Biocompatibility of the Oxygenator on Pulsatile Flow by Electron Microscope

ABSTRACT Introduction: Extracorporeal perfusion flow type requires further investigation. The aim of this study is to compare the effects of pulsatile and nonpulsatile flow on oxygenator fibers that were analyzed by scanning electron microscope (SEM) and to extensively study patients' coagulation profiles, inflammatory markers, and functional blood tests. Methods: Twelve patients who had open heart surgery were randomly divided into two groups; the nonpulsatile flow (group NP, six patients) and pulsatile flow (group P, six patients) groups. Both superficial view and axial sections of the oxygenator fiber samples were examined under SEM to compare the thickness of absorbed blood proteins and amount of blood cells on the surface of oxygenators. Platelet count, coagulation profile, and inflammatory predictors were also studied from the blood samples. Results: Fibrinogen levels after cardiopulmonary bypass were significantly lower in group NP (group P, 2.57±2.78 g/L; group NP; 2.39±0.70 g/L, P=0.03). Inflammatory biomarkers such as C-reactive protein, interleukin (IL)-6, IL-12, apelin, S100β, and tumor necrosis factor alpha were comparable in both groups. Axial sections of the oxygenator fiber samples had a mean thickness of 45.2 µm and 46.5 µm in groups P and NP, respectively, and this difference is statistically significant (P=0.006). Superficial view of the fiber samples showed obviously lower platelet, leukocyte, and erythrocyte levels in group P. Conclusion: Our study demonstrated that both cellular elements and protein adsorption on oxygenator fibers are lower in the group P than in the group NP. Pulsatile perfusion has better biocompatibility on extracorporeal circulation when analyzed by SEM technique.

Caliber-persistent labial artery: report of 3 cases

Abstract The caliber-persistent labial artery is a vascular anomaly in which a primary arterial branch penetrates into the submucosal tissue without reduction in diameter. Most lesions are benign and do not require treatment, except for complications and/or on patient demands. In this way, noninvasive diagnostic tools are preferred such as high-resolution and color Doppler ultrasonography which allow direct observation of the lesion, assessing its exact location and diameter at every axis, as well as the blood flow velocity. An excisional biopsy of these lesions or even their surgical extirpation could have a fatal outcome with profuse bleeding.

Finite Element Analysis and in vitro Hemodynamic Testing of Polyester Textile Valves with Nitinol Wires / 医用生物力学

Objective To study mechanical properties of polyethylene terephthalate (PET)-based textile valves woven with nickel-titanium (NiTi) wires by finite element method, and combined with in vitro hemodynamic testing, to analyze the effect of wire quantity and woven position on hemodynamic performance of PET textile valve. Methods The three-dimensional (3D) geometric models of PET valves without wires and models of PET valves with wires by different numbers and distributions in radial direction were constructed using modeling software. Material properties of PET valves and wires were given based on the literature and experimental data. The transvalvular pressure difference curves of PET valves obtained from in vitro pulsatile flow experiments were used as boundary conditions. Stress distributions of the valve during peak systole and diastole were studied by finite element analysis software. Hydrodynamic performance of the valve with wires was evaluated by in vitro pulsatile flow experiments. ResultsThe finite element analysis results showed that the radially woven NiTi wires could enhance support for the PET textile valve, and support force and area of the valve in belly region of the valve leaflet with evenly distributed metal wires increased with the number of metal wires. The situation of support force was similar for silk distributions on both sides of the belly. The weaving of wires reduced stress concentration on the PET textile valve to a certain extent. The pulsatile flow experiment results showed that the stability of opening and closing shapes, effective opening area (EOA), regurgitation fraction (RF) and transvalvular pressure differences for two kinds of the PET valves with woven wires were better than those of the PET valves without wires. Conclusions Weaving metal wires in radial direction of the PET textile valve can effectively reduce stress concentrations on the PET textile valve during the cardiac cycle, and reduce tearing possibility of the valve leaflet. The woven metal wires can improve opening and closing stability of PET textile valve in in vitro hydrodynamic test, increase EOA and reduce RF and transvalvular pressure difference of the PET valve.

