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Difficulty: MediumPhysiological Adaptation

A nurse is caring for a client with a mechanical small bowel obstruction who has been receiving continuous nasogastric (NG) decompression for three days. The client suddenly reports a new onset of severe, unrelenting abdominal pain. The healthcare provider orders an arterial blood gas (ABG) analysis, which reveals the following results: pH 7.28, PaCO2 36 mm Hg, and HCO3- 15 mEq/L. Based on these findings, which conclusion should the nurse draw?

  1. The client has developed uncompensated metabolic acidosis, which strongly indicates potential bowel ischemia.Answer
  2. B
    The client is exhibiting respiratory acidosis secondary to shallow breathing caused by the severe abdominal pain.
  3. C
    The client's laboratory results demonstrate an expected physiological compensation for the prolonged loss of gastric acid.
  4. D
    The client remains in a state of metabolic alkalosis due to the ongoing removal of stomach contents via the nasogastric tube.

Answer

The client has developed uncompensated metabolic acidosis, which strongly indicates potential bowel ischemia.
The ABG results demonstrate a low pH (acidosis) and a low bicarbonate level with a normal PaCO2, which is the exact diagnostic criteria for uncompensated metabolic acidosis. While continuous nasogastric decompression typically puts a client at risk for metabolic alkalosis due to the loss of stomach acid, the sudden presentation of severe, unrelenting pain combined with a shift to metabolic acidosis is a classic indicator of bowel strangulation or infarction. The necrotic tissue relies on anaerobic metabolism, producing lactic acid that rapidly depletes the body's bicarbonate stores.

Step-by-Step Solution

1
Analyze the pH value.
The pH is 7.28, which is below the normal range of 7.35-7.45.
This establishes that the client is currently in a state of acidosis.
2
Evaluate the PaCO2 and HCO3- values to determine the origin of the acidosis.
The PaCO2 is 36 mm Hg (normal range 35-45 mm Hg) and the HCO3- is 15 mEq/L (below the normal range of 22-26 mEq/L).
Because the bicarbonate (metabolic parameter) matches the acidic pH while the PaCO2 (respiratory parameter) is normal, the disturbance is uncompensated metabolic acidosis.
3
Correlate the ABG interpretation with the sudden change in the client's clinical presentation.
The sudden, severe pain coupled with a shift to metabolic acidosis in a client with a bowel obstruction suggests a critical complication.
Bowel strangulation or ischemia restricts blood flow, leading to anaerobic metabolism, lactic acid buildup, and subsequent metabolic acidosis. This is a medical emergency.

Key Concept

Interpretation of Arterial Blood Gases and Recognition of Ischemic Complications
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Topics

Physiological Adaptation

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