Inspiration from the research advances in microcirculatory dysfunction to the treatment of burn shock and burn septic shock / 中华烧伤杂志

Microcirculatory dysfunction is an important pathophysiological change of shock. In the last decade, many researches on the mechanism of microcirculatory dysfunction have been involved in areas such as the glycocalyx damage of vascular endothelial cells, macrocirculation- microcirculation discoupling, vascular hyporeactivity, and microcirculation monitoring. Accordingly, this paper discussed how these research findings can be applied to burn patients, with the aim of alerting the clinicians to improving microcirculation, and maintaining hemodynamic coordination during the treatment of burn shock and burn septic shock. In addition, with the development of accurate and reliable microcirculation monitoring techniques, it is necessary to carry out multi-center clinical trials to reveal the clinical significance of target-oriented shock resuscitation protocol combining macrocirculatory and microcirculatory parameters.

Hands Free Technique: New Tool Possibility for Image Capture of Sublingual Microcirculation with Handheld Vital Microscopy - HVM / Técnica de Manos Libres: Nueva Posibilidad de Herramienta para Capturar imágenes de Microcirculación Sublingual con Microscopía Vital Portátil ­ HVM

New microcirculatory imaging techniques allowed direct observation of microcirculation at the bedside. This study presents a new device that assists the operator with the unprecedented Hands Free technique. To this end, a replica of Handheld Vital Microscopy was developed to simulate the method of capturing the image in the sublingual area, the most used site to assess microcirculation in critically ill patients. We achieved a reduction in the displacement of micros cope replica with a Hands Free method. The immediate consequence is an increase in the stability of HVM replica by 75 times, or more, over the current 4 seconds, during its contact with the sublingual tissue. The device also offers better control of th e pressure of the tip of the HVM replica over the sublingual area. The results demonstrated that the Hands Free technique, operating in the same sublingual area for 900 seconds, should allow for future research aimed at therapeutic maneuvers in patients with serious illnesses.

Las nuevas técnicas de imagen microcirculatoria permitieron la observación directa de la microcirculación junto a la cama del paciente. Este estudio sin precedentes presenta un nuevo dispositivo que ayuda al operador con la técnica manos libres. Con este fin, se desarrolló una réplica de la Microscopía Vital Portátil para simular el método de captura de la imagen en el área sublingual, el sitio más utilizado para evaluar la microcirculación en pacientes críticos. Logramos una reducción en el desplazamiento de la réplica del microscopio con el método de manos libres. La consecuencia inmediata es un aumento en la estabilidad de la réplica de HVM en 75 veces, o más, durante los 4 segundos actuales, durante su contacto con el tejido sublingual. El dispositivo también ofrece un mejor control de la presión de la punta de la réplica de HVM sobre el área sublingual. Los resultados demostraron que la técnica de manos libres, que opera en la misma área sublingual durante 900 segundos, debería permitir futuras investigaciones destinadas a maniobras terapéuticas en pacientes con enfermedades graves.

Efeitos da morte cerebral na microvasculatura pulmonar em um modelo experimental de doador de pulmão / Brain death effects on lung microvasculature in an experimental model of lung donor

RESUMO Objetivo A morte cerebral (MC) desencadeia alterações hemodinâmicas e inflamatórias importantes, comprometendo a viabilidade dos órgãos empregados em transplantes. Para compreender melhor as alterações microcirculatórias nos pulmões de doadores com MC, o presente estudo investigou a microcirculação pulmonar em um modelo de roedor com MC via microscopia intravital. Métodos Ratos Wistar machos foram anestesiados e ventilados mecanicamente. Eles foram submetidos a trepanação e a MC induzida por meio do aumento da pressão intracraniana. Os ratos do grupo Sham (SH), utilizado como controle, foram submetidos apenas à trepanação. Em ambos os grupos, foram monitorados o O2 expiratório e o CO2, e, após 3 horas, foi realizada a toracotomia e criada uma janela para observar a superfície pulmonar usando o sistema de microscopia intravital. As expressões pulmonares das moléculas de adesão intercelular (ICAM)-1 e da óxido nítrico-sintase endotelial (eNOS) foram avaliadas por imuno-histoquímica, e as citocinas foram medidas em amostras pulmonares. Resultados Três horas após os procedimentos cirúrgicos, a perfusão pulmonar foi de 73% no grupo SH. Por outro lado, os animais com MC apresentaram uma importante diminuição na perfusão do órgão para 28% (p = 0,036). O comprometimento microcirculatório pulmonar após a indução de MC foi associado a um aumento do número de leucócitos recrutados para o tecido pulmonar, além de uma redução na expressão de eNOS e um aumento na expressão de ICAM-1 nas células endoteliais do pulmão. Os ratos com MC apresentaram valores mais elevados de O2 expiratório e valores mais baixos de CO2 em comparação com os animais SH após 3 horas de monitorização. Conclusões Os dados apresentados demonstraram que a MC desencadeia uma importante hipoperfusão e inflamação nos pulmões, comprometendo a microcirculação pulmonar do doador.

