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

NCT00719342 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 24

Last updated 2014-11-14

No results posted yet for this study

Summary

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 .

Conditions

  • Flicker-induced Vasodilatation

Interventions

DRUG

Oxygen + Carbondioxide

Mixture of 92 % oxygen and 8 % carbon dioxide for inhalation

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.

Sponsors & Collaborators

  • Medical University of Vienna

    lead OTHER

Principal Investigators

  • Michael Wolzt, MD · Department of Clinical Pharmacology, Medical University of Vienna

Study Design

Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Model
CROSSOVER

Eligibility

Min Age
18 Years
Max Age
35 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2008-07-31
Primary Completion
2009-05-31
Completion
2009-12-31

Countries

  • Austria

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT00719342 on ClinicalTrials.gov