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Einar Stefansson - One of the best experts on this subject based on the ideXlab platform.
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Retinal Oxygen Saturation is altered in diabetic retinopathy.
The British journal of ophthalmology, 2011Co-Authors: S Hardarson, Einar StefanssonAbstract:Aim Retinal Oxygen metabolism is thought to be affected in diabetic retinopathy. The aim of this study was to test whether retinal vessel Oxygen Saturation is different in patients with diabetic retinopathy from that in healthy controls. Methods The retinal oximeter is based on a fundus camera. It estimates retinal vessel Oxygen Saturation from light absorbance at 586 nm and 605 nm. Retinal vessel Oxygen Saturation was measured in one major temporal retinal arteriole and venule in healthy volunteers and in patients with diabetic retinopathy. Results Oxygen Saturation in the retinal arterioles of healthy volunteers was 93±4% and 58±6% in venules (mean±SD, n=31). The corresponding values for all diabetic patients (n=20) were 101±5% and 68±7%. The difference between healthy volunteers and diabetic patients was statistically significant (p Conclusion Retinal vessel Oxygen Saturation is higher in patients with diabetic retinopathy than in healthy controls. Possible explanations include shunting of blood through preferential channels, bypassing non-perfused capillaries in the capillary network. Parts of the retinal tissue may be hypoxic while blood in larger vessels has high Oxygen Saturation.
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Oxygen Saturation in branch retinal vein occlusion.
Acta ophthalmologica, 2011Co-Authors: S Hardarson, Einar StefanssonAbstract:. Purpose: The aim of this study was to test whether Oxygen Saturation in retinal blood vessels is affected by branch retinal vein occlusion (BRVO). Methods: The spectrophotometric retinal oximeter is based on a fundus camera. It simultaneously captures images of the retina at 586 and 605 nm and calculates optical density (absorbance) of retinal vessels at both wavelengths. The ratio of the two optical densities is approximately linearly related to haemoglobin Oxygen Saturation. Relative Oxygen Saturation was measured in retinal blood vessels in 24 patients with BRVO. Friedman’s test and Dunn’s post test were used for statistical analyses. Results: Oxygen Saturation in occluded venules ranged from 12% to 93%. The median Oxygen Saturation was 59% (range 12–93%, n = 22) in affected retinal venules, 63% (23–80%) in unaffected venules in the BRVO eye and 55% (39–80%) in venules in the fellow eye (p = 0.66). Corresponding values for arterioles were 101% (89–115%, n = 18), 95% (85–104%) (p
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Oxygen Saturation in central retinal vein occlusion
American Journal of Ophthalmology, 2010Co-Authors: S Hardarson, Einar StefanssonAbstract:Purpose To test whether Oxygen Saturation is affected in retinal blood vessels in patients with central retinal vein occlusion (CRVO). Design Prospective observational case series. Methods Oxygen Saturation of hemoglobin was measured in retinal blood vessels in 10 patients with unilateral CRVO. The duration of CRVO before measurement was from 1 day to about 6 months. Two patients were excluded because of poor quality of oximetry images. The spectrophotometric retinal oximeter is based on a fundus camera. It simultaneously captures images of the retina at 605 nm and 586 nm and calculates optical density (absorbance) of retinal vessels at both wavelengths. The ratio of the 2 optical densities is approximately linearly related to hemoglobin Oxygen Saturation. Mean Oxygen Saturation was calculated for first- and second-degree arterioles and venules in both eyes of each patient. Results The mean Oxygen Saturation of hemoglobin in retinal venules was 49% ± 12% (mean ± SD, n=8) in eyes affected by CRVO and 65% ± 6% in unaffected fellow eyes ( P = .003). The mean arteriolar Oxygen Saturation was 99% ± 3% in CRVO eyes and 99% ± 6% in the fellow eyes. Venular Oxygen Saturation was variable within and between CRVO eyes. Conclusions Oxygen Saturation in retinal venules is lower in eyes with CRVO than in fellow eyes and there is considerable variability within and between CRVO eyes. Arteriolar Saturation is the same in CRVO and fellow eyes. Retinal Oxygenation is disturbed in CRVO.