ABSTRACT Objective Brain death (BD) triggers important hemodynamic and inflammatory alterations, compromising the viability of organs suitable for transplantation. To better understand the microcirculatory alterations in donor lungs caused by BD. The present study investigated the pulmonary microcirculation in a rodent model of BD via intravital microscopy. Methods Male Wistar rats were anaesthetized and mechanically ventilated. They were trepanned and BD was induced through the increase in intracranial pressure. As control group, sham-operated (SH) rats were trepanned only. In both groups, expiratory O2 and CO2 were monitored and after three hours, a thoracotomy was performed, and a window was created to observe the lung surface using an epi-fluorescence intravital microscopy. Lung expression of intercellular adhesion molecule (ICAM)-1 and endothelial nitric oxide synthase (eNOS) was evaluated by immunohistochemistry, and cytokines were measured in lung samples. Results Three hours after the surgical procedures, pulmonary perfusion was 73% in the SH group. On the other hand, BD animals showed an important decrease in organ perfusion to 28% (p = 0.036). Lung microcirculatory compromise after BD induction was associated with an augmentation of the number of leukocytes recruited to lung tissue, and with a reduction in eNOS expression and an increase in ICAM-1 expression on lung endothelial cells. BD rats showed higher values of expiratory O2 and lower values of CO2 in comparison with SH animals after three hours of monitoring. Conclusion Data presented showed that BD triggers an important hypoperfusion and inflammation in the lungs, compromising the donor pulmonary microcirculation.

Microcirculation changes in gingival tissue after ultrasonic tooth preparation in beagle dogs

Abstract Ultrasonic wave technology is widely used during dental treatments. We previously demonstrated that this method protects the gingival tissue. However, the physiological change on the gingival microvasculature caused by this method remains unclear. Objective The aim of this study was to investigate the relationship between the morphological and physiological effects on gingival microcirculation when preparing teeth, using the conventional dental turbine or ultrasonic method. Methodology The lower premolar teeth of beagle dogs were prepared along the gingival margin by using a dental turbine or ultrasonic wave instrument. Gingival vasculature changes were investigated using scanning electron microscopy for corrosion resin casts. Gingival blood flow at the preparation site was determined simultaneously by laser Doppler flowmetry. These assessments were performed immediately (Day 0), at 7 days and 30 days after tooth preparation. Results At day 0, in the turbine group, blood vessels were destroyed and some resin leaked. Furthermore, gingival blood flow at the site was significantly increased. In contrast, the ultrasonic group demonstrated nearly normal vasculature and gingival blood flow similar to the non-prepared group for 30 days after preparation. No significant alterations occurred in gingival circulation 30 days after either preparation; however, the turbine group revealed obvious morphological changes. Conclusions Based on multiple approach analyses, this study demonstrated that ultrasonic waves are useful for microvascular protection in tooth preparation. Compared with a dental turbine, ultrasonic wave instruments caused minimal damage to gingival microcirculation. Tooth preparation using ultrasonic wave instruments could be valuable for protecting periodontal tissue.

Association between peripheral perfusion, microcirculation and mortality in sepsis: a systematic review / Associação entre perfusão periférica, microcirculação e mortalidade em sepse: uma revisão sistemática

Abstract Although increasing evidence supports the monitoring of peripheral perfusion in septic patients, no systematic review has been undertaken to explore the strength of association between poor perfusion assessed in microcirculation of peripheral tissues and mortality. A search of the most important databases was carried out to find articles published until February 2018 that met the criteria of this study using different keywords: sepsis, mortality, prognosis, microcirculation and peripheral perfusion. The inclusion criteria were studies that assessed association between peripheral perfusion/microcirculation and mortality in sepsis. The exclusion criteria adopted were: review articles, animal/pre-clinical studies, meta-analyzes, abstracts, annals of congress, editorials, letters, case-reports, duplicate and articles that did not present abstracts and/or had no text. In the 26 articles were chosen in which 2465 patients with sepsis were evaluated using at least one recognized method for monitoring peripheral perfusion. The review demonstrated a heterogeneous critically ill group with a mortality-rate between 3% and 71% (median = 37% [28%-43%]). The most commonly used methods for measurement were Near-Infrared Spectroscopy (NIRS) (7 articles) and Sidestream Dark-Field (SDF) imaging (5 articles). The vascular bed most studied was the sublingual/buccal microcirculation (8 articles), followed by fingertip (4 articles). The majority of the studies (23 articles) demonstrated a clear relationship between poor peripheral perfusion and mortality. In conclusion, the diagnosis of hypoperfusion/microcirculatory abnormalities in peripheral non-vital organs was associated with increased mortality. However, additional studies must be undertaken to verify if this association can be considered a marker of the gravity or a trigger factor for organ failure in sepsis.

