Chapter 13: Acid-Base Balance Nursing School Test Banks

Black & Hawks: Medical-Surgical Nursing, 8th Edition

Test Bank

Chapter 13: Acid-Base Balance

MULTIPLE CHOICE

1. When an individuals serum pH begins to fall below 7.35, the mechanism that responds instantaneously to return the serum pH to normal level is

a.

ammonia gas combining with H+.

b.

excretion of acid by the lungs.

c.

plasma bicarbonate buffering the acid.

d.

secretion of hydrogen ions (H+) by the kidneys.

ANS: C

Blood buffers constitute the bodys first line of defense against acid-base imbalance.

DIF: Knowledge/Remembering REF: p. 169 OBJ: N/A

MSC: Physiological Integrity Physiological Adaptation-Alteration in Body Systems

2. A client in diabetic ketoacidosis has an elevated serum potassium ion (K+) level. The nurse explains to the client that this is caused by

a.

bicarbonate loss in the urine instead of K+ loss.

b.

binding of H+ to blood proteins.

c.

increased reabsorption of K+ in the distal tubule of the nephron.

d.

secretion by the kidneys of H+ and retention of K+.

ANS: D

In cases of serum H+ excess, more H+ is secreted by renal tubular cells, whereas K+ is retained, promoting hyperkalemia. Hyperkalemia also occurs because H+ and K+ exchange places in an attempt to maintain electroneutrality, with more H+ entering cells and more K+ leaving cells.

DIF: Comprehension/Understanding REF: p. 171 OBJ: Intervention

MSC: Physiological Integrity Physiological Adaptation-Alteration in Body Systems

3. The nurse teaching a 32-year-old man with renal failure about the pathophysiologic mechanism of acid-base balance recognizes that the instructions have been understood when the client says

a.

Acidic foods must be eliminated from my diet.

b.

I lose too much acid through my kidneys.

c.

My breathing increases to correct imbalances.

d.

My urine output will increase when my pH falls.

ANS: C

When kidney disease impairs excretion of fixed acids, the respiratory system can increase ventilation to blow off excess acid as carbon dioxide.

DIF: Evaluation/Evaluating REF: pp. 172-173 OBJ: Evaluation

MSC: Physiological Integrity Physiological Adaptation-Alteration in Body Systems

4. The nurse explains to a concerned family member of a client who has developed respiratory acidosis that the kidneys

a.

achieve optimal compensation immediately.

b.

are unable to compensate.

c.

can achieve optimal compensation in about 3 days.

d.

will compensate within 24 hours.

ANS: C

The lungs or kidneys alter actual amounts of acid and base, but regulation by these systems is not instantaneous. The kidneys may require up to 72 hours to achieve optimal compensation.

DIF: Comprehension/Understanding REF: p. 173 OBJ: Intervention

MSC: Physiological Integrity Physiological Adaptation-Alteration in Body Systems

5. In an assessment of current clients, the nurse recognizes that the client most likely to develop respiratory acidosis has

a.

chronic obstructive pulmonary disease.

b.

hypokalemia.

c.

salicylate overdose.

d.

pulmonary fibrosis.

ANS: A

Chronic respiratory acidosis is most commonly caused by chronic obstructive pulmonary disease (COPD). Pulmonary fibrosis would be a much less common cause. Salicylate overdose could lead to metabolic acidosis, and hypokalemia could produce metabolic alkalosis.

DIF: Analysis/Analyzing REF: p. 175 OBJ: Assessment

MSC: Physiological Integrity Reduction of Risk Potential-Potential for Complications from Surgical Procedures and Health Alteration

6. The nurse is caring for a client who has developed metabolic acidosis and has an anion gap of 12 mEq/L. The nurse informs a family member that this finding indicates that the clients acidosis is caused by

a.

accelerated lipid metabolism.

b.

an increase of fixed acid.

c.

increases in carbonic acid.

d.

loss of bicarbonate.

ANS: D

When acidosis is the result of the addition of acid, as in lactic acidosis, bicarbonate is consumed (but not lost to the body) in buffering most of the acid load. Unmeasured anions increase in number to maintain electroneutrality, thus increasing the anion gap. But in an acidosis where the anion gap remains normal (12 + 4 mEq/L), the acidosis is caused by a loss of base. Nonanion gap acidosis is also called hyperchloremic metabolic acidosis.

DIF: Comprehension/Understanding REF: p. 177 OBJ: Intervention

MSC: Physiological Integrity Reduction of Risk Potential-Laboratory Values

7. A client is admitted to the hospital with severe vomiting and is diagnosed with metabolic alkalosis. The nurse anticipates that the laboratory value that would support this diagnosis is

a.

arterial carbon dioxide tension (PaCO2) of 30 mm Hg.Q

b.

arterial pH of 7.30.

c.

serum calcium level of 9.0 mEq/L.

d.

serum potassium level of 3.0 mEq/L.

ANS: D

In metabolic alkalosis, hypokalemia results from fluid shifts or intestinal losses because its concentration as a cation is affected by the state of hydrogen ions.

