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Medicine Feb 2024Hemodynamic coherence plays a critical role in the outcomes of septic shock. Due to the potential negative consequences of microcirculatory disorders on organ failure... (Review)
Review
Hemodynamic coherence plays a critical role in the outcomes of septic shock. Due to the potential negative consequences of microcirculatory disorders on organ failure and clinical outcomes, the maintenance of a balance between the macrocirculation and microcirculation is a topic of significant research focus. Although physical methods and specialized imaging techniques are used in clinical practice to assess microcirculation, the use of monitoring devices is not widespread. The integration of microcirculation research tools into clinical practice poses a significant challenge for the future. Consequently, this review aims to evaluate the impact of septic shock on the microcirculation, the methods used to monitor the microcirculation and highlight the importance of microcirculation in the treatment of critically ill patients. In addition, it proposes an evaluation framework that integrates microcirculation monitoring with macrocirculatory parameters. The optimal approach should encompass dynamic, multiparametric, individualized, and continuous monitoring of both the macrocirculation and microcirculation, particularly in cases of hemodynamic separation.
Topics: Humans; Shock, Septic; Microcirculation; Hemodynamics; Critical Illness
PubMed: 38394485
DOI: 10.1097/MD.0000000000037273 -
Journal of the American Society of... Sep 2022The glomerular vascular pole is the gate for the afferent and efferent arterioles and mesangial cells and a frequent location of peripolar cells with an unclear...
The glomerular vascular pole is the gate for the afferent and efferent arterioles and mesangial cells and a frequent location of peripolar cells with an unclear function. It has been studied in definitive detail for >30 years, and functionally interrogated in the context of signal transduction from the macula densa to the mesangial cells and afferent arteriolar smooth muscle cells from 10 to 20 years ago. Two recent discoveries shed additional light on the vascular pole, with possibly far-reaching implications. One, which uses novel serial section electron microscopy, reveals a shorter capillary pathway between the basins of the afferent and efferent arterioles. Such a pathway, when patent, may short-circuit the multitude of capillaries in the glomerular tuft. Notably, this shorter capillary route is enclosed within the glomerular mesangium. The second study used anti-Thy1.1-induced mesangiolysis and intravital microscopy to unequivocally establish the long-suspected contractile function of mesangial cells, which have the ability to change the geometry and curvature of glomerular capillaries. These studies led me to hypothesize the existence of a glomerular perfusion rheostat, in which the shorter path periodically fluctuates between being more and less patent. This action reduces or increases blood flow through the entire glomerular capillary tuft. A corollary is that the GFR is a net product of balance between the states of capillary perfusion, and that deviations from the balanced state would increase or decrease GFR. Taken together, these studies may pave the way to a more profound understanding of glomerular microcirculation under basal conditions and in progression of glomerulopathies.
Topics: Microcirculation; Kidney Glomerulus; Glomerular Mesangium; Arterioles; Kidney Tubules
PubMed: 35853715
DOI: 10.1681/ASN.2022030354 -
Medical Sciences (Basel, Switzerland) Aug 2021A large number of models are now available for the investigation of skin wound healing. These can be used to study the processes that take place in a phase-specific... (Review)
Review
A large number of models are now available for the investigation of skin wound healing. These can be used to study the processes that take place in a phase-specific manner under both physiological and pathological conditions. Most models focus on wound closure, which is a crucial parameter for wound healing. However, vascular supply plays an equally important role and corresponding models for selective or parallel investigation of microcirculation regeneration and angiogenesis are also described. In this review article, we therefore focus on the different levels of investigation of skin wound healing (in vivo to in virtuo) and the investigation of angiogenesis and its parameters.
Topics: Microcirculation; Models, Theoretical; Skin; Wound Healing
PubMed: 34449673
DOI: 10.3390/medsci9030055 -
Current Opinion in Critical Care Jun 2021Hemodynamic monitoring is an essential component in the care for critically ill patients. A range of tools are available and new approaches have been developed. This... (Review)
Review
PURPOSE OF REVIEW
Hemodynamic monitoring is an essential component in the care for critically ill patients. A range of tools are available and new approaches have been developed. This review summarizes their availability, affordability and feasibility for hospital settings in resource-limited settings.
