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Study of Brain Blood Flow During Induced Hypercapnia (Excess Blood Carbon Dioxide)

This study has been completed.
Information provided by:
National Institutes of Health Clinical Center (CC) Identifier:
First received: November 3, 1999
Last updated: March 3, 2008
Last verified: August 2004

This study will evaluate magnetic resonance imaging (MRI ) methods for measuring changes in the brain's blood flow during hypercapnia (a condition of excess carbon dioxide in the blood). MRI is a diagnostic tool that uses a large magnet and radio waves to produce images of the body without X-rays.

Healthy normal volunteers in this study may have as many as six MRI scans over a 2-year period. For this procedure, the person lies on a stretcher placed in a strong magnetic field produced by the MRI machine. During the scan, the person's blood carbon dioxide (CO2 ) levels will be increased either by: 1) breathing air mixtures containing up to 5% CO2; or 2) receiving an intravenous (I.V.) injection of a drug called acetazolamide.

Persons who breathe CO2 will have their heart rate, blood pressure and oxygen levels monitored throughout the procedure. Those receiving acetazolamide will have the drug injected intravenously (I.V.) into an arm vein. If the volunteer experiences any unpleasant side effects from the CO2 or acetazolamide, the study will be stopped.

The information gained from this study will be used to develop better ways to study brain function, possibly leading to better diagnostic and treatment methods.

Healthy Hypercapnia

Study Type: Observational
Official Title: MR Perfusion Imaging in Hypercapnia: Development of Technical Protocols

Further study details as provided by National Institutes of Health Clinical Center (CC):

Estimated Enrollment: 30
Study Start Date: September 1999
Estimated Study Completion Date: August 2004
Detailed Description:
Advances in MR perfusion imaging have provided clinical researchers with the opportunity to quantitate regional increases in cerebral blood flow. The purpose of this study is to acquire the technical experience required to perform MR perfusion imaging studies of the hypercapnic cerebral blood flow response. Cerebral blood flow will be increased by inhalation of carbogen (an air mixture containing 5% CO2) or IV injection of the carbonic anhydrase inhibitor acetazolamide. The technical experience obtained in this study will be used to design a study of the pharmacological and physiological mechanisms underlying cerebral blood flow increases during hypercapnia.

Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes


Any normal volunteer above the age of 18 years old who is capable of giving informed consent.


Subjects will be excluded if they have contraindications to MR scanning, such as the following: aneurism clip, implanted neural stimulator, implanted cardiac pacemaker or autodefibrillator, chochlear implant, ocular foreign body (e.g., metal shavings), or insulin pump. Also, subjects will be excluded if they have panic disorder or migrane (because of possible complications with CO2 inhilation), or if they have cirrhosis, are on high dose aspirin therapy, or have an allergy to acetazolamide injection). Subjects will be excluded if they have allergies to sulfonamide drugs or if they have a chronic respiratory illness.

  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: NCT00001845

United States, Maryland
Warren G. Magnuson Clinical Center (CC)
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
National Institutes of Health Clinical Center (CC)
  More Information

Publications: Identifier: NCT00001845     History of Changes
Other Study ID Numbers: 990164
Study First Received: November 3, 1999
Last Updated: March 3, 2008

Keywords provided by National Institutes of Health Clinical Center (CC):
Cerebral Blood Flow
CO2 Inhalation
Healthy Volunteer

Additional relevant MeSH terms:
Signs and Symptoms, Respiratory
Signs and Symptoms processed this record on September 19, 2017