Novel methodology to comprehensively assess retinal arteriolar vascular reactivity to hypercapnia |
| |
Authors: | Venkataraman Subha T Hudson Chris Fisher Joseph A Flanagan John G |
| |
Affiliation: | Retina Research Group, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1. |
| |
Abstract: | PURPOSE: (1) Describe a new methodology that permits the comprehensive assessment of retinal arteriolar vascular reactivity in response to a sustained and stable hypercapnic stimulus. (2) Determine the magnitude of the vascular reactivity response of the retinal arterioles to hypercapnic provocation in healthy, young subjects. METHODOLOGY: Eleven healthy subjects of mean age 27 years (SD 3.43) participated in the study and one eye was randomly selected. A mask attached to a sequential rebreathing circuit, and connected to a gas delivery system, was fitted to the face. To establish baseline values, subjects breathed bottled air for 15 min and at least 6 blood flow measurements of the supero-temporal arteriole were acquired using the Canon Laser Blood Flowmeter (CLBF). Air flow was then decreased until a stable increase in fractional end-tidal CO(2) concentration (F(ET)CO(2)) of 10-15% was achieved. CLBF measurements were acquired every minute (minimum of 6 measurements) during the 20-minute period of elevated F(ET)CO(2). F(et)CO(2) was then reduced to baseline levels, and 6 further CLBF measurements were acquired. Respiratory rate, blood pressure, pulse rate and oxygen saturation were monitored continuously. RESULTS: Retinal arteriolar diameter, blood velocity and blood flow increased during hypercapnia relative to baseline (p=0.0045, p<0.0001 and p<0.0001, respectively). Group mean F(ET)CO(2) showed an increase of 12.0% (SD 3.6) relative to baseline (p<0.0001). CONCLUSIONS: This study describes a new methodology that permits the comprehensive assessment of retinal arteriolar vascular reactivity in response to a sustained and stable hypercapnic stimulus. Retinal arteriolar diameter, blood velocity and blood flow increased significantly in response to a hypercapnic provocation in young, healthy subjects. |
| |
Keywords: | Vascular reactivity Hypercapnia Retinal arterioles bi-directional laser Doppler velocimetry |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|