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NCT Number: NCT06691165

Improving 24-hour Blood Pressure Stability in Spinal Cord Injury With Low Oxygen Therapy

This study examines the effects of low oxygen therapy (LOT) on the stability of 24-hour blood pressure in persons with chronic cervical spinal cord injury.

This study will examine if brief episodes of breathing lower oxygen, termed low oxygen therapy (LOT), which has been shown to enhance autonomic nervous system activity, can improve blood pressure stability in individuals with spinal cord injury. The research team will assess 24-hour blood pressure, as well as cardiac, vascular, and autonomic function before and after a 4-day LOT treatment intervention. This study will advance current understanding of treatments to mitigate cardiovascular disease risk in people with spinal cord injuries.

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Key information

Conditions

Spinal Cord Injury Central Nervous System Diseases Nervous System Diseases Spinal Cord Diseases Spinal Cord Injuries Trauma, Nervous System Wounds and Injuries

Age range

19 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1 / Phase 2

Primary location

UBC Okanagan, Kelowna, British Columbia, Canada

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About this study

Spinal cord injury (SCI) interrupts signals travelling down from the brain to the rest of the body below the level of the injury. The loss of nerve connections involved in cardiovascular control results in blood pressure instability. This can lead to sudden drops in blood pressure, such as when shifting upright or during transfers, or sudden increases during autonomic dysreflexia. These swings in blood pressure are linked to a nearly 4-fold increase in the risk of cardiovascular disease in people with SCI.

Repeated, brief exposure to breathing lower levels of oxygen, termed low oxygen therapy, has been shown to stimulate adaptation in the nervous system. This neuroplasticity increases the activity of cardiovascular control circuits, and has been shown to increase blood pressure in able-bodied individuals. Similar effects on respiratory and motor function in people with SCI, but the effects on the cardiovascular system have not been studied in this population.

This study will test the effects of a 4-day low oxygen therapy intervention on 24-hour blood pressure stability in people with chronic cervical SCI. By assessing mechanisms of cardiac, vascular, and autonomic function, this study aims to improve current understanding of the therapeutic potential of low oxygen therapy to mitigate cardiovascular disease risk in SCI.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Are between the ages of 19-65
  • Living with a chronic cervical (at or above T1) spinal cord injury of at least one year
  • Are fluent in english

Exclusion criteria

  • High-cervical injuries requiring ventilator assistance to breathe will be excluded on account of the necessity of the facemask for the delivery of hypoxia
  • Unhealed fracture, contracture, or pressure sore that might interfere with participants' ability to complete the protocol
  • Additional concurrent neurological conditions (e.g., multiple sclerosis, Parkinson disease, stroke or brain injury)
  • Uncontrolled cardiovascular or pulmonary disease
  • Severe neuropathic pain
  • Severe recurrent autonomic dysreflexia
  • History of seizure disorders
  • Known pregnancy

Treatment and study plan

Low oxygen therapy (LOT)

Drug

Participants will breathe variable concentrations of inspired oxygen, carbon dioxide, and nitrogen. The concentrations will be adjusted on a breath-by-breath basis to maintain end-tidal targets.

Each daily session of the intervention will consist of forty 1-minute intervals. Each 1-minute interval will consist of 40 seconds of hypercapnic hypoxia, increasing the partial pressure of end-tidal carbon dioxide by +4 mmHg and decreasing the partial pressure of end-tidal oxygen to 45 mmHg, followed by 20 seconds in simulated room air to return to baseline carbon dioxide and oxygen levels.

Other names: Intermittent hypoxia

Primary outcomes

  1. Change in 24-hour blood pressure

    Time frame: Change from baseline of 24-hour mean arterial blood pressure at 1-day post-intervention

    Mean arterial blood pressure (mmHg), averaged across 24 hours

Secondary outcomes

  1. Change in 24-hour blood pressure stability

    Time frame: Change from baseline of the standard deviation of 24-hour mean arterial blood pressure at 1-day post-intervention

    Mean arterial blood pressure (mmHg), standard deviation across 24 hours

  2. Change in left-ventricular contractility

    Time frame: Change from baseline of left ventricular contractility indices immediately after the first intervention session, and at 1-day and 4-days post-intervention

    Indices of load-independent pressure generation during systole: Estimated end-systolic elastance (mmHg/ml); end-systolic pressure-volume relationship slopes (mmHg/ml)

  3. Change in baroreflex gain

    Time frame: Change from baseline of baroreflex gain indices immediately after first intervention session, and at 1-day and 4-days post-intervention

    Indices of baroreflex sensitivity: Relationship of systolic blood pressure against subsequent R-R interval duration during Valsalva Maneuver phases II and IV (ms/mmHg); spectral power of low-frequency resting blood pressure variability

  4. Change in circulating catecholamines

    Time frame: Change from baseline of circulating catecholamines immediately after first intervention session, and at 1-day and 4-days post-intervention

    Venous plasma concentrations of norepinephrine and epinephrine (mmol/L)

  5. Change in cerebral neurovascular coupling and autoregulation

    Time frame: Change from baseline of the responses of cerebral blood flow indices during a visual stimulus and head-up tilt immediately after first intervention session, and at 1-day and 4-days post-intervention

    Middle and posterior cerebral artery blood flow velocity (cm/s)

  6. Change in renal filtration function

    Time frame: Change from baseline in renal biomarkers and blood flow at rest immediately after first intervention session, and at 1-day and 4-days post-intervention

    Humoral renal biomarkers (e.g., serum creatinine)

  7. Change in flow-mediated dilation

    Time frame: Change from baseline in flow-mediated dilation immediately after first intervention session, and at 1-day and 4-days post-intervention

    Brachial artery flow-mediated dilation following 5-minute forearm blood flow occlusion (mm)

  8. Change in tonic peripheral chemoreflex activity

    Time frame: Change from baseline in the magnitude of ventilatory depression in hyperoxia immediately after first intervention session, and at 1-day and 4-days post-intervention

    Magnitude of hyperoxic ventilatory depression (L/min)

  9. Change in renal vascular function

    Time frame: Change in renal blood flow velocity from baseline during the first and final hypoxia cycles on the first session of the intervention

    Renal artery blood flow velocity (cm/s)

Study contacts

Contact information is provided by the study sponsor or research team.

Glen E Foster, Ph.D.

CONTACT

[email protected]

+1 250-807-8224

Scott F Thrall, M.Sc.

CONTACT

[email protected]

+1 250-807-8083

Sponsors and collaborators

Lead sponsor

Glen Foster

Other

Registry information

Official study title

Low Oxygen Therapy as a Cardiac Treatment for Improving 24-hour Blood Pressure Stability in Spinal Cord Injury

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Nov 15, 2024
Registry last updated
Nov 18, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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