Feasibility of transesophageal echocardiography-guided transthoracic micro-incisions for the treatment of aortic dissection / 中国基层医药

Objective:To investigate the feasibility of transesophageal echocardiography (TEE)-guided transthoracic micro-incisions for the treatment of aortic dissection.Methods:Ten patients with aortic dissection who received TEE before surgery between March 2017 and March 2019 in Zhejiang Provincial Hospital of Chinese Medicine, China were included in this study. They were divided into group A (involving the aorta, n = 5) and group B (aortic arch ulcer, n = 5). Diagnosis before and after surgery was analyzed in each group. Whether guide sheath tube and guide wire rapidly entered the interlayer during the surgery was assessed. In addition, the stability and position of the occluder device and its effect on local blood flow were assessed. Results:TEE findings revealed that occlusion treatment was effective and TEE-guided transthoracic micro-incisions successfully occluded the breaks of the aortic dissection. In group A, the occluded breaks of the aortic dissection disappeared, and thrombi formed in the false lumen. Blood flow velocity decreased from 230 cm/s to 120 cm/s. In group B, aortic wall was tightly bounded to the occluder device and the breaks disappeared. The velocity of the blood flow in the arch of the aorta was 120 cm/s. The occluder device was stable before and after occlusion. It had no effect on the velocity of local blood flow. At 40 days after surgery, the position of the occluder was not deviated.Conclusion:TEE before surgery for aortic dissection can effectively assess the injury degree and avoid missed diagnosis. TEE can guide the placement of the occluder device during the surgery. TEE can also help accurately assess the surgical outcomes.

Gestantes con índice de pulsatilidad alterado en ecografía Doppler / Pregnant women with altered pulsatility index in Doppler echography

Introducción: La ecografía Doppler de las arterias uterinas es una técnica propuesta para predecir el riesgo de preeclampsia, retardo del crecimiento intrauterino y otras alteraciones perinatales adversas. Objetivos: Determinar la frecuencia de gestantes con alteración en las arterias uterinas durante el primer trimestre e identificar la presencia de preeclampsia/eclampsia, así como sus principales características clínicas. Métodos: Se efectuó un estudio descriptivo y longitudinal de 168 gestantes en el primer trimestre de embarazo, pertenecientes al municipio de Tercer Frente en Santiago de Cuba, evaluadas en una pesquisa de Genética realizada en el Policlínico Docente Cruce de los Baños, de abril a noviembre de 2018. A todas se les realizó ecografía Doppler para calcular el índice de pulsatilidad de las arterias uterinas. Resultados: En la casuística, 16 pacientes presentaron alterado el índice de pulsatilidad y, de ellas, solo en 3 se desarrolló preeclampsia, para 18,7 %; la edad promedio en estas últimas fue de 29 años y 2 eran nulíparas (66,6 %). Respecto al índice de pulsatilidad, el promedio fue de 2,5. Conclusiones: Se mantuvo un estrecho seguimiento, hasta el parto, de las pacientes con resultados patológicos, y se destacó la importancia de estudiar el índice de pulsatilidad de las arterias uterinas durante el primer trimestre del embarazo, sobre todo en las nulíparas.

Introduction: The Doppler echography of the uterine arteries is a technique suggested to predict the risk of pre-eclampsia, the intrauterine growth retardation and other adverse perinatal disorders. Objectives: To determine the frequency of pregnant women with disorder in the uterine arteries during the first trimester and to identify the pre-eclampsia/eclampsia presence, as well as their main clinical characteristics. Methods: A descriptive and longitudinal study of 168 pregnant women in the first trimester of pregnancy, belonging to the Tercer Frente municipality in Santiago de Cuba was carried out, they were evaluated by investigation of Genetics in Cruce de los Baños Teaching Polyclinic from April to November, 2018. To determine the pulsatility index of the uterine arteries, a Doppler echography was carried out. Results: In the case material 16 patients presented this parameter altered and just 3 pregnant women presented pre-eclampsia, for 18.7 %; the average age of these last ones was of 29 years and 2 were nonparous (66.6 %). Regarding the pulsatility index, the average was of 2.5. Conclusions: There was a close follow up of the patients with pathological results, until the childbirth, and the importance of studying the pulsatility index of the uterine arteries in the first trimester of the pregnancy, mainly in the nonparous, was emphasized.