Resumo Embora evidências crescentes apoiem a monitoração da perfusão periférica em pacientes sépticos, nenhuma revisão sistemática foi feita para explorar a força da associação entre a má perfusão avaliada na microcirculação dos tecidos periféricos e a mortalidade. Uma busca nas bases de dados mais importantes foi feita para encontrar artigos publicados até fevereiro de 2018 que correspondessem aos critérios deste estudo, com diferentes palavras-chave: sepse, mortalidade, prognóstico, microcirculação e perfusão periférica. Os critérios de inclusão foram estudos que avaliaram a associação entre perfusão/microcirculação periférica e mortalidade em sepse. Os critérios de exclusão adotados foram os seguintes: artigos de revisão, estudos com animais/pré-clínicos, metanálises, resumos, anais de congressos, editoriais, cartas, relatos de casos, artigos duplicados e artigos que não continham resumos e/ou texto. Foram selecionados 26 artigos nos quais 2465 pacientes com sepse foram avaliados com pelo menos um método reconhecido para monitorar a perfusão periférica. A revisão demonstrou um grupo heterogêneo de pacientes gravemente enfermos com uma taxa de mortalidade entre 3% e 71% (mediana = 37% [28%-43%]). Os métodos de avaliação mais comumente usados foram a espectroscopia na região do infravermelho próximo (Near-Infrared Spectroscopy - NIRS) (7 artigos) e a análise de imagens em campo escuro (Sidestream Dark-Field - SDF) (5 artigos). O leito vascular mais avaliado foi a microcirculação sublingual/bucal (8 artigos), seguida pela ponta do dedo (4 artigos). A maioria dos estudos (23 artigos) demonstrou uma clara relação entre má perfusão periférica e mortalidade. Em conclusão, o diagnóstico de hipoperfusão/anormalidades microcirculatórias em órgãos não vitais periféricos foi associado ao aumento da mortalidade. No entanto, estudos adicionais devem ser feitos para verificar se essa associação pode ser considerada um marcador da gravidade ou um fator desencadeante da falência de órgãos na sepse.

Effect of short-term ischemia on microcirculation and wound healing of adipocutaneous flaps in the rat

Abstract Purpose Composite flaps used in reconstructive surgery may intra- and postoperatively suffer from hypoperfusion and/or ischemia-reperfusion influencing wound healing. We aimed to follow-up the effect of ischemia on adipocutaneous flaps' wound healing and microcirculation. Methods In anesthetized rats groin flaps were formed bilaterally. In Control group the flaps were repositioned and sutured back. In Ischemia-Reperfusion (I/R) group before repositioning and suturing the flap pedicles were clamped for 60 minutes. Laser Doppler (LD) fluxmetry and temperature probes were applied on the cranial, central and caudal flap regions before/after preparation and ischemia, re-suturing, and on the 1st-3rd-5th-7th-14th postoperative days, before the final examinations and biopsies for histology. Results Flaps' skin temperature quickly recovered after repositioning. LD values were lower in the I/R group, reaching a significant level by the 3rd postoperative day, and remained lowered till the 14th day. The magnitude of alterations differed in the flap regions. Histologically normal wound healing process was seen, except for some I/R flaps, where hypertrophized mammary glands were found. Conclusions Short-term ischemia could influence flap microcirculation and wound healing, and may result in hypertrophized mammary glands. Laser Doppler could be used to evaluate intra- and postoperative microcirculatory changes and may have significance in predicting complications.

Near-infrared spectroscopy parameters in patients undergoing continuous venovenous hemodiafiltration / Espectroscopia no infravermelho próximo em pacientes sob hemodiafiltração venovenosa contínua

ABSTRACT Objective To investigate the impacts of continuous venovenous hemodiafiltration on the microcirculation in patients with acute kidney injury. Methods A prospective observational pilot study conducted in a 40-bed, open clinical-surgical intensive care unit of a private tertiary care hospital located in the city of São Paulo (SP), Brazil. Microcirculation was assessed using near-infrared spectroscopy by means of a 15mm probe placed over the thenar eminence. Vascular occlusion test was performed on the forearm to be submitted to near-infrared spectroscopy by inflation of a sphygmomanometer cuff to 30mmHg higher than the systolic arterial pressure. The primary endpoint was the assessment of near-infrared spectroscopy-derived parameters immediately before, 1, 4 and 24 hours after the initiation of continuous venovenous hemodiafiltration. Results Nine patients were included in this pilot study over a period of 2 months. Minimum tissue oxygen saturation measured during the vascular occlusion test was the only near-infrared spectroscopy-derived parameter to differed over the time (decrease compared to baseline values up to 24 hours after initiation of continuous venovenous hemodiafiltration). Conclusion The impacts of microcirculatory dysfunction on clinical outcomes of patients undergoing to continuous venovenous hemodiafiltration need to be further investigated.

