CRNI Fluid and Electrolyte Balance 4 — Questions and Answers
Question 1: A patient receiving TPN develops confusion, muscle weakness, and a serum phosphate of 1.2 mg/dL. Which condition is most likely?
- Hyperphosphatemia
- Refeeding syndrome (Correct answer)
- Hypercalcemia
- Metabolic alkalosis
Correct answer: Refeeding syndrome
Refeeding syndrome causes severe hypophosphatemia as glucose infusion shifts phosphate intracellularly.
Question 2: Which IV fluid is most appropriate for initial resuscitation of a patient with severe burns?
- 0.45% NaCl
- D5W
- Lactated Ringer's (Correct answer)
- 3% NaCl
Correct answer: Lactated Ringer's
Lactated Ringer's is the preferred fluid for burn resuscitation per the Parkland formula due to its isotonic composition.
Question 3: A patient with chronic kidney disease has a serum potassium of 6.2 mEq/L and peaked T-waves on ECG. What is the priority intervention?
- Administer sodium polystyrene sulfonate
- Infuse insulin and dextrose
- Give IV calcium gluconate (Correct answer)
- Restrict dietary potassium
Correct answer: Give IV calcium gluconate
IV calcium gluconate is the priority to stabilize cardiac membranes and prevent life-threatening dysrhythmias.
Question 4: Which finding best indicates adequate fluid resuscitation in a critically ill patient?
- MAP > 65 mmHg and urine output 0.5 mL/kg/hr (Correct answer)
- CVP of 2 mmHg
- Heart rate of 110 bpm
- Serum lactate of 5 mmol/L
Correct answer: MAP > 65 mmHg and urine output 0.5 mL/kg/hr
A MAP > 65 mmHg with urine output ≥ 0.5 mL/kg/hr reflects adequate organ perfusion and resuscitation.
Question 5: A patient's serum sodium is 118 mEq/L and they are asymptomatic. What is the safest correction rate?
- Correct to normal within 4 hours
- No more than 8-12 mEq/L in 24 hours (Correct answer)
- Raise sodium 2 mEq/L per hour
- Correct to 130 mEq/L immediately
Correct answer: No more than 8-12 mEq/L in 24 hours
Correcting hyponatremia faster than 8-12 mEq/L per 24 hours risks osmotic demyelination syndrome.
Question 6: Which electrolyte imbalance is most commonly associated with prolonged nasogastric suctioning?
- Hyperkalemia
- Hypernatremia
- Metabolic acidosis
- Hypokalemic metabolic alkalosis (Correct answer)
Correct answer: Hypokalemic metabolic alkalosis
NG suctioning removes HCl and potassium, causing hypokalemia and metabolic alkalosis from hydrogen ion loss.
Question 7: A patient on loop diuretics develops muscle cramps, fatigue, and a serum magnesium of 1.1 mEq/L. What electrolyte should also be checked?
- Serum phosphate
- Serum potassium (Correct answer)
- Serum chloride
- Serum bicarbonate
Correct answer: Serum potassium
Hypomagnesemia frequently coexists with hypokalemia because magnesium deficiency impairs renal potassium conservation.
CRNI Fluid and Electrolyte Balance 4
A patient receiving TPN develops confusion, muscle weakness, and a serum phosphate of 1.2 mg/dL.
Which condition is most likely?