Microcirculatory Alterations Research Articles

Microvascular Alteration in COVID-19 Documented by Nailfold Capillaroscopy.

COVID-19 is a multisystemic disease that mainly affects and causes dysregulation of the endothelium, causing systemic manifestations. A nailfold video capillaroscopy is a safe, easy, and noninvasive method to evaluate microcirculation alteration. In this review, we analyzed the literature available to date regarding the object of nailfold video capillaroscopy (NVC) use in patients with a SARS-CoV-2 infection, both in the acute phase and after discharge. The scientific evidence pointed out the main alterations in capillary circulation shown by NVC, so reviewing the findings of each article allowed us to define and analyze the future prospects and needs for possibly including NVC within the management of patients with COVID-19, both during and after the acute phase.

Early fluid and norepinephrine resuscitation in septic acute kidney injury diminishes pro-inflammatory cytokine levels and kidney hypoperfusion in newborn pigs

Background and Objective: Sepsis is the most frequent risk factor for acute kidney injury (AKI) in critically ill infants. Whereas sepsis-induced AKI has been studied in several animal models, alterations in renal microcirculation are unclear. The objective of this study was to use the translational swine model to evaluate the changes in renal hemodynamics during the early phase of sepsis in the first week of life. We also examined the impact of early fluid and norepinephrine (NE) resuscitation on renal hemodynamics in newborn septic AKI. Methodology: Newborn pigs (3-7 days old) were randomly allocated to three groups; 1) Sham, 2) Sepsis (cecal ligation and puncture; CLP) without subsequent resuscitation, and 3) CLP-induced sepsis with fluid and vasopressor NE resuscitation. All animals underwent standard anesthesia induction, mechanical ventilation, and intravenous fluid. Cardiac output (COP) and GFR were measured non-invasively using electrical velocimetry and a transdermal system. The pigs were instrumented to measure the mean arterial pressure (MAP), total renal blood flow (tRBF), cortical perfusion (coPf), and medullary perfusion (mePf). Also, a fiber-optic probe was placed in the medulla to measure medullary tissue oxygen tension (tPO2). Baseline values were recorded for the above indices in all groups. In resuscitated animals, fluid bolus and NE infusion were started at the 4-h to maintain MAP within 15 mmHg from baseline. The pigs were euthanized after twelve hours. Results: Compared to baseline values, MAP and COP decreased by more than two-thirds in non-resuscitated sepsis, with a proportional increase in RVR and reduction in tRBF, coPf, mePf, and tPO2 in contrast to sham. CLP also decreased GFR and increased serum creatinine, BUN, and NGAL. A few tubular coagulative necroses were observed in the septic pigs. Changes in all these parameters, except tPO2, were ameliorated in resuscitated pigs. Resuscitation also attenuated sepsis-induced increase in the levels of serum C-reactive protein, inflammatory cytokines (IL-6, IL-8, IL-12, and IL-18), liver enzymes (aspartate aminotransferase and alanine aminotransferase), and renal NLRP3 inflammasome. Conclusions: Early implementation of resuscitation to maintain MAP, COP, and kidney perfusion lessens the degree of inflammation, AKI, and liver injury in newborn pigs. The discrepancy between medullary perfusion and oxygenation indicates that optimizing perfusion and blood flow does not always correlate with improved medullary oxygen delivery in newborns, especially in cases of increased metabolic demand, as in sepsis. Sepsis is a dynamic illness with phases of hypodynamic and hyperdynamic renal perfusion; therefore, management strategies would differ based on hemodynamic status. NIH R01DK120595 and R01DK127625 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Copeptin as a Biomarker of Microcirculation Alterations in Systemic Sclerosis.

