May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Retinal Arteriolar and Middle Cerebral Artery Responses to Combined Hypercarbic / Hyperoxic Stimuli
Author Affiliations & Notes
  • M. Kisilevsky
    University of Toronto, Toronto, Ontario, Canada
  • A. Mardimae
    University of Toronto, Toronto, Ontario, Canada
  • M. Slessarev
    University of Toronto, Toronto, Ontario, Canada
  • J. Han
    University of Toronto, Toronto, Ontario, Canada
  • J. Fisher
    University of Toronto, Toronto, Ontario, Canada
  • C. Hudson
    University of Toronto, Toronto, Ontario, Canada
  • Footnotes
    Commercial Relationships  M. Kisilevsky, None; A. Mardimae, None; M. Slessarev, None; J. Han, None; J. Fisher, patent holder on the automated gas blender and sequencer (RespirAct, Thornhill Research Inc., Toronto, Canada), P; C. Hudson, patent holder on the automated gas blender and sequencer (RespirAct, Thornhill Research Inc., Toronto, Canada), P.
  • Footnotes
    Support  CIHR Operating Grant , Canada Foundation for Innovation Infrastructure Award, VSRP Doctoral Scholarship, CIHR Strategic Training Program in Vision Health Research Fellowship
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 2092. doi:https://doi.org/
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    • Get Citation

      M. Kisilevsky, A. Mardimae, M. Slessarev, J. Han, J. Fisher, C. Hudson; Retinal Arteriolar and Middle Cerebral Artery Responses to Combined Hypercarbic / Hyperoxic Stimuli. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2092. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : The relative effect of simultaneously administered oxygen and carbon dioxide on the retinal and cerebral vessels is unknown. The purpose of this study was to quantify and compare the superior-temporal retinal arteriole (RA) and middle cerebral artery (MCA) responses to a series of hypercarbic and combined hypercarbic/hyperoxic stimuli.

Methods: : Twelve young healthy volunteers participated in the study. End-tidal pressure of carbon dioxide was raised and maintained at 23% from the baseline during 3 levels of oxygen end-tidal pressure (PETO2 ) i.e. isoxia, 300 and 500 mmHg hyperoxia. Retinal vessel diameter and blood velocity was measured using the Canon Laser Blood Flowmeter; MCA blood velocity was measured using a transcranial Doppler ultrasound system.

Results: : Hypercarbia caused a 17% increase in retinal arteriolar blood velocity that resulted in a 21% increase in calculated flow. Hypercarbia/hyperoxia-500mmHg resulted in a decrease of 8% in retinal arteriolar diameter, 16% in velocity and 29% in calculated flow. Hypercarbia/hyperoxia-300mmHg induced a 14% decrease in calculated RA flow. MCA blood velocity increased 45% in response to hypercarbia. The difference in hypercarbia-induced increase in velocity was significantly greater for the MCA than RA (p<0.001). Increase in PETO2 did not change the hypercarbia-induced increase in MCA blood velocity.

Conclusions: : Hypercarbia-induced vasodilation in retinal arterioles occurs to a lesser extent than in the MCA. Hyperoxia reverses hypercarbia-induced vasodilation in retinal arterioles in a concentration-dependent manner; while hypercarbia-induced vasodilation in MCA is unaffected by subsequent increase in PETO2. The differences in vascular reactivity of the superior-temporal retinal arteriole and middle cerebral artery were quantified for the first time using precise control of end-tidal concentrations of O2 and CO2.

Keywords: retina • blood supply • oxygen 
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