Retinal Blood Flow and Retinal Blood Oxygen Saturation in Mild to Moderate Diabetic Retinopathy

2015 ◽  
Vol 56 (11) ◽  
pp. 6796 ◽  
Author(s):  
Faryan, Tayyari ◽  
Lee-Anne, Khuu ◽  
John G. Flanagan ◽  
Shaun, Singer ◽  
Michael H. Brent ◽  
...  
Keyword(s):  
Blood Flow ◽  
Diabetic Retinopathy ◽  
Oxygen Saturation ◽  
Retinal Blood Flow ◽  
Blood Oxygen ◽  
Blood Oxygen Saturation

scholarly journals Retinal blood oxygen saturation and aqueous humour biomarkers in early diabetic retinopathy

2019 ◽  
Vol 97 (5) ◽  
Author(s):  
Faryan Tayyari ◽  
Lee‐Anne Khuu ◽  
Jeremy M. Sivak ◽  
John G. Flanagan ◽  
Shaun Singer ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Oxygen Saturation ◽  
Aqueous Humour ◽  
Blood Oxygen ◽  
Blood Oxygen Saturation

Autoregulation of blood flow by oxygen lack

1962 ◽  
Vol 202 (1) ◽  
pp. 21-24 ◽  
Author(s):  
Joe M. Ross ◽  
Hilton M. Fairchild ◽  
Joe Weldy ◽  
Arthur C. Guyton
Keyword(s):  
Blood Flow ◽  
Oxygen Saturation ◽  
Left Lung ◽  
Lower Lobe ◽  
Blood Oxygen ◽  
Blood Oxygen Saturation ◽  
Hemoglobin Oxygen Saturation ◽  
Adequate Supply ◽  
Femoral Arteries ◽  
Flow Through

The effect of hemoglobin oxygen saturation upon blood flow through the hind leg of the dog was studied by perfusing the femoral arteries of five normal dogs with blood, the oxygen saturation of which was varied between 100% and 0%, and by perfusing the femoral arteries of nine spinal animals with blood, the oxygen saturation of which was varied between 100% and 10%. The blood saturation was controlled in the following manner: The blood was obtained from the lower lobe of the left lung as it was respired with a mixture of nitrogen and oxygen. By varying the ratio of the mixture, the blood oxygen saturation could be controlled exactly. Decreasing the oxygen saturation stepwise caused a correlated increase in blood flow through the leg. The results have shown that blood flow in the nonspinal dogs increased to an average of 3.4 times the normal value as oxygen saturation fell from 100% to 0%. In the spinal dogs blood flow increased to an average of 3.1 times normal as oxygen saturation fell from 100% to 10%. These experiments demonstrate that the local tissues can autoregulate their blood flow to help maintain an adequate supply of oxygen.

scholarly journals Temporal Change of Tissue Blood Oxygen Saturation in Rat Skeletal Muscle after Blood Flow Restriction by Manchette

2020 ◽  
Vol 35 (1) ◽  
pp. 49-52
Author(s):  
Tetsuo IMANO ◽  
Masanobu MURAO ◽  
Junichi AKIYAMA ◽  
Teruhiko KAWAKAMI ◽  
Masaaki NAKAJIMA
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Oxygen Saturation ◽  
Temporal Change ◽  
Blood Flow Restriction ◽  
Blood Oxygen ◽  
Rat Skeletal Muscle ◽  
Blood Oxygen Saturation ◽  
Flow Restriction

scholarly journals Tadalafil may improve cerebral perfusion in small-vessel occlusion stroke—a pilot study

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Joakim Ölmestig ◽  
Ida R Marlet ◽  
Rasmus H Hansen ◽  
Shazia Rehman ◽  
Rikke Steen Krawcyk ◽  
...  
Keyword(s):  
Blood Flow ◽  
Endothelial Function ◽  
Oxygen Saturation ◽  
Small Vessel Disease ◽  
Cerebral Small Vessel Disease ◽  
Small Vessel ◽  
Blood Oxygen ◽  
Blood Oxygen Saturation ◽  
Vessel Occlusion ◽  
Vessel Disease

Abstract New treatments for cerebral small-vessel disease are needed to reduce the risk of small-vessel occlusion stroke and vascular cognitive impairment. We investigated an approach targeted to the signalling molecule cyclic guanosine monophosphate, using the phosphodiesterase 5 inhibitor tadalafil, to explore if it improves cerebral blood flow and endothelial function in patients with cerebral small-vessel disease and stroke. In a randomized, double-blinded, placebo-controlled, cross-over pilot trial (NCT02801032), we included patients who had a previous (>6 months) small-vessel occlusion stroke. They received a single dose of either 20 mg tadalafil or placebo on 2 separate days at least 1 week apart. We measured the following: baseline MRI for lesion load, repeated measurements of blood flow velocity in the middle cerebral artery by transcranial Doppler, blood oxygen saturation in the cortical microvasculature by near-infrared spectroscopy, peripheral endothelial response by EndoPAT and endothelial-specific blood biomarkers. Twenty patients with cerebral small-vessel disease stroke (3 women, 17 men), mean age 67.1 ± 9.6, were included. The baseline mean values ± standard deviations were as follows: blood flow velocity in the middle cerebral artery, 57.4 ± 10.8 cm/s; blood oxygen saturation in the cortical microvasculature, 67.0 ± 8.2%; systolic blood pressure, 145.8 ± 19.5 mmHg; and diastolic blood pressure, 81.3 ± 9.1 mmHg. We found that tadalafil significantly increased blood oxygen saturation in the cortical microvasculature at 180 min post-administration with a mean difference of 1.57 ± 3.02%. However, we saw no significant differences in transcranial Doppler measurements over time. Tadalafil had no effects on peripheral endothelial function assessed by EndoPAT and endothelial biomarker results conflicted. Our findings suggest that tadalafil may improve vascular parameters in patients with cerebral small-vessel disease stroke, although the effect size was small. Increased oxygenation of cerebral microvasculature during tadalafil treatment indicated improved perfusion in the cerebral microvasculature, theoretically presenting an attractive new therapeutic target in cerebral small-vessel disease. Future studies of the effect of long-term tadalafil treatment on cerebrovascular reactivity and endothelial function are needed to evaluate general microvascular changes and effects in cerebral small-vessel disease and stroke.

