Evaluation of electronic measurement of capillary refill for Sepsis screening at ED triage

OBJECTIVE

To evaluate the association between capillary refill time (CRT) measured by a medical device and sepsis among patients presenting to the Emergency Department (ED).

METHODS

This prospective observational study enrolled adult and pediatric patients during ED triage when sepsis was considered a potential diagnosis by the triage nurse. Patients were enrolled at an academic medical center between December 2020 and June 2022. CRT was measured by a research assistant using an investigational medical device. The outcomes included sepsis and septic shock defined using sep-3 criteria, septic shock defined as IV antibiotics and a vasopressor requirement, ICU admission, and hospital mortality. Other measures included patient demographics and vital signs at ED triage. We evaluated univariate associations between CRT and sepsis outcomes.

RESULTS

We enrolled 563 patients in the study, 48 met Sep-3 criteria, 5 met Sep-3 shock criteria, and 11 met prior septic shock criteria (IV antibiotics and vasopressors to maintain mean arterial pressure of 65). Sixteen patients were admitted to the ICU. The mean age was 49.1 years, and 51% of the cohort was female. The device measured CRT was significantly associated with the diagnosis of sepsis by sep-3 criteria (OR 1.23, 95% CI 1.06-1-43), septic shock by sep-3 criteria (OR 1.57, 95% CI 1.02-2.40), and septic shock defined as receipt of IV antibiotics and a vasopressor requirement (OR 1.37, 95% CI 1.03-1.82). Patients with CRT >3.5 s measured by the DCR device had an odds ratio of 4.67 (95%CI 1.31-16.1) of septic shock (prior definition), and an odds ratio of 3.97 (95% CI 1.99-7.92) of ICU admission, supporting the potential for the 3.5-s cutoff of the DCR measurement.

CONCLUSIONS

CRT measured by a medical device at ED triage was associated with the diagnosis of sepsis. Objective CRT measurement using a medical device may be a relatively simple way to improve sepsis diagnosis during ED triage.

Microcirculatory dysfunction in cardiogenic shock

Cardiogenic shock is usually defined as primary cardiac dysfunction with low cardiac output leading to critical organ hypoperfusion, and tissue hypoxia, resulting in high mortality rate between 40% and 50% despite recent advances. Many studies have now evidenced that cardiogenic shock not only involves systemic macrocirculation, such as blood pressure, left ventricular ejection fraction, or cardiac output, but also involves significant systemic microcirculatory abnormalities which seem strongly associated with the outcome. Although microcirculation has been widely studied in the context of septic shock showing heterogeneous alterations with clear evidence of macro and microcirculation uncoupling, there is now a growing body of literature focusing on cardiogenic shock states. Even if there is currently no consensus regarding the treatment of microcirculatory disturbances in cardiogenic shock, some treatments seem to show a benefit. Furthermore, a better understanding of the underlying pathophysiology may provide hypotheses for future studies aiming to improve cardiogenic shock prognosis.

Tissue Oxygenation Around Capillaries: Effects of Hematocrit and Arteriole Oxygen Condition

Oxygen transfer in the microvasculature is a complex phenomenon that involves multiple physical and chemical processes and multiple media. Hematocrit, the volume fraction of red blood cells (RBCs) in blood, has direct influences on the blood flow as well as the oxygen supply in the microcirculation. On the one hand, a higher hematocrit means that more RBCs present in capillaries, and thus, more oxygen is available at the source end. On the other hand, the flow resistance increases with hematocrit, and therefore, the RBC motion becomes slower, which in turn reduces the influx of oxygen-rich RBCs entering capillaries. Such double roles of hematocrit have not been investigated adequately. Moreover, the oxygen-hemoglobin dissociation rate depends on the oxygen tension and hemoglobin saturation of the cytoplasm inside RBCs, and the dissociation kinetics exhibits a nonlinear fashion at different oxygen tensions. To understand how these factors and mechanisms interplay in the oxygen transport process, computational modeling and simulations are favorite since we have a good control of the system parameters and also we can access to the detailed information during the transport process. In this study, we conduct numerical simulations for the blood flow and RBC deformation along a capillary and the oxygen transfer from RBCs to the surrounding tissue. Different values for the hematocrit, arteriole oxygen tension, tissue metabolism rate and hemoglobin concentration and affinity are considered, and the simulated spatial and temporal variations of oxygen concentration are analyzed in conjunction with the nonlinear oxygen-hemoglobin reaction kinetics. Our results show that there are two competing mechanisms for the tissue oxygenation response to a hematocrit increases: the favorite effect of the higher RBC density and the negative effect of the slower RBC motion. Moreover, in the low oxygen situations with RBC oxygen tension less than 50 mmHg at capillary inlet, the reduced RBC velocity effect dominates, resulting in a decrease in tissue oxygenation at higher hematocrit. On the opposite, for RBC oxygen tension higher than 50 mmHg when entering the capillary, a higher hematocrit is beneficial to the tissue oxygenation. More interestingly, the pivoting arteriole oxygen tension at which the two competing mechanisms switch dominance on tissue oxygenation becomes lower for higher oxygen-hemoglobin affinity and lower hemoglobin concentration. This observation has also been analyzed based on the oxygen supply from RBCs and the oxygen-hemoglobin reaction kinetics. The results and discussions presented in this article could be helpful for a better understanding of oxygen transport in microcirculation.

