Understanding Pathophysiology: Chapter 5 Fluids and Electrolytes, Acids and Bases

A nurse is reviewing lab reports. The nurse recalls blood plasma is located in which of the following fluid compartments?

a. Intracellular fluid (ICF)

b. Extracellular fluid (ECF)

c. Interstitial fluid

d. Intravascular fluid

ANS: D

Blood plasma is the intravascular fluid. ICF is fluid in the cells. ECF is all the fluid outside the cells. Interstitial fluid is fluid between the cells and outside the blood vessels.

Water movement between the ICF and ECF compartments is determined by:

a. osmotic forces.

b. plasma oncotic pressure.

c. antidiuretic hormone.

d. buffer systems.

ANS: A

Osmotic forces determine water movement between the ECF and ICF compartments.

Oncotic pressure pulls water at the end of the capillary, which makes it move between intra and extra as interstitial is considered extra. The antidiuretic hormone regulates water balance, which would make water move between the intra- and extracellular spaces. Buffer systems help regulate acid balance.

Which of the following conditions would cause the nurse to monitor for hyperkalemia?

a. Excess aldosterone

b. Acute acidosis

c. Insulin usage

d. Metabolic alkalosis

ANS: B

In acidosis, ECF hydrogen ions shift into the cells in exchange for ICF potassium and sodium; hyperkalemia and acidosis therefore often occur together. Acidosis does not cause excess aldosterone. Insulin would help treat hyperkalemia, not cause it.

Alkalosis does not lead to hyperkalemia.

Which organ system should the nurse monitor when the patient has long-term potassium deficits?

a. Central nervous system (CNS)

b. Lungs

c. Kidneys

d. Gastrointestinal tract

ANS: C

Long-term potassium deficits lasting more than 1 month may damage renal tissue, with interstitial fibrosis and tubular atrophy. Long-term potassium deficits are not associated with damage to the CNS, GI tract, or lungs.

A 42-year-old female presents to her primary care provider reporting muscle weakness and cardiac abnormalities. Laboratory tests indicate that she is hypokalemic. Which of the following could be the cause of her condition?

a. Respiratory acidosis

b. Constipation

c. Hypoglycemia

d. Laxative abuse

ANS: D

Losses of potassium from body stores are usually caused by gastrointestinal and renal disorders. Diarrhea, intestinal drainage tubes or fistulae, and laxative abuse also result in hypokalemia. Acidosis is related to hyperkalemia, not hypokalemia. Constipation can occur with hypokalemia but does not cause it. Hypoglycemia is not related to muscle weakness.

A 19-year-old male presents to his primary care provider reporting restlessness, muscle cramping, and diarrhea. Lab tests reveal that he is hyperkalemic. Which of the following could have caused his condition?

a. Primary hyperaldosteronism

b. Acidosis

c. Insulin secretion

d. Diuretic use

ANS: B

During acute acidosis, hydrogen ions accumulate in the ICF and potassium shifts out of the cell to the ECF, causing hyperkalemia. Primary hyperaldosteronism is associated with hypokalemia, not hyperkalemia. Insulin secretion helps reduce potassium levels in the cell; it does not cause hyperkalemia. Diuretics would cause hypokalemia, not hyperkalemia.

A 60-year-old female is diagnosed with hyperkalemia. Which assessment finding should the nurse expect to observe?

a. Weak pulse

b. Excessive thirst

c. Oliguria

d. Constipation

ANS: C

Hyperkalemia is manifested by oliguria. Hypokalemia is manifested by a weak pulse; it is not caused by hyperkalemia. Hypokalemia is manifested by excessive thirst. Diarrhea, not constipation, is a manifestation of hyperkalemia.

Which of the following buffer pairs is considered the major plasma buffering system?

a. Protein/fat

b. Carbonic acid/bicarbonate

c. Sodium/potassium

d. Amylase/albumin

ANS: B

The carbonic acid/bicarbonate buffer pair operates in both the lung and the kidney and is a major extracellular buffer. Protein and fat are nutrients not related to the buffering system. Sodium and potassium are electrolytes for fluid and electrolyte balance, not the major plasma buffering system for acid-base balance. Amylase is a carbohydrate enzyme, and albumin is a protein; neither is a buffering system.

A nurse recalls that regulation of acid-base balance through removal or retention of volatile acids is accomplished by the:

a. buffer systems.

b. skin.

c. lungs.

d. liver.