Systemic sclerosis is a connective tissue disease characterized by vasculopathy and progressive fibrosis, leading to multiorgan dysfunction. Given the complex and not fully elucidated pathogenesis, biomarkers of rapid disease progression and therapeutic response are lacking. Copeptin, which reflects vasopressin activity in serum, is used in diagnosing or prognosing different cardiometabolic conditions. The aim of study was to investigate the concentration of copeptin in patients with systemic sclerosis and correlate it with specific clinical symptoms. Serum copeptin was measured in patients with systemic sclerosis (34 women and 3 men; mean age 57.6 years) and in healthy individuals (n=30) using commercially available ELISA kits. According to the criteria of LeRoy our systemic sclerosis cohort consisted of 17 patients with limited cutaneous systemic sclerosis (45.9%) and 20 diffuse cutaneous systemic sclerosis patients (54.1%). According to the criteria of LeRoy our systemic sclerosis cohort consisted of 17 patients with limited cutaneous systemic sclerosis (45.9%) and 20 diffuse cutaneous systemic sclerosis patients (54.1%). The median duration of the disease was 10 [4-14] years. We found significantly higher copeptin concentration in patients with systemic sclerosis (4.21 pmol/L [3.04-5.42]) in comparison to control group (3.40 pmol/L [2.38-3.76], p<0.01). Copeptin significantly correlated with Raynaud's condition score (r=0.801, p<0.05). Patients with "late" capillaroscopic patterns had higher copeptin concentrations (5.37 pmol/L [4.29-8.06]) than patients with "early" (2.43 pmol/L [2.25-3.20], p<0.05) and "active" patterns (3.93 pmol/L [2.92-5.16], p<0.05]). Copeptin was found to be significantly higher in SSc patients with DUs (5.71 pmol/L [IQR 4.85-8.06]) when compared to SSc patients without DUs (3.31 pmol/L, [2.28-4.30], p<0.05). Additionally, copeptin concentration had good diagnostic accuracy in discriminating between patients with and without digital ulcers (AUC=0.863). Alprostadil decreased copeptin concentration from 4.96 [4.02-6.01] to 3.86 pmol/L [3.17-4.63] (p<0.01) after 4-6 cycles of administration. Our findings suggest that copeptin may be a promising biomarker of microcirculation alterations in systemic sclerosis.

Beat-to-beat finger photoplethysmography in atrial fibrillation patients undergoing electrical cardioversion

Atrial fibrillation (AF)-induced peripheral microcirculatory alterations have poorly been investigated. The present study aims to expand current knowledge through a beat-to-beat analysis of non-invasive finger photoplethysmography (PPG) in AF patients restoring sinus rhythm by electrical cardioversion (ECV). Continuous non-invasive arterial blood pressure and left middle finger PPG pulse oximetry waveform (POW) signals were continuously recorded before and after elective ECV of consecutive AF or atrial flutter (AFL) patients. The main metrics (mean, standard deviation, coefficient of variation), as well as a beat-to-beat analysis of the pulse pressure (PP) and POW beat-averaged value (aPOW), were computed to compare pre- and post-ECV phases. 53 patients (mean age 69 ± 8 years, 79% males) were enrolled; cardioversion was successful in restoring SR in 51 (96%) and signal post-processing was feasible in 46 (87%) patients. In front of a non-significant difference in mean PP (pre-ECV: 51.96 ± 13.25, post-ECV: 49.58 ± 10.41 mmHg; p = 0.45), mean aPOW significantly increased after SR restoration (pre-ECV: 0.39 ± 0.09, post-ECV: 0.44 ± 0.06 a.u.; p < 0.001). Moreover, at beat-to-beat analysis linear regression yielded significantly different slope (m) for the PP (RR) relationship compared to aPOW(RR) [PP(RR): 0.43 ± 0.18; aPOW(RR): 1.06 ± 0.17; p < 0.001]. Long (> 95th percentile) and short (< 5th percentile) RR intervals were significantly more irregular in the pre-ECV phases for both PP and aPOW; however, aPOW signal suffered more fluctuations compared to PP (p < 0.001 in both phases). Present findings suggest that AF-related hemodynamic alterations are more manifest at the peripheral (aPOW) rather than at the upstream macrocirculatory level (PP). Restoring sinus rhythm increases mean peripheral microvascular perfusion and decreases variability of the microvascular hemodynamic signals. Future dedicated studies are required to determine if AF-induced peripheral microvascular alterations might relate to long-term prognostic effects.