Microcirculatory effects of rewarming in experimental hemorrhagic shock

BACKGROUND

Rewarming is a recommended therapy during the resuscitation of hypothermic patients with hemorrhagic shock. In experimental models, however, it increases inflammatory response and mortality. Although microcirculation is potential target of inflammation, the microvascular effects of rewarming during the resuscitation of hemorrhagic shock have not been studied. Our goal was to assess the systemic and microcirculatory effects of an increase in core temperature (T°) during the retransfusion of hemorrhagic shock in sheep. Our hypothesis was that rewarming could hamper microcirculation.

METHODS

In anesthetized and mechanically ventilated sheep, we measured systemic, intestinal, and renal hemodynamics and oxygen transport. O₂ consumption (VO₂) and respiratory quotient were measured by indirect calorimetry. Cortical renal, intestinal villi and sublingual microcirculation were assessed by IDF-videomicroscopy. After basal measurements, hemorrhagic shock was induced and T° was reduced to ~33 °C. After 1 h of shock and hypothermia, blood was retransfused and Ringer lactate solution was administered to prevent arterial hypotension. In the control group (n = 12), T° was not modified, while in the intervention (rewarming) group, it was elevated ~3 °C. Measurements were repeated after 1 h.

RESULTS

During shock, both groups showed similar systemic and microvascular derangements. After retransfusion, VO₂ remained decreased compared to baseline in both groups, but was lower in the control compared to the rewarming group. Perfused vascular density has a similar behavior in both groups. Compared to baseline, it remained reduced in peritubular (control vs. rewarming group, 13.8 [8.7-17.5] vs. 15.7 [10.1-17.9] mm/mm², PNS) and villi capillaries (14.7 [13.6-16.8] vs. 16.3 [14.2-16.9] mm/mm², PNS), and normalized in sublingual mucosa (19.1 [16.0-20.3] vs. 16.6 [14.7-17.2] mm/mm², PNS).

CONCLUSIONS

This is the first experimental study assessing the effect of rewarming on systemic, regional, and microcirculatory perfusion in hypothermic hemorrhagic shock. We found that a 3 °C increase in T° neither improved nor impaired the microvascular alterations that persisted after retransfusion. In addition, sublingual mucosa was less susceptible to reperfusion injury than villi and renal microcirculation.

The role of nailfold capillaroscopy in pediatric patients with Kawasaki disease

BACKGROUND

Nailfold capillaroscopy has been used as a non-invasive diagnostic method for microvasculature evaluation in various rheumatological disorders. The present study aimed to determine the utility of nailfold capillaroscopy in the diagnosis of Kawasaki Disease (KD).

METHOD

In this case-control study nailfold capillaroscopy was performed in 31 patients with KD and 30 healthy controls. All nailfold images were evaluated for capillary distribution and capillary morphology such as enlargement, tortuosity, and dilatation of the capillaries.

RESULT

Abnormal capillaroscopic diameter was identified in 21 patients from the KD group and 4 patients in the control group. The most common abnormality in capillary diameter was irregular dilatation in 11 (35.4%) KD patients and in 4 people (13.3%) in the control group. Distortions of the normal capillary architecture was commonly seen in the KD group (n=8). A positive correlation was observed between coronary involvement and abnormal capillaroscopic results (r=.65, P<.03). The sensitivity and specificity of capillaroscopy for the diagnosis of KD were 84.0% (95%CI: 63.9-95.5%) and 72.2% (95%CI: 54.8-85.8%), respectively. The PPV and NPV of capillaroscopy for KD were 67.7% (95%CI: 48.6-83.3) and 86.7% (95% CI: 69.3-96.2), respectively.

CONCLUSION

Capillary alterations are more common in KD patients compared to control group. Thus, nailfold capillaroscopy can be useful in detecting these alterations. Capillaroscopy is a sensitive test for detecting capillary alternations in KD patients. It could be used as a feasible diagnostic modality for evaluating microvascular damage in KD.

Skin microvascular reactivity in patients with diabetic retinopathy

AIMS

Early detection of microangiopathic complications of diabetes mellitus (DM) is necessary to analyze the patient's condition and prevent disease progression. The study was aimed to investigate the relationship between the presence of retinopathy and decreased reactivity of the microcirculatory bed in patients with diabetes.

METHODS

The study involved 130 subjects: healthy volunteers (n = 48), DM patients without retinopathy (n = 53) and with retinopathy (n = 29). Skin microvascular reactivity was assessed on the forearm using laser Doppler flowmetry with a local heating test combined with occlusion.