RESUMO Objetivo Avaliar o impacto da hemodiafiltração venovenosa contínua na microcirculação de pacientes com lesão renal aguda. Métodos Estudo piloto, prospectivo e observacional conduzido em uma unidade de terapia intensiva clínico-cirúrgica aberta, com 40 leitos, localizada em um hospital terciário, privado, na cidade de São Paulo (SP), Brasil. A microcirculação foi avaliada empregando-se a espectroscopia no infravermelho próximo, por meio de uma sonda de 15mm posicionada sobre a eminência tenar. O teste de oclusão vascular foi realizado no antebraço a ser submetido à espectroscopia no infravermelho próximo, inflando-se o manguito de um esfigmomanômetro a um valor 30mmHg acima da pressão arterial sistólica. O desfecho primário foi a avaliação dos parâmetros derivados por espectroscopia no infravermelho próximo imediatamente antes, 1, 4 e 24 horas após o início da hemodiafiltração venovenosa contínua. Resultados Foram incluídos nove pacientes neste estudo piloto ao longo de 2 meses. A saturação de oxigênio tecidual mínima mensurada durante o teste de oclusão vascular foi o único parâmetro derivado por espectroscopia no infravermelho próximo que diferiu ao longo do tempo, com queda em relação aos valores iniciais nas primeiras 24 horas após o início da hemodiafiltração venovenosa contínua. Conclusão A influência da disfunção microcirculatória sobre os desfechos clínicos de pacientes submetidos à hemodiafiltração venovenosa contínua precisa ser melhor investigada.

Is the early or delayed remote ischemic preconditioning the more effective from a microcirculatory and histological point of view in a rat model of partial liver ischemia-reperfusion?

Abstract Purpose: To compare early- and late-effect remote ischemic preconditioning (RIPC) by analysing the microcirculatory, hemodynamic and histological changes in partial liver ischemia-reperfusion of rats. Methods: 60-minute partial liver ischemia followed by 120-minute reperfusion was performed without (Control group, n=7) or with preconditioning. In RIPC groups a tourniquet was applied around the left thigh using 3 cycles of 10-minute ischemia/10-minute reperfusion, one (RIPC-1, n=7) or twenty-four hours (RIPC-24, n=7) before I/R. Hemodynamic and microcirculatory measurements were performed before and after ischemia and in 30th, 60th and 120th minute of reperfusion and histological examination at the end of reperfusion. Results: Blood pressure decreased in all groups followed by biphasic changes in Control group. In RIPC groups R120 values returned almost to normal. Heart rate increased in Control and RIPC-1 groups at R120, while RIPC-24 did not show significant changes. Microcirculation of non-ischemic liver stayed constant in Control and showed significant changes in RIPC-24 group, while in ischemic liver elevated by R120 in all groups. RIPC didn't reduce histological alterations. Conclusion: Considering the survival and the results, both remote ischemic preconditioning protocols had beneficial effect in hepatic ischemia-reperfusion, however the histopathological findings were controversial.

Association of Inflammation and Endothelial Dysfunction with Coronary Microvascular Resistance in Patients with Cardiac Syndrome X / Associação de Inflamação e Disfunção Endotelial com Resistência Microvascular Coronariana em Pacientes com Síndrome Cardíaca X

Abstract Background: Although a proportion of CSX patients have impaired brachial artery flow-mediated dilatation (FMD) in response to hyperemia, suggesting that endothelial dysfunction in these patients may be systemic and not just confined to the coronary circulation; the underlying mechanisms triggering endothelial dysfunction in these patients are still incompletely understood. Objectives: To assess the association of the index of Microcirculatory Resistance (IMR) with endothelial dysfunction and inflammation in patients with CSX. Methods: We studied 20 CSX patients and 20 age and gender-matched control subjects. Thermodilution-derived coronary flow reserve (CFR) and IMR were measured using a pressure-temperature sensor-tipped guidewire. Brachial artery FMD was measured using high-resolution, two-dimensional ultrasound images obtained with a Doppler ultrasound device (HDI-ATL 5000, USA) with a 5 MHz to 12 MHz linear-array transducer. Results: Compared with in control subjects, CFR was significantly lower (2.42 ± 0.78 vs. 3.59 ± 0.79, p < 0.001); IMR was higher (32.2 ± 8.0 vs. 19.5 ± 5.5, p < 0.001); the concentration of hs-CRP and FMD was higher (4.75 ± 1.62 vs. 2.75 ± 1.50; 5.24 ± 2.41 vs. 8.57 ± 2.46, p < 0.001) in CSX patients. The Duke treadmill score (DTS) was correlated positively to CFR and FMD (0.489 and 0.661, p < 0.001), it was negative to IMR and hsCRP (-0.761 and -0.087, p < 0.001) in CSX patients. Conclusions: The main finding in this study is that the DTS measured in patients with CSX was associated to hsCRP and FMD. Moreover, the independent effects of exercise tolerance can significantly impair FMD and hsCRP in CSX patients; especially it is particularly important to whom where FMD was associated negatively with IMR.

