the chief mechanism for maintaining fluid balance is to

ATI RN

ATI Fluid and Electrolytes

1. 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.

2. The term used to describe a blood sodium level of more than 145 mEq/L is:

A. hyponatremia.
B. hyperkalemia.
C. hypernatremia.
D. hypercalcemia.

Correct answer: C

Rationale: The correct answer is C: hypernatremia. Hypernatremia refers to an elevated level of sodium in the blood, specifically when it is more than 145 mEq/L. Choice A, hyponatremia, is incorrect as it refers to low sodium levels. Choice B, hyperkalemia, is incorrect as it refers to high potassium levels, not sodium. Choice D, hypercalcemia, is also incorrect as it relates to elevated calcium levels, not sodium.

3. A nurse assesses a client who is admitted with an acid-base imbalance. The clients arterial blood gas values are pH 7.32, PaO2 85 mm Hg, PaCO2 34 mm Hg, and HCO3 16 mEq/L. What action should the nurse take next?

A. Assess clients rate, rhythm, and depth of respiration.
B. Measure the clients pulse and blood pressure.
C. Document the findings and continue to monitor.
D. Notify the physician as soon as possible.

Correct answer: A

Rationale:

4. A 73-year-old man who slipped on a small carpet in his home and fell on his hip is alert and oriented; PERRLA (pupils equally round and reactive to light and accommodation) is intact, and he has come by ambulance to the emergency department (ED). Heart rate elevated, he is anxious and thirsty. A Foley catheter is in place and 40mL of urine is present. The nurse's most likely explanation for the urine output is:

A. The man urinated prior to his arrival in the ED and will probably not need to have the Foley catheter kept in place.
B. The man has a brain injury, lacks ADH, and needs vasopressin.
C. The man is in heart failure and is releasing atrial natriuretic peptide, which results in decreased urine output.
D. He is having a sympathetic reaction, which has stimulated the renin-angiotensin-aldosterone system that results in diminished urine output.

Correct answer: D

Rationale: Renin is released by the juxtaglomerular cells of the kidneys in response to decreased renal perfusion. Angiotensin-converting enzyme converts angiotensin I to angiotensin II. Angiotensin II, with its vasoconstrictor properties, increases arterial perfusion pressure and stimulates thirst. As the sympathetic nervous system is stimulated, aldosterone is released in response to an increased release of renin, which decreases urine production. Based on the nursing assessment and mechanism of injury, this is the most likely cause of the lower urine output. Choices A, B, and C are incorrect because there is no indication of urination prior to arrival, brain injury, lack of ADH, or heart failure present in the scenario provided. The symptoms and context described point more towards a physiological response related to the sympathetic nervous system and the renin-angiotensin-aldosterone system rather than the other conditions mentioned.