diuretics may be used to decrease calcium levels. Oral vitamin D supplements are part of the treatment for hypocalcemia but not for impending tetany.
A patient with chronic kidney disease has hyperphosphatemia. What is a commonly associate electrolyte imbalance?
a. Hypokalemia
b. Hyponatremia
c. Hypocalcemia
d. Hypomagnesemia
c. Hypocalcemia
Kidneys are the major route of phosphate excretion, a function that is impaired in renal failure. A reciprocal relationship exists between phosphorus and calcium and high serum phosphate levels of kidney failure cause low calcium concentration in the serum.
What is the normal PH range of the blood and what ratio of base to acid does this reflect?
a. 7.32 to 7.42; 25 to 2
b. 7.32 to 7.42; 28 to 2
c. 7.35 to 7.45; 20 to 1
d. 7.35 to 7.45; 30 to 1
c. 7.35 to 7.45; 20 to 1
7. 35 to 7.45; 20 to 1. The other answers are incorrect.
What are the characteristics of carbonic acid-bicarbonate buffer system (select all that apply)?
a. CO2 is eliminated by the lung
b. Neutralizes HCl acid to yield carbonic acid and salt
c. H2CO3 formed by neutralization dissociates into H20 and CO2
d. Shifts H+ in and out of cell in exchange for other cations such as potassium and sodium
e. Free basic radicals dissociate into ammonia and OH+ that combines with H+ to form water
a. CO2 is eliminated by the lung
b. Neutralizes HCl acid to yield carbonic acid and salt
c. H2CO3 formed by neutralization dissociates into H20 and CO2
Shifts of H+ in and out of the cell are characteristics of the cellular buffer system. Free basic radical dissociation in characteristic of the protein buffer system.
What are characteristics of the phosphate buffer system (select all that apply)?
a. Neutralizes a strong base to a weak base and water
b. Resultant sodium biphosphate is eliminated by kidneys
c. Free acid radials dissociate into H+ and CO2, buffering excess base
d. Neutralizes a strong acid to yield sodium biphosphate, a weak acid, and salt
e. Shifts chloride in and out of red blood cells in exchanged for sodium bicarbonate, buffering both acids and bases
a. Neutralizes a strong base to a weak base and water
b. Resultant sodium biphosphate is eliminated by kidneys
d. Neutralizes a strong acid to yield sodium biphosphate, a weak acid, and salt
Free acid radical dissociation is characteristic of the protein buffer system. Chloride shifting in and out of red blood cells is characteristic of the hemoglobin buffer system.
A patient who has a large amount of carbon dioxide in the blood also has what in the blood?
a. Large amount of carbonic acid and low hydrogen ion concentration
b. Small amount of carbonic acid and low hydrogen ion concentration
c. Large amount of carbonic and high hydrogen ion concentration
d. Small amount of carbonic acid and high hydrogen ion concentration
c. Large amount of carbonic and high hydrogen ion concentration
The amount of carbon dioxide in the blood directly relates to carbonic acid concentration and subsequently hydrogen ion concentration. The carbon dioxide combines with water in the blood to form carbonic acid and in cases in which carbon dioxide is retained in the blood, acidosis occurs.
Acid base imbalance: Increased carbonic acid (H2CO3)
Mechanism
Respiratory acidosis
Decreased carbonic acid (H2CO3)
Mechanism
Respiratory alkalosis
Increased base bicarbonate (HC03)
Mechanism
Metabolic alkalosis
Decreased base bicarbonate (HC03)
Mechanism
Metabolic acidosis
What isa compensatory mechanism for metabolic alkalosis?
a. Shifting of bacarbonate into cells in exchange for chloride
b. Kidney conservation of bicarbonate and excretion of hydrogen ions
c. Deep, rapid respirations (Kussmaul respirations) to increase CO2 excretion
d. Decreased respiratory rate and depth to retain CO2 and kidney excretion of bicarbonate
Decreased respiratory rate and depth to retain CO2 and kidney excretion of bicarbonate
Rational: Decreased respiratory rate and kidney excretion of HCO3 compensates for metabolic alkalosis. Shifting of bicarbonate for CL may buffer acute respiratory alkalosis. The kidney conserves bicarbonate and excretes hydrogen to compensate for respiratory acidosis. Kussmaul respirations occur with metabolic acidosis to compensate.
Metabolic acidosis common causes
1) Renal failure
2) Severe shock
3) Diabetic ketosis
Respiratory acidosis common causes
1) Respiratory failure
2) Sedative or opioid overdose
Metabolic alkalosis common causes
1) Prolonged vomiting
2) Baking soda used as antacid
Respiratory alkalosis common causes
1) Mechanical over ventilation
2) Response to anxiety, fear, and pain
To provide free water and intracellular fluid hydration for a patient with acute gastroenteritis who is NPO, the nurse would expect administration of which infusion?
a. Dextrose 5% in water
b. Dextrose 10% in water
c. Lactated Ringer’s solution
d. Dextrose 5% in normal saline (0.9%0
a. Dextrose 5% in water
Fluids such as 5% dextrose in water (D5W) allows water to move from the extracellular fluid to the intracellular fluid. Although D5W is physiologically isotonic, the dextrose is rapidly metabolized, leaving free water to shift into cells.
What is an example of an IV solution that would be appropriate to treat an extracellular fluid volume deficit?
a. D5W
b. 3% saline
c. Lactated Ringer’s solution
d. D5W in ½ normal saline (0.45%)
c. Lactated Ringer’s solution
An isotonic solution does not change the osmolality of the blood and does not cause fluid shifts between the extracellular fluid and intracellular fluid. In the case of extracellular fluid loss, an isotonic solution, such as lactated Ringer’s solution, is ideal because it stays in the extracellular compartment. A hypertonic solution would pull fluid from the cells into the extracellular compartment, resulting in cellular fluid loss and possible vascular overload.
The nurse is reviewing a patient’s morning laboratory results. Which result is of greatest concern?
a. Serum Na+ of 150 mEq/L
b. Serum Mg2+ of 1.1 mEq/L
c. Serum PO4 3- of 4.5 mg/Dl
d. Serum Ca2+ (total) of 8.6 mg/Dl
b. Serum Mg2+ of 1.1 mEq/L
With a low magnesium level there is an increased risk for hypokalemia and hypocalcemia as well as altered sodium-potassium pump and altered carbohydrate and protein metabolism. Hypokalemia could lead to dysrhythmias and severe muscle weakness. The sodium and phosphate levels are also not within normal limits. However, the implications are not as life-threatening. The calcium level is normal.