Resumo Fundamentos: Embora uma proporção de pacientes com SCX tenha dilatação mediada por fluxo da artéria braquial (DMF) prejudicada em resposta à hiperemia, sugerindo que a disfunção endotelial nestes pacientes pode ser sistémica e não limitar-se à circulação coronariana, os mecanismos subjacentes que desencadeiam a disfunção endotelial nestes pacientes ainda não são completamente compreendidos. Objetivos: Avaliar a associação do índice de resistência microcirculatória (IMR) com a disfunção endotelial e a inflamação em pacientes com SCX. Métodos: Estudaram-se 20 pacientes com SCX e 20 sujeitos de controle emparelhados em idade e género. A reserva de fluxo coronariano derivada da termodiluição (RFC) e a IMR forma medidas usando um fio guia com ponta de sensor de temperatura e pressão. A DMF da artéria braquial foi medida utilizando imagens ultrassónicas bidimensionais de alta resolução obtidas com um aparelho de ultrassom Doppler (HDI-ATL 5000, EE.UU.) com transdutor linear de 5 MHz a 12 MHz. Resultados: Em comparação com os sujeitos de controle, a RFC foi significativamente menor (2,42 ± 0,78 vs 3,59 ± 0,79, p < 0,001); o IMR foi maior (32,2 ± 8,0 frente a 19,5 ± 5,5, p < 0,001); a concentração de PCR-as e DMF foi maior (4,75 ± 1,62 frente a 2,75 ± 1,50, 5,24 ± 2,41 diante de 8,57 ± 2,46, p < 0,001) em pacientes com SCX. A escore de Duke (ED) se correlacionou positivamente com RFC e DMF (0,489 e 0,661, p < 0,001), foi negativa para IMR e PCR-as (-0,761 e -0,087, p < 0,001) em pacientes com SCX. Conclusões: O principal achado neste estudo é que o ED medido em pacientes com SCX esteve associado a PCR-as e DMF. Por outra parte, os efeitos independentes da tolerância ao exercício podem piorar significativamente a DMF e a PCR-as em pacientes com SCX especialmente, é particularmente importante que a DMF se associou negativamente com a RIM.

Recentes avanços na avaliação da microcirculação à beira do leito em pacientes graves / Recent advances in bedside microcirculation assessment in critically ill patients

RESUMO Parâmetros relacionados à macrocirculação, como pressão arterial média, pressão venosa central, débito cardíaco e saturação venosa mista e central de oxigênio, são comumente utilizados na avaliação hemodinâmica de pacientes graves. No entanto, diversos estudos demonstram que existe dissociação entre estes parâmetros e o estado da microcirculação neste grupo de pacientes. Técnicas que permitem a visualização direta da microcirculação não estão completamente difundidas e nem incorporadas ao manejo clínico dos pacientes em choque. Entre as inúmeras técnicas desenvolvidas para avaliação da microcirculação encontram-se: avaliação clínica (por exemplo: índice de perfusão periférica e gradiente de temperatura); fluxometria por laser Doppler; eletrodos de avaliação de oxigênio tecidual; videomicroscopia (imagem espectral por polarização ortogonal, análise em campo escuro de fluxo lateral, ou iluminação incidental em campo escuro); e espectroscopia no infravermelho próximo. A monitorização e a otimização da perfusão tecidual por meio da visualização direta e da avaliação da microcirculação pode, em um futuro próximo, tornar-se uma meta a ser atingida na ressuscitação hemodinâmica dos pacientes graves.

ABSTRACT Parameters related to macrocirculation, such as the mean arterial pressure, central venous pressure, cardiac output, mixed venous saturation and central oxygen saturation, are commonly used in the hemodynamic assessment of critically ill patients. However, several studies have shown that there is a dissociation between these parameters and the state of microcirculation in this group of patients. Techniques that allow direct viewing of the microcirculation are not completely disseminated, nor are they incorporated into the clinical management of patients in shock. The numerous techniques developed for microcirculation assessment include clinical assessment (e.g., peripheral perfusion index and temperature gradient), laser Doppler flowmetry, tissue oxygen assessment electrodes, videomicroscopy (orthogonal polarization spectral imaging, sidestream dark field imaging or incident dark field illumination) and near infrared spectroscopy. In the near future, the monitoring and optimization of tissue perfusion by direct viewing and microcirculation assessment may become a goal to be achieved in the hemodynamic resuscitation of critically ill patients.

