Clinical Mysteries • Respiratory Medicine
The COPD Patient Who Got Sleepier
The presentation
Oxygen saturation looked excellent after high-flow oxygen, while the patient became increasingly drowsy.
The first explanation was plausible, but the pattern did not fully fit. A deliberate second look focused on physiology, medication/exposure history, serial observations and the clue that the initial diagnosis could not explain.
The turn
ABG revealed rising PaCO₂ and respiratory acidosis.
Diagnosis
Acute hypercapnic respiratory failure
Why this case matters
Treat oxygenation and ventilation as separate problems.
Take-home message: When the clinical course contradicts the working diagnosis, stop escalating the same treatment and rebuild the problem from first principles.