RESULTS

The slope of local thermal hyperemia curve (Slope-120) and other parameters of microvascular reactivity showed difference in pairwise comparisons between the groups. Slope-120 had the highest sensitivity (0.759) and specificity (0.717) in detection of diabetic retinopathy. The decrease of Slope-120 was associated with retinopathy (odds ratio (OR) - 8.3 (2.9-24.1), p < 0.001), even after adjusting for other factors (OR - 11.0 (1.6-77.2), p = 0.016).

CONCLUSIONS

Thus, assessment of skin microvascular reactivity may be a useful test for detecting signs of microangiopathic complications and for screening patients in risk group. Decreased microvascular reactivity has been shown to be prospective as an independent indicator of retinopathy in type 1 DM.

A network-based model of dynamic cerebral autoregulation

Cerebrovascular diseases continue to be one of the leading causes of morbidity and mortality in humans. Abnormalities in dynamic cerebral autoregulation (dCA) have been implicated in many of these disease conditions. Accurate models are therefore needed to better understand the complex pathophysiology behind impaired dCA. We thus present here a simple framework for modelling a vessel-driven network model of dCA in the microvasculature, as opposed to the conventional compartmental modelling approach. Network models incorporate the actual connectivity and anatomy of the vasculature, thereby allowing us to include and trace changes in the calibre and morphology of individual vessels, investigate the spatial specificity and heterogeneity of the various control mechanisms to help disentangle their contributions, and link the model parameters to the actual network physiology. The proposed control feedback mechanisms are incorporated at the level of the individual vessel, and the dynamic pressure and flow fields are solved for here within a simple vessel network. In response to an upstream pressure drop, the network is found to be able to recover cerebral blood flow (CBF) while exhibiting the characteristic autoregulatory behaviour in terms of changes in vessel calibre and the biphasic flow response. We assess the feasibility of our formulation in larger networks by comparing the simulation results to those obtained using a one-dimensional (1D) model of CBF applied to the same microvasculature network and find that our model results are in very good agreement with the 1D solution, while significantly reducing the computational cost, thus enabling more detailed models of network behaviour to be adopted in the future. Accurate and computationally feasible models of dCA that are more representative of the vasculature can help increase the translatability of haemodynamic models into the clinical environment, which would help develop more informed treatment guidelines for patients with cerebrovascular diseases.

How Does Weight Loss After Bariatric Surgery Impact the Ocular Parameters? A Review

Our review aimed to assess the effects of bariatric surgery-induced weight loss on ocular functions. We focused on retinochoroidal microcirculation, glaucomatous factors, and the condition of the eye surface pre- and postoperatively. The review covered 23 articles, including five case reports. Bariatric surgery positively impacts retinochoroidal microcirculation. The arterial perfusion and vascular density improve, venules constrict, and the arteriole-to-venule ratio increases. Weight loss positively correlates with intraocular pressure decrease. The impact of postoperative weight loss on the choroidal thickness (CT) and the retinal nerve fiber layer (RNFL) is still unclear. The correlation between ocular symptoms and hypovitaminosis A needs to be evaluated. Further research is required, especially regarding CT and RNFL, mainly focusing on long-term follow-up.

Advanced pathophysiology mimicking lung models for accelerated drug discovery

BACKGROUND

Respiratory diseases are the 2nd leading cause of death globally. The current treatments for chronic lung diseases are only supportive. Very few new classes of therapeutics have been introduced for lung diseases in the last 40 years, due to the lack of reliable lung models that enable rapid, cost-effective, and high-throughput testing. To accelerate the development of new therapeutics for lung diseases, we established two classes of lung-mimicking models: (i) healthy, and (ii) diseased lungs - COPD.

METHODS

To establish models that mimic the lung complexity to different extents, we used five design components: (i) cell type, (ii) membrane structure/constitution, (iii) environmental conditions, (iv) cellular arrangement, (v) substrate, matrix structure and composition. To determine whether the lung models are reproducible and reliable, we developed a quality control (QC) strategy, which integrated the real-time and end-point quantitative and qualitative measurements of cellular barrier function, permeability, tight junctions, tissue structure, tissue composition, and cytokine secretion.

RESULTS

The healthy model is characterised by (i) continuous tight junctions, (ii) physiological cellular barrier function, (iii) a full thickness epithelium composed of multiple cell layers, and (iv) the presence of ciliated cells and goblet cells. Meanwhile, the disease model emulates human COPD disease: (i) dysfunctional cellular barrier function, (ii) depletion of ciliated cells, and (ii) overproduction of goblet cells. The models developed here have multiple competitive advantages when compared with existing in vitro lung models: (i) the macroscale enables multimodal and correlative characterisation of the same model system, (ii) the use of cells derived from patients that enables the creation of individual models for each patient for personalised medicine, (iii) the use of an extracellular matrix proteins interface, which promotes physiological cell adhesion and differentiation, (iv) media microcirculation that mimics the dynamic conditions in human lungs.

CONCLUSION

Our model can be utilised to test safety, efficacy, and superiority of new therapeutics as well as to test toxicity and injury induced by inhaled pollution or pathogens. It is envisaged that these models can also be used to test the protective function of new therapeutics for high-risk patients or workers exposed to occupational hazards.