Evaluation of retinal microcirculation alterations using OCTA in hyperopic ametropic amblyopia patients before and after treatment

PurposeWe aimed to compare retinal microcirculation in hyperopic ametropic amblyopia patients before and after treatment and in healthy children using optical coherence tomography angiography (OCTA), and to explore the pathogenesis of hyperopic ametropic amblyopia.MethodsEighteen patients with hyperopic ametropic amblyopia aged 4–8 years were selected as the patient group, and 18 age-matched healthy children were randomly selected as controls. The foveal avascular zone (FAZ) area, perimeter and circularity, vessel density (VD) and perfusion density (PD) of macular superficial retinal capillary plexus, macular thickness, peripapillary retinal nerve fiber layer thickness, and ganglion cell-inner plexiform layer thickness were compared between both groups. After 6 months of amblyopia treatment, the same parameters were measured again.ResultsThe VD and PD in the central, inner, inner nasal, and inner inferior regions in hyperopic ametropic amblyopia were lower than in the control group after adjustment for axial length. After 6 months of treatment, the VD increased significantly, except in the outer nasal and outer inferior regions. The PD in the central (p < 0.001), inner superior (p = 0.001), inner inferior (p = 0.011) and inner temporal (p = 0.026) regions increased. The FAZ perimeter and circularity significantly differed between the groups. After 6 months of treatment, the FAZ area and perimeter decreased, but circularity increased.ConclusionHyperopic ametropic amblyopia eyes showed a significant decrease in vessel and perfusion densities. After amblyopia treatment, the vessel and perfusion densities of patients with hyperopic ametropic amblyopia increased, suggesting that abnormalities in the microvascular system are a pathogenic factor of amblyopia.

The acute effect of respiratory muscle training on microcirculation in patients with chronic heart failure

Background: Patients with chronic heart failure (CHF) present microcirculation alterations and vascular endothelial dysfunction. Exercise training programs have been shown to improve the functional status of these patients, however less is known yet about the acute systemic effect of exercise on peripheral muscle microcirculation. The aim of the present study was to investigate the acute effect of a respiratory muscle exercise bout on the microcirculation of non-exercising muscles (systemic effect). Materials and Methods: Thirty-four (30♂/4♀) stable CHF patients, with a mean age of61.4±9.2 years, ejection fraction (EF): 33.9±7.8%, maximal inspiratory pressure (MIP): 78.2±27.1 cmH2O, VO2max: 17.5±4.05 ml/kg/min, VE/VCO2 slope: 32.7±6.4 and a New York Heart Association classification (NYHA) ≥ ΙΙ participated in the study. Microcirculatory assessment was performed at rest and immediately after the respiratory exercise program (5 sets/10 repetitions, training load: 60% of MIP). Basal tissue oxygen saturation (StO2),oxygen consumption rate (OCR) and reperfusion rate (RR) were measured utilizing near-infrared spectroscopy(NIRS) at the thenar muscle along with the vascular occlusion test (VOT). Results: RR (%/min), following the release of vascular occlusion, as well as OCR (%/min) increased after the respiratory exercise program (from 3.4±1.6 to 3.9±1.7, p=0.007, and from 12.7±3.8 to 13.2±3.9, p=0.021 respectively), whereas the corresponding basal StO2values difference did not reach the level of statistical significance (from 85.5±6.4. to 84.7±6.2, p=0.065). Conclusions: In the present study, concerning patients with CHF, after an acute respiratory exercise bout, dynamic microcirculatory indices assessed by NIRS in peripheral, non-exercising muscles, were significantly altered.

Retinal Manifestations in Patients with Myeloproliferative Disorders

Ocular involvement in myeloproliferative diseases (MPD) is common and retinal findings are various. Retinal manifestations are due to hematologic changes, microcirculatory alterations, and hyperviscosity of blood. Ocular findings might precede the diagnosis of MPD and might regress following treatment for MPD. Therefore, in cases with atypical retinal findings refractory to treatment, MPD must be kept in mind in the differential diagnosis. The early diagnosis of the underlying disease and its appropriate treatment will affect morbidity and mortality in these patients. Retinal findings might also be asymptomatic in patients with MPD. Patients with MPD must, therefore, have regular ocular examinations in follow-up.

