P233 Outcomes of diagnostic and therapeutic CPAP trials in the management of patients with suspected obstructive sleep apnoea

Introduction and Objectives Oximetry is a widely used, but insensitive, screening test for obstructive sleep apnoea (OSA). Patients with non-diagnostic oximetry may be referred for a trial of continuous positive airway pressure (CPAP) based on symptoms of OSA due to lack of availability of polysomnography. We assessed the efficacy of CPAP in these patients compared to those with confirmed OSA. Methods We retrospectively reviewed 54 patients referred for a CPAP trial between January and June 2018. 34 patients were selected with a 4% oxygen desaturation index (ODI) 15/hour (high ODI group). Baseline demographics and follow up data on CPAP adherence and symptoms was collected. Results Patients with a lower ODI were younger (44.0±11.6 vs 55.5±14.2 years, p At initial follow up (median 87 days in low ODI group vs 56 days in high ODI group), 58.9% patients in the low ODI group continued to use CPAP vs 95% in the high ODI group, p=0.09 (figure 1). The low ODI patients used CPAP less than the high ODI patients (average usage 3.43±2.0 vs 6.32±2.08 hours/night, p Conclusions Although some patients with unconfirmed OSA benefit from CPAP, they are less likely to use it than those with confirmed OSA. Performing a polysomnogram following non-diagnostic oximetry may prevent unnecessary CPAP trials.