Serum vascular endothelial growth factor affects tissue fluid accumulation and is associated with deteriorating tissue perfusion and oxygenation in severe sepsis: a prospective observational study

BACKGROUND

Positive fluid balance and tissue fluid accumulation are associated with adverse outcomes in sepsis. Vascular endothelial growth factor (VEGF) increases in sepsis, promotes vascular permeability, and may affect tissue fluid accumulation and oxygenation. We used near-infrared spectroscopy (NIRS) to estimate tissue hemoglobin (Hb) oxygenation and water (H₂O) levels to investigate their relationship with serum VEGF levels.

MATERIAL AND METHODS

New-onset severe sepsis patients admitted to the intensive care unit were enrolled. Relative tissue concentrations of oxy-Hb ([HbO₂]), deoxy-Hb ([HbR]), total Hb ([HbT]), and H₂O ([H₂O]) were estimated by near-infrared spectroscopy (NIRS) for three consecutive days and serum VEGF levels were measured. Comparisons between oliguric and non-oliguric patients were conducted and the correlations between variables were analyzed.

RESULTS

Among 75 eligible patients, compared with non-oliguric patients, oliguric patients were administrated more intravascular fluids (median [IQR], 1926.00 [1348.50-3092.00] mL/day vs. 1069.00 [722.00-1486.75] mL/day, p < 0.001) and had more positive daily net intake and output (mean [SD], 1,235.06 [1303.14] mL/day vs. 313.17 [744.75] mL/day, p = 0.012), lower [HbO₂] and [HbT] over the three-day measurement (analyzed by GEE p = 0.01 and 0.043, respectively) and significantly higher [H₂O] on the third day than on the first two days (analyzed by GEE p = 0.034 and 0.018, respectively). Overall, serum VEGF levels were significantly negatively correlated with [HbO₂] and [HbT] (rho = - 0.246 and - 0.266, p = 0.042 and 0.027, respectively) but positively correlated with [H₂O] (rho = 0.449, p < 0.001). Subgroup analysis revealed a significant correlation between serum VEGF and [H2O] in oliguric patients (rho = 0.532, p = 0.003). Multiple regression analysis determined the independent effect of serum VEGF on [H₂O] (standardized coefficient = 0.281, p = 0.038).

CONCLUSIONS

In severe sepsis, oliguria relates to higher positive fluid balance, lower tissue perfusion and oxygenation, and progressive tissue fluid accumulation. Elevated serum VEGF is associated with worsening tissue perfusion and oxygenation and independently affects tissue fluid accumulation.

Microcirculatory response to cold stress test in the healthy hand

OBJECTIVE

Cold sensitivity of the fingers is common in several conditions. It has been linked to digital vasospasm, microvascular dysfunction, and neural mechanisms. This study aimed to investigate the normal digital microvascular response to a cold stress test in healthy individuals using Laser Speckle Contrast Imaging (LSCI).

METHODS

Twenty-six healthy individuals, mean age 31 (SD 9) years were included. Skin perfusion of digits II-V was measured using Laser Speckle Contrast Imaging before and after a standardized cold stress test. Changes in skin perfusion from baseline were analyzed between hands, digits, and sexes.

RESULTS

Skin perfusion was significantly (p < 0.0001) affected by cold provocation in both the cold exposed and the contralateral hands in all participants of the study. This effect was significantly different between the radial (digit II and III) and the ulnar (digit V) side of the hands (p < 0.001). There was a trend towards a larger decrease in perfusion in men (ns), and a faster recovery to baseline values in women (ns). A larger inter subject variability was seen in perfusion values in women.

CONCLUSIONS

The normal microvascular response to cold provocation may involve both centrally and regionally mediated processes. When exposing one hand to a cold stress test, the contralateral hand responds with simultaneous but smaller decreases in perfusion.

Structural and functional characteristics of the pulmonary hemomicrocirculatory bed in induced systemic sclerosis: an experimental study

The objective of this study was to investigate the effects of prolonged exposure to the oxidative agent NaClO on histopathological changes in the lung tissues of laboratory animals. Specifically, the study aimed to examine morphological changes in the pulmonary microcirculation and the level of vascular cell adhesion molecule-1 (VCAM-1) as a functional activity indicator of endothelial cells in animals with induced systemic sclerosis (SSc). A laboratory animal model was used to assess the impact of long-term exposure to NaClO on lung tissues. The animals were divided into three groups: the experimental group (25 rats) was exposed to NaClO, while the control group (20 rats) received an isotonic solution, and the intact group (15 animals) was without any exposure. The concentration of VCAM-1 in the serum of the animals was measured using an enzyme-linked immunosorbent assay. Histopathological analysis of lung tissue specimens was performed using both light and electron microscopy. The concentration of VCAM-1 in the serum of the animals in the experimental group was significantly higher than that of the control group (91.25 [85.63-143.75] vs 19.50 [13.53-22.20], p < 0.05). The histopathological analysis revealed significant abnormalities in the lung tissue specimens from the experimental group, including disruption in the structure of the hemocapillaries of the lungs, narrowing of the microvessel lumen, and perivascular infiltration by polymorphonuclear cells. The electron microscopic analysis showed several ultrastructural changes in the endotheliocytes of the hemocapillaries, including uneven expansion of the perinuclear space, swollen mitochondria, and fragmentation of the membranes of the granular endoplasmic reticulum. Additionally, the basement membrane of hemocapillaries showed uneven thickening with indistinct contours, and the peripheral parts of endotheliocytes were marked by numerous micropinocytotic vesicles and vacuoles. Erythrocyte aggregates and leukocyte adhesion were identified in the lumen of many hemocapillaries, while adhesion and aggregation of platelets were also observed in several hemocapillaries. Long-term exposure to NaClO can cause significant histopathological changes in lung tissues, including damage to the hemocapillaries and disruption in the structure of endotheliocytes.