Ultra-High-Resolution Photon-Counting CT Imaging of the Chest: A New Era for Morphology and Function.

After a decade of preclinical testing, photon-counting computed tomography (PCCT) has now entered daily routine, enabling radiologists to start investigating thoracic disorders in unprecedented conditions. The improved spatial resolution of the ultra-high-resolution (UHR) scanning mode is a major step for the analysis of bronchopulmonary disorders, making abnormalities at the level of small anatomical structures such as secondary pulmonary lobules accessible to radiologists. Distal divisions of pulmonary and systemic vessels also benefit from UHR protocols as alterations of lung microcirculation were previously excluded from confident analysis with energy-integrating detector CT. Although noncontrast chest CT examinations were the initial target of UHR protocols, the clinical value of this mode is also applicable to chest CT angiographic examinations with improved morphological evaluation and higher-quality lung perfusion imaging. The clinical benefits of UHR have been evaluated in initial studies, allowing radiologists to foresee the field of future applications, all combining high diagnostic value and radiation dose reduction. The purpose of this article is to highlight the technological information relevant to daily practice and to review the current clinical applications in the field of chest imaging.

Evaluation of retinal microcirculation alterations using optical coherence tomography angiography in patients with hyperopia ametropic amblyopia: A case-control study.

Given that there are controversial findings regarding vessel density in amblyopia, we quantified retinal microcirculation using optical coherence tomography angiography and compared it between hyperopic ametropic amblyopia eyes and age-matched control eyes. This case-control study was conducted from March 2021 to March 2022 at the Affiliated Eye Hospital of Nanchang University, Nanchang, China. Both groups included 72 eyes. Foveal avascular zone area, circularity and perimeter, perfusion density and vessel density of macular superficial retinal capillary plexus, macular thickness, macular volume, peripapillary retinal nerve fiber layer thickness, and ganglion cell-inner plexiform layer thickness were compared between hyperopia ametropic amblyopia eyes and age-matched control eyes. Additionally, best-corrected visual acuity, maximum corneal curvature, minimum corneal curvature, and anterior chamber depth were measured. In the hyperopia ametropic amblyopia eyes and control eyes, vessel density was 7.51 ± 2.13 and 9.91 ± 2.71 mm-1 in the central, 17.20 ± 1.38 and 18.25 ± 1.37 mm-1 in the inner, and 17.90 ± 0.88 and 18.43 ± 0.97 mm-1 in the full regions, respectively. The perfusion densities were 0.17 ± 0.06 and 0.23 ± 0.07 in the central, 0.41 ± 0.05 and 0.44 ± 0.03 in the inner, and 0.44 ± 0.03 and 0.46 ± 0.02 in the full regions, respectively. The central macular thicknesses of hyperopia ametropic amblyopia and control eyes were 240.04 ± 20.11 and 235.08 ± 24.41 µm, respectively. Foveal avascular zone perimeter and circularity (P < .043 and P = .001) significantly differed between the 2 groups. Hyperopia ametropic amblyopia eyes showed lower appreciably in vessel and perfusion densities, which could be one of the major pathophysiological mechanisms of hyperopia ametropic amblyopia and provide a new direction for the diagnosis and treatment of amblyopia.

Peripheral microcirculation alteration as cause of postero-superior rotator cuff tear: the possible indirect contribution of nailfold capillaroscopy.

