Mild Intermittent Hypoxia: A Prophylactic for Autonomic Dysfunction in Individuals With Spinal Cord Injuries

The prevalence of autonomic dysfunction and sleep disordered breathing (SDB) is increased in individuals with spinal cord injury (SCI). The loss of autonomic control results in autonomic dysreflexia (AD) and orthostatic hypotension (OH) which explains the increase in cardiovascular related mortality in these Veterans. There is no effective prophylaxis for autonomic dysfunction. The lack of prophylactic treatment for autonomic dysfunction, and no best clinical practices for SDB in SCI, are significant health concerns for Veterans with SCI. Therefore, the investigators will investigate the effectiveness of mild intermittent hypoxia (MIH) as a prophylactic for autonomic dysfunction in patients with SCI. The investigators propose that MIH targets several mechanisms associated with autonomic control and the co-morbidities associated with SDB. Specifically, exposure to MIH will promote restoration of homeostatic BP control, which would be beneficial to participation in daily activities and independence in those with SCI.

Inclusion Criteria: * Motor incomplete spinal cord injury at or above the 12th thoracic vertebrae * Signs or symptoms of autonomic dysfunction (this will be determined by the Autonomic Dysfunction Following Spinal Cord Injury (ADFSCI) and ISAFSCI questions. The ADFSCI requires a score of 1 on questions 16 and 22, and the International Standards to document Autonomic Function following SCI (ISAFSCI) requires a score of 1 on any parameter) * Chronic injuries (\>1 year post injury) Exclusion Criteria: * Pregnant * Smoker * Drug addiction * Complete spinal cord injury * Spinal cord injury below the 6th thoracic vertebrae * Insulin dependent diabetes * Shift workers (i.e., disrupted circadian rhythm) * Active skin breakdown or pressure sores