Which acid-base imbalance is most commonly seen in a patient with severe diarrhea?

NORCET 10 Mains

Medical Surgical Nursing

Hard

Appeared in: NORCET 10 Mains

Explanation

Severe diarrhea causes the loss of large volumes of intestinal fluid.
Intestinal fluid is rich in bicarbonate (HCO₃⁻), which is a base.
The significant loss of bicarbonate, a base, leads to a state where the body's acids are relatively more concentrated.
This shift results in metabolic acidosis, characterized by a low pH and low serum bicarbonate.
This is a form of normal anion gap metabolic acidosis (NAGMA).

Option A: Metabolic alkalosis is caused by the loss of acid, not base.
Option C: Lactic acidosis is caused by the buildup of lactic acid from anaerobic metabolism, not directly by bicarbonate loss.
Option D: Respiratory acidosis is a primary respiratory problem related to CO₂ retention.

Visual 1: Flowchart: Pathophysiology of Metabolic Acidosis in Diarrhea. Shows the sequence: Severe Diarrhea → Loss of Bicarbonate-Rich Intestinal Fluid → Decreased Serum HCO₃⁻ → Lower Blood pH → Metabolic Acidosis.
Visual 2: Diagram: The Henderson-Hasselbalch Equation. Illustrates how a decrease in HCO₃⁻ (the metabolic component) shifts the blood pH to the acidic side.

Clinical Relevance

Nursing practice connection: Use the key finding related to Pathophysiology of acid-base imbalances resulting from gastrointestinal fluid loss to guide bedside assessment, documentation, and the next nursing action.
Nurses must closely monitor patients with severe diarrhea for signs of dehydration and metabolic acidosis, including altered mental status, Kussmaul respirations (deep, rapid breathing), and hypotension.
Key nursing interventions include administering IV fluids to restore volume, replacing electrolytes, and monitoring arterial blood gases (ABGs) and serum electrolytes.
What if? If the patient had severe vomiting instead of diarrhea, the most likely imbalance would be metabolic alkalosis due to the loss of hydrochloric acid from the stomach. The nurse's focus would shift to monitoring for signs of alkalosis (e.g., muscle cramps, tetany) and replacing chloride.

How to Approach the Question

First, identify the key condition in the question stem: 'severe diarrhea'.
Next, recall the composition of fluid in the lower gastrointestinal tract. It is alkaline and rich in bicarbonate.
Consider the effect of losing large amounts of this fluid. Losing a base (bicarbonate) will make the body more acidic.
Evaluate the options based on this understanding. 'Metabolic' refers to the kidneys and body fluids, while 'respiratory' refers to the lungs. Since the cause is GI loss, it's a metabolic problem.
Because a base is being lost, the resulting imbalance is an acidosis. Therefore, the correct answer is metabolic acidosis.
Eliminate the other options by recalling their primary causes: metabolic alkalosis (loss of acid, e.g., vomiting), lactic acidosis (anaerobic metabolism), and respiratory acidosis (CO₂ retention).

Concept Tested & Keywords

Concept Tested: Pathophysiology of acid-base imbalances resulting from gastrointestinal fluid loss.
Stem keywords: acid-base imbalance, severe diarrhea
Lead-in keywords: most commonly seen

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