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Cerebrovascular Reactivity in Obstructive Sleep Apnea (OSA) Subjects

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified October 2010 by University Health Network, Toronto.
Recruitment status was:  Recruiting
Information provided by (Responsible Party):
University Health Network, Toronto Identifier:
First received: May 20, 2010
Last updated: December 16, 2014
Last verified: October 2010

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.

Sleep Apnea

Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Prospective
Official Title: Spatial and Temporal Response of Cerebrovascular Response in OSA

Resource links provided by NLM:

Further study details as provided by University Health Network, Toronto:

Primary Outcome Measures:
  • 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:
  • 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 ]

Estimated Enrollment: 60
Study Start Date: February 2010
Estimated Study Completion Date: April 2015
Estimated Primary Completion Date: February 2015 (Final data collection date for primary outcome measure)
Control without Sleep Apnea
Subjects with 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.

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

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
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01133717

Contact: Clodagh M Ryan, MD 4163404719
Contact: Ann battisti, BSc

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
Principal Investigator: Clodagh M Ryan Toronto General Hospital
  More Information

Responsible Party: University Health Network, Toronto Identifier: NCT01133717     History of Changes
Other Study ID Numbers: 09-0831-BE
Study First Received: May 20, 2010
Last Updated: December 16, 2014

Keywords provided by University Health Network, Toronto:
Sleep Apnea
Cerebrovascular Reactivity

Additional relevant MeSH terms:
Sleep Apnea Syndromes
Respiration Disorders
Respiratory Tract Diseases
Signs and Symptoms, Respiratory
Signs and Symptoms
Sleep Disorders, Intrinsic
Sleep Wake Disorders
Nervous System Diseases processed this record on June 23, 2017