Máquina de perfusão versus armazenamento estático na preservação renal de doadores com morte encefálica: revisão sistemática e metanálise / Machine perfusion versus cold storage in renal preservation of deceased donors with brain death: systematic review and meta-analysis

RESUMO Com a utilização crescente da máquina de perfusão no transplante renal, tem sido constatado que a isquemia dinâmica correlaciona-se à melhora da preservação orgânica. Nesse contexto, realizamos uma revisão sistemática que procurou avaliar a eficácia do uso de máquina de perfusão portátil (LifePort Kidney Transporter Machine®), utilizada no Brasil, comparada ao armazenamento estático, no que tange à função retardada do transplante renal de doadores com morte encefálica. Foi efetuada pesquisa bibliográfica, nas bases LILACS, MEDLINE via PubMed, Scopus, Clarivate Analytics, Cochrane Library, Embase, SciELO, além de busca manual no Google acadêmico. A revisão sistemática, finalizada em abril 2017, foi constituída somente por ensaios clínicos randomizados. Para metanálise, foram avaliadas Razão de Risco e Razão de Chance. Foram identificados 86 documentos e selecionados, ao final, dois artigos com critérios de elegibilidade para metanálise, de grupos europeus e brasileiros. Nestes, 374 rins foram alocados para a máquina de perfusão, e igual número para o armazenamento estático. A função retardada do enxerto foi constatada em 84 e 110 pacientes, respectivamente. Na metanálise, foram obtidas uma Razão de Risco de 0,7568 (p=0,0151) e uma Razão de Chance de 0,6665 (p=0,0225), ambas com intervalo de confiança de 95%. A máquina de perfusão reduziu a incidência de função retardada do enxerto de doadores com morte encefálica.

ABSTRACT With the increasing use of machine perfusion in kidney transplantation, it has been observed that dynamic ischemia correlates with the improvement of organ preservation. In this context, we performed a systematic review that aimed to evaluate the efficacy of the portable machine perfusion (LifePort Kidney Transporter Machine®), used in Brazil, compared to cold storage, regarding the delayed graft function of deceased donors with brain death. Literature search was carried out in LILACS, MEDLINE via PubMed, Scopus, Clarivate Analytics, Cochrane Library, Embase, and SciELO, as well as in Google Scholar manually. The systematic review consisted only of randomized clinical trials. For meta-analysis, relative risk and odds ratio were evaluated. Eighty-six documents were identified and two papers from European and Brazilian groups were selected at the end, with eligibility criteria for meta-analysis. In these, 374 kidneys were assigned to machine perfusion and 374 kidneys were assigned to cold storage. Delayed graft function was observed in 84 and 110 patients, respectively. In meta-analysis, a risk ratio of 0.7568 (p=0.0151) and an odds ratio of 0.6665 (p=0.0225) were obtained, both with a 95% confidence interval. Machine perfusion reduced the incidence of delayed graft function of deceased donors with brain death.

Analysis of blood flow energy characteristics of pulsatile and non-pulsatile flow during extracorporeal circulation / 中华外科杂志

