The decreased PaCO₂ and increased pH is marked in:

NVS- 2025

Medical & Surgical Nursing

Easy

Appeared in: NVS- 2025

Explanation

Respiratory alkalosis is defined by a primary decrease in PaCO₂ (hypocapnia) and a subsequent increase in blood pH (alkalemia).
This condition arises from alveolar hyperventilation, where the lungs excrete too much carbonic acid (CO₂).
The loss of CO₂, an acidic compound, causes the blood's pH to rise above the normal upper limit of 7.45.
Common causes include anxiety, pain, fever, hypoxemia, and brainstem injury, all of which can stimulate the respiratory center and increase the rate and depth of breathing.

Option A: Metabolic acidosis is characterized by a decreased pH (acidosis) and a primary decrease in bicarbonate (HCO₃⁻), which is the opposite of the parameters given in the question.
Option B: While metabolic alkalosis does involve an increased pH, the primary disturbance is an increase in bicarbonate (HCO₃⁻), not a decrease in PaCO₂.
Option D: Respiratory acidosis is the direct opposite of respiratory alkalosis. It involves an increased PaCO₂ (hypercapnia) and a decreased pH (acidosis).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Arterial Blood Gas (ABG) Interpretation: Respiratory Alkalosis as background academic context rather than a clinical decision trigger.
Nurses must quickly identify respiratory alkalosis from ABG results, as it often signals underlying issues like anxiety, pain, fever, or hypoxia that require immediate intervention.
Nursing interventions are aimed at treating the underlying cause and helping the patient slow their breathing to retain CO₂. This can involve breathing coaching, providing a paper bag for rebreathing (with caution), or administering anxiolytics as ordered.
What if? If the patient's ABG showed a decreased pH and an increased PaCO₂, the diagnosis would be respiratory acidosis, and nursing interventions would focus on improving ventilation (e.g., deep breathing exercises, bronchodilators, or mechanical ventilation) rather than slowing it down.

How to Approach the Question

First, analyze the pH. An increased pH (above 7.45) indicates alkalosis.
Second, analyze the PaCO₂. A decreased PaCO₂ (below 35 mm Hg) indicates a respiratory issue.
Third, correlate the pH and PaCO₂. The ROME mnemonic (Respiratory Opposite, Metabolic Equal) is a useful tool. Here, the pH is high and PaCO₂ is low (opposite directions), confirming a respiratory disorder.
Combine the findings: an increased pH (alkalosis) with a respiratory cause points directly to respiratory alkalosis.
Finally, review the options to select the one that matches this conclusion.

Concept Tested & Keywords

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

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