RECENT FINDINGS
Evidence for the performance of specific hemodynamic monitoring tools or strategies in low-income and middle-income countries (LMICs) is limited. Repeated physical examination and basic observations remain a cornerstone for patient monitoring and have a high sensitivity for detecting organ hypoperfusion, but with a low specificity. Additional feasible approaches for hemodynamic monitoring in LMICs include: for tissue perfusion monitoring: urine output, skin mottling score, capillary refill time, skin temperature gradients, and blood lactate measurements; for cardiovascular monitoring: echocardiography and noninvasive or minimally invasive cardiac output measurements; and for fluid status monitoring: inferior vena cava distensibility index, mini-fluid challenge test, passive leg raising test, end-expiratory occlusion test and lung ultrasound. Tools with currently limited applicability in LMICs include microcirculatory monitoring devices and pulmonary artery catheterization, because of costs and limited added value. Especially ultrasound is a promising and affordable monitoring device for LMICs, and is increasingly available.
SUMMARY
A set of basic tools and approaches is available for adequate hemodynamic monitoring in resource-limited settings. Future research should focus on the development and trialing of robust and context-appropriate monitoring technologies.
Topics: Cardiac Output; Critical Illness; Hemodynamic Monitoring; Hemodynamics; Humans; Microcirculation; Monitoring, Physiologic
PubMed: 33899817
DOI: 10.1097/MCC.0000000000000830 -
American Journal of Physiology. Heart... May 2022Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of... (Review)
Review
Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of morbidity and mortality, particularly in the setting of metabolic syndrome. The coronary endothelium plays a pivotal role in maintaining homeostasis, though factors such as diabetes, hypertension, hyperlipidemia, and obesity can contribute to endothelial injury and consequently arteriolar vasomotor dysfunction. These disturbances in the coronary microvasculature clinically manifest as diminished coronary flow reserve, which is a known independent risk factor for cardiac death, even in the absence of macrovascular atherosclerotic disease. Therefore, a growing body of literature has examined the molecular mechanisms by which coronary microvascular injury occurs at the level of the endothelium and the consequences on arteriolar vasomotor responses. This review will begin with an overview of normal coronary microvascular physiology, modalities of measuring coronary microvascular function, and clinical implications of CMD. These introductory topics will be followed by a discussion of recent advances in the understanding of the mechanisms by which inflammation, oxidative stress, insulin resistance, hyperlipidemia, hypertension, shear stress, endothelial cell senescence, and tissue ischemia dysregulate coronary endothelial homeostasis and arteriolar vasomotor function.
Topics: Coronary Circulation; Coronary Vessels; Endothelium, Vascular; Humans; Hypertension; Microcirculation; Microvessels
PubMed: 35333122
DOI: 10.1152/ajpheart.00603.2021 -
Cells Aug 2021The microcirculation includes an invisible network of micro-vessels that are up to a few hundred microns in diameter [...].
The microcirculation includes an invisible network of micro-vessels that are up to a few hundred microns in diameter [...].
Topics: Animals; Cell- and Tissue-Based Therapy; Endothelium, Vascular; Humans; Microcirculation; Stem Cells
PubMed: 34440914
DOI: 10.3390/cells10082144 -
International Journal of Environmental... Mar 2021Peripheral artery disease (PAD) is characterized by the development of atherosclerotic plaques in the lower-body conduit arteries. PAD is commonly accompanied by... (Review)
Review
Peripheral artery disease (PAD) is characterized by the development of atherosclerotic plaques in the lower-body conduit arteries. PAD is commonly accompanied by microvascular disease, which may result in poor wound healing, plantar ulcer development, and subsequent limb amputation. Understanding the mechanisms underlying the development of plantar ulcers is a critical step in the development of adequate treatment options for patients with PAD. Skin is classified into two major components: glabrous and non-glabrous. These skin types have unique microcirculation characteristics, making it important to differentiate between the two when investigating mechanisms for plantar ulcer development in PAD. There is evidence for a microcirculation compensatory mechanism in PAD. This is evident by the maintenance of basal microcirculation perfusion and capillary filling pressure despite a reduced pressure differential beyond an occlusion in non-critical limb ischemia PAD. The major mechanism for this compensatory system seems to be progressive vasodilation of the arterial network below an occlusion. Recently, heat therapies have emerged as novel treatment options for attenuating the progression of PAD. Heat therapies are capable of stimulating the cardiovascular system, which may lead to beneficial adaptations that may ultimately reduce fatigue during walking in PAD. Early work in this area has shown that full-body heating is capable of generating an acute cardiovascular response, similar to exercise, which has been suggested as the most efficient treatment modality and may generate adaptations with chronic exposure. Heat therapies may emerge as a conservative treatment option capable of attenuating the progression of PAD and ultimately impeding the development of plantar ulcers.