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Retinal vessel diameter affects Oxygen Saturation measurements
Acta Ophthalmologica, 2010Co-Authors: S Hardarson, Hr Bergvinsson, Einar StefanssonAbstract:Purpose To test whether retinal vessel Oxygen Saturation measurements are affected by vessel diameter and to compare Saturation between the temporal and nasal retina. Methods The Oxymap retinal oximeter is based on a fundus camera. It measures light absorbance at two wavelengths of light and calculates Oxygen Saturation in retinal vessels as well as vessel diameter. Measurements were performed on 12 healthy individuals. The effect of vessel diameter on Saturation measurements was tested by measuring before and after the first bifurcation in the retina (1st degree parent vessels and 2nd degree daughter vessels). Arteriolar Saturation can be assumed to be equal before and after bifurcation. Results The ratio between Oxygen Saturation in 1st degree parent arteriole and 2nd degree daughter arteriole was 0.97±0.02 (mean±SD). The ratio was significantly lower than the theoretical value of 1.00 (p
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Glaucoma filtration surgery and retinal Oxygen Saturation.
Investigative ophthalmology & visual science, 2009Co-Authors: S Hardarson, Maria Soffia Gottfredsdottir, Gisli H. Halldorsson, Robert Arnar Karlsson, Jon Atli Benediktsson, Thor Eysteinsson, James M. Beach, Alon Harris, Einar StefanssonAbstract:PURPOSE Glaucoma may involve disturbances in retinal Oxygenation and blood flow. The purpose of this study was to measure the effect of glaucoma filtration surgery on retinal vessel Oxygen Saturation. METHODS A noninvasive spectrophotometric retinal oximeter was used to measure hemoglobin Oxygen Saturation in retinal arterioles and venules before and after glaucoma filtration surgery. Twenty-five consecutive patients were recruited, and 19 had adequate image quality. Fourteen underwent trabeculectomy and five glaucoma tube surgery. Twelve had primary open-angle glaucoma and seven had exfoliative glaucoma. IOP decreased from 23 +/- 7 to 10 +/- 4 mm Hg (mean +/- SD, P = 0.0001). RESULTS Oxygen Saturation increased in retinal arterioles from 97% +/- 4% to 99% +/- 6% (n = 19; P = 0.046) after surgery and was unchanged in venules (63% +/- 5% before surgery and 64% +/- 6% after, P = 0.76). There were no significant changes in Saturation in the fellow eyes (P > 0.60). The arteriovenous difference was 34% before and 36% after surgery (P = 0.35). CONCLUSIONS Glaucoma filtration surgery had almost no effect on retinal vessel Oxygen Saturation.
S Hardarson - One of the best experts on this subject based on the ideXlab platform.
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Retinal Oxygen Saturation in health and disease
Acta Ophthalmologica, 2012Co-Authors: S HardarsonAbstract:Purpose Measurements of retinal vessel Oxygen Saturation can provide insight into the nature of several eye diseases. Methods Dual wavelength oximeters are used by our group and others. They measure light absorbance at one Oxygen-sensitive and one Oxygen-insensitive wavelength and use the absorbance values to calculate retinal vessel Oxygen Saturation. Results Oxygen Saturation in the larger retinal venules is decreased in central retinal vein occlusion but increased in diabetic retinopathy and age-related macular degeneration. In glaucoma, retinal venous Oxygen Saturation increases with increased visual field defect. Conclusion Oxygen Saturation in the larger retinal vessels, particularly the venules, reflects the balance between Oxygen supply and Oxygen consumption in the retina. In glaucoma, for example, a rise in the retinal venous Oxygen Saturation is most likely due to tissue atrophy and less Oxygen consumption. Oxygen Saturation in the larger vessels can also be affected by the efficiency of Oxygen distribution by the retinal capillaries. Increased retinal venous Oxygen Saturation in diabetic retinopathy may for example partly be explained by shunting of blood through preferential channels in the capillary network. Commercial interest
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Retinal Oxygen Saturation is altered in diabetic retinopathy.
