SLEEPY IN THE MOUNTAINS

ABSTRACT

Introduction: Central sleep apnea (CSA) is a rare disorder caused by a reduction of airflow and ventilatory effort during sleep. CSA is rarely idiopathic and associated with medical conditions including heart failure, opioid medications, treatment emergent and high-altitude periodic breathing. At higher altitudes, hypoxemia induces periodic breathing with periods of deep and rapid breathing alternating with central apnea. Patients with high-altitude periodic breathing experience fragmented sleep, poor sleep quality, excessive daytime sleepiness, morning headaches and witnessed apnea. We discuss a patient with obstructive sleep apnea (OSA) who developed new-onset central sleep apnea after relocating to a higher altitude location. Report of Cases A 75-year-old male with a history of moderate obstructive sleep apnea well controlled on CPAP for eight years, with no known cardiovascular or pulmonary disease, presented with new-onset excessive daytime sleepiness. He had recently relocated to an area in the Colorado mountains (7000 ft elevation) from his previous home in Los Angeles (sea level). His residual apneahypopnea index (r-AHI) displayed on his CPAP machine increased to 7-14/ hr from his normal of 1-2/hr after his relocation. Review of his compliance data revealed his central apnea index was elevated, contributing to his high r-AHI. A one-night nocturnal oximeter was mailed to the patient to use while on CPAP. Data revealed oxygen desaturation to less than 88% for about 2 hours of the night, worse during the early morning hours. The patient was advised to undergo a polysomnography and adaptive servo-ventilation titration if significant central sleep apnea was present. The patient declined due to concern about the COVID-19 pandemic. Supplemental nocturnal oxygen was initiated at 2L/min with normalization of the r-AHI. Conclusion: Patients with OSA who experience worsening symptoms or increased r-AHI despite excellent compliance with PAP therapy should be considered for repeat polysomnography or titration study. While it is expected that high-altitude central sleep apnea will improve with acclimatization, nocturnal supplemental oxygen in addition to PAP therapy is indicated for patients with high-altitude central sleep apnea to diminish hypoxemia and improve residual AHI and sleep quality.