Chapter 25

Fully compensated respiratory acidosis is demonstrated by a. pH 7.36, PaCO2 55, HCO3 36. b. pH 7.45, PaCO2 40, HCO3 28. c. pH 7.26, PaCO2 60, HCO3 26. d. pH 7.40, PaCO2 40, HCO3 24.

ANS: A Compensation for respiratory acidosis involves conservation of HCO3 in the body; an HCO3 of 36 is a key finding; the normal pH (7.36) indicates compensation. Low HCO3 is not indicative of compensated respiratory acidosis. Low pH indicates no compensation or only partial compensation. Values of pH 7.40, PaCO2 40, and HCO3 24 are all normal.

Respiratory alkalosis is caused by a. hyperventilation. b. pneumonia. c. chest muscle weakness. d. pulmonary edema.

ANS: A Hyperventilation causes respiratory alkalosis as a result of loss of carbonic acid. Pneumonia, chest muscle weakness, and pulmonary edema cause carbonic acid to accumulate in the blood and result in respiratory acidosis.

The body compensates for metabolic alkalosis by a. hypoventilation. b. decreasing arterial carbon dioxide. c. increasing bicarbonate ion excretion. d. hyperventilation.

ANS: A In metabolic alkalosis, the lungs compensate by hypoventilation to conserve CO2 in the body. Decreasing arterial carbon dioxide would worsen metabolic alkalosis. The respiratory system compensates for metabolic acid and base disturbances; the lungs do not increase bicarbonate ion excretion. Hyperventilation would blow off CO2 and cause respiratory alkalosis.

The finding of ketones in the blood suggests that a person may have a. metabolic acidosis. b. metabolic alkalosis. c. respiratory acidosis. d. respiratory alkalosis.

ANS: A Ketones are produced from breakdown of fat in the body as a result of starvation or lack of ability to utilize glucose in diabetes mellitus. Ketoacids in the blood indicate a very high ketone level in the body, which leads to metabolic acidosis. Ketonuria from high ketones in the blood would not indicate metabolic alkalosis. The respiratory system does not influence ketone level.

Uncompensated metabolic alkalosis would result in a. increased pH, increased HCO3- b. increased pH, decreased HCO3- c. decreased pH, increased HCO3- d. decreased pH, decreased HCO3-

ANS: A Metabolic alkalosis is characterized by increased HCO3- and increased pH. HCO3- is a base and would be increased. Decreased pH indicates an uncompensated or partially compensated acidosis

Respiratory acidosis is associated with a. increased carbonic acid. b. hypokalemia. c. increased neuromuscular excitability. d. increased pH

ANS: A Respiratory acidosis causes an excess of carbonic acid that may be because of impaired gas exchange, inadequate neuromuscular function, and impairment of respiratory control of the brainstem. Hypokalemia is associated with alkalosis. Acidosis is associated with decreased neuromuscular excitability. Increased pH is associated with alkalosis; in acidosis the pH is low.

Diarrhea and other lower intestinal fluid losses will contribute to a. metabolic alkalosis. b. metabolic acidosis. c. respiratory acidosis. d. mixed acid-base disorders.

ANS: B Diarrhea results in loss of bicarbonate and leads to metabolic acidosis. Loss of bicarbonate (a base) would not lead to metabolic alkalosis. Respiratory conditions lead to respiratory acid and base disturbances; diarrhea is not a respiratory condition. Bicarbonate loss through diarrhea would not lead to any respiratory acid/base disturbance.

Vomiting of stomach contents or continuous nasogastric suctioning may predispose to development of a. carbonic acid deficit. b. metabolic acid deficit. c. metabolic acidosis. d. carbonic acid excess.

ANS: B Gastric contents are rich in hydrochloric acid; loss of this through suctioning or vomiting leads to a metabolic acid deficit and alkalosis. Carbonic acid is related to the respiratory system. Vomiting produces metabolic alkalosis as a result of loss of acid-rich gastric contents, it does not increase carbonic acid.

Early manifestations of a developing metabolic acidosis include a. coma. b. headache. c. muscle cramps. d. short and shallow respirations.

ANS: B Headache is an early manifestation of a developing metabolic acidosis. Coma is a very late symptom of metabolic acidosis. Muscle cramps are not characteristic of metabolic acidosis. Deep rapid respirations are the compensatory mechanism for metabolic acidosis.

