FCCS FCCS Fluid and Electrolyte Management 1 — Questions and Answers
Question 1: Which electrolyte is the primary determinant of extracellular fluid volume and intravascular volume?
- Potassium
- Sodium (Correct answer)
- Chloride
- Bicarbonate
Correct answer: Sodium
Sodium is the principal extracellular cation and the primary osmole that determines extracellular fluid volume.
Question 2: Which IV fluid is considered isotonic and is appropriate for initial fluid resuscitation in hypovolemia?
- 5% Dextrose in water (D5W)
- 0.45% Normal saline
- 0.9% Normal saline (Correct answer)
- 3% Hypertonic saline
Correct answer: 0.9% Normal saline
0.9% normal saline is isotonic (308 mOsm/L) and remains in the extracellular space, making it appropriate for volume resuscitation.
Question 3: What is the normal serum sodium concentration range?
- 120–130 mEq/L
- 125–135 mEq/L
- 135–145 mEq/L (Correct answer)
- 145–155 mEq/L
Correct answer: 135–145 mEq/L
Normal serum sodium ranges from 135 to 145 mEq/L; values outside this range indicate hypo- or hypernatremia.
Question 4: Which urine output threshold is commonly used to indicate adequate fluid resuscitation in critically ill adults?
- 0.1 mL/kg/hr
- 0.3 mL/kg/hr
- 0.5 mL/kg/hr (Correct answer)
- 1.5 mL/kg/hr
Correct answer: 0.5 mL/kg/hr
A urine output of at least 0.5 mL/kg/hr reflects adequate renal perfusion and is a standard resuscitation endpoint.
Question 5: What is the most common cause of hyponatremia in ICU patients?
- Diabetes insipidus
- Excessive sodium intake
- Syndrome of Inappropriate Antidiuretic Hormone (SIADH) (Correct answer)
- Hyperglycemia
Correct answer: Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
SIADH causes inappropriate free water retention, diluting serum sodium and is the most frequent cause of hyponatremia in hospitalized ICU patients.
Question 6: Which IV fluid is considered a balanced crystalloid and is preferred over normal saline to reduce hyperchloremic acidosis?
- D5W
- Lactated Ringer's solution (Correct answer)
- 0.45% NaCl
- 3% NaCl
Correct answer: Lactated Ringer's solution
Lactated Ringer's solution has a composition closer to plasma and contains less chloride, reducing the risk of hyperchloremic metabolic acidosis.
Question 7: A patient with hemorrhagic shock has a blood pressure of 80/50 mmHg and heart rate of 130 bpm. What is the most appropriate initial fluid strategy?
- Administer 250 mL D5W bolus
- Restrict all fluids until bleeding is controlled
- Administer 1–2 L balanced crystalloid bolus (Correct answer)
- Give 50 mEq sodium bicarbonate IV
Correct answer: Administer 1–2 L balanced crystalloid bolus
Initial resuscitation in hemorrhagic shock uses 1–2 L of balanced crystalloid (Lactated Ringer's or normal saline) while preparing for blood product administration.
FCCS FCCS Fluid and Electrolyte Management 1
Which electrolyte is the primary determinant of extracellular fluid volume and intravascular volume?