American Heart Association- Stroke/Hypoxia Study

Of the 795,000 people who experience a stroke every year in the US, only a small percentage will achieve full recovery. While current therapies promote strength and endurance, none directly address the unique potential of the brain to reorganize following injury. The goal of this project is to explore the effects of a novel therapy, acute intermittent hypoxia (AIH). During this therapy, individuals receive brief bouts of reduced oxygen levels by inhalation through a face mask. (This is akin to being on top of a tall mountain). In brief exposures, AIH is known to trigger the release of specific proteins that help the brain adapt to oxygen reductions. Published results in people with incomplete spinal cord injury have shown that AIH enhances muscle strength and coordination rather quickly. The research team aims to study the effects of AIH in stroke survivors.

Stroke is the second leading cause of death and a leading cause of long-term disability worldwide. Despite the spontaneous recovery that occurs following a hemispheric stroke, more than half of stroke patients show substantial residual impairments, imposing a significant human and economic burden. This burden is likely to increase in coming decades, due to a rapidly aging population, and the associated progression of cardiovascular risk factors. Accordingly, new interventions to alleviate impairment in stroke survivors are urgently needed. The development and testing of one such novel intervention, termed Acute Intermittent Hypoxia (AIH), is the primary focus of this AHA Innovative Project Award.

The aim is to answer questions related to safety and preliminary efficacy of AIH in stroke survivors. First, the Investigators will establish whether brief reductions in inhaled oxygen concentration can be safely tolerated in stroke survivors. A clinician will closely monitor subjects for any adverse events.

The second aim is to establish the effects of AIH on elbow flexion/extension strength, and on hand grip and pinch strength. Subjects will be monitored closely for any adverse events during these experiments. Data will be analyzed to determine if there is an improvement in key outcomes at any dose level.

Eligibility Criteria:
Inclusion criteria:

Age ≥18 years;

A first time, unilateral, ischemic, hemispheric stroke, confirmed by magnetic resonance imaging (MRI);

Chedoke assessment \> 3

Ability to open and close affected hand

Able to understand and communicate in English

Be able to consent independently

≥ 6 months post stroke

Must have a hemoglobin level above 10g/dl (to be confirmed using handheld noninvasive lab equipment)

Must have ability to attend research visits with a companion for assistance

WOCBP must be comfortable confirming negative pregnancy prior to hypoxia experimental therapy.

Exclusion criteria:

Brain stem or cerebellar stroke; mean Fazekas score rated on initial fluid-attenuated inversion recovery MRI ≥3

Severe aphasia, preventing subject from understanding the protocol and giving written consent;

History of prior neurological disorder;

Pre-existing hypoxic pulmonary disease,

Severe hypertension (\>160/100)

Ischemic cardiac disease.