Topics: Amputation, Surgical; Hot Temperature; Humans; Hydrotherapy; Microcirculation; Peripheral Arterial Disease
PubMed: 33804430
DOI: 10.3390/ijerph18052384 -
Cardiology Journal 2020
Topics: Betacoronavirus; COVID-19; Cardiovascular Diseases; Coronavirus Infections; Humans; Microcirculation; Pandemics; Pneumonia, Viral; SARS-CoV-2
PubMed: 33165898
DOI: 10.5603/CJ.2020.0154 -
BMC Ophthalmology Jul 2022The study aims to assess the alterations in retinal oxygen saturation and retinal and choroidal blood flow in lipemia retinalis.
PURPOSE
The study aims to assess the alterations in retinal oxygen saturation and retinal and choroidal blood flow in lipemia retinalis.
METHODS
This was a cross-sectional study on 10 eyes (5 patients) with history of lipemia retinalis. The study comprised 10 eyes with documented history of lipemia retinalis and 10 participants as healthy controls. Patients with a confirmed history of lipemia retinalis were grouped into two cohorts based on their most recent fundus examination: untreated lipemia retinalis (abnormal fundus) and resolved lipemia retinalis (normal fundus). Both retinal arteriolar and venular oxygen saturation were measured using the non-invasive spectrophotometric retinal oximeter (Oxymap T1). The mean blur rate (MBR) of the optic nerve and choroidal blood flow were analyzed using a laser speckle flowgraph (LSFG).
RESULTS
Patients with untreated lipemia retinalis had a significantly higher retinal arteriolar and venular oxygen saturation than that of the other two groups (p < 0.001). Moreover, patients with untreated lipemia retinalis had significantly smaller retinal arteriolar and venular diameters (p < 0.001). On LSFG, there was a significant difference in the overall MBR (p = 0.007) and vessel MBR of the optic nerve between the groups (p = 0.011). The patients with history of lipemia retinalis (untreated and resolved) exhibited a high overall MBR and vessel MBR of the optic nerve than that of the control group. There was a significant elevation of the optic nerve (p = 0.002) and choroidal blowout score (p < 0.001), while the resistivity index of the optic nerve (p = 0.001) and choroids (p = 0.002) was significantly lower in patients with resolved and untreated lipemia retinalis.
CONCLUSIONS
There was a significant alteration in retinal oximetry, in untreated lipemia retinalis, and in retinal blood flow, in both the resolved and untreated groups. The increase in retinal blood flow and oxygen saturation may elucidate the preservation of visual acuity and function despite the fundus changes observed in lipemia retinalis.
Topics: Cross-Sectional Studies; Fundus Oculi; Humans; Hyperlipidemias; Microcirculation; Oxygen; Retinal Diseases
PubMed: 35794613
DOI: 10.1186/s12886-022-02515-7 -
ELife Jul 2023Aging is a major risk factor for cognitive impairment. Aerobic exercise benefits brain function and may promote cognitive health in older adults. However, underlying...
Aging is a major risk factor for cognitive impairment. Aerobic exercise benefits brain function and may promote cognitive health in older adults. However, underlying biological mechanisms across cerebral gray and white matter are poorly understood. Selective vulnerability of the white matter to small vessel disease and a link between white matter health and cognitive function suggests a potential role for responses in deep cerebral microcirculation. Here, we tested whether aerobic exercise modulates cerebral microcirculatory changes induced by aging. To this end, we carried out a comprehensive quantitative examination of changes in cerebral microvascular physiology in cortical gray and subcortical white matter in mice (3-6 vs. 19-21 months old), and asked whether and how exercise may rescue age-induced deficits. In the sedentary group, aging caused a more severe decline in cerebral microvascular perfusion and oxygenation in deep (infragranular) cortical layers and subcortical white matter compared with superficial (supragranular) cortical layers. Five months of voluntary aerobic exercise partly renormalized microvascular perfusion and oxygenation in aged mice in a depth-dependent manner, and brought these spatial distributions closer to those of young adult sedentary mice. These microcirculatory effects were accompanied by an improvement in cognitive function. Our work demonstrates the selective vulnerability of the deep cortex and subcortical white matter to aging-induced decline in microcirculation, as well as the responsiveness of these regions to aerobic exercise.
Topics: Animals; Mice; Microcirculation; Aging; Cognitive Dysfunction; White Matter; Cognition; Cerebral Cortex
PubMed: 37402178
DOI: 10.7554/eLife.86329