ATI RN
Fluid and Electrolytes ATI
1. The healthcare professional working in the PACU is aware that which of the following procedures may contribute to extracellular losses?
- A. Removal of an ingrown toenail
- B. Tooth extraction
- C. Abdominal surgery
- D. Cataract surgery
Correct answer: C
Rationale: Fluid loss from the extracellular compartment can be caused by abdominal surgery as it involves opening the abdominal cavity, potentially leading to significant fluid losses. Choices A, B, and D do not typically result in substantial extracellular losses compared to abdominal surgery.
2. The nurse in the intensive care unit receives arterial blood gases (ABG) with a patient who is complaining of being 'short of breath.' The ABG has the following values: pH = 7.21, PaCO2 = 64 mm Hg, HCO3 = 24 mmol/L. The labs reflect:
- A. Respiratory acidosis
- B. Metabolic alkalosis
- C. Respiratory alkalosis
- D. Metabolic acidosis
Correct answer: A
Rationale: The ABG values indicate respiratory acidosis. A pH below 7.40, a PaCO2 above 40 mm Hg, and a normal HCO3 level (24 mmol/L) suggest respiratory acidosis. In this case, the patient has an acidic pH (7.21) and an elevated PaCO2 (64 mm Hg), indicating inadequate ventilation. The normal HCO3 level suggests that compensation by the kidneys has not occurred, implying an acute event. Choices B, C, and D can be ruled out based on the given ABG values and the criteria for acid-base disorders.
3. 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.
4. The nurse is admitting a patient with a suspected fluid imbalance. The most sensitive indicator of body fluid balance is:
- A. Daily weight
- B. Serum sodium levels
- C. Measured intake and output
- D. Blood pressure
Correct answer: A
Rationale: Daily weight is the most sensitive indicator of body fluid balance because it can show trends over time, helping in assessing the effectiveness of interventions and medications. While serum sodium levels provide objective data on electrolyte balance, they may not accurately reflect fluid balance, especially if a patient is dehydrated. Measured intake and output are crucial for assessing fluid balance, but it can be challenging to match the two due to various ways fluid is lost from the body. Blood pressure and other vital signs may not always be reliable indicators of fluid balance as they can be influenced by other factors beyond fluid status.
5. A nurse admitting a patient with a history of emphysema reviews her past lab reports and notes that the patient's PaCO2 has been 56 to 64 mmHg. The nurse will be cautious administering oxygen because:
- A. The patient's calcium will rise dramatically due to pituitary stimulation.
- B. The oxygen will increase the patient's intracranial pressure and create confusion.
- C. The oxygen may cause the patient to hyperventilate and become acidotic.
- D. Using oxygen may result in the patient developing carbon dioxide narcosis and hypoxemia.
Correct answer: D
Rationale: When PaCO2 chronically exceeds 50 mm Hg, it creates insensitivity to CO2 in the respiratory medulla, and the use of oxygen may result in the patient developing carbon dioxide narcosis and hypoxemia. Choice A is incorrect because administering oxygen does not lead to a dramatic rise in calcium due to pituitary stimulation. Choice B is incorrect because administering oxygen does not directly increase intracranial pressure or create confusion. Choice C is incorrect because administering oxygen to a patient with emphysema and high PaCO2 levels is more likely to cause respiratory depression than hyperventilation and acidosis.
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