Objective@#To analyze the magnitude of blood flow energy and characteristics of frequency domain between pulsatile flow and nonpulsatile flow during cardiopulmonary bypass and physiological flow.@*Methods@#From January 2017 to December 2017, 60 cases of patients with mitral valve disease scheduled for mitral valve replacement or repair at Department of Cardiasurgery, Shanghai Chest Hospital, Shanghai Jiaotong University were randomly divided into 2 groups: pulsatile perfusion (PP) and non-pulsatile perfusion (NP). The magnitude of blood flow energy during pulsatile and non-pulsatile was calculated using energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) while fast Fourier transformation (FFT) was used to perform power spectral density analysis to identify the frequency domain characteristics between artificial and physiological flow (prior to CPB). The data was analyzed by analysis of variance or t test.@*Results@#At the different time-points after occlusion, the EEP and SHE in PP group were respectively 1.52 to 1.62 and 2.03 to 2.22 times higher than NP at the distal of artery filter. The power density analysis revealed that the blood flow energy of physiological pulsatile flow patterns was within 40 Hz and the ratio of low frequency energy was more than 90% before clamp. The spectral energy ratio of low frequency decreased in both group compared with physiological flow was more obvious in NP group at the radial artery. The ratio of estimated value of power density of PP and NP groups analysis showed the corresponding 0 to 5 Hz, 0 to 10 Hz, 0 to 40 Hz frequency range values measured at the radial artery and filter were 9.51, 4.68, 3.59 and 3.87, 2.69, 2.38 respectively after occulusion. In each frequency range, the energy of PP is higher than that of NP, and the lower the frequency, the greater the difference. The ratio of estimated value of power density of PP and NP groups for the three frequencies measured at the radial artery before and after occlusion were 2.86, 2.83, 2.75 and 14.70, 12.74, 9.85 respectively, and decreased significantly in NP group and low frequency energy. The ratio of estimated value of power density of PP and NP groups under the three different frequencies measured at the radial artery and filter were 26.35, 33.15, 37.36 and 37.41, 54.18, 56.64 respectively, in the conduction process from filter to radial artery, energy exhaustion is significant, especially in group NP.@*Conclusions@#The PP provides significantly more energy than the NP whereby the PP is closer to the physiological pulsatile on the energy frequency structure and attenuation characteristics, with mainly low frequency energy of 0 to 5 Hz and weak energy attenuation. The energy loss of non-pulsatile flow is obvious, especially the low frequency energy.

Oral Administration of Cilostazol Increases Ocular Blood Flow in Patients with Diabetic Retinopathy

PURPOSE: To investigate the effect of cilostazol on ocular hemodynamics and to determine whether the administration of cilostazol increases the ocular blood flow in patients with diabetic retinopathy. METHODS: This prospective observational study investigated the effect of orally administered cilostazol on diabetic retinopathy. Before and after administration for 1 week, pulsatile ocular blood flow (POBF) and retrobulbar hemodynamics were measured using a POBF analyzer and transcranial Doppler imaging, respectively. Visual acuity, intraocular pressure, and blood pressure were also evaluated before and after treatment. RESULTS: Twenty-five eyes of 25 patients were included in this study. POBF increased significantly (16.8 ± 4.6 µL/sec vs. 19.6 ± 6.2 µL/sec, p < 0.001) after administration of cilostazol, while no significant change was identified in visual acuity, intraocular pressure, and blood pressure. Mean flow velocity in the ophthalmic artery as measured with transcranial Doppler imaging also increased significantly after medication (23.5 ± 5.6 cm/sec vs. 26.0 ± 6.9 cm/sec, p = 0.001). The change in POBF directly correlated with the change in mean flow velocity (r = 0.419, p = 0.007). CONCLUSIONS: Cilostazol was effective in increasing ocular blood flow in patients with diabetic retinopathy, possibly by modulating retrobulbar circulation.

Dinámica de flujo computacional en aneurismas cerebrales / Computational fluid dynamics in intracranial aneurysm

Los aneurismas cerebrales son lesiones arteriales caracterizadas por el debilitamiento y la dilatación de un segmento del vaso sanguíneo. Representan una gran amenaza para la vida del paciente debido al riesgo de ruptura, trombo-embolias o compresión del tejido adyacente. Los aneurismas cerebrales rotos son la causa más común de la hemorragia subaracnoidea y puede causar una significativa morbilidad y mortalidad. Con el fin de entender el comportamiento hemodinámico de los aneurismas cerebrales se han desarrollado estudios computacionales que simulan las condiciones y propiedades de dichas lesiones en modelos virtuales similares a la realidad; la mayoría de ellos se realizan en un sistema experimental conocido como dinámica de fluido computacional. Este artículo presenta una revisión del estado de la técnica aplicada a hemodinámica de flujo en aneurismas y pretende recopilar los avances más importantes del método que servirán en un futuro, para el desarrollo de una herramienta de apoyo al diagnóstico y tratamiento de estas dolencias.

