1241 A Case of Chronic Hypoventilation of Unknown Etiology with Improvement from a Wake Promoting Agent

Introduction We present a patient with chronic insomnia, excessive daytime sleepiness, and sleep-related hypoventilation that improved with a wake promoting agent in conjunction with BPAP. Report of Case A 15-year-old male with Cystic Fibrosis (single F508del mutation, positive sweat test, FEV1% of 98%) and Autism who presented with frequent headaches, chronic insomnia, and daytime sleepiness (PDSS of 22). Current medications included albuterol as needed. Sleep history was significant for restless leg symptoms. Labs revealed low serum ferritin. Sleep study two years prior showed an AHI of 3.4 and PMLD of 18.4. After completion of iron therapy and initiation of gabapentin, his chronic insomnia and serum ferritin improved. However, patient continued to have aggressive behavior, headaches, and snoring. Sleep study was repeated and revealed mild OSA with hypoventilation (AHI of 6.41, >28% of total sleep time with TCO2 above 50 mm Hg). Initial serum bicarbonate was 29 mmol/L and progressively increased to 34 mmol/L. Due to evidence of persistent chronic hypoventilation, patient was trialed on BPAP. Subsequent sleep study with BPAP showed an AHI of 0, but with worsening sleep related hypoventilation (TCO2 of 56mmHg, > 70% total sleep time with TCO2 above 50 mm Hg). Genetic, endocrine, and neurological work up for hypoventilation was negative. Due to persistent daytime sleepiness (PDSS of 24), MSLT was performed and showed evidence of hypersomnia. Modafinil was then initiated. With the combination of nocturnal BPAP use and Modafinil, daytime sleepiness improved (PDSS of 15) and he had normalization of CO2 and bicarbonate levels. Conclusion We present a patient with CF, with minimal lung disease, who demonstrated a negative work up for sleep related hypoventilation, in which dysregulation of control of breathing improved with the use of a wake promoting agent in conjunction with BPAP.