A patient's ABG result: pH 7.48, PCO2 is 32, PO2 is 88 and HCO3 is 24. According to this result, the patient is suffering from?

Appeared in: JIPMER Nursing Officer - 2020

Explanation

The pH of 7.48 is above the normal range of 7.35-7.45, which indicates a state of alkalosis.
The PaCO₂ of 32 mmHg is below the normal range of 35-45 mmHg. Since CO₂ acts as an acid in the blood, a low level (caused by hyperventilation) leads to alkalosis.
The mnemonic ROME (Respiratory Opposite, Metabolic Equal) can be applied. The pH is high and the PaCO₂ is low (opposite direction), confirming a respiratory origin.
The HCO₃⁻ (bicarbonate) level of 24 mEq/L is within the normal range of 22-26 mEq/L. This shows that the metabolic system has not yet compensated for the imbalance.

Option A: Respiratory acidosis is characterized by a low pH (acidosis) and a high PaCO₂ due to hypoventilation. The patient's values are the opposite.
Option C: Metabolic acidosis involves a low pH (acidosis) and a low HCO₃⁻. The patient's pH is high (alkalosis) and HCO₃⁻ is normal.
Option D: Metabolic alkalosis involves a high pH and a high HCO₃⁻. While the patient's pH is high, the HCO₃⁻ is normal, ruling out a primary metabolic cause.

Clinical Relevance

Nursing practice connection: Knowing Arterial Blood Gas (ABG) interpretation helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Respiratory alkalosis is most commonly caused by hyperventilation, which can be triggered by anxiety, pain, fever, hypoxia, or certain medications that stimulate the respiratory center.
Nursing interventions are aimed at treating the underlying cause. This includes managing pain, reducing fever, providing emotional support to an anxious patient, and encouraging slow, regular breathing.
In some situations, having the patient breathe into a paper bag can help them rebreathe exhaled CO₂, raising their PaCO₂ levels back to normal. This must be done cautiously and under supervision.

How to Approach the Question

First, analyze the pH to determine if the condition is acidosis or alkalosis. A pH of 7.48 is greater than 7.45, indicating alkalosis.
Second, examine the PaCO₂ (the respiratory parameter). A value of 32 mmHg is low (normal is 35-45). A low PaCO₂ causes alkalosis. Since this matches the pH finding, the primary disorder is respiratory.
Third, examine the HCO₃⁻ (the metabolic parameter). A value of 24 mEq/L is within the normal range (22-26). This confirms the problem is not metabolic in origin.
Fourth, determine compensation. Since the non-causative parameter (HCO₃⁻) is still within the normal range, the condition is uncompensated.
Finally, combine the findings: a primary respiratory disorder causing alkalosis with no compensation. This leads to the diagnosis of uncompensated respiratory alkalosis.

Concept Tested & Keywords

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E6 Nursing Fundamentals Taylor p. 785-787

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