A person with acute hypoxemia may hyperventilate and develop a. respiratory acidosis. b. respiratory alkalosis. c. metabolic alkalosis. d. metabolic acidosis.

ANS: B Hyperventilation causes much carbonic acid to be blown off, resulting in respiratory alkalosis. Respiratory acidosis is caused by hypoventilation and retention of carbonic acid. Hyperventilation does not cause metabolic acid or base disturbances

Which acid are the kidneys unable to excrete? a. Metabolic b. Carbonic c. Bicarbonate d. Ammonia

ANS: B The kidneys can excrete any acid except carbonic acid. The kidneys are able to excrete metabolic acids and ammonia. The kidneys are able to excrete bicarbonate, but bicarbonate is a base, not an acid.

A patient has been hospitalized several times in 6 months with severe ECV depletion and hypokalemia resulting from chronic laxative abuse. Which blood gas results should be relayed to the physician? a. pH in high part of normal range, PaO2 normal, PaCO2 normal, bicarbonate normal b. pH in high part of normal range, PaO2 normal, PaCO2 high, bicarbonate high c. pH in low part of normal range, PaO2 normal, PaCO2 low, bicarbonate low d. pH in low part of normal range, PaO2 normal, PaCO2 normal, bicarbonate normal

ANS: B The laboratory values of pH in high part of normal range, PaO2 normal, PaCO2 high, and bicarbonate high indicate compensated metabolic alkalosis, which is not consistent with increased excretion of bicarbonate in chronic diarrhea from laxative abuse, so you should page the physician. The laboratory values of pH in low part of normal range, PaO2 normal, PaCO2 low, and bicarbonate low indicate compensated metabolic acidosis, which is consistent with increased excretion of bicarbonate in chronic diarrhea from laxative abuse. The other answer options are normal laboratory values.

The major buffer in the extracellular fluid is a. hemoglobin. b. albumin. c. bicarbonate. d. phosphate.

ANS: C Bicarbonate is the major buffer in the extracellular fluid. Hemoglobin is in erythrocytes, which are in the vascular compartment, but not in the interstitial portion of extracellular fluid. Albumin is in the vascular compartment, but not in the interstitial portion of extracellular fluid. Phosphate is an important buffer in urine and intracellular fluid.

The patient who requires the most careful monitoring for development of metabolic acidosis is a patient who a. is in the diuretic phase of acute renal failure. b. has had hypokalemia for over a week. c. has had diarrhea for over a week. d. has newly diagnosed Cushing syndrome

ANS: C Diarrhea causes increased excretion of the base bicarbonate, which can lead to metabolic acidosis. Although the oliguric phase of acute renal failure causes metabolic acidosis, the diuretic phase does not, because the kidneys can still excrete metabolic acids. Hypokalemia is associated with metabolic alkalosis. Cushing syndrome is cortisol excess, which can cause metabolic alkalosis from increased renal excretion of hydrogen ions.

Diarrhea causes a. respiratory acidosis. b. respiratory alkalosis. c. metabolic acidosis. d. metabolic alkalosis

ANS: C Diarrhea causes metabolic acidosis as the intestinal fluids are rich in bicarbonate ions. Diarrhea causes a metabolic acid-base imbalance and is not related to the respiratory system. Diarrhea involves increased excretion of bicarbonate and causes an acidic condition.

A person who experiences a panic attack and develops hyperventilation symptoms may experience a. neuromuscular depression. b. anxiety acidosis. c. numbness and tingling in the extremities. d. acute compensatory metabolic acidosis

ANS: C Numbness and tingling in the extremities occurs in alkalosis as a result of increased neuromuscular irritability. Numbness and tingling as a result of hyperventilation result from increased neuromuscular irritability, not neuromuscular depression. Acidosis depresses neuromuscular irritability and thus would not cause numbness and tingling, even in compensation

A 3-year-old is diagnosed with starvation ketoacidosis. What signs and symptoms should you anticipate in your assessment? a. Slow, shallow breathing, belligerence, hyperexcitability b. Slow, shallow breathing, numbness and tingling around his mouth c. Rapid, deep breathing, lethargy, abdominal pain d. Rapid, deep breathing, tremors, elevated blood pressure

ANS: C Rapid, deep breathing, lethargy, and abdominal pain are clinical manifestations of metabolic acidosis and its respiratory compensation. The other answer options are not clinical manifestations of metabolic acidosis and its respiratory compensation.