The British journal of ophthalmology, 2011Co-Authors: S Hardarson, Einar StefanssonAbstract:Aim Retinal Oxygen metabolism is thought to be affected in diabetic retinopathy. The aim of this study was to test whether retinal vessel Oxygen Saturation is different in patients with diabetic retinopathy from that in healthy controls. Methods The retinal oximeter is based on a fundus camera. It estimates retinal vessel Oxygen Saturation from light absorbance at 586 nm and 605 nm. Retinal vessel Oxygen Saturation was measured in one major temporal retinal arteriole and venule in healthy volunteers and in patients with diabetic retinopathy. Results Oxygen Saturation in the retinal arterioles of healthy volunteers was 93±4% and 58±6% in venules (mean±SD, n=31). The corresponding values for all diabetic patients (n=20) were 101±5% and 68±7%. The difference between healthy volunteers and diabetic patients was statistically significant (p Conclusion Retinal vessel Oxygen Saturation is higher in patients with diabetic retinopathy than in healthy controls. Possible explanations include shunting of blood through preferential channels, bypassing non-perfused capillaries in the capillary network. Parts of the retinal tissue may be hypoxic while blood in larger vessels has high Oxygen Saturation.
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Oxygen Saturation in branch retinal vein occlusion.
Acta ophthalmologica, 2011Co-Authors: S Hardarson, Einar StefanssonAbstract:. Purpose: The aim of this study was to test whether Oxygen Saturation in retinal blood vessels is affected by branch retinal vein occlusion (BRVO). Methods: The spectrophotometric retinal oximeter is based on a fundus camera. It simultaneously captures images of the retina at 586 and 605 nm and calculates optical density (absorbance) of retinal vessels at both wavelengths. The ratio of the two optical densities is approximately linearly related to haemoglobin Oxygen Saturation. Relative Oxygen Saturation was measured in retinal blood vessels in 24 patients with BRVO. Friedman’s test and Dunn’s post test were used for statistical analyses. Results: Oxygen Saturation in occluded venules ranged from 12% to 93%. The median Oxygen Saturation was 59% (range 12–93%, n = 22) in affected retinal venules, 63% (23–80%) in unaffected venules in the BRVO eye and 55% (39–80%) in venules in the fellow eye (p = 0.66). Corresponding values for arterioles were 101% (89–115%, n = 18), 95% (85–104%) (p
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Oxygen Saturation in central retinal vein occlusion
American Journal of Ophthalmology, 2010Co-Authors: S Hardarson, Einar StefanssonAbstract:Purpose To test whether Oxygen Saturation is affected in retinal blood vessels in patients with central retinal vein occlusion (CRVO). Design Prospective observational case series. Methods Oxygen Saturation of hemoglobin was measured in retinal blood vessels in 10 patients with unilateral CRVO. The duration of CRVO before measurement was from 1 day to about 6 months. Two patients were excluded because of poor quality of oximetry images. The spectrophotometric retinal oximeter is based on a fundus camera. It simultaneously captures images of the retina at 605 nm and 586 nm and calculates optical density (absorbance) of retinal vessels at both wavelengths. The ratio of the 2 optical densities is approximately linearly related to hemoglobin Oxygen Saturation. Mean Oxygen Saturation was calculated for first- and second-degree arterioles and venules in both eyes of each patient. Results The mean Oxygen Saturation of hemoglobin in retinal venules was 49% ± 12% (mean ± SD, n=8) in eyes affected by CRVO and 65% ± 6% in unaffected fellow eyes ( P = .003). The mean arteriolar Oxygen Saturation was 99% ± 3% in CRVO eyes and 99% ± 6% in the fellow eyes. Venular Oxygen Saturation was variable within and between CRVO eyes. Conclusions Oxygen Saturation in retinal venules is lower in eyes with CRVO than in fellow eyes and there is considerable variability within and between CRVO eyes. Arteriolar Saturation is the same in CRVO and fellow eyes. Retinal Oxygenation is disturbed in CRVO.