Most of the recent literature regarding rotator cuff tear etiology identifies in peripheral microcirculation disorders the probable main cause of tissue degeneration, and consequently of tendon rupture. Nailfold capillaroscopy is a practical and inexpensive diagnostic technique used to evaluate the health status of the peripheral microcirculation and, recently, its use has found other indications in addition to that of diagnosing connective tissue diseases and Raynaud's phenomenon. We verified the possible indirect contribution of nailfold capillaroscopy in the identification of peripheral microcirculation disturbances in a group of patients with rotator cuff tear and whether these possible alterations could be related to rotator cuff tear size. A case control study was performed. 100 patients [(56M-44F; mean age(SD): 60.46 (5.46)] with different sized postero-superior cuff tears and 100 healthy controls [(38M:62F mean age (SD):60.40(6.34)] were submitted to capillaroscopic exam. The following parameters were examined: capillary morphology and density; avascular areas; visibility of the sub-papillary venous plexus; enlarged and giant capillaries; ectasias and microaneurysms; neo-angiogenesis; hemosiderin deposits; pericapillary edema; capillary blood flow. Severe exclusion criteria were applied. Statistical analysis was performed. Visibility of SPVP (p<0.001), pericapillary edema (p<0.001), capillary blood flow (p<0.001), ectasias and microaneurysms (p<0.001) and neo-angiogenesis (p = 0.04) were significantly associated with presence of RCT. Our results contribute to support the hypothesis that microcirculation disorder has a relevant role on the genesis of cuff degeneration and, consequently, of tendon rupture. However, these alterations do not seem to be related to rotator cuff tear size.

Retinal microvasculature is a potential biomarker for acute mountain sickness.

Increased cerebral blood flow resulting from altered capillary level autoregulation at high altitudes leads to capillary overperfusion and then vasogenic cerebral edema, which is the leading hypothesis of acute mountain sickness (AMS). However, studies on cerebral blood flow in AMS have been mostly restricted to gross cerebrovascular endpoints as opposed to the microvasculature. This study aimed to investigate ocular microcirculation alterations, the only visualized capillaries in the central neural system (CNS), during early-stage AMS using a hypobaric chamber. This study found that after high altitude simulation, the optic nerve showed retinal nerve fiber layer thickening (P=0.004-0.018) in some locations, and the area of the optic nerve subarachnoid space (P=0.004) enlarged. Optical coherence tomography angiography (OCTA) showed increased retinal radial peripapillary capillary (RPC) flow density (P=0.003-0.046), particularly on the nasal side of the nerve. The AMS-positive group had the largest increases in RPC flow density in the nasal sector (AMS-positive, Δ3.21±2.37; AMS-negative, Δ0.01±2.16, P=0.004). Among multiple ocular changes, OCTA increase in RPC flow density was associated with simulated early-stage AMS symptoms (beta=0.222, 95%CI, 0.009-0.435, P=0.042). The area under the receiver operating characteristics curve (AUC) for the changes in RPC flow density to predict early-stage AMS outcomes was 0.882 (95%CI, 0.746-0.998). The results further confirmed that overperfusion of microvascular beds is the key pathophysiologic change in early-stage AMS. RPC OCTA endpoints may serve as a rapid, noninvasive potential biomarker for CNS microvascular changes and AMS development during risk assessment of individuals at high altitudes.

Intra-renal microcirculatory alterations on non-traumatic hemorrhagic shock induced acute kidney injury in pigs.

Acute kidney injury (AKI) is frequently seen in patients with hemorrhagic shock due to hypotension, tissue hypoxia, and inflammation despite adequate resuscitation. There is a lack of information concerning the alteration of renal microcirculation and perfusion during shock and resuscitation. The aim of this study was to investigate the possible role of renal microcirculatory alterations on development of renal dysfunction in a pig model of non-traumatic hemorrhagic shock (HS) induced AKI.Fully instrumented female pigs were divided into the two groups as Control (n = 6) and HS (n = 11). HS was achieved by withdrawing blood until mean arterial pressure (MAP) reached around 50 mmHg. After an hour cessation period, fluid resuscitation with balanced crystalloid was started for the duration of 1h. The systemic and renal hemodynamics, renal microcirculatory perfusion (contrast-enhanced ultrasound (CEUS)) and the sublingual microcirculation were measured.CEUS peak enhancement was significantly increased in HS during shock, early-, and late resuscitation indicating perfusion defects in the renal cortex (p < 0.05 vs. baseline, BL) despite a stable renal blood flow (RBF) and urine output. Following normalization of systemic hemodynamics, we observed persistent hypoxia (high lactate) and high red blood cell (RBC) velocity just after initiation of resuscitation resulting in further endothelial and renal damage as shown by increased plasma sialic acid (p < 0.05 vs. BL) and NGAL levels. We also showed that total vessel density (TVD) and functional capillary density (FCD) were depleted during resuscitation (p < 0.05).In this study, we showed that the correction of systemic hemodynamic variables may not be accompanied with the improvement of renal cortical perfusion, intra-renal blood volume and renal damage following fluid resuscitation. We suggest that the measurement of renal injury biomarkers, systemic and renal microcirculation can be used for guiding to the optimization of fluid therapies.

