ATI RN
ATI Fluid Electrolyte and Acid-Base Regulation
1. . A medical nurse educator is reviewing a patients recent episode of metabolic acidosis with members of the nursing staff. What should the educator describe about the role of the kidneys in metabolic acidosis?
- A. The kidneys retain hydrogen ions and excrete bicarbonate ions to help restore balance.
- B. The kidneys excrete hydrogen ions and conserve bicarbonate ions to help restore balance
- C. The kidneys react rapidly to compensate for imbalances in the body
- D. The kidneys regulate the bicarbonate level in the intracellular fluid.
Correct answer: B
Rationale:
2. The nurse is assessing the patient for the presence of a Chvostek's sign. What electrolyte imbalance does a positive Chvostek's sign indicate?
- A. Hypermagnesemia
- B. Hypomagnesemia
- C. Hypocalcemia
- D. Hyperkalemia
Correct answer: C
Rationale: Chvostek's sign is characterized by a brief contraction of the upper lip, nose, or side of the face and is indicative of hypocalcemia, making choice C the correct answer. Hypomagnesemia (choice B) is associated with Trousseau's sign, not Chvostek's sign. Hypermagnesemia (choice A) is not related to Chvostek's sign. Hyperkalemia (choice D) is not typically associated with Chvostek's sign; instead, it may present with muscle weakness and cardiac arrhythmias.
3. A nurse in the medical-surgical unit is giving a patient with low blood pressure a hypertonic solution, which will increase the number of dissolved particles in his blood, creating pressure for fluids in the tissues to shift into the capillaries and increase the blood volume. Which of the following terms is associated with this process?
- A. Hydrostatic pressure
- B. Osmosis and osmolality
- C. Diffusion
- D. Active transport
Correct answer: B
Rationale: Osmosis is the movement of fluid from a region of low solute concentration to a region of high solute concentration across a semipermeable membrane. The number of dissolved particles contained in a unit of fluid determines the osmolality of a solution, which influences the movement of fluid between the fluid compartments. Giving a patient who has low blood pressure a hypertonic solution will increase the number of dissolved particles in the blood, creating pressure for fluids in the tissues to shift into the capillaries and increase the blood volume. Option A is incorrect; hydrostatic pressure refers to changes in water or volume related to water pressure. Option C is incorrect; diffusion is the movement of solutes from an area of greater concentration to lesser concentration. The solutes in an intact vascular system are unable to move, so diffusion should not normally take place. Option D is incorrect; active transport is the movement of molecules against the concentration gradient and requires ATP as an energy source. This process typically takes place at the cellular level and is not involved in vascular volume changes.
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.
5. A nurse sees a variety of patients in the community health clinic. Which of the following patients would be at the greatest risk of dehydration?
- A. An 18-year-old basketball player with a stress fracture of the right foot
- B. An infant with diarrhea
- C. A 45-year-old with stomach flu
- D. An elderly patient living alone
Correct answer: B
Rationale: The correct answer is B. Infants are particularly vulnerable to dehydration due to diarrhea because they have a higher fluid turnover and less reserve. Option A, the 18-year-old basketball player with a stress fracture, is less likely to be at the greatest risk of dehydration compared to an infant with diarrhea. Option C, the 45-year-old with stomach flu, may experience dehydration but is not at the same level of risk as an infant with diarrhea. Option D, the elderly patient living alone, could be at risk of dehydration, but infants with diarrhea are at the greatest risk due to their unique physiological characteristics.
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