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Retinal vessel diameter affects Oxygen Saturation measurements
Acta Ophthalmologica, 2010Co-Authors: S Hardarson, Hr Bergvinsson, Einar StefanssonAbstract:Purpose To test whether retinal vessel Oxygen Saturation measurements are affected by vessel diameter and to compare Saturation between the temporal and nasal retina. Methods The Oxymap retinal oximeter is based on a fundus camera. It measures light absorbance at two wavelengths of light and calculates Oxygen Saturation in retinal vessels as well as vessel diameter. Measurements were performed on 12 healthy individuals. The effect of vessel diameter on Saturation measurements was tested by measuring before and after the first bifurcation in the retina (1st degree parent vessels and 2nd degree daughter vessels). Arteriolar Saturation can be assumed to be equal before and after bifurcation. Results The ratio between Oxygen Saturation in 1st degree parent arteriole and 2nd degree daughter arteriole was 0.97±0.02 (mean±SD). The ratio was significantly lower than the theoretical value of 1.00 (p
Djillali Annane - One of the best experts on this subject based on the ideXlab platform.
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Masseter tissue Oxygen Saturation predicts normal central venous Oxygen Saturation during early goal-directed therapy and predicts mortality in patients with severe sepsis.
Critical care medicine, 2012Co-Authors: Gwenhael Colin, Olivier Nardi, Andrea Polito, Jerome Aboab, Virginie Maxime, Bernard Clair, Diane Friedman, David Orlikowski, Tarek Sharshar, Djillali AnnaneAbstract:OBJECTIVE This study aimed to investigate, in patients with severe sepsis, the correlation between central venous Oxygen Saturation and tissue Oxygen Saturation at different levels. DESIGN Prospective observational study. SETTING General intensive care unit at an academic medical center in France. PATIENTS Thirty-eight patients with underresuscitated severe sepsis and septic shock on intensive care unit admission. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS During early resuscitation according to the 6-hr bundles of the Surviving Sepsis Campaign guidelines, tissue Oxygen Saturation was recorded every other hour at the level of the thenar, masseter, and deltoid muscles along with central hemodynamics, arterial lactate concentrations, and central venous Oxygen Saturation. Over the 6-hr resuscitation period, thenar tissue Oxygen Saturation was consistently higher than masseter tissue Oxygen Saturation (p = .04) and deltoid tissue Oxygen Saturation (p = .002), and masseter tissue Oxygen Saturation was consistently higher than deltoid tissue Oxygen Saturation (p = .04). Receiver operating characteristic curves analyses showed that masseter tissue Oxygen Saturation was better predictor of central venous Oxygen Saturation >70% than thenar tissue Oxygen Saturation (area under the curve, 0.80; 95% confidence interval 0.71-0.89 vs. 0.67; 95% confidence interval 0.56-0.77; p = .02). The crude 28-day mortality was 36.8%. Receiver operating characteristic curve analysis showed that masseter tissue Oxygen Saturation (area under the curve 0.87; 0.75-0.98) and deltoid tissue Oxygen Saturation (area under the curve 0.88; 0.77-0.98) but not thenar tissue Oxygen Saturation (area under the curve 0.66; 0.46-0.86) or central venous Oxygen Saturation (area under the curve 0.56; 0.38-0.80) were strong predictors of 28-day mortality. CONCLUSIONS This study suggested that in the early 6-hr resuscitation period, masseter tissue Oxygen Saturation accurately identified patients with severe sepsis and central venous Oxygen Saturation >70%. Both masseter tissue Oxygen Saturation and deltoid tissue Oxygen Saturation but not central venous Oxygen Saturation or thenar tissue Oxygen Saturation are strong predictors of 28-day mortality.