Ischemia with Nonobstructive Coronary Artery Disease and Atrial Cardiomyopathy-Two Sides of the Same Story?

Ischemia with nonobstructive coronary artery disease (INOCA) is increasingly recognized as a significant cause of angina, myocardial remodeling, and eventually heart failure (HF). Coronary microvascular dysfunction (CMD) is a major endotype of INOCA, and it is caused by structural and functional alterations of the coronary microcirculation. At the same time, atrial cardiomyopathy (ACM) defined by structural, functional, and electrical atrial remodeling has a major clinical impact due to its manifestations: atrial fibrillation (AF), atrial thrombosis, stroke, and HF symptoms. Both these pathologies share similar risk factors and have a high comorbidity burden. CMD causing INOCA and ACM frequently coexist. Thus, questions arise whether there is a potential link between these pathologies. Does CMD promote AF or the reverse? Which are the mechanisms that ultimately lead to CMD and ACM? Are both part of a systemic disease characterized by endothelial dysfunction? Lastly, which are the therapeutic strategies that can target endothelial dysfunction and improve the prognosis of patients with CMD and ACM? This review aims to address these questions by analyzing the existing body of evidence, offering further insight into the mechanisms of CMD and ACM, and discussing potential therapeutic strategies.

Longitudinal Strain Analysis and Correlation with TIMI Frame Count in Patients with Ischemia with No Obstructive Coronary Artery (INOCA) and Microvascular Angina (MVA).

Background: The aim of the study is to evaluate the subclinical alterations of cardiac mechanics detected using speckle-tracking echocardiography and compare these data with the coronary angiography indices used during coronary angiography in a population of patients diagnosed with ischemia with no obstructive coronary artery (INOCA) and microvascular angina (MVA). Methods: The study included 85 patients admitted to our center between November 2019 and January 2022 who were diagnosed with INOCA compared with a control group of 70 healthy patients. A collection of anamnestic data and a complete cardiovascular physical examination, and echocardiogram at rest with longitudinal strain were performed for all patients. Furthermore, the TIMI frame count (TFC) for the three coronary vessels was calculated according to Gibson's indications. All parameters were compared with a control population with similar characteristics. Results: Patients with INOCA compared to the control population showed statistically significant changes in the parameters assessed on the longitudinal strain analysis. In particular, patients with INOCA showed statistically significant changes in GLS (-16.71) compared to the control population (-19.64) (p = 0.003). In patients with INOCA, the total TIMI frame count (tTFC) correlated with the GLS value with a correlation coefficient of 0.418 (p = 0.021). Conclusions: In patients with angina, documented myocardial ischemia, the absence of angiographically significant stenosis (INOCA) and LVEF > 50%, the prevalence of microvascular dysfunction documented by TFC was extremely represented. A statistically significant reduction in GLS was observed in these patients. TFC and longitudinal strain, therefore, appear to be two reliable, sensitive and easily accessible methods for the study of alterations in coronary microcirculation and the characterization of patients with INOCA and microvascular angina.

Assessment of Indices of Conjunctival Microvascular Function in Patients With and Without Obstructive Coronary Artery Disease

