1196 Use of Home Sleep Apnea Testing to Investigate Persistent Hypoxia in the Remote Setting

Introduction Nocturnal oxygen titrations can be resource intensive, and often require the patient to undergo an attended polysomnogram (PSG). Veterans who live in remote areas are often reluctant to undergo PSG, particularly in those with multiple medical comorbidities that prohibit prolonged travel. We present a case of a veteran with severe OSA and persistent nocturnal hypoxia who underwent a remote oxygen titration using home sleep apnea testing (HSAT) equipment. Report of case(s) 79-year-old male with history of hypertension and diabetes diagnosed with severe OSA (AHI 38 events/hour), with significant oxygen nadir of 65%. He was prescribed automatic positive airway pressure (APAP) of 6-16 cmH2O and a follow up 3-night oximetry was ordered which showed persistent nocturnal hypoxia. Remote monitoring showed regular PAP use with AHI < 5/hr during the nights of oximetry. Unfortunately, the patient was unable to travel for attended PAP and oxygen titration study for further diagnostic assessment. It was instead decided to repeat 3-night oximetry with use of supplemental oxygen (1, 2, 3 liters/minute for nights one, two, and three respectively). Results again showed persistent nocturnal hypoxia with AHI < 5/hr on remote data monitoring. 3-night HSAT connected to the patient’s APAP device was ordered, with bleed in oxygen at 2, 3, and then 4 liters/minute over the consecutive nights of the study. Results included the C-flow channel, which surprisingly showed persistent snoring and obstructive events (average AHI of 8/h) despite APAP, a discordant finding to that on remote data monitoring. The decision was made to transition patient to an automatic bilevel positive airway pressure mode with two-liter oxygen bleed in. This resulted in adequate treatment of OSA and nocturnal hypoxia as confirmed by follow up HSAT. It is notable that ongoing diagnostic evaluation of hypoxia is underway. Conclusion Aside from its promise in diagnosing moderate to severe OSA, HSAT over oximetry alone may provide additional diagnostic information (C-flow channel) in patients with residual nocturnal hypoxia despite PAP. In patients who are not able to undergo formal attended titration studies such as those who live in remote settings, this is a potential alternative. Support (if any)