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Masseter muscle Oxygen Saturation is associated with central venous Oxygen Saturation in patients with severe sepsis
Journal of clinical monitoring and computing, 2010Co-Authors: Olivier Nardi, Hélène Gonzalez, Abdallah Fayssoil, Djillali AnnaneAbstract:Objective This monocentric prospective study was conducted to determine if tissue Oxygen Saturation measured non invasively over masseter muscle site (Masseter-StO2) can predict the central venous Oxygen Saturation (ScvO2) level in severe sepsis and septic shock.
Peter E. Spronk - One of the best experts on this subject based on the ideXlab platform.
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Femoral venous Oxygen Saturation is no surrogate for central venous Oxygen Saturation.
Critical care medicine, 2012Co-Authors: Paul A. Van Beest, Alice Van Der Schors, Henriette Liefers, Ludo G. J. Coenen, Richard L. Braam, Najib Habib, Annemarije Braber, Thomas Scheeren, Michael A. Kuiper, Peter E. SpronkAbstract:Objective: The purpose of our study was to determine if central venous Oxygen Saturation and femoral venous Oxygen Saturation can be used interchangeably during surgery and in critically ill patients. Design: Prospective observational controlled study. Setting: Nonacademic university-affiliated teaching hospital in The Netherlands. Patients: One hundred cardiac outpatients, 30 high-risk surgical patients, and 30 critically ill patients. Interventions: None. Methods and Main Results: We concurrently determined femoral venous Oxygen Saturation and central venous Oxygen Saturation in a group of 100 stable cardiac patients, which served as control group. Furthermore, we determined simultaneously femoral venous Oxygen Saturation and central venous Oxygen Saturation in 30 surgical patients and in 30 critically ill patients and evaluated changes over time. Correlation and agreement of femoral venous Oxygen Saturation and central venous Oxygen Saturation were assessed, including the difference between femoral venous Oxygen Saturation and central venous Oxygen Saturation. Despite significant correlation between obtained values of femoral venous Oxygen Saturation and central venous Oxygen Saturation (r(s) = 0.55; p
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Femoral venous Oxygen Saturation is no surrogate for central venous Oxygen Saturation
Critical Care, 2011Co-Authors: Alice Van Der Schors, Paul A. Van Beest, Henriette Liefers, Richard L. Braam, L Coenen, Peter E. SpronkAbstract:Objective: The purpose of our study was to determine if central venous Oxygen Saturation and femoral venous Oxygen Saturation can be used interchangeably during surgery and in critically ill patients. Design: Prospective observational controlled study. Setting: Nonacademic university-affiliated teaching hospital in The Netherlands. Patients: One hundred cardiac outpatients, 30 high-risk surgical patients, and 30 critically ill patients. Interventions: None. Methods and Main Results: We concurrently determined femoral venous Oxygen Saturation and central venous Oxygen Saturation in a group of 100 stable cardiac patients, which served as control group. Furthermore, we determined simultaneously femoral venous Oxygen Saturation and central venous Oxygen Saturation in 30 surgical patients and in 30 critically ill patients and evaluated changes over time. Correlation and agreement of femoral venous Oxygen Saturation and central venous Oxygen Saturation were assessed, including the difference between femoral venous Oxygen Saturation and central venous Oxygen Saturation. Despite significant correlation between obtained values of fem oral venous Oxygen Saturation and central venous Oxygen Saturation (r s = 0.55; p < .001), the limits of agreement were wide in the control group (mean bias 2.7% ± 7.9%; 95% limits of agreement −12.9% to 18.2%). In both the surgical and critically ill patients, limits of agreement (mean bias of −1.9% ± 9.3%; 95% limits of agreement −20.0% to 16.3%, and mean bias of 4.6% ± 14.3%; 95% limits of agreement −23.5% to 32.6%, respectively) were wide. Results for changes of femoral venous Oxygen Saturation and central venous Oxygen Saturation were similar. During initial treatment of critically ill patients, the difference between femoral venous Oxygen Saturation and central venous Oxygen Saturation including its range of variation diminished. Conclusion: There is lack of agreement between femoral venous Oxygen Saturation and central venous Oxygen Saturation in both stable and unstable medical conditions. Thus, femoral venous Oxygen Saturation should not be used as surrogate for central venous Oxygen Saturation. (Crit Care Med 2012; 40:0–0)
Olivier Nardi - One of the best experts on this subject based on the ideXlab platform.
