Stefan Palkovits1, Michael Lasta1, Reinhard Told2, Doreen Schmidl2, Agnes Boltz2, Katarzyna J Napora1, René M Werkmeister3, Alina Popa-Cherecheanu4, Gerhard Garhöfer1, Leopold Schmetterer2. 1. Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria. 2. Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria. 3. Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria. 4. Department of Ophthalmology, Emergency University Hospital, Bucharest, Romania.
Abstract
PURPOSE: To characterize retinal metabolism during normoxia and hyperoxia in healthy subjects. METHODS: Forty-six healthy subjects were included in the present study, and data of 41 subjects could be evaluated. Retinal vessel diameters, as well as oxygen saturation in arteries and veins, were measured using the Dynamic Vessel Analyzer. In addition, retinal venous blood velocity was measured using bidirectional laser Doppler velocimetry, retinal blood flow was calculated, and oxygen and carbon dioxide partial pressures were measured from arterialized capillary blood from the earlobe. Measurements were done during normoxia and during 100% oxygen breathing. RESULTS: Systemic hyperoxia caused a significant decrease in retinal venous diameter (-13.0% ± 4.5%) and arterial diameter (-12.1% ± 4.0%), in retinal blood velocity (-43.4% ± 7.7%), and in retinal blood flow (-57.0% ± 5.7%) (P < 0.001 for all). Oxygen saturation increased in retinal arteries (+4.4% ± 2.3%) and in retinal veins (+19.6% ± 6.2%), but the arteriovenous oxygen content difference significantly decreased (-29.4% ± 19.5%) (P < 0.001 for all). Blood oxygen tension in arterialized blood showed a pronounced increase from 90.2 ± 7.7 to 371.3 ± 92.7 mm Hg (P < 0.001). Calculated oxygen extraction in the eye decreased by as much as 62.5% ± 9.5% (P < 0.001). CONCLUSIONS: Our data are compatible with the hypothesis that during 100% oxygen breathing a large amount of oxygen, consumed by the inner retina, comes from the choroid, which is supported by previous animal data. Interpretation of oxygen saturation data in retinal arteries and veins without quantifying blood flow is difficult. (ClinicalTrials.gov number, NCT01692821.). Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
PURPOSE: To characterize retinal metabolism during normoxia and hyperoxia in healthy subjects. METHODS: Forty-six healthy subjects were included in the present study, and data of 41 subjects could be evaluated. Retinal vessel diameters, as well as oxygen saturation in arteries and veins, were measured using the Dynamic Vessel Analyzer. In addition, retinal venous blood velocity was measured using bidirectional laser Doppler velocimetry, retinal blood flow was calculated, and oxygen and carbon dioxide partial pressures were measured from arterialized capillary blood from the earlobe. Measurements were done during normoxia and during 100% oxygen breathing. RESULTS: Systemic hyperoxia caused a significant decrease in retinal venous diameter (-13.0% ± 4.5%) and arterial diameter (-12.1% ± 4.0%), in retinal blood velocity (-43.4% ± 7.7%), and in retinal blood flow (-57.0% ± 5.7%) (P < 0.001 for all). Oxygen saturation increased in retinal arteries (+4.4% ± 2.3%) and in retinal veins (+19.6% ± 6.2%), but the arteriovenous oxygen content difference significantly decreased (-29.4% ± 19.5%) (P < 0.001 for all). Blood oxygen tension in arterialized blood showed a pronounced increase from 90.2 ± 7.7 to 371.3 ± 92.7 mm Hg (P < 0.001). Calculated oxygen extraction in the eye decreased by as much as 62.5% ± 9.5% (P < 0.001). CONCLUSIONS: Our data are compatible with the hypothesis that during 100% oxygen breathing a large amount of oxygen, consumed by the inner retina, comes from the choroid, which is supported by previous animal data. Interpretation of oxygen saturation data in retinal arteries and veins without quantifying blood flow is difficult. (ClinicalTrials.gov number, NCT01692821.). Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
Authors: Lorenzo Iuliano; Giovanni Fogliato; Giuseppe Querques; Francesco Bandello; Marco Codenotti Journal: Graefes Arch Clin Exp Ophthalmol Date: 2017-03-23 Impact factor: 3.117
Authors: Joanna Miłkowska-Dymanowska; Adam J Białas; Anna Zalewska-Janowska; Paweł Górski; Wojciech J Piotrowski Journal: Int J Chron Obstruct Pulmon Dis Date: 2015-07-15
Authors: René M Werkmeister; Doreen Schmidl; Gerold Aschinger; Veronika Doblhoff-Dier; Stefan Palkovits; Magdalena Wirth; Gerhard Garhöfer; Robert A Linsenmeier; Rainer A Leitgeb; Leopold Schmetterer Journal: Sci Rep Date: 2015-10-27 Impact factor: 4.379