Cerebrovascular Reactivity in Obstructive Sleep Apnea (OSA) Subjects

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01133717
Recruitment Status : Unknown
Verified October 2010 by University Health Network, Toronto.
Recruitment status was:  Recruiting
First Posted : May 31, 2010
Last Update Posted : December 18, 2014
Information provided by (Responsible Party):
University Health Network, Toronto

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 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

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Sleep Apnea

Control without Sleep Apnea
Subjects with Sleep Apnea

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 ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 80 Years   (Adult, Older Adult)
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.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): 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

Responsible Party: University Health Network, Toronto Identifier: NCT01133717     History of Changes
Other Study ID Numbers: 09-0831-BE
First Posted: May 31, 2010    Key Record Dates
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:
Sleep Apnea Syndromes
Respiration Disorders
Respiratory Tract Diseases
Signs and Symptoms, Respiratory
Signs and Symptoms
Sleep Disorders, Intrinsic
Sleep Wake Disorders
Nervous System Diseases