PT - JOURNAL ARTICLE AU - Berra, Lorenzo AU - Medeiros, Kyle J AU - Marrazzo, Francesco AU - Patel, Sarvagna AU - Imber, David AU - Rezoagli, Emanuele AU - Yu, Binglan AU - Sonny, Abraham AU - Bittner, Edward A AU - Fisher, Daniel AU - Chipman, Daniel AU - Sharma, Rohit AU - Shah, Hardik AU - Gray, Brianna E AU - Harris, N Stuart AU - Ichinose, Fumito AU - Mootha, Vamsi K TI - Feasibility of Delivering 5-Day Normobaric Hypoxia Breathing in a Hospital Setting AID - 10.4187/respcare.11928 DP - 2024 Nov 01 TA - Respiratory Care PG - 1400--1408 VI - 69 IP - 11 4099 - http://rc.rcjournal.com/content/69/11/1400.short 4100 - http://rc.rcjournal.com/content/69/11/1400.full AB - BACKGROUND: Beneficial effects of breathing at < 0.21 on disease outcomes have been reported in previous preclinical and clinical studies. However, the safety and intra-hospital feasibility of breathing hypoxic gas for 5 d have not been established. In this study, we examined the physiologic effects of breathing a gas mixture with as low as 0.11 in 5 healthy volunteers.METHODS: All 5 subjects completed the study, spending 5 consecutive days in a hypoxic tent, where the ambient oxygen level was lowered in a stepwise manner over 5 d, from of 0.16 on the first day to of 0.11 on the fifth day of the study. All the subjects returned to an environment at room air on the sixth day. The subjects' , heart rate, and breathing frequency were continuously recorded, along with daily blood sampling, neurologic evaluations, transthoracic echocardiography, and mental status assessments.RESULTS: Breathing hypoxia concentration dependently caused profound physiologic changes, including decreased and increased heart rate. At of 0.14, the mean was 92%; at of 0.13, the mean was 93%; at of 0.12, the mean was 88%; at of 0.11, the mean was 85%; and, finally, at an of 0.21, the mean was 98%. These changes were accompanied by increased erythropoietin levels and reticulocyte counts in blood. All 5 subjects concluded the study with no adverse events. No subjects exhibited signs of mental status changes or pulmonary hypertension.CONCLUSIONS: Results of the current physiologic study suggests that, within a hospital setting, delivering as low as 0.11 is feasible and safe in healthy subjects, and provides the foundation for future studies in which therapeutic effects of hypoxia breathing are tested.