ANS: C

The volatile acid is carbonic acid (H2CO3), which readily dissociates into carbon dioxide (CO2) and water (H2O). The CO2 is then eliminated by the lungs. Buffer systems are throughout the body and operate in the extracellular and intracellular systems. Neither the liver nor the skin regulates acid-base balance.

Which patient is most prone to metabolic alkalosis? A patient with:

a. retention of metabolic acids.

b. hypoaldosteronism.

c. excessive loss of chloride (Cl).

d. hyperventilation.

ANS: C

When acid loss is caused by vomiting, renal compensation is not very effective because loss of Cl stimulates renal retention of bicarbonate, leading to alkalosis. Retention of metabolic acids would lead to acidosis, not alkalosis. Hypoaldosteronism leads to hyponatremia and does not cause alkalosis. Hyperventilation leads to respiratory alkalosis, not metabolic alkalosis.

Which patient should the nurse assess for both hyperkalemia and metabolic acidosis? A patient diagnosed with:

a. diabetes insipidus.

b. pulmonary disorders.

c. Cushing syndrome.

d. renal failure.

ANS: D

Renal failure is associated with hyperkalemia and metabolic acidosis. Diabetes insipidus results in hypernatremia. Pulmonary disorders are a cause of respiratory acidosis or alkalosis but do not affect hyperkalemia. Cushing syndrome results in hypernatremia.

For a patient experiencing metabolic acidosis, the body will compensate by:

a. excreting H+ through the kidneys.

b. hyperventilating.

c. retaining CO2 in the lungs.

d. secreting aldosterone.

ANS: B

It is the lungs hyperventilating that would compensate for metabolic acidosis by blowing off CO2, not any function associated with the kidneys. CO2 retention would increase the acidotic state. Aldosterone would conserve water but does not help compensate for acidosis.

Which finding would support the diagnosis of respiratory acidosis?

a. Vomiting

b. Hyperventilation

c. Pneumonia

d. An increase in noncarbonic acids

ANS: C

Respiratory acidosis occurs with hypoventilation, and pneumonia leads to hypoventilation. Vomiting leads to loss of acids and then to alkalosis. Hyperventilation leads to respiratory alkalosis. Metabolic acidosis is caused by an increase in noncarbonic acids.

A 54-year-old male with a long history of smoking complains of excessive tiredness, shortness of breath, and overall ill feelings. Lab results reveal decreased pH, increased CO2, and normal bicarbonate ion. These findings help to confirm the diagnosis of:

a. respiratory alkalosis.

b. metabolic acidosis.

c. respiratory acidosis.

d. metabolic alkalosis.

ANS: C

A decreased pH indicates acidosis. With increased CO2, it is respiratory acidosis. The bicarbonate is normal, so it cannot be metabolic acidosis.

For a patient with respiratory acidosis, chronic compensation by the body will include:

a. kidney excretion of H+.

b. kidney excretion of HCO3.

c. prolonged exhalations to blow off CO2.

d. protein buffering.

ANS: A

The kidneys excrete H+ to compensate for respiratory acidosis. The kidneys do not excrete HCO3 to compensate; this would increase acidosis. Prolonged exhalations would not be effective for compensation, especially in a chronic state. Protein buffering is intracellular and would not be effective enough to compensate for respiratory acidosis.

A 55-year-old female presents to her primary care provider and reports dizziness, confusion, and tingling in the extremities. Blood tests reveal an elevated pH, decreased PCO2, and slightly decreased HCO3. Which of the following is the most likely diagnosis?

a. Respiratory alkalosis with renal compensation

b. Respiratory acidosis with renal compensation

c. Metabolic alkalosis with respiratory compensation

d. Metabolic acidosis with respiratory compensation

ANS: A

With an elevated pH, the diagnosis must be alkalosis. Since the PCO2 is low, it is likely respiratory, with a slight decrease in HCO3 indicating renal compensation.

A 60-year-old male with a 30-year history of smoking is diagnosed with a hormone-secreting lung tumor. Further testing indicates that the tumor secretes ADH. Which of the following assessment findings should the nurse expect? (select all that apply)

a. Confusion

b. Weakness

c. Nausea

d. Muscle twitching

e. Increased reflexes

ANS: A, B, C, D

Secretion of ADH leads to water intoxication with symptoms of cerebral edema, including confusion, convulsions, weakness, nausea, and muscle twitching. Depressed reflexes are associated with water intoxication.