BackgroundAtherosclerotic heart disease often remains asymptomatic until presentation with a major adverse cardiovascular event. Primary preventive therapies improve outcomes, but conventional screening often misattributes risk. Vascular imaging can be utilised to detect atherosclerosis, but often involves ionising radiation. The conjunctiva is a readily accessible vascular network allowing non-invasive hemodynamic evaluation. AimTo compare conjunctival microcirculatory function in patients with and without obstructive coronary artery disease. MethodsWe compared the conjunctival microcirculation of myocardial infarction patients (MI-cohort) to controls with no obstructive coronary artery disease (NO-CAD cohort). Conjunctival imaging was performed using a smartphone and slit-lamp biomicroscope combination. Microvascular indices of axial (Va) and cross-sectional (Vcs) velocity; blood flow rate (Q); and wall shear rate (WSR) were compared in all conjunctival vessels between 5 and 45 μm in diameter. ResultsA total of 127 patients were recruited (66 MI vs 61 NO-CAD) and 3602 conjunctival vessels analysed (2414 MI vs 1188 NO-CAD). Mean Va, Vcs and Q were significantly lower in the MI vs NO-CAD cohort (Va 0.50 ± 0.17 mm/s vs 0.55 ± 0.15 mm/s, p < 0.001; Vcs 0.35 ± 0.12 mm/s vs 0.38 ± 0.10 mm/s, p < 0.001; Q 154 ± 116 pl/s vs 198 ± 130 pl/s, p < 0.001). To correct for differences in mean vessel diameter, WSR was compared in 10–36 μm vessels (3268/3602 vessels) and was lower in the MI-cohort (134 ± 64 s−1 vs 140 ± 63 s−1, p = 0.002). ConclusionsConjunctival microcirculatory alterations can be observed in patients with obstructive coronary artery disease. The conjunctival microvasculature merits further evaluation in cardiovascular risk screening.

Recent Advances in Fluids and Electrolyte Management in Sepsis

Sepsis condition can cause life-threatening complications including organ dysfunction, circulatory failure, or mortality. Electrolyte abnormalities, including hyperkalaemia, hyponatremia, hypophosphatemia, and hypocalcaemia, have been observed in the later stages of sepsis due to cellular damage or ion channel dysfunction. Fluid resuscitation has been suggested as the common intervention to improve the patient’s condition when in septic shock. Fluids can help in an enhanced distribution of both intravascular and extravascular compartments, thereby increasing cardiac output. Timely fluid administration has shown improved survival rates with fewer severe microcirculatory alterations and mitochondrial dysfunctions. Fluid and electrolyte management is an effective strategy for treating sepsis but certain factors including timing, dosage, type of fluid and the health status of the individual needs to be carefully considered. Early intervention therapy seems to be effective in individuals with sepsis and has minimized the requirement for additional fluid administration. Certain aspects of fluid management including the future potentiality of dynamic fluid responsiveness and the role of albumin administration in sepsis treatment still need to be clarified. This review focuses on the updated management strategies that can be used for fluid and electrolyte management in individuals with sepsis. Keywords: Sepsis; Fluid resuscitation; electrolyte replacement therapy; albumin; intravenous therapy; septic shock Highlights In patients with sepsis, fluid resuscitation has been an effective intervention and earlier administration of therapy has minimized the need for additional fluid administration. Future research lends scope for improvement and advancements in electrolyte replacement therapy, effects of resuscitation, the effectiveness of fluid responsiveness and role of albumin in fluid management.

MICROCIRCULATORY ALTERATIONS IN STABLE CORONARY ARTERY DISEASE PATIENTS WITH CONCOMITANT COVID-19.

The aim: To evaluate the alterations in microcirculation of stable coronary artery disease (SCAD) patients with concomitant COVID-19. Materials and methods: The cross-sectional study analyzed the data from 80 patients, being subdivided as follows: group 1 (G1) - SCAD without COVID-19 (n=30); group 2 (G2) - SCAD with concomitant COVID-19 (n=25); group 3 (G3) - COVID-19 without SCAD (n=25). The control group included 30 relatively healthy volunteers. The state of microcirculation was assessed by nailfold videocapillaroscopy (NVC) and laser Doppler flowmetry (LDF). Results: NVC data from G2 revealed the sings of capillary bed remodeling, along with the most pronounced decrease in capillary (arteriolar part of the loop) blood flow velocity (vs. G1 and G3). LDF data from G2 were evident for the alterations in both endothelium-dependent and -independent mechanisms of microvascular flow regulation. The 72 % of G2 constituted the cases of microcirculatory hemodynamic «congestion-stasis» (MHCS) type (characterized by the decreased laser Doppler perfusion index and reduced endothelium-dependent microvascular reactivity [MVR]), and the cases of mixed type with reduced MVR. The pooled hyporeactive profile (of both MHCS type and a mixed type with reduced MVR) demonstrated the higher frequency of G2 patients (40 %), as against 11 % in the pooled alternative hemodynamic group (p<0,001) (included 80 % of cases with preserved MVR). Conclusions: G2 profile demonstrated the predomination of patients, possessing a MHCS type or a mixed type with reduced MVR. The pooled microcirculatory hyporeactive profile was presented with G2 cases to a greater extent, than in the pooled profile with predominantly preserved MVR.