DIF: Application/Applying REF: p. 171 OBJ: Assessment

MSC: Physiological Integrity Reduction of Risk Potential-Laboratory Values

8. The nurse assesses that the client admitted in respiratory acidosis has compensated when the arterial blood gas (ABG) readings are

a.

carbon dioxide level of 50 mm Hg and bicarbonate level of 30 mEq/L.

b.

carbon dioxide level of 50 mm Hg and bicarbonate level of 20 mEq/L.

c.

carbon dioxide level of 30 mm Hg and bicarbonate level of 30 mEq/L.

d.

carbon dioxide level of 30 mm Hg and bicarbonate level of 24 mEq/L.

ANS: A

If compensation is present, carbon dioxide and bicarbonate are abnormal (or nearly so) in opposite directions (e.g., one is acidotic and the other alkalotic).

DIF: Analysis/Analyzing REF: p. 173 OBJ: Assessment

MSC: Physiological Integrity Reduction of Risk Potential-Laboratory Values

9. For a 34-year-old client in renal failure who develops acidosis, the nurse would assess for

a.

drowsiness.

b.

hypoventilation.

c.

muscle hyperactivity.

d.

paresthesias.

ANS: A

Metabolic acidosis may be accompanied by compensatory hyperventilation and other manifestations of acidemia, such as lethargy, stupor, and hypotension.

DIF: Application/Applying REF: p. 178 OBJ: Assessment

MSC: Physiological Integrity Physiological Adaptation-Alteration in Body Systems

10. To prevent error in sampling arterial blood gases (ABGs), the nurse will

a.

place the sample immediately in ice water.

b.

shake the sample to mix in heparin.

c.

transfer the sample from syringe to air-tight glass test tube.

d.

use a large beveled needle to withdraw the sample.

ANS: A

The sample should be placed in ice water immediately to prevent the effects of metabolism of white blood cells.

DIF: Application/Applying REF: p. 180 OBJ: Intervention

MSC: Safe, Effective Care Environment Safety and Infection Control-Error Prevention

11. The nurse performs Allens test before obtaining an ABG specimen to determine

a.

if an allergy to heparin is present.

b.

if ulnar circulation is adequate.

c.

the patency of the radial artery.

d.

the presence of neuromuscular weakness.

ANS: B

Before radial puncture to obtain ABG specimens, Allens test should be performed to ascertain adequate ulnar circulation. Failure to assess ulnar circulation could result in ischemic injury to the clients hand.

DIF: Application/Applying REF: p. 180 OBJ: Intervention

MSC: Safe, Effective Care Environment Safety and Infection Control-Injury Prevention

12. A client is brought to the emergency department in cardiac arrest. The nurse is aware that the associated acid-base imbalance that will require treatment is

a.

both respiratory and metabolic acidosis.

b.

both respiratory and metabolic alkalosis.

c.

respiratory acidosis.

d.

respiratory alkalosis.

ANS: A

In cardiac arrest, lactic acid quickly accumulates as a result of anaerobic metabolism. Carbonic acid is elevated as a result of respiratory arrest.

DIF: Comprehension/Understanding REF: p. 178 OBJ: Intervention

MSC: Physiological Integrity Physiological Adaptation-Medical Emergencies

13. Receiving a clients ABG report with pH of 7.40, PaCO2 of 55 mm Hg, and bicarbonate level of 20 mEq/L, the nurse interprets these values to indicate

a.

erroneous blood gas data.

b.

metabolic alkalosis.

c.

mixed acid-base disorder.

d.

respiratory alkalosis.

ANS: A

The nurse should suspect sampling error or transcription error when the reported values lack internal consistency or external congruity. Internal consistency means that the values make sense when considered as a whole. External congruity means that the ABG findings are consistent with other laboratory data and with clinical assessment findings. In this case the PaCO2 is high, indicating an acidotic state. The pH is within normal range, which would indicate compensation, except the bicarbonate level is actually low, showing that no compensation is occurring to maintain normal pH in the presence of a high PaCO2. This would lead the nurse to conclude that the ABG results are in error.

DIF: Analysis/Analyzing REF: pp. 180-181 OBJ: Assessment

MSC: Physiological Integrity Reduction of Risk Potential-Laboratory Values

14. A client has a blood pH of 7.30 and is being treated with an infusion of sodium bicarbonate. The nurse should assess this client for a possible delayed reaction of increasing levels of which component in the blood?

a.

Bicarbonate

b.

Calcium

c.

Carbon dioxide

d.

Glucose

ANS: C

In acidosis, intravenous administration of sodium bicarbonate may have an immediate beneficial effect on pH. Eventually, however, blood levels of CO2 rise because HCO3 fuels the hydrolysis reaction in reverse.