Microcirculation Surrounding End-Stage Human Chronic Skin Wounds is Associated with Endoglin/CD146/ALK-1 Expression, Endothelial Cell Proliferation and an absence of p16Ink4a

Angiogenesis is an essential part of normal skin healing, re-establishing blood flow in developing granulation tissue. Non-healing skin wounds are associated with impaired angiogenesis and although the role of re-establishing macroscopic blood flow to limbs to prevent wound chronicity is well investigated, less is known about vascular alterations at the microcirculatory level. We hypothesized that significant phenotypic changes would be evident in blood vessels surrounding chronic skin wounds. Wound edge tissue, proximal to wound (2 cm from wound edge) and non-involved skin (>10 cm from wound edge) was harvested under informed consent from twenty patients undergoing elective amputation due to critical limb ischemia. To assess blood vessel structure and viability, tissue was prepared for histological analysis and labelled with antibodies specific for PECAM-1 (CD31), CD146, endoglin, ALK-1, ALK-5, and p16^Ink4a as a marker of cellular senescence. Density of microvasculature was significantly increased in wound edge dermis, which was concomitant with increased labeling for endoglin and CD146. The number of CD31 positive vessel density was unchanged in wound edge tissue relative to non-involved tissue. Co-labelling of endoglin with the transforming growth factor receptor ALK-1, and to a lesser extent ALK-5, demonstrated activation of endothelial cells which correlated with PCNA labeling indicative of proliferation. Analysis of p16^Ink4a staining showed a complete lack of immunoreactivity in the vasculature and dermis, although staining was evident in sub-populations of keratinocytes. We conclude that the endoglin-ALK-1-endothelial proliferation axis is active in the vasculature at the edge of chronic skin wounds and is not associated with p16^Ink4a mediated senescence. This information could be further used to guide treatment of chronic skin wounds and optimize debridement protocols.

Identifying a sublingual triangle as the ideal site for assessment of sublingual microcirculation

The sublingual mucosa is a commonly used intraoral location for identifying microcirculatory alterations using handheld vital microscopes (HVMs). The anatomic description of the sublingual cave and its related training have not been adequately introduced. The aim of this study was to introduce anatomy guided sublingual microcirculatory assessment. Measurements were acquired from the floor of the mouth using incident dark-field (IDF) imaging before (T0) and after (T1) sublingual cave anatomy instructed training. Instructions consists of examining a specific region of interested identified through observable anatomical structures adjacent and bilaterally to the lingual frenulum which is next to the sublingual papilla. The anatomical location called the sublingual triangle, was identified as stationed between the lingual frenulum, the sublingual fold and ventrally to the tongue. Small, large, and total vessel density datasets (SVD, LVD and TVD respectively) obtained by non-instructed and instructed measurements (NIN (T0) and IM (T1) respectively) were compared. Microvascular structures were analyzed, and the presence of salivary duct-related microcirculation was identified. A total of 72 video clips were used for analysis in which TVD, but not LVD and SVD, was higher in IM compared to NIM (NIM vs. IM, 25 ± 2 vs. 27 ± 3 mm/mm2 (p = 0.044), LVD NIM vs. IM: 7 ± 1 vs. 8 ± 1mm/mm2 (p = 0.092), SVD NIM vs. IM: 18 ± 2 vs. 20 ± 3 mm/mm2 (p = 0.103)). IM resulted in microcirculatory assessments which included morphological properties such as capillaries, venules and arterioles, without salivary duct-associated microcirculation. The sublingual triangle identified in this study showed consistent network-based microcirculation, without interference from microcirculation associated with specialized anatomic structures. These findings suggest that the sublingual triangle, an anatomy guided location, yielded sublingual based measurements that conforms with international guidelines. IM showed higher TVD values, and future studies are needed with larger sample sizes to prove differences in microcirculatory parameters.

Improving the Clinical Interpretation of Transcutaneous Carbon Dioxide and Oxygen Measurements in the Neonatal Intensive Care Unit

INTRODUCTION

Transcutaneous blood gas monitoring allows for continuous non-invasive evaluation of carbon dioxide and oxygen levels. Its use is limited as its accuracy is dependent on several factors. We aimed to identify the most influential factors to increase usability and aid in the interpretation of transcutaneous blood gas monitoring.

