PSA PSA Fluid and Electrolyte Prescribing 2 — Questions and Answers
Question 1: A patient has a serum potassium of 2.8 mEq/L with ECG changes showing U waves. What is the most appropriate management?
- Oral potassium supplementation only
- IV potassium replacement with cardiac monitoring (Correct answer)
- Restrict dietary potassium
- Administer sodium polystyrene sulfonate
Correct answer: IV potassium replacement with cardiac monitoring
Symptomatic hypokalemia with ECG changes requires IV potassium replacement with continuous cardiac monitoring due to arrhythmia risk.
Question 2: What is the maximum recommended rate of IV potassium infusion via a peripheral line to minimize risk of phlebitis and cardiac toxicity?
- 40 mEq/hour
- 20 mEq/hour
- 10 mEq/hour (Correct answer)
- 5 mEq/hour
Correct answer: 10 mEq/hour
Peripheral IV potassium should not exceed 10 mEq/hour to minimize the risk of vein irritation and potentially fatal cardiac arrhythmias.
Question 3: A patient with severe hyperkalemia (K+ 6.8 mEq/L) shows peaked T waves on ECG. What is the most immediate priority?
- Administer sodium bicarbonate
- Give IV calcium gluconate to stabilize the cardiac membrane (Correct answer)
- Start insulin and dextrose infusion
- Administer oral sodium polystyrene sulfonate
Correct answer: Give IV calcium gluconate to stabilize the cardiac membrane
IV calcium gluconate is given first in severe hyperkalemia with ECG changes because it immediately stabilizes the cardiac membrane to prevent arrhythmias.
Question 4: A patient on loop diuretics presents with muscle cramps and a serum magnesium of 1.0 mg/dL (normal 1.7–2.2 mg/dL). Their hypokalemia is refractory to potassium replacement. What should be corrected first?
- Increase oral potassium supplementation
- Correct hypomagnesemia before further potassium replacement (Correct answer)
- Switch to a potassium-sparing diuretic
- Add IV calcium
Correct answer: Correct hypomagnesemia before further potassium replacement
Hypomagnesemia causes renal potassium wasting; correcting magnesium deficiency is necessary for potassium replacement to be effective.
Question 5: Which of the following is the correct treatment for severe symptomatic hyponatremia (Na+ 115 mEq/L with seizures)?
- Fluid restriction alone
- Hypertonic saline (3% NaCl) infusion (Correct answer)
- Rapid free water administration
- Oral salt tablets
Correct answer: Hypertonic saline (3% NaCl) infusion
Severe symptomatic hyponatremia with seizures requires hypertonic saline infusion to rapidly raise sodium and reduce cerebral edema.
Question 6: A patient with chronic kidney disease has a phosphate level of 6.5 mg/dL. Which medication class is most appropriate to reduce serum phosphate?
- Loop diuretics
- Phosphate binders (e.g., calcium carbonate, sevelamer) (Correct answer)
- Potassium supplements
- Vitamin D analogues
Correct answer: Phosphate binders (e.g., calcium carbonate, sevelamer)
Phosphate binders work in the gastrointestinal tract to reduce phosphate absorption and are first-line treatment for hyperphosphatemia in CKD.
PSA PSA Fluid and Electrolyte Prescribing 2
A patient has a serum potassium of 2.8 mEq/L with ECG changes showing U waves.
What is the most appropriate management?