RT Journal Article
SR Electronic
T1 Feasibility of Delivering a 5-Day Normobaric Hypoxia Breathing in Healthy Volunteers in a Hospital Setting
JF Respiratory Care
FD American Association for Respiratory Care
SP respcare.11928
DO 10.4187/respcare.11928
A1 Berra, Lorenzo
A1 Medeiros, Kyle J
A1 Marrazzo, Francesco
A1 Patel, Sarvagna
A1 Imber, David
A1 Rezoagli, Emanuele
A1 Yu, Binglan
A1 Sonny, Abraham
A1 Bittner, Edward A
A1 Fisher, Daniel
A1 Chipman, Daniel
A1 Sharma, Rohit
A1 Shah, Hardik
A1 Gray, Brianna E
A1 Harris, N Stuart
A1 Ichinose, Fumito
A1 Mootha, Vamsi K
YR 2024
UL http://rc.rcjournal.com/content/early/2024/07/30/respcare.11928.abstract
AB BACKGROUND: Beneficial effects of breathing at FIO2 < 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 FIO2 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 FIO2 of 0.16 on the first day to FIO2 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' SpO2, 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 SpO2 and increased heart rate. At FIO2 of 0.14, the mean SpO2 was 92%; at FIO2 of 0.13, the mean SpO2 was 93%; at FIO2 of 0.12, the mean SpO2 was 88%; at FIO2 of 0.11, the mean SpO2 was 85%; and, finally, at an FIO2 of 0.21, the mean SpO2 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 FIO2 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.