Blood Oxygen Saturation After Ischemia is Altered With Abnormal Microvascular Reperfusion

Adingupu, Damilola D.; Thorn, Clare; Casanova, Francesco; Elyas, Salim; Gooding, Karen M.; Gilchrist, Mark; Gates, Phillip E.; Shore, Angela C.; Strain, W. David

doi:10.1111/micc.12198

Cited by 12 publications

(15 citation statements)

References 27 publications

(36 reference statements)

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“…Such abnormalities in PORH have functional consequences as they are associated with abnormal reoxygenation . The recent development of combined LDF and white light reflectance probes make possible a simultaneous assessment of skin flow and oxygenation .…”

Section: Which Dynamic Tests Are Commonly Used?mentioning

confidence: 99%

Current Methods to Assess Human Cutaneous Blood Flow: An Updated Focus on Laser‐Based‐Techniques

Cracowski

Roustit

2016

Microcirculation

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Several noninvasive techniques have been developed using laser light interaction in the skin to explore the skin's microcirculation. Combined with laser Doppler or LSCI, reactivity tests are used to explore skin endothelial and neurovascular function in humans, including PORH, LTH, PIV, and iontophoresis of vasodilators. Recent advances in our comprehension of the physiological pathways underlying these reactivity tests have been possible through topical or intradermal delivery of drugs that produce elevated local concentrations. Skin microvascular function has also been proposed as a prognostic biomarker or for evaluating the effect of drugs. Comprehension of the physiological pathways, together with recent technological improvements in microcirculation imaging, has provided reliable and reproducible tools to study skin microcirculation.

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Section: Which Dynamic Tests Are Commonly Used?mentioning

confidence: 99%

Current Methods to Assess Human Cutaneous Blood Flow: An Updated Focus on Laser‐Based‐Techniques

Cracowski

Roustit

2016

Microcirculation

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“…(Adingupu et al . ). Structural alterations in the microcirculation (Schiffrin, ) can also influence its ability to respond to ischemia‐reperfusion, which might influence the upstream WSR stimulus.…”

Section: Discussionmentioning

confidence: 97%

Arterial wall shear rate response to reactive hyperaemia is markedly different between young and older humans

Aizawa

Ramalli

Sbragi

et al. 2019

The Journal of Physiology

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Key points The vasodilatory response to reactive hyperaemia is impaired with advancing age, but it is unclear whether this is because of an altered wall shear rate (WSR) stimulus or an altered flow‐mediated dilatation (FMD) response. Using new technology that allows detailed WSR measurement, we assessed the WSR–FMD response in healthy older people. Our data show that older people have a markedly altered and diminished WSR response to reactive hyperaemia compared to young people, but reduced WSR alone does not fully explain reduced FMD. In young people, WSR appears to be coupled to FMD but, by age ∼65 years, the arterial vasodilatory response has begun to uncouple from the WSR stimulus. These findings point to the importance and utility of comprehensively characterizing the WSR–FMD response when using reactive hyperaemia to assess vascular function, as well as giving new insight into the age‐related alteration in vascular function. Abstract The vasodilatory response to reactive hyperaemia is impaired with age, but it is unknown whether this is because of an altered wall shear rate (WSR) stimulus or an altered flow‐mediated dilatation (FMD) response to the WSR stimulus. Inherent difficulties in measuring blood flow velocity close to the arterial wall have prevented detailed assessment of the WSR–FMD response. Using an enhanced multigate spectral Doppler ultrasound system (ultrasound advanced open platform), we aimed to produce new data on the WSR–FMD relationship in healthy older adults. Sixty healthy people, comprising 28 young (27.5 ± 5.5 years) and 32 older (64.9 ± 3.7 years) individuals, underwent FMD assessment. Raw data were post‐processed using custom‐designed software to obtain WSR and diameter parameters. The data revealed that older people have a much altered and diminished WSR response to reactive hyperaemia compared to younger people [e.g. WSR peak: 622 (571–673) vs. 443 (396–491) 1/s in young and older respectively; P < 0.05]. However, reduced WSR alone does not appear to fully explain the reduced FMD response in older people because associations between WSR and FMD were few and weak. This was in contrast to young adults, where associations were strong. We conclude that WSR during FMD is much altered and diminished in older people, and there appears to be an ‘uncoupling’ of WSR from FMD in older people that may reflect a loss of precision in the reactive hyperaemia stimulus–response relationship. These findings also point to the importance and utility of comprehensively characterizing the WSR–FMD response when using reactive hyperaemia to assess vascular function.

