A client is admitted with an acute exacerbation of chronic obstructive pulmonary disease (COPD). Based on the assessment findings below, which nursing intervention is the priority?

Oxygen therapy in acute COPD exacerbation: why start low?

Reviewing the arterial blood gas (ABG) results, the pH of 7.31, PaCO₂ of 65 mmHg, and HCO₃⁻ of 28 mEq/L indicate acute respiratory acidosis with partial compensation. In addition, the PaO₂ of 55 mmHg and SpO₂ of 86% reflect significant hypoxemia.

The danger of high-concentration oxygen in COPD relates to how these clients regulate breathing. In healthy people, a rising PaCO₂ (hypercapnia) is the primary stimulus to the respiratory center. In clients with long-standing COPD, however, chronic CO₂ retention blunts that sensitivity to CO₂. Breathing then becomes driven mainly by the hypoxic drive—peripheral chemoreceptors sense the low PaO₂ and signal the client to breathe. If high-concentration oxygen is given abruptly, that hypoxic drive is suppressed, respirations slow or become depressed, CO₂ accumulates further, and the client can progress to CO₂ narcosis ^[1].

Therefore, the correct answer is to deliver the prescribed low-flow oxygen via a Venturi mask. A Venturi mask entrains room air with a regulated oxygen flow, delivering a precise and consistent oxygen concentration (FiO₂). For clients at risk for hypercapnic respiratory failure, such as those in acute COPD exacerbation, this is the safest way to cautiously correct hypoxemia while maintaining a target SpO₂ of 88–92% ^[1].

Here is why the other options are inappropriate.
1. Deliver 100% high-flow oxygen via a nonrebreather mask: This can completely abolish the hypoxic drive, causing respiratory depression and a rapid worsening of CO₂ retention.
2. Place the client supine with the head of bed flat: In COPD the diaphragm is flattened and the chest wall is stiff, so lying supine allows abdominal organs to push the diaphragm upward and makes breathing more difficult. For a client in respiratory distress, an upright semi-Fowler's position is the priority.
3. Administer the prescribed IV opioid analgesic: Opioids such as morphine directly depress the respiratory center; giving one to a client who already has respiratory acidosis and CO₂ retention can worsen respiratory failure to a fatal degree.
5. Instruct the client to breathe into a paper bag: Paper-bag breathing relieves symptoms of respiratory alkalosis from hyperventilation by allowing CO₂ rebreathing. This client has the opposite problem—excessive CO₂ retention with respiratory acidosis—so rebreathing CO₂ would make the condition far more dangerous.

Application to clinical practice
When giving oxygen during an acute COPD exacerbation, always start at a low concentration (24–28%) and monitor ABGs and SpO₂ continuously. If dyspnea does not improve or the level of consciousness declines after oxygen is started, consider noninvasive positive-pressure ventilation (NIV) or endotracheal intubation rather than simply increasing the oxygen concentration. The goal is not just to correct the oxygen deficit but to support ventilation itself so that CO₂ can be eliminated.