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Masseter tissue Oxygen Saturation predicts normal central venous Oxygen Saturation during early goal-directed therapy and predicts mortality in patients with severe sepsis.
Critical care medicine, 2012Co-Authors: Gwenhael Colin, Olivier Nardi, Andrea Polito, Jerome Aboab, Virginie Maxime, Bernard Clair, Diane Friedman, David Orlikowski, Tarek Sharshar, Djillali AnnaneAbstract:OBJECTIVE This study aimed to investigate, in patients with severe sepsis, the correlation between central venous Oxygen Saturation and tissue Oxygen Saturation at different levels. DESIGN Prospective observational study. SETTING General intensive care unit at an academic medical center in France. PATIENTS Thirty-eight patients with underresuscitated severe sepsis and septic shock on intensive care unit admission. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS During early resuscitation according to the 6-hr bundles of the Surviving Sepsis Campaign guidelines, tissue Oxygen Saturation was recorded every other hour at the level of the thenar, masseter, and deltoid muscles along with central hemodynamics, arterial lactate concentrations, and central venous Oxygen Saturation. Over the 6-hr resuscitation period, thenar tissue Oxygen Saturation was consistently higher than masseter tissue Oxygen Saturation (p = .04) and deltoid tissue Oxygen Saturation (p = .002), and masseter tissue Oxygen Saturation was consistently higher than deltoid tissue Oxygen Saturation (p = .04). Receiver operating characteristic curves analyses showed that masseter tissue Oxygen Saturation was better predictor of central venous Oxygen Saturation >70% than thenar tissue Oxygen Saturation (area under the curve, 0.80; 95% confidence interval 0.71-0.89 vs. 0.67; 95% confidence interval 0.56-0.77; p = .02). The crude 28-day mortality was 36.8%. Receiver operating characteristic curve analysis showed that masseter tissue Oxygen Saturation (area under the curve 0.87; 0.75-0.98) and deltoid tissue Oxygen Saturation (area under the curve 0.88; 0.77-0.98) but not thenar tissue Oxygen Saturation (area under the curve 0.66; 0.46-0.86) or central venous Oxygen Saturation (area under the curve 0.56; 0.38-0.80) were strong predictors of 28-day mortality. CONCLUSIONS This study suggested that in the early 6-hr resuscitation period, masseter tissue Oxygen Saturation accurately identified patients with severe sepsis and central venous Oxygen Saturation >70%. Both masseter tissue Oxygen Saturation and deltoid tissue Oxygen Saturation but not central venous Oxygen Saturation or thenar tissue Oxygen Saturation are strong predictors of 28-day mortality.
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Masseter muscle Oxygen Saturation is associated with central venous Oxygen Saturation in patients with severe sepsis
Journal of clinical monitoring and computing, 2010Co-Authors: Olivier Nardi, Hélène Gonzalez, Abdallah Fayssoil, Djillali AnnaneAbstract:Objective This monocentric prospective study was conducted to determine if tissue Oxygen Saturation measured non invasively over masseter muscle site (Masseter-StO2) can predict the central venous Oxygen Saturation (ScvO2) level in severe sepsis and septic shock.