Evaluación de la microcirculación con sidestream dark field (SDF) Microscan® como método de monitorización en microcirugía en modelo porcino / Microcirculation assessment with sidestream dark field (SDF) Microscan® as flap monitoring method in microsurgery in a porcine model

Objetivo: Determinar la factibilidad de la monitorización en microcirugía por medio de la evaluación no invasiva de la microcirculación con sidestream dark field (SDF) y compararla con otros métodos. Materiales y métodos: Estudio experimental. En 8 cerdos se elevó colgajo pectoral y se disecó pedículo. Se llevó a cabo una instalación sucesiva de dispositivos cutáneos para la evaluación de la microcirculación: SDF para evaluar flujo, y near infrared spectroscopy (NIRS) para evaluar saturación de O2 (SatO2). Posteriormente se evaluó la oclusión venosa, arterial y total con pinzamiento durante 180 s. Resultados: SDF en oclusión venosa: disminución del flujo: 51 s (59-62); SDF en oclusión arterial: disminución del flujo: 3 s (1-5); SDF en oclusión vascular total: disminución del flujo: 3,5 s (2-5). NIRS en oclusión venosa: disminución de la SatO2:15,2 ± 5,3%; NIRS en oclusión arterial: disminución de la SatO2 23,9 ± 13,8%; NIRS en oclusión vascular total: disminución de la SatO2 23,85 ± 13,9%. Doppler en oclusión venosa: no desapareció; Doppler en oclusión arterial y oclusión vascular total: desapareció a los 2 s. En cada una de las mediciones, los cambios clínicos fueron más tardíos que los observados con SDF. Conclusión: Es factible la monitorización en microcirugía por medio de la evaluación de la microcirculación con Microscan®. Este método permite realizar el diagnóstico de oclusión vascular más tempranamente que con NIRS y evaluación clínica.

Aim: Determine the feasibility of using SDF Microscan® as a non-invasive method for monitoring free flap microcirculation, and compare it to other methods. Materials and methods: Experimental study. In 8 pigs a pectoral myocutaneous flap was raised. Microcirculation was evaluated using: SDF Microscan®, near infrared spectroscopy (NIRS), clinical examination and Doppler. Venous, arterial and total occlusion was performed by clamping the vascular pedicle. Mean time to blood flow impairment diagnosis was measured. Results: SDF in venous occlusion: reduced microcirculatory flow index at: 51 s (59-62). SDF in arterial occlusion: reduced microcirculatory flow index at: 3 s (1-5). SDF in total vascular occlusion: reduced microcirculatory flow index at: 3.5 s (2-5). NIRS in venous occlusion: SatO2 decrease was 15.2 ± 5.3%. NIRS in arterial occlusion: SatO2 decrease was 23.9 ± 13.8%. NIRS in total vascular occlusion: SatO2 decrease was 23.85 ± 13.9%. Doppler in venous occlusion: The signal did not disappear. Doppler arterial and total vascular occlusion disappears at 2 s. The clinical changes were later than SDF. Conclusion: Microcirculation monitoring is feasible using SDF Microscan® in a pig model. This method allows to detect blood flow disruption earlier than NIRS and clinical evaluation.

AST-120 Improves Microvascular Endothelial Dysfunction in End-Stage Renal Disease Patients Receiving Hemodialysis

PURPOSE: Endothelial dysfunction (ED) is a pivotal phenomenon in the development of cardiovascular disease (CVD) in patients receiving hemodialysis (HD). Indoxyl sulfate (IS) is a known uremic toxin that induces ED in patients with chronic kidney disease. The aim of this study was to investigate whether AST-120, an absorbent of IS, improves microvascular or macrovascular ED in HD patients. MATERIALS AND METHODS: We conducted a prospective, case-controlled trial. Fourteen patients each were enrolled in respective AST-120 and control groups. The subjects in the AST-120 group were treated with AST-120 (6 g/day) for 6 months. Microvascular function was assessed by laser Doppler flowmetry using iontophoresis of acetylcholine (Ach) and sodium nitroprusside (SNP) at baseline and again at 3 and 6 months. Carotid arterial intima-media thickness (cIMT) and flow-mediated vasodilation were measured at baseline and 6 months. The Wilcoxon rank test was used to compare values before and after AST-120 treatment. RESULTS: Ach-induced iontophoresis (endothelium-dependent response) was dramatically ameliorated at 3 months and 6 months in the AST-120 group. SNP-induced response showed delayed improvement only at 6 months in the AST-120 group. The IS level was decreased at 3 months in the AST-120 group, but remained stable thereafter. cIMT was significantly reduced after AST-120 treatment. No significant complications in patients taking AST-120 were reported. CONCLUSION: AST-120 ameliorated microvascular ED and cIMT in HD patients. A randomized study including a larger population will be required to establish a definitive role of AST-120 as a preventive medication for CVD in HD patients.

