ATI RN
ATI Fluid and Electrolytes
1. Which positive ion is most prevalent in intracellular fluid?
- A. Calcium
- B. Potassium
- C. Sodium
- D. Magnesium
Correct answer: B
Rationale: The correct answer is Potassium (K+). Potassium is the predominant cation found within cells, making it the most prevalent positive ion in intracellular fluid. Calcium, sodium, and magnesium are also essential ions in the body, but they are not as abundant in intracellular fluid. Calcium is vital for bone health and muscle function, sodium helps in maintaining fluid balance and nerve function, and magnesium is involved in numerous biochemical reactions.
2. The nurse is caring for a patient who is diaphoretic from a fever. The amount of sodium excreted in the urine will:
- A. Decrease
- B. Increase
- C. Remain unchanged
- D. Fluctuate
Correct answer: A
Rationale: Increased sweating (diaphoresis) causes the loss of sodium and other electrolytes from the body. As a result, the body tries to conserve sodium, leading to a decrease in the amount of sodium excreted in the urine. Choice B is incorrect because increased sweating results in sodium loss, not retention. Choice C is incorrect because with increased sweating, there is a need to conserve sodium, leading to a decrease in its excretion. Choice D is incorrect as there is a clear physiological response to sweating that results in a more consistent decrease in sodium excretion.
3. Third spacing occurs when fluid moves out of the intravascular space but not into the intracellular space. Based on this fluid shift, the nurse will expect the patient to demonstrate:
- A. Hypertension
- B. Bradycardia
- C. Hypervolemia
- D. Hypovolemia
Correct answer: D
Rationale: In the scenario of third-spacing fluid shift, where fluid moves out of the intravascular space but not into the intracellular space, the patient is expected to demonstrate hypovolemia. Hypertension (Choice A) is unlikely as hypovolemia typically leads to decreased blood pressure. Bradycardia (Choice B) is not a common manifestation of hypovolemia, as the body often tries to compensate by increasing heart rate. Hypervolemia (Choice C) indicates an excess of fluid, which is the opposite of what occurs in third spacing.
4. You are an emergency-room nurse caring for a trauma patient. Your patient has the following arterial blood gas results: pH 7.26, PaCO2 28, HCO3 11 mEq/L. How would you interpret these results?
- A. Respiratory acidosis with no compensation
- B. Metabolic alkalosis with a compensatory alkalosis
- C. Metabolic acidosis with no compensation
- D. Metabolic acidosis with a compensatory respiratory alkalosis
Correct answer: D
Rationale: A low pH indicates acidosis (normal pH is 7.35 to 7.45). The PaCO2 is also low, which causes alkalosis. The bicarbonate is low, which causes acidosis. The pH bicarbonate more closely corresponds with a decrease in pH, making the metabolic component the primary problem. Therefore, the correct interpretation of the arterial blood gas results is metabolic acidosis with a compensatory respiratory alkalosis. Choices A, B, and C are incorrect because they do not accurately reflect the primary acid-base disturbance and the compensatory response seen in the given results.
5. The chief mechanism for maintaining fluid balance is to:
- A. adjust fluid intake so it equals fluid output.
- B. adjust fluid intake so it is slightly above fluid output.
- C. adjust fluid output so it equals fluid input.
- D. adjust fluid intake so it is slightly below fluid output.
Correct answer: C
Rationale: The correct answer is C: 'adjust fluid output so it equals fluid input.' Maintaining fluid balance involves ensuring that the amount of fluid lost through processes like urination, sweating, and respiration equals the amount of fluid taken in. This ensures that the body stays properly hydrated. Choices A, B, and D are incorrect because they do not focus on the balance between fluid input and output, which is crucial for maintaining proper fluid balance. By adjusting fluid output to equal fluid input, the body can regulate hydration levels effectively, preventing dehydration or overhydration.
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