Key result
Breathing 100% O2 and 5% CO2 significantly altered retinal arteriolar diameters in normotensive subjects, whereas this vascular reactivity was diminished in the 6 hypertensive subjects.
Why the study?
Do acute changes in vascular tone induced by oxygen and carbon dioxide alter retinal vascular network geometry differently in hypertensive versus normotensive subjects?
Population
12 subjects (6 hypertensive and 6 normotensive)
Comparison
Breathing 5% CO2 and 100% O2 for 5 min periods vs Breathing air for 5 min periods
Design
Other, random order of breathing conditions
Follow-up
5 min periods per condition
Authors
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Retinal O2/CO2 reactivity testing may detect early microvascular dysfunction in hypertension; extends acute gas-challenge data to hypertensives in this RCT.
RCT (n=12)
random order
Do acute changes in vascular tone induced by oxygen and carbon dioxide alter retinal vascular network geometry differently in hypertensive versus normotensive subjects?
Vascular reactivity in the retinal arteriolar bed is diminished in hypertensive subjects, but arteriolar diameters at bifurcations maintain optimality principles under acute vasoactive stress.
Chapman et al. (2000) conducted an RCT in Hypertension (n=12). 100% O2 and 5% CO2 (with 12% O2) vs. Air was evaluated on Retinal arteriolar network geometry (bifurcation angles, arteriolar diameters, and junction exponents). Breathing 100% O2 and 5% CO2 significantly altered retinal arteriolar diameters in normotensive subjects, whereas this vascular reactivity was diminished in the 6 hypertensive subjects.
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