Summary - fluid and electrolytes, Exams of Nursing

Download Summary - fluid and electrolytes and more Exams Nursing in PDF only on Docsity!

Fluid and Electrolytes: 100 Multiple Choice

Questions with Answers and Rationales

Question 1

A patient has a serum potassium level of 5.8 mEq/L. Which ECG change would the nurse expect to observe? A. U waves B. ST segment depression C. Tall peaked T waves D. Prolonged PR interval Answer: C Rationale: Hyperkalemia (potassium >5.0 mEq/L) typically causes tall, peaked T waves on ECG. U waves (A) are associated with hypokalemia. ST depression (B) is seen with hypokalemia and digitalis toxicity. Prolonged PR interval (D) occurs in both hypo- and hyperkalemia, but peaked T waves are the classic early sign of hyperkalemia.

Question 2

A patient with heart failure is receiving furosemide. Which electrolyte imbalance is the patient at greatest risk for developing? A. Hyperkalemia B. Hypokalemia C. Hypernatremia D. Hypermagnesemia Answer: B Rationale: Furosemide is a loop diuretic that causes potassium wasting in the distal tubule, leading to hypokalemia. Hyperkalemia (A) is not caused by

mEq/hr, and Option D provides 40 mEq/L at 75 mL/hr = 30 mEq/hr, both exceeding safe rates.

Question 5

A patient's arterial blood gas results show: pH 7.32, PaCO₂ 48 mmHg, HCO₃⁻ 24 mEq/L. Which condition does this indicate? A. Metabolic acidosis B. Metabolic alkalosis C. Respiratory acidosis D. Respiratory alkalosis Answer: C Rationale: The pH is low (acidosis, <7.35). PaCO₂ is elevated (>45 mmHg), indicating a respiratory cause. HCO₃⁻ is normal (22-26 mEq/L), showing no metabolic compensation. This is uncompensated respiratory acidosis.

Question 6

Which assessment finding is consistent with hypernatremia? A. Decreased deep tendon reflexes B. Dry mucous membranes C. Muscle twitching D. Bradycardia Answer: B Rationale: Hypernatremia causes cellular dehydration, leading to dry mucous membranes, intense thirst, and oliguria. Decreased deep tendon reflexes (A) and muscle twitching (C) are associated with hypocalcemia. Bradycardia (D) is associated with hyperkalemia.

Question 7

A patient's serum magnesium level is 1.0 mEq/L. Which assessment finding would the nurse expect? A. Hyperactive deep tendon reflexes B. Flaccid paralysis C. Respiratory depression D. Bradycardia Answer: A Rationale: Hypomagnesemia (normal range 1.5-2.5 mEq/L) causes neuromuscular hyperexcitability, including hyperactive reflexes, tremors, and positive Chvostek's sign. Flaccid paralysis (B), respiratory depression (C), and bradycardia (D) are signs of hypermagnesemia.

Question 8

A patient has an arterial blood gas result showing pH 7.48, PaCO₂ 32 mmHg, HCO₃⁻ 24 mEq/L. How should the nurse interpret this? A. Uncompensated metabolic alkalosis B. Uncompensated respiratory alkalosis C. Partially compensated metabolic alkalosis D. Partially compensated respiratory alkalosis Answer: B Rationale: pH is elevated (>7.45), indicating alkalosis. PaCO₂ is decreased (<35 mmHg), indicating a respiratory cause. HCO₃⁻ is normal, showing no renal compensation. This is uncompensated respiratory alkalosis.

Question 9

Which patient is at highest risk for developing hyperkalemia?

C. pH 7.48, PaCO₂ 48 mmHg D. pH 7.32, PaCO₂ 28 mmHg Answer: B Rationale: Metabolic acidosis is characterized by low pH (<7.35) and low HCO₃⁻ (<22 mEq/L). Option A indicates metabolic alkalosis. Option C indicates respiratory acidosis. Option D indicates respiratory alkalosis with metabolic compensation.

Question 12

A patient is receiving IV fluids at 125 mL/hr. The nurse should monitor for which sign of fluid overload? A. Decreased blood pressure B. Crackles in lung bases C. Decreased urine output D. Flat neck veins Answer: B Rationale: Crackles (rales) in lung bases indicate pulmonary congestion from fluid overload. Decreased blood pressure (A) and decreased urine output (C) indicate hypovolemia. Flat neck veins (D) indicate dehydration.

Question 13

Which intravenous fluid is considered isotonic? A. 0.45% sodium chloride B. 3% sodium chloride C. 0.9% sodium chloride D. D5W after administration Answer: C

Rationale: 0.9% sodium chloride (normal saline) is isotonic with a tonicity of 308 mOsm/L. 0.45% sodium chloride (A) is hypotonic. 3% sodium chloride (B) is hypertonic. D5W (D) becomes hypotonic after glucose is metabolized.

