The emergence of central respiratory events during PAP titration for treatment of obstructive sleep apnea is:

• A. Mixed sleep apnea
• B. Hypoventilation syndrome
• C. Complex sleep apnea
• D. Cheyne-stokes breathing

Answer: (C)

When CPAP therapy for obstructive sleep apnea introduces central breathing pauses that were not present before, the phenomenon is described as complex sleep apnea, or treatment-emergent central sleep apnea. The idea is that once the airway obstruction is relieved and pressures are set to treat OSA, the brain’s respiratory control can become unstable in some individuals, allowing central apneas to appear even though the airway is open. These central events reflect a problem with respiratory drive rather than a blocked airway, which is why they emerge specifically during therapy.

This pattern is distinct from mixed sleep apnea, where an individual event has both obstructive and central components in a single episode; from Cheyne-Stokes breathing, which is a regular central breathing pattern often linked to conditions like heart failure or brain injury; and from hypoventilation syndrome, which involves chronic underventilation with elevated CO2 independent of PAP titration. Complex sleep apnea highlights how treatment can unmask an underlying propensity for central apnea during airway therapy, guiding clinicians to adjust the approach, such as considering adaptive ventilation strategies.