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“…To assess the skin microcirculatory status using laser Doppler flowmetry and reflectance spectroscopy, the reactivity of the microvessels after a microcirculatory provocation is usually studied [9,24,27]. The most common microvascular tests are thermal provocations, post-occlusive reactive hyperemia and iontophoresis.…”

Section: Microvascular Reactivity Testsmentioning

confidence: 99%

“…Strain et al [36] reported an abnormal reperfusion pattern, a rapid early peak in perfusion after occlusion, related to cardiovascular risk. Adingupu et al [27] added measurements on oxygen saturation and showed an altered oxygen saturation seen as a result from the abnormal reperfusion found in [36]. …”

Section: Systolic Occlusionmentioning

confidence: 99%

“…Vasodilation could therefore be assumed to be predominant in larger vessels with a higher average speed. Adingupu et al [27] reported an abnormal reperfusion pattern after ischemia that resulted in a deranged oxygen saturation pattern. By measuring both oxygen saturation and conventional perfusion, the microvascular dysfunction in perfusion and the consequence on oxygen saturation could be directly visualized.…”

Section: Clinical Applications and Future Researchmentioning

confidence: 99%

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Model-based quantitative assessment of skin microcirculatory blood flow and oxygen saturation

Jonasson¹

2016

Linköping Studies in Science and Technology. Dissertations

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The microcirculation, involving the smallest vessels in the body, is where the oxygen transport to all tissue occurs. Evaluating microcirculatory parameters is, therefore, important and involves the quantification of oxygen content of red blood cells (RBCs), the amount of RBCs and their speed.Diffuse reflectance spectroscopy (DRS) can be used to estimate blood oxygen saturation and fraction of RBCs in tissue since oxygenated and deoxygenated blood have different light absorption characteristics. By illuminating the skin with white light and detecting the spectrum of the backscattered light, tissue absorption and scattering can be assessed. Laser Doppler flowmetry (LDF) is a technique to measure blood flow in tissue. When laser light encounter moving objects in tissue, i.e. RBCs, the light is Doppler shifted, which can be detected and used to calculate tissue perfusion (the fraction of moving RBCs times their speed). With a small distance between light source and detector, both techniques measure superficially where most vessels are microcirculatory vessels. Photon transport in tissue can be simulated with Monte Carlo techniques and the simulations form the basis of modeled DRS and LDF spectra. The estimated microcirculatory parameters are given by the model that best describe measured DRS and LDF data.This thesis describes the development and the evaluation of an optical method to simultaneously measure oxygen saturation, RBC tissue fraction and speed resolved perfusion in absolute units by integrating DRS and LDF. By combining DRS and LDF into one system with a common tissue model, the two modalities can benefit from each other's strengths. Different calibration methods and model assumptions for the system were evaluated in optical phantoms and in skin measurements. A simple calibration method with two detector distances for DRS was found adequate to accurately estimate absorption and scattering in optical phantoms. It was also necessary to model blood located in vessels, rather than homogeneously distributed in the skin, to obtain accurate parameter estimates. The system was evaluated in healthy subjects during standard provocations, where the parameters were in agreement with other studies and followed an expected pattern during the provocations. In patients with diabetes type 2, tissue fraction of RBCs and nutritive blood flow were reduced in baseline compared to healthy controls. These differences were not related to prevalence of microalbuminuria, a marker sign of microvascular complications in the kidneys.A combined system with DRS and LDF enables a more comprehensive assessment of the microcirculation by measuring oxygen saturation, RBC tissue fraction and speed resolved perfusion simultaneously and in absolute units. This system has clinical potential to assist in the evaluation of the microcirculation both in healthy and diseased individuals. POPULÄRVETENSKAPLIG SAMMANFATTNINGMikrocirkulationen innefattar de minsta kärlen i kroppen och det är här syretransporten till all vävnad i kroppen sker. ...

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Blood Oxygen Saturation After Ischemia is Altered With Abnormal Microvascular Reperfusion

Abstract: Individuals with abnormal microvascular reperfusion had a markedly altered pattern of oxygen increase during reperfusion. We propose that this may represent dysfunctional microvascular autoregulation that is clinically important in the etiopathology of target organ damage.

Cited by 12 publications

References 27 publications

Current Methods to Assess Human Cutaneous Blood Flow: An Updated Focus on Laser‐Based‐Techniques

Current Methods to Assess Human Cutaneous Blood Flow: An Updated Focus on Laser‐Based‐Techniques

Arterial wall shear rate response to reactive hyperaemia is markedly different between young and older humans

Model-based quantitative assessment of skin microcirculatory blood flow and oxygen saturation

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