Question 14

A patient's serum calcium level is 7.0 mg/dL. Which assessment finding would the nurse expect? A. Positive Trousseau's sign B. Positive Chvostek's sign C. Both A and B D. Neither A nor B Answer: C Rationale: Hypocalcemia (normal 8.5-10.5 mg/dL) causes neuromuscular irritability. Both Trousseau's sign (carpal spasm with BP cuff inflation) and Chvostek's sign (facial twitching with facial nerve tap) are positive. Severe hypocalcemia can also cause tetany and seizures.

Question 15

A patient has a serum potassium level of 2.8 mEq/L. Which ECG change would the nurse expect to observe? A. Tall peaked T waves B. Widened QRS complex C. U waves D. Prolonged QT interval Answer: C Rationale: Hypokalemia (potassium <3.5 mEq/L) causes U waves, ST segment depression, and flattened T waves. Tall peaked T waves (A) are seen in hyperkalemia. Widened QRS complex (B) and prolonged QT interval (D) are seen in hyperkalemia.

Question 18

A patient's arterial blood gas shows pH 7.22, PaCO₂ 55 mmHg, HCO₃⁻ 24 mEq/L. The nurse should: A. Administer sodium bicarbonate B. Prepare for mechanical ventilation C. Administer oxygen only D. Administer potassium supplements Answer: B Rationale: This represents uncompensated respiratory acidosis with severe hypercapnia (PaCO₂ 55 mmHg). The patient may need mechanical ventilation to correct hypoventilation. Sodium bicarbonate (A) is not indicated because the primary problem is respiratory. Oxygen alone (C) will not correct CO₂ retention.

Question 19

A patient's serum sodium level is 118 mEq/L. The nurse should expect which assessment finding? A. Thirst and dry mucous membranes B. Muscle cramps and seizures C. Increased urine output D. Tachycardia and hypotension Answer: B Rationale: Severe hyponatremia (sodium <120 mEq/L) causes cerebral edema, leading to confusion, seizures, and coma. Thirst and dry mucous membranes (A) are signs of hypernatremia. Increased urine output (C) and tachycardia/hypotension (D) are not specific to hyponatremia.

Question 20

Which of the following is a hypertonic solution? A. 0.45% sodium chloride B. 5% dextrose in water (D5W) C. 3% sodium chloride D. 0.9% sodium chloride Answer: C Rationale: 3% sodium chloride is hypertonic (513 mOsm/L). 0.45% sodium chloride (A) is hypotonic. D5W (B) is isotonic initially but becomes hypotonic after glucose metabolism. 0.9% sodium chloride (D) is isotonic.

Question 21

A patient with chronic kidney disease has a serum potassium level of 6.8 mEq/L. The priority nursing intervention is to: A. Administer kayexalate B. Prepare for hemodialysis C. Administer calcium gluconate D. Place the patient on cardiac monitor Answer: D Rationale: The priority is to monitor for cardiac dysrhythmias, the most life- threatening complication of severe hyperkalemia. Calcium gluconate (C) is administered for cardiac protection but after monitoring is initiated. Kayexalate (A) and hemodialysis (B) are definitive treatments but are not the priority action.

Question 22

A patient's serum magnesium level is 3.8 mEq/L. Which finding would the nurse expect?

C. Decreased HCO₃⁻ D. Increased PaCO₂ Answer: A Rationale: Respiratory alkalosis is caused by hyperventilation, which decreases PaCO₂. pH is increased (alkalotic), not decreased (B). HCO₃⁻ may be normal or decreased with compensation. PaCO₂ is decreased, not increased (D).

Question 25

Which electrolyte imbalance is most commonly associated with digoxin toxicity? A. Hyperkalemia B. Hypokalemia C. Hypercalcemia D. Hypomagnesemia Answer: B Rationale: Hypokalemia potentiates digoxin toxicity by increasing binding to the Na-K ATPase pump. Hyperkalemia (A) can also occur but is less commonly associated. Hypercalcemia (C) and hypomagnesemia (D) can also increase digoxin toxicity, but hypokalemia is the most common.

Question 26

A patient's serum phosphorus level is 1.8 mg/dL. Which of the following foods should the nurse encourage? A. Milk and yogurt B. Green leafy vegetables C. Citrus fruits D. Whole grains and nuts

Answer: A Rationale: Hypophosphatemia requires foods high in phosphorus, such as dairy products (milk, yogurt, cheese), meat, and fish. Green leafy vegetables (B) and citrus fruits (C) are not significant phosphorus sources. Whole grains and nuts (D) contain phosphorus but are not as high as dairy.

