Can persistent symptoms on CPAP reflect incompletely controlled sleep-disordered breathing?

Persistent symptoms during CPAP use can reflect residual, incompletely treated sleep-disordered breathing rather than “residual sleepiness” alone. The evidence strongly supports reassessing treatment delivery and efficacy, particularly in a 74-year-old patient in whom symptom burden and consequences of disrupted sleep may be substantial.

Treatment effectiveness and monitoring

• Clinically significant unintentional mask leak can reduce effective PAP delivery and leave obstructive events insufficiently controlled. Importantly, high leak also makes device-derived residual-event detection unreliable; a low or high device-reported AHI should therefore be interpreted alongside leak data, usage patterns, and event type where available.
• Inadequate or poorly matched pressure is a recognized cause of residual obstructive events. Persistent or recurrent symptoms despite apparently good adherence warrant review of pressure settings/profile, residual AHI, oxygenation if available, and objective nightly use—not immediate attribution to nonspecific residual sleepiness.
• If device data suggest ineffective therapy or remain difficult to interpret, follow-up home sleep apnea testing or polysomnography and attended PAP retitration are reasonable.

Position- and REM-dependent obstruction

• Supine sleep and REM sleep increase upper-airway vulnerability and may require higher CPAP pressure. AASM titration guidance seeks control of apneas, hypopneas, respiratory-effort–related arousals, and snoring during supine REM, ideally with RDI <5/hour plus acceptable leak and oxygenation.
• Supine pressure requirements may exceed lateral requirements by >2 cm H₂O. In one study of fixed CPAP, mean residual AHI was 6.1/hour overall and 8.4/hour during supine REM, illustrating why a pressure that appears adequate in other sleep conditions may fail during higher-demand periods.

Clinical implications

• Ongoing respiratory events and arousal-related sleep fragmentation provide a well-established mechanism for non-restorative sleep and daytime symptoms.
• Bottom line: Mask leak, suboptimal pressure, and position- or REM-specific residual obstruction are remediable, evidence-supported explanations for persistent symptoms on CPAP. Systematic review of leak, pressure adequacy, residual events, and control during supine REM should precede conclusions about persistent symptoms from other causes.