Intracranial aneurysms are lesions of the arterial wall characterized by weakening and dilation of an arterial segment. These lesions are a major threat to the patient’s life because of the risk of rupture, thrombo-emboli, or compression of adjacent tissue. The rupture of an intracranial aneurysm causes subarachnoid hemorrhage associated with high mortality and morbidity rates. In order to understand the intracranial aneurysm hemodynamics, it has been developed computational studies, which simulate the boundary conditions and properties of these lesions in virtual models (models similar to reality), most of them are made in a computational fluid dynamic model (CFD). This study reviews the state of arts of the CFD technique applied to the aneurysm flow hemodynamics that claims to collect the most important progress of the method that will be useful in the tool’s developments that will become a rely on a diagnosis and treatment tool.

O Índice de Perfusão da Oximetria de Pulso na Avaliação da Função Endotelial na Aterosclerose / Evaluation of Endothelial Function on Atherosclerosis using Perfusion Index from Pulse Oximeter

Fundamento: A disfunção endotelial se caracteriza por um fenômeno vascular, com importância evidente em todos os processos da aterogênese. Interessa, assim, a busca por métodos de avaliação da disfunção endotelial mais acurados, práticos e menos dispendiosos, objetivando melhoria na prevenção e tratamento das doenças ateroscleróticas. Objetivo: Verificar o potencial do índice de perfusão derivado da oximetria de pulso (IPP) como método de avaliação da disfunção endotelial em pacientes portadores de aterosclerose Métodos: Foram selecionados 18 pacientes controles e 24 pacientes portadores de doenças ateroscleróticas, em tratamento otimizado, selecionados em Unidades Básicas de Saúde. Foram avaliados os valores do IPP antes a após a aplicação de um estímulo vasodilatador dependente do endotélio - a hiperemia reativa. Também foram analisados os valores do IPP especificamente no período que possui a maior contribuição do óxido nítrico para a vasodilatação (IPP90-120). Os resultados do IPP foram discutidos, por meio da literatura, estimando o seu potencial diagnóstico e prognóstico. Resultados: A resposta vasodilatadora dependente do endotélio mensurada pelo IPP foi significantemente menor em indivíduos com aterosclerose em comparação aos controles a partir de 45 segundos após a hiperemia reativa. Foram observados, do mesmo modo, valores menores do IPP90-120 em pacientes com aterosclerose [35% (4% - 53%) vs. 73% (55% - 169%); p < 0,001]. Tais valores se mantiveram menores tanto em indivíduos masculinos quanto femininos. Conclusões: Os resultados do IPP, demonstrados na avaliação de pacientes ateroscleróticos, associados ao baixo custo da aparelhagem, tornam esse método ...

Background: Endothelial dysfunction is vascular phenomenon that plays an important role in atherosclerosis development. With the purpose of improving the prevention and treatment of atherosclerotic diseases, the searching for accurate, practical and cheaper methods for evaluating endothelial function have become of interest. Objectives: Verify the potential of Peripheral Perfusion Index from pulse oximetry (IPP) as a method of endothelial dysfunction evaluation in patients with atherosclerotic diseases. Methods: There were recruited 18 control patients and 24 patients with atherosclerotic diseases under optimized treatment, in basic health units. The values of IPP were evaluated before and after an endothelial-dependent stimulus, the reactive hyperemia. The values of IPP were also evaluated in period which the major contribution of Nitric Oxide (NO) for the vasodilation occurs (IPP90-120). The results of IPP were discussed using the literature and estimating their diagnostic and prognostic potential Results: The endothelium-dependent vasodilatory response measured by IPP was significantly lower in patients with atherosclerosis compared to control group, since 45 seconds after reactive hyperemia. Also, the values of IPP90-120 were significantly lower in patients with atherosclerosis [35% (4 - 53%) vs 73% (55 - 169%); p<0,001]. Similarly, the IPP values were lower in atherosclerosis group when it was separated by gender. Conclusion: The results of this study, in association with the low cost of pulse oximeter, suggest a good potential for IPP as an endothelial dysfunction evaluation method. New studies must be done in order to clarify this potential and possibly contribute with the prevention and treatment of atherosclerotic diseases. .