Question 27

A patient's arterial blood gas results show pH 7.46, PaCO₂ 40 mmHg, HCO₃⁻ 30 mEq/L. This indicates: A. Respiratory acidosis B. Metabolic alkalosis C. Respiratory alkalosis D. Metabolic acidosis Answer: B Rationale: pH is elevated (>7.45), indicating alkalosis. PaCO₂ is normal, ruling out a respiratory cause. HCO₃⁻ is elevated (>26 mEq/L), indicating a metabolic cause. This is uncompensated metabolic alkalosis.

Question 28

Which of the following is a sign of fluid volume deficit? A. Distended neck veins B. Edema C. Decreased skin turgor D. Crackles in the lungs Answer: C Rationale: Decreased skin turgor (poor turgor) is a classic sign of fluid volume deficit (dehydration). Distended neck veins (A), edema (B), and crackles in the lungs (D) are signs of fluid volume excess.

Question 31

A patient with hypocalcemia would most likely exhibit which of the following? A. Diarrhea B. Positive Trousseau's sign C. Constipation D. Hypotension Answer: B Rationale: Positive Trousseau's sign is a classic manifestation of hypocalcemia due to neuromuscular irritability. Diarrhea (A) and constipation (C) are not typical. Hypotension (D) is not a direct sign; hypocalcemia can cause cardiac effects but hypotension is not expected.

Question 32

The nurse is caring for a patient with hyperkalemia. Which medication should the nurse expect to administer? A. Potassium chloride B. Sodium bicarbonate C. Potassium-sparing diuretic D. Potassium supplements Answer: B Rationale: Sodium bicarbonate shifts potassium into cells, temporarily lowering serum potassium. Potassium chloride (A), potassium-sparing diuretics (C), and potassium supplements (D) would worsen hyperkalemia.

Question 33

A patient has been vomiting for 3 days. Which acid-base imbalance is the patient at risk for?

A. Metabolic acidosis B. Metabolic alkalosis C. Respiratory acidosis D. Respiratory alkalosis Answer: B Rationale: Vomiting causes loss of gastric acid (HCl), leading to metabolic alkalosis. Metabolic acidosis (A) occurs with diarrhea or diabetic ketoacidosis. Respiratory imbalances (C, D) are not caused by vomiting.

Question 34

A patient's arterial blood gas shows pH 7.30, PaCO₂ 32 mmHg, HCO₃⁻ 16 mEq/L. What is the interpretation? A. Uncompensated metabolic acidosis B. Partially compensated metabolic acidosis C. Uncompensated respiratory acidosis D. Partially compensated respiratory acidosis Answer: B Rationale: pH is low (acidosis). HCO₃⁻ is low (metabolic cause). PaCO₂ is low (respiratory compensation). Both metabolic and respiratory components are abnormal, indicating partial compensation. This is partially compensated metabolic acidosis.

Question 35

Which of the following IV fluids would the nurse administer to a patient with cerebral edema? A. 0.45% sodium chloride B. 3% sodium chloride C. 0.9% sodium chloride D. 5% dextrose in water

Rationale: The normal serum sodium range is 135-145 mEq/L. 3.5-5. mEq/L (A) is potassium. 8.5-10.5 mg/dL (B) is calcium. 1.5-2.5 mEq/L (D) is magnesium.

Question 38

A patient with diabetes insipidus is at risk for which electrolyte imbalance? A. Hypernatremia B. Hyponatremia C. Hypokalemia D. Hyperkalemia Answer: A Rationale: Diabetes insipidus causes excessive water loss through dilute urine, leading to hypernatremia. Hyponatremia (B) is associated with SIADH. Hypokalemia (C) and hyperkalemia (D) are not directly associated with diabetes insipidus.

Question 39

A patient's serum calcium level is 12.0 mg/dL. Which finding would the nurse expect? A. Positive Chvostek's sign B. Muscle cramps C. Constipation D. Tetany Answer: C Rationale: Hypercalcemia (>10.5 mg/dL) causes constipation, nausea, and polyuria. Positive Chvostek's sign (A), muscle cramps (B), and tetany (D) are signs of hypocalcemia.

Question 40

Which medication is used to treat hyperkalemia by shifting potassium into cells? A. Sodium polystyrene sulfonate B. Calcium gluconate C. Regular insulin with dextrose D. Furosemide Answer: C Rationale: Regular insulin with dextrose shifts potassium into cells, temporarily lowering serum potassium. Sodium polystyrene sulfonate (A) removes potassium from the body. Calcium gluconate (B) stabilizes cardiac membranes but does not shift potassium. Furosemide (D) excretes potassium but does not shift it into cells.

Question 41

A patient has a serum chloride level of 116 mEq/L. The nurse recognizes this as: A. Hyperchloremia B. Hypochloremia C. Normal chloride level D. Critical value Answer: A Rationale: Normal serum chloride is 98-106 mEq/L. Chloride 116 mEq/L is hyperchloremia. Hypochloremia (B) would be <98 mEq/L. This is not normal (C) and while elevated, is not necessarily a critical value unless associated with severe metabolic acidosis (D).