METHODS

In this retrospective cohort study, transcutaneous blood gas measurements were paired to arterial blood gas withdrawals in neonates admitted to the neonatal intensive care unit. The effects of patient-related, microcirculatory, macrocirculatory, respiratory, and sensor-related factors on the difference between transcutaneously and arterially measured carbon dioxide and oxygen values (ΔPCO2 and ΔPO2) were evaluated using marginal models.

RESULTS

A total of 1,578 measurement pairs from 204 infants with a median [interquartile range] gestational age of 273/7 [261/7-313/7] weeks were included. ΔPCO2 was significantly associated with the postnatal age, arterial systolic blood pressure, body temperature, arterial partial pressure of oxygen (PaO2), and sensor temperature. ΔPO2 was, with the exception of PaO2, additionally associated with gestational age, birth weight Z-score, heating power, arterial partial pressure of carbon dioxide, and interactions between sepsis and body temperature and sepsis and the fraction of inspired oxygen.

CONCLUSION

The reliability of transcutaneous blood gas measurements is affected by several clinical factors. Caution is recommended when interpreting transcutaneous blood gas values with an increasing postnatal age due to skin maturation, lower arterial systolic blood pressures, and for transcutaneously measured oxygen values in the case of critical illness.

Inner retinal layers' alterations of the microvasculature in early stages of Parkinson's disease: a cross sectional study

PURPOSE

To investigate microcirculation characteristics of the inner retinal layers at the macula and the peripapillary area using Optical Coherence Tomography Angiography (OCT-A) of patients in early stages of Parkinson's disease (PD).

METHODS

32 PD patients and 46 age- and gender-matched healthy controls were included in this cross sectional study. OCT-A imaging was performed to analyze microcirculation characteristics at each separate macular region (fovea, parafovea, and perifovea) and the peripapillary area of the inner retinal layers.

RESULTS

Individuals with PD had significantly lower parafoveal, perifoveal and total vessel density (VD) in the superficial capillary plexus (SCP) than controls (all p < 0.001), while foveal VD was higher in PD eyes than that of controls, though not statistically significant. Similarly, individuals with PD had significantly lower parafoveal, perifoveal and total perfusion in the SCP than control eyes (all p < 0.001), while foveal perfusion was significantly higher in PD eyes than that of controls (p = 0.008). PD eyes had significantly smaller FAZ area and perimeter accompanied by decreased circularity at the SCP as compared to controls (all p < 0.001). Concerning the peripapillary area, individuals with PD had significantly lower radial peripapillary capillary perfusion density and flux index at the SCP than controls (all p < 0.001). All p values remained statistically significant even after using the Bonferroni correction for multiple comparisons, except for that of foveal perfusion.

CONCLUSIONS

Our study indicates alterations of the inner retinal layers at the macula and the peripapillary area at the preliminary stages of PD. OCT-A parameters could potentially comprise imaging biomarkers for PD screening and improve the diagnostic algorithms.

Chronic PCSK9 inhibitor therapy leads to sustained improvements in endothelial function, arterial stiffness, and microvascular function

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) effectively decrease low-density lipoprotein cholesterol (LDL-C) and reduce cardiovascular events in patients at very high cardiovascular risk. Recent short-term studies suggest a partially LDL-C independent beneficial effect of PCSK9 inhibitor (PCSK9i) therapy on endothelial function and arterial stiffness, whereas it is unknown if this effect persists and what the effect is on microcirculation.

OBJECTIVE

To investigate the effects of PCSK9i therapy on vascular parameters beyond its lipid lowering effect.

METHODS

In this prospective trial, 32 patients at very high cardiovascular risk and indication for PCSK9i therapy were included. Measurements were performed at baseline and after 6 months of PCSK9i treatment. Endothelial function was assessed as flow-mediated dilation (FMD). Arterial stiffness was measured as pulse wave velocity (PWV) and aortic augmentation index (AIx). Peripheral tissue oxygenation (StO₂) as a marker of microvascular function was assessed at the distal extremities using near-infrared spectroscopy camera.

RESULTS

Six months of PCSK9i therapy decreased LDL-C levels from 141 ± 54 to 60 ± 30 mg/dl (-56 ± 21 %, p < 0.001), FMD significantly increased from 5.4 ± 1.7 % to 6.4 ± 1.9 % (+19 ± 10 %, p < 0.001), PWV decreased in male patients significantly from 8.9 ± 2.1 to 7.9 ± 1.5 m/s (-12 ± 9 %, p = 0.025). AIx decreased from 27.1 ± 10.4 % to 23.0 ± 9.7 % (-16 ± 14 %, p < 0.001), StO₂ significantly increased from 67 ± 12 % to 71 ± 11 % (+7 ± 6 %, p = 0.012). Brachial and aortic blood pressure showed no significant changes after six months. There was no correlation between LDL-C reduction and changes in vascular parameters.