A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging

Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61) and healthy age-matched subjects (n=24). Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; P<0.01). With regard to post-occlusive reactive hyperemia-induced vasodilation, the patients also presented reduced responses compared to the controls (0.42±0.15 vs 0.50±0.13 APU/mmHg; P=0.04). In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men.

How to choose the therapeutic goals to improve tissue perfusion in septic shock / Como escolher os alvos terapêuticos para melhorar a perfusão tecidual no choque séptico

The early recognition and treatment of severe sepsis and septic shock is the key to a successful outcome. The longer the delay in starting treatment, the worse the prognosis due to persistent tissue hypoperfusion and consequent development and worsening of organ dysfunction. One of the main mechanisms responsible for the development of cellular dysfunction is tissue hypoxia. The adjustments necessary for adequate tissue blood flow and therefore of oxygen supply to metabolic demand according to the assessment of the cardiac index and oxygen extraction rate should be performed during resuscitation period, especially in high complexity patients. New technologies, easily handled at the bedside, and new studies that directly assess the impact of macro-hemodynamic parameter optimization on microcirculation and in the clinical outcome of septic patients, are needed.

O reconhecimento e o tratamento precoce da sepse grave e do choque séptico é a chave para o sucesso terapêutico. Quanto maior o atraso no início do tratamento, pior é o prognóstico, em decorrência da hipoperfusão tecidual persistente, e do consequente desenvolvimento e agravamento das disfunções orgânicas. Um dos principais mecanismos responsáveis pelo desenvolvimento da disfunção celular é a hipóxia. A adequação do fluxo sanguíneo tecidual e, consequentemente, da oferta de oxigênio à demanda metabólica, de acordo com a avaliação do índice cardíaco e da taxa de extração de oxigênio, deve ser realizada durante a ressuscitação, principalmente nos pacientes de alta complexidade. Novas tecnologias, de fácil manuseio à beira do leito, e novos estudos, que avaliem diretamente o impacto da otimização dos parâmetros macro-hemodinâmicos na microcirculação e no desfecho clínico dos pacientes sépticos, são necessários.

Intra and postoperative evaluations of microcirculation and micro-rheological parameters in a rat model of musculocutaneous flap ischemia-reperfusion

PURPOSE:To examine how the ischemia-reperfusion injury of latissimus dorsi-cutaneous maximus (LDCM) musculocutaneous flap affects the microcirculatory (flap's skin surface) and hemorheological parameters, and whether an intraoperative deterioration would predictively suggest flap failure in the postoperative period.METHODS: Ten healthy male rats were subjected to the study. In Group I the left flap was sutured back after 2-hour, while the contralateral side was right after its elevation. In Group II the same technique was applied, but the pedicle of the left flap was atraumatically clamped for 2-hour. The contralateral side was left intact. On the flap skin surface laser Doppler tissue flowmetry measurements were done before and after and during the protocols applied in the groups. Microcirculatory and hemorheological examinations were done postoperatively.RESULTS: The microcirculatory parameters significantly decreased during immobilization and ischemia. Afterwards, all the regions showed normalization. In the retrospective analysis there was a prominent difference between the microcirculatory parameters of necrotic and survived flap during the early postoperative days (1-3) in Group II. Erythrocyte aggregation and deformability showed only slight differences.CONCLUSIONS: Two-hour ischemia and reperfusion caused deterioration in latissimus dorsi-cutaneous maximus flap microcirculation. Predicting the possible postoperative complication, the intraoperative laser Doppler measurement can be informative.

Skin microcirculatory changes reflect early the circulatory deterioration in a fulminant sepsis model in the pig

PURPOSE: In the pathophysiology of sepsis tissue perfusion dysfunction is a crucial driving force. Thus the early recognition is highly important. Concerning the early hours of bacteremia, and the systemic inflammatory response reaction leading to sepsis we aimed to investigate the micro- and macrocirculatory changes. METHODS: In 20 juvenile Hungahib pigs were anesthetized and the femoral artery and external jugular vein were prepared unilaterally and cannulated. For assisted ventilation tracheostomy was performed. In Sepsis group (n=11) live E. coli was intravenously administered (increasing concentration, 9.5x10∧6 in 3h). In Control group (n=9) bacteria-free saline was administered at the same volume. Modified shock index (MSI), core and skin temperature, and skin microcirculation (laser Doppler) were measured before inducing bacteremia then hourly for 4h. RESULTS: In Control group parameters were stable, while six animals in the Sepsis group died before the 4th hour. Core and skin temperature did not show significant alterations. In Sepsis group microcirculation showed a large impairment already by the 1st hour, while in MSI only by the 3rd hour. CONCLUSION: During bacteremia and the early phase of sepsis microcirculatory impairment can be detected soon, even hours before the deterioration in hemodynamic parameters in this porcine model. .