Analysis of the Effect of Renal Replacement Therapy: In the Prolonged Extracorporeal Membrane Oxygenation Patients

BACKGROUND: This paper aimed to verify the effects of renal replacement therapy on changing the levels of serum creatinine for different veno-arterial and veno-venous configurations in prolonged extracorporeal membrane oxygenation (ECMO) patients. METHODS: The subjects were chosen 71 patients who had undergone more than 1,440 minutes (24 hours) of the therapy from among 117 patients who had undergone ECMO insertion between January 2008 and December 2012. The patients were separated into the veno-arterial configuration group I (51 patients) and the veno-venous configuration group II (20 patients). The difference in the level of serum creatinine (DeltaCr) between before or just after ECMO insertion (CrI) and the level when the pump time was between 2,880 and 4,320 minutes (CrF) was checked (DeltaCr=CrF-CrI), and the average DeltaCr for each group was compared using a Student t-test at the confidence interval (CI) of 95%. RESULTS: The change in the level of serum creatinine was an increase of 0.341 mg/dL (sigma=0.9202) for group I and a decrease of 0.120 mg/dL (sigma=1.5292) for group II. The change was significantly high for group I (p=0.011, CI=95%). Meanwhile, within group I, when renal replacement therapy was not done, there was a significant increase in the level of serum creatinine (p=0.009, CI=95%). CONCLUSION: For ECMO insertion patients whose pump time was more than 1,440 minutes, there was a significant change in the level of serum creatinine when renal replacement therapy was not done, for the veno-arterial configuration of group I.

The clinical value of stroke volume variation and pleth variability index in predicting fluid responsiveness during increased intra-abdominal pressure / 中国基层医药

Objective To evaluate the abilities and thresholds of stroke volume variation (SVV) and pleth variability index (PVI) in predicting fluid responsiveness during increased intra-abdominal pressure.Methods 28 patients undergoing laparoscopy-assisted radical gastrectomy were selected.PV1 was continuously displayed by the Masimo.Radical 7.All patients were also monitored with Vigileo/FloTrac system.Haemodynamic data such as MAP,HR,SVI,SVV,PI,PVI and C VP were recorded before and after volume expansion(HES 6％,7ml/kg).Fluid responsiveness was defined as an increase in SVI≥ 15％ (△ SVI ≥ 15).Results The SVV threshold of 9.5％ before volume expansion was able to diserimihate the responders from the non-responders with a sensitivity of 100％,and a specificity of 63.6％.The threshold for PVI was 14.0％,the sensitivity of 100％ and specificity of 81.8％ were obtained.There was no significant difference between the area under the receiver operating characteristics (ROC) curves of SVV and PVI(0.981,0.939,respectively),and there was significant correlation between the baseline SVV and the baseline PVI(r =0.740,P ＜ 0.01).Conclusion SVV and PVI can predict fluid responsiveness accurately during increased intra-abdominal pressure,the baseline SVV is correlated well with baseline PVI,and the ability of SVV and PVI in predicting fluid responsiveness is similar.

Caracterización del flujo pulsante vascular mediante observaciones in vitro en modelos biológico y mecánico / Characterization of the vascular pulsatile flow through in vitro observations on biologic and mechanical models

Objetivo: Tras las evidencias acumuladas con el uso de dispositivos de asistencia circulatoria de flujo pulsante y continuo, surge la polémica sobre los efectos del tipo de flujo en el sistema circulatorio. Este artículo propone la caracterización del flujo pulsante en conductos elásticos, para analizar la influencia de la pulsación en el sistema y entender las peculiaridades del flujo en el lecho vascular. Métodos: Utilizando un dispositivo de bombeo tipo saco elástico de accionamiento neumático, se procedió a la observación visual e instrumental del flujo a través de conductos tanto flexibles (vaso venoso bovino) como rígidos (tubo plástico), y se analizaron las características biomecánicas de la pulsación en ambos. Resultados: Basado en la observación experimental y el análisis biomecánico del flujo pulsante en un conducto elástico, se caracterizó el patrón de la pulsación y se planteó un modelo que explica la influencia de la pulsación en el sistema vascular y los efectos de su ausencia. El modelo propuesto incluye la condición general de flujo (componente mecánico) y su aplicación al sistema vascular (componente fisiológico). Conclusiones: El modelo planteado permite determinar la relación entre las condiciones del flujo y la reacción de la pared, así como unificar la interpretación de factores fluido-dinámicos involucrados a la vez, que advierte sobre los efectos del cambio de flujo y su significado en lo que sería la operación de dispositivos de asistencia circulatoria.

