A 68-year-old client with COPD is admitted with an exacerbation. Oxygen is ordered to be titrated to SpO2 88% to 92%. After 30 minutes on nasal cannula at 2 L/min, the client is alert, speaking in full sentences, RR 22/min, SpO2 86%. Arterial blood gas: pH 7.37, PaCO2 49 mm Hg, PaO2 52 mm Hg, HCO3 28 mEq/L. The client's documented baseline PaCO2 is 48 mm Hg. Which action should the nurse take?

Quick answer
Titrate up to 3 L/min and recheck: the client is below target and the ABG shows no acute acidosis.

Why this is correct
Two details separate this item from the low-flow slogan. First, the SpO2 of 86% and PaO2 of 52 mm Hg are below the ordered target, so hypoxemia is still untreated. Second, pH 7.37 with PaCO2 49 against a baseline of 48 and HCO3 28 shows compensated chronic CO2 retention, not acute hypercapnic failure. The safe action is a small titration step toward 88% to 92% with close reassessment of SpO2, mental status, and a repeat ABG as ordered.

Easy analogy or mental picture
Oxygen in COPD is a dimmer switch, not an on-off switch: turn it up one notch at a time until the room is bright enough, then stop.

Memory hook
Below 88: turn it up a notch. Above 92: turn it down. Watch the pH, not just the CO2.

NCLEX decision rule
In COPD, treat hypoxemia by titrating to 88% to 92%; judge the need for ventilatory support by pH and trend, not by an elevated PaCO2 alone.

Why the other choices are wrong
Keeping the flow at 2 L/min is the option the "low flow for COPD" slogan points to, but leaving the client below target risks hypoxemic harm, and the hypoxic-drive theory is an oversimplification. A non-rebreather at 15 L/min fixes the low SpO2 quickly, which is tempting, but aiming above 94% in COPD raises the risk of worsening hypercapnia. Noninvasive ventilation is correct for acute hypercapnic respiratory acidosis, yet this PaCO2 matches the client's baseline and the pH is normal.