Hypoxia Pathways for Early Recovery After Spinal Cord Injury

"aAIH (augmented acute intermittent hypoxia) consists of 3, 5-minute episodes of low oxygen (9-13% O2), interspersed with 3-min room air intervals.~Each study participant will complete one session of augmented AIH (aAIH), which consists of 3, 5-minute exposures. Each exposure involves a 5-minute hypoxic episode (9-131% inspired O2), with a 3-min interval of room air breathing (21% O2). Gas mixtures will be delivered via Douglas bags (pre-filled with desired gas mixture) that are coupled to a non-rebreathing valve and facemask. A manual-control valve allows seamless gas mixture switching. Participant safety will be continuously monitored in real-time using non-invasive sensors and LabChart software. For instance, inspired and expired concentrations of O2 will be monitored by continuous recordings of arterial O2 saturation and end-tidal gas, respectively. Furthermore, vital signs (respiratory rate, tidal volume, heart rate, and blood pressure) will be continuously monitored."

"AIHH consists of 1-min episodes of low oxygen (9% O2) and elevated carbon dioxide (5% CO2), interspersed with 1.5 min room air.~Each participant will complete one session of AIHH exposure, which consists of 15, 1-minute hypercapnic hypoxic episodes (4-5% inspired CO2, 9-131% inspired O2), with 1.5-minute intervals of room air breathing (21% O2). Gas mixtures will be delivered in the same manner described for AIH intervention. Participant safety will be continuously monitored in real-time using LabChart software. For instance, inspired and expired concentrations of CO2 and O2 will be monitored by continuous recordings of arterial O2 saturation and end-tidal gas, respectively. Furthermore, vital signs (respiratory rate, heart rate, and blood pressure) will be monitored."

"A single session of sham AIH with episodes of normal room air (21% O2).~Sham experiments will use methods identical to AIH/AIHH protocols except that normoxic gas (21% inspired O2) will be delivered. Since the timing and intervals vary with each protocol, the sham will use a distinct protocol involving 5, 3-min episodes with 2 min intervals between each episode. The valve on the non-rebreathing mask will be turned to deliver these episodes, but 21% O2 will be delivered throughout."