The purpose of this study is to determine how mild breathing bouts of low oxygen may restore walking and leg strength in persons who have sustained a spinal cord injury.
The goal of the study is to determine whether repeatedly breathing mild bouts of low oxygen for brief periods (termed acute intermittent hypoxia (AIH)) improves recovery of walking and strength after spinal cord injury. This idea stems from animal studies on respiration, in which investigators showed that mild AIH improves breathing in rats with spinal injuries. These studies showed that AIH induces plasticity, strengthening neural connections by increasing the production of key proteins and improving the sensitivity of spinal cord circuitry. The ultimate goal of this research is to assess the potential of mild AIH as a therapeutic approach not only in persons with chronic spinal cord injury but also in persons with subacute injury. By applying AIH during early stages of recovery, the investigators hope to expand the potential benefits of AIH to a broader range of persons with spinal injury, thereby improving functional independence and quality of life for servicemen and civilians.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
125
Each participant will be exposed to 10 sessions of daily acute intermittent hypoxia (dAIH) via air generators. The generator will fill reservoir bags attached to a non-rebreathing facemask. Each session will consist of 15 episodes which include intervals of 1.5 minute hypoxia (FIO2=0.10±0.02, i.e. 10% O2) and 1 minute normoxia (FIO2=0.21±0.02). Participants will receive 5 consecutive days of daily acute intermittent hypoxia (dAIH).
Each participant will be exposed to 10 sessions of daily room air (dSHAM) via air generators. The generator will fill reservoir bags attached to a non-rebreathing facemask. Each session will consist of 15 episodes of 1.5 minute normoxia (FIO2=0.21±0.02). Participants will receive 5 consecutive days of daily room air (dSHAM).
Shepherd Center
Atlanta, Georgia, United States
Spaulding Rehabilitation Hospital
Cambridge, Massachusetts, United States
Change in walking recovery, assessed by timed up-and-go (TUG) test
The TUG test is used to assess the dynamic balance of an individual. It measures the amount of time (recorded in seconds) it takes for the individual to rise from a standard arm chair, walk a distance of 3 meters and return to the initial position resting against the back of the chair. Participants will perform up to three trials of the TUG test. Average speed across TUG trials will be used for analysis. Change is the difference between the end of session 10 and baseline.
Time frame: Baseline, Post-session 10 (up to two weeks)
Change in walking recovery, assessed by 6 minute walk test (6MWT)
Participants perform the 6MWT at their fastest, most comfortable walking speed sustainable for 6 minutes. Distances will be recorded at 2 and 6 minutes. The test will be based upon the participant's ability to finish each assessment without human assistance. Change is the difference between the end of session 10 and baseline.
Time frame: Baseline, Post-session 10 (up to two weeks)
Change in walking recovery, assessed by 10 meter walk test (10MWT)
Participants walk ten meters without assistance at their fastest, but safest speed with a minimum of 1-minute of rest between two trials. Average speed across the up to three 10MWT trials will be used for analysis. Change is the difference between the end of session 10 and baseline.
Time frame: Baseline, Post-session 10 (up to two weeks)
Change in pain severity
Participants will report their pain level using the Wong-Baker FACES scale. The scale is from 0 to 5; 0 being no pain and 5 being extreme pain. Change is the difference between the end of session 10 and baseline.
Time frame: Baseline, Post-session 10 (up to two weeks)
Change in spasticity
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Participants will participate in 10 days of walking practice sessions. Walking practice sessions will immediately follow (within 60 minutes) the breathing intervention during training visits and will last for 60 minutes. Walking practice will incorporate 5 walking-related tasks: 1. walking balance (e.g., walking with turns) 2. skilled walking tasks (e.g., negotiating obstacles) 3. walking with secondary task (e.g., walking and talking) 4. endurance 5. speed
Spasticity will be assessed using the Spinal Cord Assessment Tool for Spastic Reflexes (SCATS). The study team will quantify the total lower extremity spasticity score using the cumulative sum of 3 SCATS subscales: clonus (0=no spasticity; 3=severe), flexor (0=no spasticity; 3=severe), and extensor (0=no spasticity; 3=severe). Change is the difference between the end of session 10 and baseline.
Time frame: Baseline, Post-session 10 (up to two weeks)
Systemic hypertension incidence rate
Participants will have their systolic and diastolic blood pressure measured. A systemic hypertensive event is quantified as a systolic pressure exceeding 140mmHg and/or diastolic pressure exceeding 90mmHg. A hypertension incident rate is the number of hypertensive events divided by the total person-time. Person-time is in units of person-measures (the sum of the total number of BP measurements) taken for each person. Person-measures accounts for the total number of chances for detecting a hypertensive event and accounts for measurements not made due to drop-out or a disqualifying adverse event
Time frame: Post-session 10 (up to two weeks)
Autonomic dysreflexia incidence rate
The occurrence of autonomic dysreflexia will be assessed. An autonomic dysreflexia event will constitute a participant having a systolic blood pressure (SBP) increase from baseline of 20mmHg or SBP greater than 150mmHg with complaints of headache, diaphoresis, and/or blurred vision and will be diagnosed by the study team clinicians.
Time frame: Post-session 10 (up to two weeks)