Effect of Breathing a Mixture of 92% Oxygen (O2) + 8% Carbon Dioxide (CO2) on Flicker Induced Blood Flow Changes in Ocular Perfusion

The recruitment status of this study is unknown because the information has not been verified recently.
Verified December 2008 by Medical University of Vienna.
Recruitment status was  Recruiting
Sponsor:
Information provided by:
Medical University of Vienna
ClinicalTrials.gov Identifier:
NCT00719342
First received: July 1, 2008
Last updated: December 18, 2008
Last verified: December 2008
  Purpose

It has been shown that diffuse luminance flicker increases retinal and optic nerve head blood flow. This indicates that a neuro-vascular coupling between neural activity and blood flow exists in the retina as described previously for the brain. Although a lot of mediators such as NO, pO2, pCO2, H+ and K+ have been proposed, the mechanism of this coupling is still a matter of controversy. However, it has been shown in an animal experiment, that an increase in blood flow, evoked by diffuse luminance flicker stimulation is paralleled by decrease in pO2 in the tissue. In a recently performed study we could show that breathing of 100% O2 did not influence flicker induced changes in the retina and optic nerve head. However, breathing of 100% oxygen also leads to a pronounced vasoconstriction of the retinal vessels and in turn to a increased tension of the vessel wall. Recent evidence indicates that a combination of 92% O2 and 8% CO2 can, at least partially, counteract the vasoconstrictory effect of O2 and increases tissue pO2. Thus, in this study the investigators set out to investigate the flicker light induced increase in blood flow under a mixture of O2/CO2 .


Condition Intervention
Flicker-Induced Vasodilatation
Drug: Oxygen + Carbondioxide
Other: full field flickering light at 12.5 Hz

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Safety/Efficacy Study
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Investigator)
Primary Purpose: Basic Science
Official Title: Effect of Breathing a Mixture of 92% O2 + 8% CO2 on Flicker Induced Blood Flow Changes in Ocular Perfusion

Resource links provided by NLM:


Further study details as provided by Medical University of Vienna:

Primary Outcome Measures:
  • Optic nerve head blood flow [ Time Frame: 1 hour ] [ Designated as safety issue: No ]
  • Retinal vessel diameters [ Time Frame: 1 hour ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • blood pressure [ Time Frame: 1 hour ] [ Designated as safety issue: Yes ]
  • pulse rate [ Time Frame: 1 hour ] [ Designated as safety issue: Yes ]

Estimated Enrollment: 24
Study Start Date: June 2008
Estimated Study Completion Date: August 2009
Estimated Primary Completion Date: August 2009 (Final data collection date for primary outcome measure)
Intervention Details:
    Drug: Oxygen + Carbondioxide
    Mixture of 92 % oxygen and 8 % carbon dioxide for inhalation
    Other Names:
    • O² + CO²
    • Oxymix
    Other: full field flickering light at 12.5 Hz
    1 minute stimulation with full field flickering light at 12.5 Hz during measurement of vessel diameters and measurement of blood flow.
  Eligibility

Ages Eligible for Study:   18 Years to 35 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Men and Women aged between 18 and 35 years, nonsmokers
  • Body mass index between 15th and 85th percentile
  • Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
  • Normal laboratory values unless the investigator considers an abnormality to be clinically irrelevant
  • Normal ophthalmic findings, ametropy < 3 Dpt.

Exclusion Criteria:

  • Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study
  • Treatment in the previous 3 weeks with any drug
  • Symptoms of a clinically relevant illness in the 3 weeks before the first study day
  • Blood donation during the previous 3 weeks
  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 ClinicalTrials.gov identifier: NCT00719342

Contacts
Contact: Gerhard Garhöfer, MD +43 40400 ext 2981 gerhard.garhoefer@meduniwien.ac.at

Locations
Austria
Department of Clinical Pharmacology, Medical University of Vienna Not yet recruiting
Vienna, Austria, 1090
Department of Clinical Pharmacology, Medical University of Vienna Recruiting
Vienna, Austria, 1090
Sponsors and Collaborators
Medical University of Vienna
Investigators
Principal Investigator: Michael Wolzt, MD Department of Clinical Pharmacology, Medical University of Vienna
  More Information

No publications provided

Responsible Party: Gerhard Garhöfer, MD, Department of Clinical Pharmacology, Medical University of Vienna
ClinicalTrials.gov Identifier: NCT00719342     History of Changes
Other Study ID Numbers: OPHT-030606
Study First Received: July 1, 2008
Last Updated: December 18, 2008
Health Authority: Austria: Agency for Health and Food Safety

Keywords provided by Medical University of Vienna:
Retinal vessel diameter
Flicker-induced vasodilatation
Optic nerve head blood flow
Ocular Physiology
Regional Blood Flow

ClinicalTrials.gov processed this record on August 28, 2014