DIF: Application/Applying REF: p. 176 OBJ: Assessment

MSC: Physiological Integrity Pharmacological and Parenteral Therapies-Adverse Effects/Contraindications

15. The nurse caring for a trauma victim who has received massive transfusions of whole blood is diligent in assessment for metabolic alkalosis because

a.

multiple transfusions of whole blood cause a decrease in serum potassium level.

b.

the anticoagulant in the blood is metabolized to bicarbonate.

c.

transfused blood is less stable, releasing bicarbonate from the blood cells.

d.

whole blood utilizes bicarbonate as a preservative.

ANS: D

The citrate anticoagulant used for storage of blood is metabolized to bicarbonate.

DIF: Application/Applying REF: p. 176 OBJ: Assessment

MSC: Physiological Integrity Reduction of Risk Potential-Potential for Complications of Diagnostic Tests/Treatments/Procedures

16. The nurse is assigned to a client with insulin-dependent diabetes who was brought to the emergency department because of shortness of breath and confusion. On admission, the clients blood glucose level is 720 mg/ml, and ABG values are pH of 7.28, PaCO2 of 35 mm Hg, and bicarbonate level of 15 mEq/L. The nurse interprets these readings as indicating

a.

compensated metabolic acidosis.

b.

compensated respiratory acidosis.

c.

uncompensated metabolic acidosis.

d.

uncompensated respiratory acidosis.

ANS: C

Diabetic ketoacidosis is one etiology of metabolic acidosis. The low pH represents an uncompensated state. The normal PaCO2 backs up the nurses assessment that the respiratory system has not yet started compensating.

DIF: Analysis/Analyzing REF: pp. 173, 177 OBJ: Assessment

MSC: Physiological Integrity Reduction of Risk Potential-Laboratory Values

17. A client with a diagnosis of chronic renal failure has pH of 7.35, PaCO2 of 29 mm Hg, and bicarbonate level of 16 mEq/L. The nurse interprets these ABG results as

a.

compensated metabolic acidosis.

b.

compensated respiratory acidosis.

c.

uncompensated metabolic acidosis.

d.

uncompensated respiratory acidosis.

ANS: A

Renal failure is one etiology of metabolic acidosis. Compensation is present when PaCO2 and bicarbonate values are abnormal (or nearly so) in opposite directions (e.g., one is acidotic and the other alkalotic), and when the pH is in the normal range.

DIF: Analysis/Analyzing REF: pp. 173, 177 OBJ: Assessment

MSC: Physiological Integrity Reduction of Risk Potential-Laboratory Values

18. The nurse is caring for an 80-year-old client admitted to the hospital with pneumonia and who is becoming progressively more confused. Her vital signs are as follows: T, 101 F; P, 112 beats/min; R, 28 breaths/min; BP, 100/70 mm Hg. ABG results are pH 7.50, PaCO2 25 mm Hg, and bicarbonate level 18 mEq/L. The nurse interprets these findings to indicate

a.

metabolic acidosis secondary to fever.

b.

metabolic alkalosis secondary to bicarbonate excess.

c.

respiratory acidosis secondary to anxiety.

d.

respiratory alkalosis secondary to hypoxemia.

ANS: D

Pneumonia is one cause of respiratory alkalosis, because the respiratory rate increases to compensate for hypoxemia, and excess blowing off of CO2 occurs.

DIF: Analysis/Analyzing REF: pp. 173, 174 OBJ: Assessment

MSC: Physiological Integrity Reduction of Risk Potential-Laboratory Values

19. The nurse caring for a client who experienced cardiopulmonary arrest and has a mixed respiratory/metabolic acidosis explains to a concerned family member that the mechanical ventilator can eliminate

a.

carbonic acid.

b.

lactic acid.

c.

phosphoric acid.

d.

sulfuric acid.

ANS: A

Carbonic acid in the blood can be transformed into hydrogen ions and carbon dioxide, which can be eliminated through the lungs. The other acids are fixed acids that must be excreted in the urine.

DIF: Comprehension/Understanding REF: p. 169 OBJ: Intervention

MSC: Physiological Integrity Physiological Adaptation-Alteration in Body Systems

MULTIPLE RESPONSE

1. Age-related physiologic changes the nurse would consider when planning care for an elderly client admitted with an acid-base abnormality include (Select all that apply)

a.

decreased pulmonary and renal function limit the ability to compensate.

b.

hypermetabolism predisposes the elderly to metabolic acidosis.

c.

hypoventilation can easily cause respiratory acidosis in the elderly.

d.

renal perfusion is diminished because of decreased cardiac output.

e.

there is decreased alveolar surface area for gas exchange.

ANS: A, C, D, E

Many age-related physiologic changes limit the clients ability to compensate for acid-base disturbances, including options a, c, d, and e above, plus the fact that the elderly take more medications that can contribute to hypokalemia and metabolic alkalosis. Aldosterone is also less effective in older persons, as is ammonia buffering. The elderly are not hypermetabolic.

DIF: Application/Applying REF: p. 179 OBJ: Intervention

MSC: Health Promotion and Maintenance Growth and Development Through the Lifespan-Age Related Differences

Elsevier items and derived items 2009 by Saunders, an imprint of Elsevier Inc.

Some material was previously published.

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