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

Summary

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.

Conditions

• Spinal Cord Injuries
• Autonomic Dysreflexia

Interventions

OTHER

Mild Intermittent Hypoxia

Participants will breathe 8% oxygen through a non-diffusable bag that is connected to a 5-way stopcock. The inspiration side of the system is then connected to a 2-way non-rebreathing valve which is connected to a pneumotachometer that is connected to a tight fitting facemask. 100% oxygen and carbon dioxide are titrated into the system to ensure the appropriate hypoxic and hypercapnic stimulus is delivered. The investigators will lower oxygen to 55-60 mmHg and maintain end-tidal carbon dioxide 1-3 mmHg above individual baseline values. The protocol starts with 10 minutes of baseline breathing (room air) then followed by 10 more minutes of breathing room air with the additional carbon dioxide. Thereafter, individuals undergo 12 2-minute bouts of hypoxia with 2 minutes of normoxia (room air) interspersed between episodes. The intervention protocol concludes with 20 minutes of monitoring all breathing and cardiovascular measurements.

OTHER

Sham

Participants will breathe 21% oxygen through a non-diffusable bag that is connected to a 5-way stopcock. The inspiration side of the system is then connected to a 2-way non-rebreathing valve which is connected to a pneumotachometer that is connected to a tight fitting facemask. No supplemental oxygen or carbon dioxide will be used during the sham protocol. The protocol starts with 10 minutes of baseline breathing (room air) then followed by 10 more minutes of breathing room air with the additional carbon dioxide. Thereafter, individuals undergo 12 2-minute bouts of hypoxia with 2 minutes of normoxia (room air) interspersed between episodes. The intervention protocol concludes with 20 minutes of monitoring all breathing and cardiovascular measurements.

Sponsors & Collaborators

• John D. Dingell VA Medical Center

  collaborator FED

• VA Office of Research and Development

  lead FED

Principal Investigators

• Gino Panza, PhD · John D. Dingell VA Medical Center, Detroit, MI

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

60 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2022-10-01

Primary Completion

2026-10-29

Completion

2026-10-29

Countries

• United States

Study Locations