If an individual has a fully compensated metabolic acidosis, the blood pH is a. high. b. low. c. in the normal range. d. either high or low, depending on the type of compensation.

ANS: C The blood pH is in the normal range if an individual has fully compensated for an acid-base imbalance. High blood pH indicates alkalosis. Low blood pH indicates uncompensated or partially compensated acidosis

The arterial blood gas pH = 7.52, PaCO2 = 30 mm Hg, HCO3 = 24 mEq/L demonstrates a. metabolic acidosis. b. respiratory acidosis. c. respiratory alkalosis. d. mixed alkalosis

ANS: C The high pH, low PaCO2, and normal HCO3 indicate respiratory alkalosis. Metabolic and respiratory acidosis would decrease the pH. The HCO3 is normal, so no metabolic imbalance is indicated.

Causes of metabolic acidosis include a. hyperventilation. b. massive blood transfusion. c. tissue anoxia. d. hypoventilation.

ANS: C Tissue anoxia can cause metabolic acidosis resulting from lactic acid production during anaerobic metabolism. Hyperventilation causes excretion of too much carbonic acid and respiratory alkalosis. The liver metabolizes the citrate in transfused blood into bicarbonate. Hypoventilation causes CO2 retention and respiratory acidosis.

Renal compensation for respiratory acidosis is evidenced by a. decreased carbon dioxide. b. elevated carbon dioxide. c. decreased bicarbonate ion concentration. d. elevated bicarbonate ion concentration

ANS: D Elevated bicarbonate ion concentration is evidence of compensation for a respiratory acidosis. The lungs manage the carbon dioxide concentration. Elevated carbon dioxide is evidence of respiratory acidosis, not of compensation for it. Decreased bicarbonate ion concentration would make acidosis worse.

Emesis causes a. respiratory acidosis. b. respiratory alkalosis. c. metabolic acidosis. d. metabolic alkalosis.

ANS: D Emesis causes metabolic alkalosis as the stomach is a major reservoir for acids. Emesis causes a metabolic acid-base imbalance as it is not related to the respiratory system. Emesis involves loss of gastric acid and fluid and causes an alkalotic disruption.

Metabolic alkalosis is often accompanied by a. hypernatremia. b. hyponatremia. c. hyperkalemia. d. hypokalemia.

ANS: D Hypokalemia often accompanies metabolic alkalosis because it can cause metabolic alkalosis or be caused by it. Metabolic alkalosis and hypernatremia, hyponatremia, and hyperkalemia are not often associated with each other.

Respiratory acidosis may be caused by a. hyperventilation. b. massive blood transfusion. c. tissue hypoxia. d. hypoventilation.

ANS: D Hypoventilation causes carbonic acid retention and respiratory acidosis. Hyperventilation causes excretion of too much carbonic acid and respiratory alkalosis. The liver metabolizes the citrate in transfused blood into bicarbonate. Tissue hypoxia causes lactic acid production during anaerobic metabolism and metabolic acidosis.

Two primary acid-base disorders that are present independently are referred to as a. metabolic acidosis. b. metabolic alkalosis. c. respiratory alkalosis. d. mixed acid-base imbalance.

ANS: D Mixed acid-base disorders occur when two primary acid-base disorders are present independently. They may arise from simultaneous dysfunction of the respiratory system and kidneys. Metabolic acidosis is an acid disorder. Metabolic alkalosis and respiratory alkalosis are base disorders.

The ________ system compensates for metabolic acidosis and alkalosis. a. gastrointestinal b. renal c. cardiovascular d. respiratory

ANS: D When metabolic acids are out of balance, the respiratory system compensates for the altered pH by adjusting the amount of carbon dioxide in the blood. The gastrointestinal system is not a major compensatory mechanism in acid-base imbalances. The kidneys are overwhelmed or dysfunctional in a metabolic acid-base imbalance. The cardiovascular system is not a major compensatory mechanism in acid-base imbalances.