The nurse is caring for a patient with severe burns who is receiving IV fluid resuscitation with lactated Ringer's solution. The nurse understands that this type of solution is used for this patient because it:

Choice A reason:

pH 7.50, PaCO2 40 mm Hg, HCO3- 30 mEq/L. This choice is correct because it shows a high pH, a normal PaCO2, and a high HCO3-, which are consistent with metabolic alkalosis. Metabolic alkalosis occurs when there is a loss of acid or a gain of base in the body fluids, such as from prolonged nasogastric suctioning. The kidneys try to compensate by excreting more bicarbonate, but this process is slow and incomplete.

Choice B reason:

pH 7.35, PaCO2 35 mm Hg, HCO3- 24 mEq/L. This choice is incorrect because it shows normal values for pH, PaCO2, and HCO3-, which indicate no acid-base imbalance. A client with metabolic alkalosis would have an elevated pH and bicarbonate level.

Choice C reason:

pH 7.25, PaCO2 50 mm Hg, HCO3- 26 mEq/L. This choice is incorrect because it shows a low pH, a high PaCO2, and a normal HCO3-, which are consistent with respiratory acidosis. Respiratory acidosis occurs when there is impaired gas exchange or hypoventilation, leading to an accumulation of carbon dioxide in the blood. The kidneys try to compensate by retaining more bicarbonate, but this process is slow and incomplete.

Choice D reason:

pH 7.30, PaCO2 30 mm Hg, HCO3- 18 mEq/L. This choice is incorrect because it shows a low pH, a low PaCO2, and a low HCO3-, which are consistent with metabolic acidosis. Metabolic acidosis occurs when there is a gain of acid or a loss of base in the body fluids, such as from diabetic ketoacidosis or diarrhea. The lungs try to compensate by increasing the rate and depth of breathing to expel more carbon dioxide, but this process is fast and limited.

Choice A: Decreased serum pH. This is incorrect because hypokalemia usually causes increased serum pH, not decreased. This is because low potassium levels can lead to metabolic alkalosis, a condition where the blood is too alkaline due to loss of acid from the body. This can happen in cases of vomiting, diuretic use, or mineralocorticoid excess.

Choice B:

Increased serum calcium. This is incorrect because hypokalemia does not directly affect serum calcium levels. However, hypokalemia can cause hypomagnesemia, or low magnesium levels, which can in turn cause hypercalcemia, or high calcium levels. This is because magnesium is needed for the secretion of parathyroid hormone (PTH), which regulates calcium balance in the body. Low magnesium levels can lead to increased PTH secretion and increased calcium reabsorption from the bones and kidneys.

Choice C:

Decreased serum magnesium. This is correct because hypokalemia and hypomagnesemia often occur together, especially in cases of chronic diarrhea, malabsorption, alcoholism, or diuretic use. This is because potassium and magnesium are both lost in the urine or stool when these conditions are present. Hypomagnesemia can also cause hypokalemia by impairing the reabsorption of potassium in the kidneys and increasing the entry of potassium into the cells.

Choice D:

Increased serum bicarbonate. This is incorrect because hypokalemia usually causes decreased serum bicarbonate, not increased. This is because low potassium levels can lead to metabolic acidosis, a condition where the blood is too acidic due to accumulation of acid in the body. This can happen in cases of diabetic ketoacidosis, renal tubular acidosis, or chronic kidney disease.