CONCLUSIONS

Chronic PCSK9i therapy is associated with sustained improvements in endothelial function, arterial stiffness, and microvascular function independent from lipid lowering.

Erythrocyte deformability profile evaluated by laser diffractometry in patients with multiple myeloma: Re-examination of our cases

BACKGROUND

Multiple myeloma is a complex pathology which represents about 10 % of all hematological neoplasms. It can often present changes in the hemorheological profile and, in relation to this last topic, our aim is to evaluate the hemorheological profile in a group of multiple myeloma patients, with reference to erythrocyte deformability.

METHODS

We have examined the profile of the erythrocyte deformability in multiple myeloma enrolling 29 patients; this profile, expressed as elongation index at several shear stress, has been obtained using the diffractometric method.

RESULTS

By comparing normal controls and MM patients, a significant decrease in erythrocyte deformability, especially at low shear stresses, but we did not observe any significant differences about this profile subdividing the whole group of MM patients according to the degree of bone marrow plasma cell infiltration, to the red blood cell distribution width and to the serum values of LDH.

CONCLUSIONS

In this paper we have taken in consideration all the hypothesis for a possible explanation of the behaviour of this a reduced erythrocyte deformability in multiple myeloma. Erythrocyte deformability interferes with the physiological release of oxygen to tissues, with several clinical implications.

Reliability of laser-Doppler flowmetry derived measurements of forearm and calf cutaneous vasodilation during gradual local heating in young adults

OBJECTIVES

Evaluate reliability of laser-Doppler flowmetry derived cutaneous vasodilation on the upper and lower limbs during gradual local heating.

METHODS

In twenty-eight young adults (21 (SD 3) years, 14 females), absolute cutaneous vascular conductance (CVC_abs) and CVC normalized to maximum vasodilation at 44 °C (%CVC_max) were assessed at two adjacent sites on each of the forearm and calf during gradual local skin heating (33-42 °C at 1 °C·5 min^-1) for two identical trials (∼1 week apart). Responses were assessed for baseline, the steady-state heating plateau at 42 °C and the span (i.e. plateau-baseline).

RESULTS

Between-day reliability was characterized as measurement consistency across trials. Within-day reliability was characterized as within-limb measurement consistency across adjacent skin sites. Between- and within-day absolute reliability (coefficient of variation) generally improved with heating, from poor (>25 %) at baseline to good (<10 %) for %CVC_max and moderate (10-25 %) for CVC_abs for plateau and span. However, relative reliability (intraclass correlation coefficient) was generally not acceptable (<0.70) for any condition. Responses were generally consistent for females and males and there were no major forearm and calf differences.

CONCLUSIONS

Consistency of CVC estimates improved during gradual local heating with negligible limb and sex differences, which are important considerations for experimental design and interpretation.

Microvascular reactivity using laser Doppler measurement in type 2 diabetes with subclinical atherosclerosis

Microangiopathy should be noted in diabetes with subclinical vascular diseases. Little is known about whether various surrogate markers of systemic arterial trees exacerbate simultaneously in preclinical atherosclerosis. To clarify the association of skin microvascular reactivity with arterial stiffness is essential to elucidating early atherosclerotic changes. The post-occlusive reactive hyperemia of skin microcirculation was evaluated in 27 control and 65 type 2 diabetic subjects, including 31 microalbuminuria (MAU) and 34 normoalbuminuria (NAU) patients. The laser Doppler skin perfusion signals were transformed into three frequency intervals for the investigation of endothelial, neurogenic, and myogenic effects on basal and reactive flow motion changes. The analysis of spectral intensity and distribution provided insight into potential significance of microvascular regulation in subclinical atherosclerotic diseases. Systemic arterial stiffness was studied by the brachial ankle pulse wave velocity (baPWV). Following occlusive ischemia, the percent change of endothelial flow motion was lower in MAU than in NAU and control groups. The MAU group revealed a relative increase in myogenic activity and a decrease in endothelial activity in normalized spectra. The baPWV showed more significant associations with reactive endothelial change (r = - 0.48, P < 0.01) and normalized myogenic value (r = - 0.37, P < 0.05) than diabetes duration and HbA1c. By multivariate regression analysis, only endothelial vasomotor changes independently contributed to the decreased baPWV (OR 3.47, 95% CI 1.63-7.42, P < 0.05). Impaired microcirculatory control is associated with increased arterial stiffness in preclinical atherosclerosis. To identify the early manifestations is necessary for at-risk patients to prevent from further vascular damage.

