Cerebrovascular Reactivity in Obstructive Sleep Apnea (OSA) Subjects

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

UNKNOWN

Total Enrollment

60 participants

Study Classification

OBSERVATIONAL

Study Start Date

2010-02-28

Study Completion Date

2015-04-30

Brief Summary

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Obstructive sleep apnea (OSA) is a prevalent sleep breathing disorder in the general population in which recurrent collapse of the upper airway occurs during sleep. OSA is more prevalent in subjects with stroke and is associated with a 3 fold increased risk of stroke. This makes it a serious public health problem. Approximately 50% of subjects with OSA are asymptomatic and are often only detected following investigation for the cause of heart disease or a stroke. In subjects who are treated for OSA many are intolerant or poorly compliant with treatment. Therefore, the identification of those subjects with OSA most at risk of adverse consequences such as stroke is important, so that treatment compliance can be improved.

Therfore, the investigators want to determine if compared to subjects without OSA, subjects with OSA have evidence of increased stroke risk by assessment of changes in cerebral blood flow (cerebrovascular reactivity) as measured on Doppler ultrasound of the middle cerebral artery (TCD) and blood oxygen level-dependent magnetic resonance imaging of patterns of cerebral blood flow (BOLD MRI) to two stimuli. These stimuli include increased carbon dioxide concentrations (causes increased cerebral blood flow) and reduced oxygen concentrations (causing decreased cerebral blood flow). In order to deliver these stimuli the investigators will use a special machine (RespiractTM) which allows for the precise control of carbon dioxide and oxygen concentrations in the lungs and blood. The precise control of carbon dioxide and oxygen in conjunction with BOLD MRI has enabled the production of detailed maps of the brain that identify areas of healthy and abnormal blood supply.

Detailed Description

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OSA is associated with increased risk of cardiovascular and cerebrovascular disease compared to the general population. The mechanism for the increased stroke risk in OSA is unknown. However, the constellation of adverse pathophysiological consequences, including intermittent hypoxia and carbon-dioxide retention as a result of OSA may be detrimental to CVR and predispose the brain to ischemia. Previous studies in OSA subjects have measured CVR only using TCD. Therefore, our study will examine CVR by two methods (TCD and BOLD-MRI) with reliable and reproducible hypercapnia and independent control of oxygen saturation (RespiractTM). Patterns seen on CVR may eventually allow the identification of OSA patients who will be at greatest risk for stroke and will therefore, require aggressive risk reduction and/or treatment irrespective of symptoms.

Conditions

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Sleep Apnea

Keywords

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Sleep Apnea Cerebrovascular Reactivity

Study Design

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Observational Model Type

COHORT

Study Time Perspective

PROSPECTIVE

Study Groups

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Control without Sleep Apnea

No interventions assigned to this group

Subjects with Sleep Apnea

No interventions assigned to this group

Eligibility Criteria

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Inclusion Criteria

* Subjects referred for sleep studies

Exclusion Criteria

* Known cardiac, neurological or major liver or kidney disease -
* Cardioverter/defibrillator metal heart valve or pacemaker
* Vascular stent implanted within 6 weeks
* Severe claustrophobia
* Pregnancy
* Shrapnel or history of ophthalmic foreign body
* Resting oxygen saturation on room air \< 95%
* Insulin-dependent diabetes
* Obstructive or restrictive lung disease such that subject is unable to walk up 2 flights of stairs
* Major depression.

Minimum Eligible Age

18 Years

Maximum Eligible Age

80 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Clodagh M Ryan

Role: PRINCIPAL_INVESTIGATOR

Toronto General Hospital

Locations

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Toronto Gneral Hospital

Toronto, Ontario, Canada

Site Status RECRUITING

Countries

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Canada

Central Contacts

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Clodagh M Ryan, MD

Role: CONTACT

Phone: 4163404719

Email: [email protected]

Ann battisti, BSc