Question 1

After a patient has received fluid therapy for several hours, her supine and standing heart rate and blood pressure are recorded. Which of the following results indicates a need for further therapy?

Accepted Answer

Choice C shows an increase in heart rate of 22 beats per minute when standing, which is considered an abnormal response to orthostatic changes. The supine and standing blood pressures are within normal limits, but the increase in heart rate indicates a potential need for further fluid therapy. The other choices show minimal changes in heart rate and blood pressure when standing, indicating a successful response to fluid therapy.

Question 2

A patient's serum sodium level upon admission was 148 mEq/L, her heart rate was 110 lying supine, and her blood pressure was 88/60. What is the most appropriate fluid therapy?

Accepted Answer

The patient's high serum sodium level indicates hypernatremia, which can be caused by insufficient water intake or excessive water loss. The low blood pressure and tachycardia suggest hypovolemia. Therefore, the most appropriate fluid therapy would be administering IV normal saline (0.9%), which will increase intravascular volume and correct the electrolyte imbalance. Pushing oral fluids may not be sufficient to rapidly correct the hypovolemia and hypernatremia. Free water restriction may exacerbate hypovolemia and cause further electrolyte imbalances. Administering IV 5% dextrose in water may be appropriate in some cases, but not in this situation as it does not address the hypovolemia and hypernatremia.

Question 3

A serum sodium level is obtained and shows a level of 142 mEq/L. Which of the following is a correct interpretation of this value?

Accepted Answer

A serum sodium level of 142 mEq/L falls within the normal range of 135-145 mEq/L. It is not indicative of any water or saline imbalance.

Question 4

A 14-month-old girl is brought to urgent care by her parents for persistent fever, vomiting, and diarrhea. Upon questioning, the parents report that the child has had only one to two wet diapers per day for the last 2 days. The child's weight is noted to be 2 pounds less than her normal weight. This is equivalent to approximately how much fluid loss?

Accepted Answer

One pound of weight loss is equal to approximately 500 mL of fluid loss. The child has lost 2 pounds, which is equivalent to 1000 mL or 1 liter of fluid loss.

Question 5

Which fluid will be most effective in restoring extracellular volume?

Accepted Answer

Normal saline (0.9%) is the most effective in restoring extracellular volume as it closely resembles the electrolyte composition of extracellular fluid. Solution A (5% dextrose in water) and Solution D (10% dextrose in water) contain a high concentration of dextrose, which can effectively provide energy, but are not effective in restoring extracellular volume as they do not have sufficient electrolytes. Solution C (half normal saline) may be helpful in certain situations, but it is not as effective as normal saline in restoring extracellular volume.

Question 6

Because of continuing decreased urine output, the function of a patient's kidneys is evaluated with urine electrolytes. The urine Na⁺ is found to be quite low. This is most likely due to

Accepted Answer

A low urine sodium concentration is often due to the effect of aldosterone, which promotes sodium reabsorption in the kidney tubules, leading to decreased sodium excretion in urine.

Question 7

An electrolyte disorder that frequently accompanies ketoacidosis is

Accepted Answer

Ketoacidosis often leads to hyperkalemia due to the shift of potassium from cells to the blood as a result of acidosis, despite total body potassium being low.

Question 8

C.G. is a 42-year-old patient with type 1 diabetes that is normally well controlled with insulin. Three days ago, she developed a viral infection with high fever and has not been checking her blood glucose regularly. She is now in the emergency department complaining of abdominal pain and flu symptoms. C.G.'s urine is positive for glucose and ketones, and serum glucose and blood gases are obtained. What fluid balance problem is C.G. at risk for secondary to glycosuria?

Accepted Answer

C.G. is at risk for a water deficit due to glycosuria, which can cause an osmotic diuresis and lead to dehydration. The high serum glucose levels can also cause an osmotic shift of fluids from the intracellular to the extracellular compartment, further contributing to dehydration.

Quiz 24: Fluid and Electrolyte Homeostasis and Imbalances