A nurse is caring for patient on diuretic therapy. The nurse would monitor the patient for which acid base disorder?

Appeared in: DSSSB - 28 August 2019 (Shift-1)

Explanation

Diuretic therapy, especially with loop and thiazide diuretics, is a primary cause of metabolic alkalosis.
The mechanism involves increased renal excretion of hydrogen (H⁺), potassium (K⁺), and chloride (Cl⁻) ions.
Fluid loss from diuresis also leads to a 'contraction alkalosis,' where the concentration of bicarbonate in the blood increases as the fluid volume decreases.
Associated hypokalemia (low potassium) further promotes alkalosis as the kidneys attempt to conserve potassium by excreting more hydrogen ions.

Option A: Respiratory alkalosis is caused by hyperventilation, which leads to excessive blowing off of carbon dioxide (CO₂). This is a lung-mediated process, not a primary effect of diuretics, which act on the kidneys.
Option B: Metabolic acidosis is characterized by a decrease in bicarbonate or a buildup of acid. While some diuretics like acetazolamide (a carbonic anhydrase inhibitor) can cause metabolic acidosis, the most commonly used diuretics (loop and thiazide) cause the opposite effect.
Option C: Respiratory acidosis is caused by hypoventilation, which leads to the retention of carbon dioxide (CO₂). This is related to impaired lung function or respiratory drive, not the renal action of diuretics.

Clinical Relevance

Nursing practice connection: Use the key finding related to Acid-base imbalance caused by diuretic therapy to guide bedside assessment, documentation, and the next nursing action.
Nurses must diligently monitor patients on diuretics for signs of metabolic alkalosis and hypokalemia, such as muscle weakness, cramps, confusion, and cardiac arrhythmias.
Monitoring includes regular checks of serum electrolytes (especially potassium, chloride) and arterial blood gases (ABGs) to assess pH and bicarbonate levels.
Patient education should include dietary sources of potassium (if on a potassium-losing diuretic) and reporting symptoms of electrolyte imbalance.

How to Approach the Question

First, identify the core of the question: the effect of 'diuretic therapy' on 'acid-base' balance.
Recall that diuretics primarily act on the kidneys. This makes a 'metabolic' disorder more likely than a 'respiratory' one. This helps eliminate Respiratory Alkalosis and Respiratory Acidosis as primary effects.
Next, differentiate between metabolic acidosis and metabolic alkalosis. Remember that the most common diuretics (loop and thiazide) cause the body to lose acid (hydrogen ions) and potassium in the urine.
Losing acid leads to a more alkaline (basic) state in the body. Therefore, metabolic alkalosis is the logical consequence.
Select the option that matches this physiological effect.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 564-566, 565-567

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