Investigating the effect of therapeutic acute intermittent hypoxia on upper limb and respiratory function in people more than one year post spinal cord injury: The AERO-SCI trial
Assessing the effect of therapeutic acute intermittent hypoxia protocols on upper limb and respiratory function in people with chronic spinal cord injury: a Bayesian Optimal Phase II Design trial
Austin Health
40 participants
Jun 1, 2022
Interventional
Conditions
Summary
A spinal cord injury (SCI) results in disruption of the neural connections between the brain and spinal cord causing muscle paralysis and loss of sensation below the injury. Therapeutic acute intermittent hypoxia (AIH) is currently an emerging topic in the SCI research field because of its potential to restore function to muscles paralysed after SCI through ‘neuroplasticity’. This means the therapy changes the way the brain and spinal cord connect to improve muscle function. Treatment with AIH involves breathing air with an oxygen content equivalent to standing on top of a mountain at 6000 m (20,000 ft) altitude. It is safe to do this as the low oxygen air is breathed for short periods at a time (i.e. 1 minute) and is alternated with a short period (i.e. 1 minute) of breathing “normal” air (i.e. level of oxygen the same as sea level). In many previous studies of the breathing muscles in animals with SCI and some studies in limb muscles in humans with SCI, it has been shown that just one 30-minute session of therapeutic AIH can boost the function of previously paralysed and partially paralysed muscles for more than an hour. This study aims to understand the mechanisms of action of this therapy in people with SCI so that we will be able to identify the best way forward to target, tailor and apply this treatment clinically for people with both chronic and acute SCI.
Eligibility
Inclusion Criteria6
- Young adults (aged 18 to 50 years)
- Independently ventilating with a history of chronic SCI (>1 year post-injury or impairment onset. American Spinal Injury Association Impairment Scale [ASIA] A to D; with incomplete paralysis in target muscle groups)
- Able to perform one block on the Box and Block Test
- Medically stable
- Ability to follow verbal and visual commands
- Ability to provide informed consent
Exclusion Criteria9
- Medically unstable, including current or recent infection or inflammation
- Current or recent (within the previous 6 weeks) pressure ulcers or cutaneous lesions
- Poorly controlled diabetes
- An episode of autonomic dysreflexia in the previous 6 months
- Significant other neurological, psychiatric, pulmonary, cardiovascular, orthopedic (including osteoporosis and/or previous post-SCI fracture) or oncological conditions
- Severe untreated obstructive sleep apnoea
- Recent change in medication prescription
- Not proficient in English
- Pregnancy
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Interventions
The intervention will involve the implementation of therapeutic acute intermittent hypoxia (AIH) alone or AIH in combination with task-specific training. Participants will be randomly allocated to one of two intervention arms in this Bayesian Optimal Phase II design. These will comprise either: • Acute intermittent hypoxia • Acute intermittent hypoxia + task-specific training (upper limb and respiratory muscle training) Participants will be asked to undertake 10 intervention sessions over a 2-week period, in the presence of an experienced physiotherapist (5 consecutive days x 2 consecutive weeks). Sessions will be conducted on-site (hospital, university or research institute location), or in the participant's home if feasible. In both trial arms, acute intermittent hypoxia will be generated via a Hypoxico-123 air generator device (Hypoxico Altitude Training Systems Inc, New York, USA, 10001). The AIH protocol for each intervention session will comprise 15 periods (repetitions) of: 60 seconds in which participants breathe air with ~9% fraction of inspired oxygen (FiO2) (equivalent to low 80%’s oxygen saturation (SpO2)), followed by 60 seconds of breathing medical-grade room air (~21% FiO2). This AIH protocol is estimated to take a total of 30 minutes per session. In the acute intermittent hypoxia + task-specific training arm, the upper limb and respiratory training will be standardised and delivered by the same experienced physiotherapist, following each AIH component. Tasks will include 3 sets of 8-10 handgrips, wrist contractions and breaths through an inspiratory muscle training device (such as a Philips Threshold IMT or similar) at 70% of the maximal voluntary contraction each session. A dexterity task using pegs and holes will also be practiced each session for 15 minutes. Total duration of the task-specific training component is approximately 30 minutes per session. Adherence to the intervention will be recorded by the supervising clinician during each session (session attendance checklists)
Locations(2)
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ACTRN12622000648729