Objective: The evidence accumulated on the use of pulsatile and non-pulsatile flow-dependent devices raises a controversy concerning the effects of the flow type on the Circulatory system. This paper proposes to characterize the properties of pulsatile flow in elastic conduits in order to determine how the pulse affects the system and to determine the specific details of the flow in the vascular bed. Methods: The biomechanical properties of pulsatile flow were measured on flexible (calf venous vessel), and rigid (plastic pipe) conduits in which the flow was implemented using a pneumatic elastic sack-like pumping device. Results: The experimental data and the biomechanical analysis of the pulsing flow was used to determine the flow pattern in order to develop a mechanical model explaining the effects of the pulse on the vascular system. The resulting model includes the flow's general condition (mechanical component) and its effects on the vascular system (biological/physiological component). Conclusions: The model proposed here allows determining the relationship between the flow conditions and the reaction on the wall; it also allows unifying the interpretation of fluid-dynamic factors affecting these phenomena and represents a warning system about the effects of flow changes on the operation of circulatory assistance devices.

Similarity measurement of blood pressure waveforms for pulsatile flow simulation system / 医用生物力学

Objective To study a quantitative indicator for measuring the similarity between blood pressure waveforms and its application in the analysis on the simulated blood pressure waveform for pulsatile flow simulation system.Methods Based on the past similarity measurement algorithm and the known feature of blood pressure waveforms, the weighted average algorithm was presented in this paper, which possessed advantages of both global matching and partial matching by integrating the correlation coefficient with the characteristic parameter algorithm, and calculating similarity degrees through overall and partial waveform.Results The weighted average algorithm was proved to be more suitable for the analysis on the blood pressure waveform similarity compared with the angle cosine method, average absolute deviation method, and numeric similarity coefficient method.Conclusions The weighted average algorithm showed excellent ability in calculating the similarity degree between different waveforms, or in comparing the performance with different pulsatile flow simulation systems, and it could be applied to other physiological waveforms with further improvement.

Carotid-cerebral pulse wave velocity and its influencing factors / 国际脑血管病杂志

Objective To investigate the correlation between the measurement methods of carotidcerebral pulse wave velocity (ccPWV) and the traditional method of brachial-ankle pulse wave velocity (baPWV).Methods A total of 136 healthy volunteers were divided into a youth group (20-39 years),a middleaged group (40-59 years),and an elderly group (more than 60 years) according to their ages.While detecting baPWV,transcranial Doppler ultrasound was used to simultaneously monitor the ipsilateral common carotid artery and the terminal segment of internal carotid artery.The time differences of the beating points of their cardiac cycles and the distanceses of the skin surfaces between the 2 probes were measured and ccPWV was calculated.Results The systolic blood pressure,pulse pressure and mean arterial pressure in the elderly group were signifificantly higher than those in the middle-aged group and the young group.The ccPWVs in the youth,middle-aged and elderly groups were 418 ± 52 cm/s,489 ±54 cm/s,and 599 ± 58 cm/s,respectively.The elderly group was significantly faster than the middle-aged group (t =7.308,P ＜0.001),and the middle-aged group was significantly faster than the youth group (t=6.758,P＜0.001).A Pearson correlation analysis showed that ccPWV was significantly positively associated with the age (r=0.847,P＜0.001) and baPWV (r =0.548,P ＜0.001).The multiple linear regression analysis showed that ccPWV was significantly positively associated with the age and diastolic blood pressure (partial correlation coefficients were 0.742 and 0.293respectively,P ＜0.001 and ＜0.010 respectively).Conchlusions ccPWV is a new measurement method for cerebrovascular stiffneas,and it has a good correlation with the traditional measurement method.

Arterial stiffness and cerebrovascular diseases / 国际脑血管病杂志

In recent years, much attention has been paid to arterial stiffness detection,but the relation between arterial stiffness and cerebrovascular disease has not been fully elucidated.This article reviews the detective methods of arterial stiffness and its relationship between the risk factors for cerebrovascular disease, ischemic stroke (including asymptomatic cerebral infarction) and cerebral hemorrhage.

