The arterial blood gas (ABG) report of a client shows a pH of 7.32, PCO2 - 52 mm Hg, PO2 - 89 mm Hg and HCO3 of 27 mEq/L. The nurse interprets that the client has?

Appeared in: SCTIMST Staff Nurse - 2015 (Set-A)

Explanation

The primary disorder is identified by matching the pH with the respiratory or metabolic component.
A pH of 7.32 is acidic.
A PaCO₂ of 52 mm Hg is high (acidic) and is opposite to the direction of the pH change (which is low), indicating a respiratory origin.
Therefore, the condition is Respiratory Acidosis.
The HCO₃⁻ of 27 mEq/L is elevated, showing that the kidneys are attempting to compensate by retaining bicarbonate to buffer the excess acid.
Since the pH is still abnormal, the compensation is partial.

Option B: This patient's HCO₃⁻ is high (27 mEq/L), whereas metabolic acidosis is defined by a low HCO₃⁻ (less than 22 mEq/L).
Option C: This patient's pH is low (7.32) and PaCO₂ is high (52 mm Hg). Respiratory alkalosis is the opposite, with a high pH (greater than 7.45) and a low PaCO₂ (less than 35 mm Hg).
Option D: This patient's pH is low (7.32), indicating acidosis. Metabolic alkalosis is defined by a high pH (greater than 7.45) due to an excess of bicarbonate.

Clinical Relevance

Nursing practice connection: Knowing Interpretation of Arterial Blood Gas (ABG) results to identify acid-base imbalances helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Respiratory acidosis is a critical condition caused by alveolar hypoventilation, where the lungs fail to eliminate enough CO₂. Nursing priorities include improving ventilation and oxygenation.
Key nursing interventions for respiratory acidosis include encouraging deep breathing and coughing, maintaining a patent airway, administering bronchodilators or oxygen as prescribed, and monitoring for changes in respiratory status and level of consciousness.
What if the patient's PaCO₂ was normal (e.g., 40 mmHg) and the HCO₃⁻ was low (e.g., 18 mEq/L)? With a pH of 7.32, the diagnosis would shift to Metabolic Acidosis, as the primary cause would be a deficit of bicarbonate.

How to Approach the Question

First, analyze the pH. A value below 7.35 indicates acidosis. A value above 7.45 indicates alkalosis.
Second, examine the PaCO₂ (the respiratory parameter). A high PaCO₂ (above 45) causes acidosis, while a low PaCO₂ (below 35) causes alkalosis.
Third, examine the HCO₃⁻ (the metabolic parameter). A low HCO₃⁻ (below 22) causes acidosis, while a high HCO₃⁻ (above 26) causes alkalosis.
Use the ROME mnemonic (Respiratory Opposite, Metabolic Equal) to find the primary cause. In this case, pH is low and PaCO₂ is high (Opposite), so it's Respiratory Acidosis.
Finally, check for compensation. The parameter that is not the primary cause (in this case, HCO₃⁻) will move to counteract the imbalance. Since HCO₃⁻ is high but the pH is not yet normal, it is partial compensation.

Concept Tested & Keywords

Concept Tested: Interpretation of Arterial Blood Gas (ABG) results to identify acid-base imbalances.
Stem keywords: arterial blood gas, ABG, pH, PCO2, PO2, HCO3
Lead-in keywords: interprets
Clinical cues: pH 7.32 indicates acidosis
Clinical cues: PCO2 52 mm Hg indicates a respiratory cause

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E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 56-58

E6 Nursing Fundamentals Taylor p. 785-787

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 2 — Subpart A (pp 1-239 of 478) p. 82-84

Practise the full SCTIMST Staff Nurse - 2015 (Set-A)

Attempt every question from this paper in a timed mock, then review the full solution for each one.