Simulation of Angiogenesis in Three Dimensions: Development of the Retinal Circulation

A theoretical model is used to describe the three-dimensional development of the retinal circulation in the human eye, which occurs after the initial spread of vasculature across the inner surface of the retina. In the model, random sprouting angiogenesis is driven by a growth factor that is produced in tissue at a rate dependent on oxygen level and diffuses to existing vessels. Vessel sprouts connect to form pathways for blood flow and undergo remodeling and pruning. These processes are controlled by known or hypothesized vascular responses to hemodynamic and biochemical stimuli, including conducted responses along vessel walls. The model shows regression of arterio-venous connections on the surface of the retina, allowing perfusion of the underlying tissue. A striking feature of the retinal circulation is the formation of two vascular plexuses located at the inner and outer surfaces of the inner nuclear layer within the retina. The model is used to test hypotheses regarding the formation of these structures. A mechanism based on local production and diffusion of growth factor is shown to be ineffective. However, sprout guidance by localized structures on the boundaries of the inner nuclear layer can account for plexus formation. The resulting networks have vascular density, perfusion and oxygen transport characteristics consistent with observed properties. The model shows how stochastic generation of vascular sprouts combined with a set of biologically based response mechanisms can lead to the generation of a specialized three-dimensional vascular structure with a high degree of organization.

Unfractionated Heparin Protects Microcirculation in Endotoxemic Rats by Antagonizing Histones

INTRODUCTION

Levels of extracellular histones are highly increased in sepsis and may facilitate microcirculatory dysfunction. Unfractionated heparin (UFH) binds histones and neutralizes their cytotoxicity. We investigated the effect of UFH on microcirculatory dysfunction by interacting with extracellular histones in endotoxemic rats.

METHODS

Twenty-four Wistar rats were randomly divided into three groups: control, lipopolysaccharide (LPS) group, and LPS + UFH group. In the LPS and LPS + UFH groups, 10 mg/kg LPS was injected to induce endotoxemia, and 100 IU/kg/h UFH was administered intravenously in the LPS + UFH group. The rats underwent midline laparotomy, and then intestinal microcirculation was evaluated using an incident dark field microscope. Circulating histones and microstructures of the rat intestinal microvascular endothelium were also detected. Additionally, the antagonistic effect of UFH on histone-induced cytotoxicity was investigated in human intestinal microvascular endothelial cells.

RESULTS

UFH protected the microcirculation of the intestinal serosa and mucosa in endotoxemic rats, as evidenced by increased total vessel density, perfused vessel density, and proportion of perfused vessels of both the serosa and mucosa, and increased microcirculatory flow index of the mucosa in the LPS + UFH group. UFH treatment decreased the levels of circulating histones and alleviated intestinal microvascular endothelial injuries in endotoxemic rats. Furthermore, UFH inhibited histone cytotoxicity in vitro.

CONCLUSIONS

UFH attenuated microcirculatory dysfunction in endotoxemic rats by antagonizing extracellular histones, thereby providing a potential therapeutic strategy for sepsis.

Significant retinal microvascular impairments in multiple sclerosis assessed through optical coherence tomography angiography

PURPOSE

Multiple sclerosis (MS) is associated with different ocular disorders. This study aimed to investigate the retinal microvascular changes detected by optical coherence tomography angiography (OCTA) in eyes with MS with or without a history of optic neuritis (ON).

METHODS

A comprehensive literature search was conducted in the Web of Science, Embase, PubMed, and Cochrane Library databases on September 26, 2021 for articles focused on OCTA manifestations in the eyes of MS patients compared with healthy controls. RevMan Manager (v.5.4) and Stata (v.14.1) were used to analyze the main differences and publication risks. Weighted mean differences and 95% confidence intervals were calculated for continuous estimates. This study also included subgroup analysis between three groups: eyes with multiple sclerosis and with optic neuritis (MSON); eyes with multiple sclerosis and without optic neuritis (MSNON); and healthy controls.

RESULTS

Thirteen studies with a total of 1803 eyes were identified, including 957 eyes with MS and 846 eyes of healthy controls. The vessel density of the MS eyes decreased significantly in most areas of the radial peripapillary capillary. A marked reduction in the macular superficial capillary plexus of MS eyes regardless of ON history was also confirmed.

CONCLUSION

The results suggest that MS patients demonstrated significant retinal microvasculature impairment regardless of ON history, compared to healthy controls. Retinal vessel density attenuation detected by OCTA may serve as a reliable early marker of MS.

Analysis of Monocyte Recruitment During Inflammation by Intravital Imaging

Monocytes play essential roles in the inflammatory and anti-inflammatory processes that take place during an immune response, acting both within the vascular network and interstitially. Monocytes are activated, mobilized, and recruited in response to an inflammatory stimulus or different forms of tissue injury. The recruitment of circulating monocytes to the inflamed tissue is essential to resolving the injury.Monocyte recruitment is a multistep process that begins with a decrease in rolling velocity, is followed by adhesion to the endothelium and crawling over the luminal vessel surface, and culminates in monocyte transmigration into the surrounding tissue. Intravital microscopy is a powerful visualization tool for the study of leukocyte behavior and function, intercellular interactions, cell trafficking, and recruitment in pathological and physiological conditions. This modality is therefore widely used for the detailed analysis of the immune response to multiple insults and the molecular mechanisms underlying monocyte interactions within the vascular system in vivo. This chapter describes a protocol for the use of intravital microscopy to analyze monocyte recruitment from the blood vessel to the inflammatory site.