Oxalate Nephropathy.

Oxalate Nephropathy.

Effect of silicone oil on retinal microcirculation after vitrectomy for rhegmatogenous retinal detachment evaluated by OCT angiography: a literature review.

Silicone oil (SO) has been widely used as intravitreal tamponade agent for rhegmatogenous retinal detachment (RRD) and has been occasionally associated with incomplete retinal structural and functional recovery. The use of Optical Coherence Tomography Angiography (OCT-A) has recently attracted significant attention for detailed analysis of retinal capillary plexus and blood flow changes as predicting factors for postoperative outcomes. A detailed literature search was performed in PubMed database until October 2022. The following keywords were used: rhegmatogenous retinal detachment, silicone oil, optical coherence tomography angiography, macular microvasculature, peripapillary capillary plexus, vessel density, and foveal avascular zone. We identified and reviewed 19 studies referring to microcirculation alterations of the retinal capillary plexus as seen on OCT-A in eyes treated by vitrectomy with intravitreal SO for RRD. A comprehensive update revealed variability of microcirculation characteristics of the retinal capillary plexus including the macular and the peripapillary capillaries. Further studies are warranted to clarify the OCT-A values in an attempt to identify the potential effect of SO on retinal tissue in clinical practice. A review of the existing literature sheds light on the effect of SO on retinal capillary plexus and the potential impact on functional outcomes after vitrectomy for RRD. This article discusses important aspects of key publications on the topic, highlights the importance to identify distinct alterations of the microvasculature status, and proposes the need for further future research in this field.

Is the Weight of the Newborn Puppy Related to Its Thermal Balance?

Hypothermia, a factor associated with neonatal mortality, can occur immediately after birth as a protective mechanism to prevent hypoxic damage in neonates, or to reduce the metabolic rate to improve the chances of survival in the first hours of life. The heat interchange through the superficial temperature of animals can be evaluated with infrared thermography (IRT). However, to date, there is no information on thermal windows in puppies. This study aimed to evaluate, with the use of IRT, the microcirculatory alterations in 8 different thermal windows identified at 7 different times in 289 newborn puppies assigned to different groups. Three thermograms were taken from four zones of each puppy: the facial, frontal, right lateral, and left lateral regions. Newborn puppies were grouped in 4 quartiles according to their weight: Q1 (126-226 g) n = 73, Q2 (227-330 g) n = 72, Q3 (331-387 g) n = 74, and Q4 (388-452 g) n = 70. A total of 8 thermal windows were considered at 7 evaluation times from Wet at birth until 24 h after birth (AB). Two-way mixed ANOVA within and between subjects' design for each thermal window (eight models) was performed. Results revealed a positive correlation between the puppy's weight and its ability to achieve thermostability in all the evaluated thermal windows. Statistically significant differences (p &lt; 0.0001) between the 4 quartiles (Q1, Q2, Q3, and Q4) were found. The lowest temperatures were recorded when the pups were still wet and the highest at 24 h AB. Thermal windows with the highest temperatures were abdominal (34.234 ± 0.056 °C), thoracic (33.705 ± 0.049 °C), nasal (30.671 ± 0.110 °C), and upper left palpebral (34.066 ± 0.052 °C), while the lowest were thoracic limb brachial biceps (27.534 ± 0.051 °C), thoracic limb elbow (27.141 ± 0.049 °C), thoracic limb metacarpal (27.024 ± 0.062 °C), and femoral pelvic limb (27.654 ± 0.055 °C). Assessing the thermal response in newborn puppies can help identify drastic temperature reductions or deficient thermoregulatory compensation during the first hours of life, preventing the consequences of hypothermia.