scholarly journals A theoretical investigation of the increase in venous oxygen saturation levels in advanced glaucoma patients

2016 ◽  
Vol 1 (1) ◽  
pp. 64-87
Author(s):  
Lucia Carichino ◽  
Alon Harris ◽  
Giovanna Guidoboni ◽  
Brent A. Siesky ◽  
Luis Abegão Pinto ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Saturation ◽  
Oxygen Demand ◽  
Blood Oxygen ◽  
Vascular Changes ◽  
Blood Oxygen Saturation ◽  
Venous Oxygen Saturation ◽  
Model Predictions ◽  
Advanced Glaucoma ◽  
Krogh Cylinder

Purpose: Vascular changes have been observed among glaucoma patients, but it is not yet known whether these vascular changes occur primary or secondary to glaucomatous damage. In this study, a theoretical mathematical model of the retinal vasculature is applied to a set of oximetry data obtained from healthy individuals and glaucoma patients and is used to propose possible explanations for the clinically observed increases in venous blood oxygen saturation in advanced glaucoma patients.Methods: Given clinical measurements of intraocular pressure (IOP), mean arterial pressure and arterial blood oxygen saturation from healthy persons and advanced (visual field mean defect (MD) ≥ 10 dB) primary open angle glaucoma (POAG, IOP > 21 mmHg) patients and advanced normal tension glaucoma (NTG, IOP ≤ 21 mmHg)patients, the model is used to predict the oxygen demand or Krogh cylinder tissue width that would yield the clinically-measured venous oxygen saturation in each population.Results: A decrease in retinal tissue oxygen demand (M0), an impairment in blood flow autoregulation, or a decrease in Krogh cylinder tissue width (d) can independently lead to increased venous saturation. The model predicts that a decrease in M0 or a decrease in d is more likely to yield the increased venous saturation levels observed in POAG patients, while impairing blood flow autoregulation with no change in M0 or d is more likely to yield the increased venous saturation levels observed in NTG patients.Conclusions: The combined theoretical and clinical model predictions suggest that the mechanisms leading to increased venous saturation might differ between POAG and NTG patients. The model predictions are used to hypothesize that a decrease in oxygen demand might be more relevant to the increase in venous saturation observed in advanced POAG, while impairment in autoregulation mechanisms might be more relevant to the increase in venous saturation observed in advanced NTG.

scholarly journals PSIX-9 Impacts of bunk management on feedlot performance, carcass characteristics, hydrogen sulfide concentration and blood oxygen saturation in steers fed 25 or 50% modified distillers grains plus solubles

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 422-422
Author(s):  
Rebecca L Moore ◽  
Cierrah J Kassetas ◽  
Leslie A LeKatz ◽  
Bryan W Neville
Keyword(s):  
Hydrogen Sulfide ◽  
Oxygen Saturation ◽  
Management Strategy ◽  
Distillers Grains ◽  
Feed Ratio ◽  
Sulfide Concentration ◽  
Blood Oxygen ◽  
Blood Oxygen Saturation ◽  
Feedlot Performance ◽  
Arterial Blood

Abstract One hundred and twenty-six yearling angus steers (initial body weight 445.87 ± 7.13 kg) were utilized in a 2 x 2 factorial design to evaluate the impacts of bunk management and modified distillers grains plus solubles (mDGS) inclusion on feedlot performance, hydrogen sulfide concentrations and blood oxygen saturation. Treatments included bunk management strategy either control bunk management (CON; clean bunks at the time of next day’s feeding) or long bunk management (LONG; feed remaining at time of next day’s feeding), and two inclusion rates of mDGS either 25% or 50% (DM Basis). On d 0, 7, 14, 21, 28 and 35 rumen gas samples were collected via rumenocentesis, and arterial blood samples were collected on two steers from each pen. No differences (P ≥ 0.09) were observed for dry matter intake, average daily gain and gain-to-feed ratio for bunk management or mDGS inclusion. Hot carcass weight, ribeye area, marbling score and quality grade were not affected (P ≥ 0.48) by either bunk management or mDGS inclusion. Back fat was greater (P = 0.04) for CON steers compared to LONG (1.30 vs 1.12 ± 0.05cm, respectively), but was not affected (P = 0.59) by mDGS inclusion. Steers on CON had greater (P = 0.03) yield grades compared to LONG (3.21 vs 2.96 ± 0.11, respectively). Bunk management strategy did not impact hydrogen sulfide concentrations or blood oxygen saturation (P = 0.82). Hydrogen sulfide concentrations increased (P < 0.001) with increasing mDGS inclusion. Blood oxygen saturation was influenced by day of sampling (P = 0.01). Blood oxygen saturation was not affected (P = 0.07) by mDGS inclusion. The fact that ruminal hydrogen sulfide concentrations increased while blood oxygen saturation remained similar raises questions about the quantity of hydrogen sulfide and metabolic fate of excess hydrogen sulfide in the blood of ruminant animals.

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