Mesenteric hypoperfusion and inflammation induced by brain death are not affected by inhibition of the autonomic storm in rats

OBJECTIVES: Brain death is typically followed by autonomic changes that lead to hemodynamic instability, which is likely associated with microcirculatory dysfunction and inflammation. We evaluated the role of the microcirculation in the hemodynamic and inflammatory events that occur after brain death and the effects of autonomic storm inhibition via thoracic epidural blockade on mesenteric microcirculatory changes and inflammatory responses. METHODS: Male Wistar rats were anesthetized and mechanically ventilated. Brain death was induced via intracranial balloon inflation. Bupivacaine (brain death-thoracic epidural blockade group) or saline (brain death group) infusion via an epidural catheter was initiated immediately before brain death induction. Sham-operated animals were used as controls (SH group). The mesenteric microcirculation was analyzed via intravital microscopy, and the expression of adhesion molecules was evaluated via immunohistochemistry 180 min after brain death induction. RESULTS: A significant difference in mean arterial pressure behavior was observed between the brain death-thoracic epidural blockade group and the other groups, indicating that the former group experienced autonomic storm inhibition. However, the proportion of perfused small vessels in the brain death-thoracic epidural blockade group was similar to or lower than that in the brain death and SH groups, respectively. The expression of intercellular adhesion molecule 1 was similar between the brain death-thoracic epidural blockade and brain death groups but was significantly lower in the SH group than in the other two groups. The number of migrating leukocytes in the perivascular tissue followed the same trend for all groups. CONCLUSIONS: Although thoracic epidural blockade effectively inhibited the autonomic storm, it did not affect mesenteric hypoperfusion or inflammation induced by brain death. .

Andreas Vesalius as a renaissance innovative neuroanatomist: his 5th centenary of birth / Andreas Vesalius como neuroanatomista inovador renascentista: seu 5° centenário de nascimento

Andreas Vesalius (1514-1564) is considered the Father of Modern Anatomy, and an authentic representative of the Renaissance. His studies, founded on dissection of human bodies, differed from Galeno, who based his work on dissection of animals, constituted a notable scientific advance. Putting together science and art, Vesalius associated himself to artists of the Renaissance, and valued the images of the human body in his superb work De Humani Corporis Fabrica.This paper aims to honor this extraordinary European Renaissance physician and anatomist, who used aesthetic appeal to bind text and illustration, science and art. His achievements are highlighted, with an especial attention on neuroanatomy. Aspects about his personal life and career are also focused.

Andreas Vesalius (1514-1564) é considerado o Pai da Anatomia Moderna e um autêntico representante da Renascença. Seus estudos, baseados na dissecação de corpos humanos, diferiam dos de Galeno, que baseava seu trabalho em dissecação de animais, constituiu-se em um notável avanço científico. Reunindo ciência e arte, Vesalius associou-se a artistas da Renascença e valorizou as imagens do corpo humano em seu soberbo trabalho De Humani Corporis Fabrica. Este artigo visa honrar esse extraordinário médico e anatomista da Renascença europeia, que fez uso do apelo estético para coligar texto e ilustração, ciência e arte. Suas realizações são realçadas, com atenção especial na neuroanatomia. Também são colocados em foco aspectos da sua vida pessoal e de sua carreira.

Determinantes precoces en el desarrollo de injuria renal aguda durante la sepsis abdominal experimental / Early determinants of acute kidney injury during experimental intra-abdominal sepsis

Background: Sepsis-induced acute kidney injury (AKI) is an early and frequent organ dysfunction, associated with increased mortality. Aim: To evaluate the impact of macrohemodynamic and microcirculatory changes on renal function and histology during an experimental model of intra-abdominal sepsis. Material and Methods: In 18 anaesthetized pigs, catheters were installed to measure hemodynamic parameters in the carotid, right renal and pulmonary arteries. After baseline assessment and stabilization, animals were randomly divided to receive and intra-abdominal infusion of autologous feces or saline. Animals were observed for 18 hours thereafter. Results: In all septic animals, serum lactate levels increased, but only eight developed AKI (66%). These animals had higher creatinine and interleukin-6 levels, lower inulin and para-aminohippurate clearance (decreased glomerular filtration and renal plasma flow), and a negative lactate uptake. Septic animals with AKI had lower values of mean end arterial pressure, renal blood flow and kidney perfusion pressure, with an associated increase in kidney oxygen extraction. No tubular necrosis was observed in kidney histology. Conclusions: The reduction in renal blood flow and renal perfusion pressure were the main mechanisms associated with AKI, but were not associated with necrosis. Probably other mechanisms, such as microcirculatory vasoconstriction and inflammation also contributes to AKI development.