Cerebrovascular Reactivity in Obstructive Sleep Apnea (OSA) Subjects

Study Description

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Brief Summary:

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.

Condition or disease
Sleep Apnea

Detailed Description:

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.

Study Design

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Study Type :	Observational
Estimated Enrollment :	60 participants
Observational Model:	Cohort
Time Perspective:	Prospective
Official Title:	Spatial and Temporal Response of Cerebrovascular Response in OSA
Study Start Date :	February 2010
Estimated Primary Completion Date :	February 2015
Estimated Study Completion Date :	April 2015

Groups and Cohorts

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Group/Cohort
Control without Sleep Apnea
Subjects with Sleep Apnea

Outcome Measures

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Primary Outcome Measures :

1. Document the diurnal differences in global CVR as measured by TCD, between those with and without OSA [ Time Frame: Between 8pm and 7am approximately ]

Secondary Outcome Measures :

1. Use BOLD MRI to quantify global and regional CVR in various regions and vascular territories of the brain in subjects with OSA. [ Time Frame: one week ]

Eligibility Criteria

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Ages Eligible for Study:	18 Years to 80 Years (Adult, Senior)
Sexes Eligible for Study:	All
Accepts Healthy Volunteers:	Yes
Sampling Method:	Non-Probability Sample

Study Population

Community Population

Criteria

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.

Contacts and Locations

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Contacts

Contact: Clodagh M Ryan, MD	4163404719	clodagh.ryan@uhn.on.ca
Contact: Ann battisti, BSc		abattist@uhnres.utoronto.ca

Locations

Canada, Ontario
Toronto Gneral Hospital	Recruiting
Toronto, Ontario, Canada, M5G 2N2
Principal Investigator: Clodagh Ryan, MD
Sub-Investigator: J Fisher, MD
Sub-Investigator: J Duffin, PhD
Sub-Investigator: D Mikulis, MD
Sub-Investigator: a Battisti, BSc
Sub-Investigator: O Pucci, BSc

Sponsors and Collaborators

University Health Network, Toronto

Investigators

Principal Investigator:	Clodagh M Ryan	Toronto General Hospital

More Information

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Responsible Party:	University Health Network, Toronto
ClinicalTrials.gov Identifier:	NCT01133717 History of Changes
Other Study ID Numbers:	09-0831-BE
First Posted:	May 31, 2010
Last Update Posted:	December 18, 2014
Last Verified:	October 2010

Keywords provided by University Health Network, Toronto:

Sleep Apnea; Cerebrovascular Reactivity

Additional relevant MeSH terms:

Apnea; Sleep Apnea Syndromes; Respiration Disorders; Respiratory Tract Diseases; Signs and Symptoms, Respiratory	Signs and Symptoms; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Wake Disorders; Nervous System Diseases