Residual sleep-disordered breathing during autotitrating continuous positive airway pressure therapy

Obstructive sleep apnoea (OSA) is often treated with auto-titrating positive airway pressure devices (autoCPAP). Clinical and bench tests of these devices have suggested performance limitations. These studies do not indicate whether this is a failure to detect, or a failure to respond, to airway obstruction. In this randomised, crossover trial, 34 patients with moderate-to-severe OSA underwent polysomnography on two laboratory visits. The autoCPAP device was randomly set to a fixed sub-therapeutic pressure (detection assessment) or auto-titrating mode (response assessment). Airflow was measured both from the autoCPAP (autoCPAP-flow) and directly from the nasal mask, and recorded on polysomnography. Apnoea hypopnoea indices (AHI) measured at the two sites and also from the autoCPAP-download report were compared. Regarding detection, the AHI measured from the nasal mask showed good agreement with the autoCPAP-flow AHI. But agreement was lower with the autoCPAP-report AHI. In auto-titrating mode, there was significant misclassification of those with and without OSA (AHI≥10/h) on the autoCPAP-report. Regarding response, residual OSA (AHI≥10/h) was still evident in 24 % of patients during auto-titration. In some patients autoCPAP fails to detect and/or respond to sleep apnoea. Clinicians should consider limitations of each device and use caution when using autoCPAP report statistics to verify effective treatment