The prognostic values of the pulsatility index and serum neuron-specific enolase in patients achieved return of spontaneous circulation after cardiopulmonary resuscitation: a cohort study / 国际脑血管病杂志

Objective To investigate the predictive values of the pulsatility index detected by transcranial Doppler (TCD) and serum neuron-specific enolase (NES) in patients achieved return of spontaneous circulation after cardiopulmonary resuscitation (CPR). Methods The patients with CPR restoration of spontaneous circulation who were still in coma were divided into survival group and death group. TCD monitoring and serum NSE detection were performed at 48 hours after CPR restoration of spontaneous circulation. Receiver operating characteristic (ROC) curves were used to evaluate the predictive values of the pulsatility index detected by TCD and serum NES in patients after successful CPR. Results Seventy patients were collected, 32 patients (19 males and 13 females) in the survival group, age 54. 63 ± 13. 28 years; 38 patients (22 males and 16 females) in the death group, age 58. 00 ± 13. 15 years. There were no significant differences in age and gender between the survival and death groups. The pulsatility index was 1. 217 + 0. 352 in the death group, and it was significantly higher than 0.841 +0. 163 in the survival group; the serum NSE content was 130. 968±59.634 ng/ml in the death group, and it was signiflcantly higher than 49. 465 ± 26. 864 ng/ml in the survival gronp (P＜0. 01). When the pulsatility index was used to predict the death of patients, the ROC area under the curve was 0. 794 (P=0. 000,95% confidence interval [CI] O. 679-0. 908);when the cutoff value was 1. 110, the sensitivity was 68.4%, the specificity was 100%,positive predictive value was 100%, and negative predictive value was 72. 7%. When serum NSE level was used to predict the death of the patients, the ROC area under the curve was 0. 756 (P= 0. 000, 95% CI 0. 672-0. 885); when the cutoff value was 56. 502 ng/ml, the sensitivity was 80. 8%, the specificity was 65. 4%, positive predictive value was 82. 5%, and negative predictive value was 76. 6%. Conclusions The pulsatility index detected by TCD and serum NSE content can be used as predictors in patients achieved return of spontaneous circulation after CPR.

Three-dimensional simulation of blood flow in human thoracic aorta / 第二军医大学学报

Objective: To reconstruct a three-dimensional model of the human thoracic aorta, so as to numerically simulate and study the pulsating blood flow in human thoracic aorta. Methods: A three-dimensional reconstruction of the human thoracic aorta arch was obtained using CT scan imaging on a human aorta by Mimics, a software for image processing. The numerical simulations were obtained based on the principle of computational fluid mechanics and hemodynamics. Results: The distribution of velocity, pressure, and path of the blood flow in the aortic arch of normal people were calculated at a given pulsating and parabolic initial cycle. Our numerical results demonstrated that the blood velocity of distal end was greatly faster than that of proximal end on the interface between branch and aortic arch. There was an obvious pressure gradient between the inner wall and outer wall of blood vessels. The areas where the blood velocity and pressure changed greatly were consistent with the location of the thoracic aortic dissection, especially the area 2-3 cm below the left subclavian artery, suggesting that the blood pressure and velocity may greatly influence the progress of aortic dissection. Conclusion: Numerical simulation and modeling based on CT scan data can help to study bio-fluid mechanics. At the same time, the numerical simulation of blood flow will greatly help the diagnosis and treatment of the aortic dissection and arteriosclerosis.

Análise do perfil hidrodinâmico em diferentes modelos de bombas de rolete utilizadas em circulação extracorpórea / Analysis of the hydrodynamic profile in different roller pumps models used in cardiopulmonary bypass

OBJETIVO: Dentre os equipamentos utilizados em circulação extracorpórea, as bombas de rolete têm grande importância, com diversos modelos disponíveis de vários fabricantes. A calibração é um fator importante nas taxas de hemólise e o seu potencial difere em cada uma delas. Pesquisadores nem sempre abordam detalhes sobre os perfis do leito rígido, supondo que as formas padronizadas de calibração garantem valores iguais e comparáveis para todos os modelos de bombas de rolete. Dispomos principalmente de dois métodos para a calibração das bombas, o que também interfere com o potencial hemolítico. Nenhum dos métodos considera as características de impulsão do fluído, definido pela forma construtiva do leito rígido. O objetivo é avaliar o perfil hidrodinâmico de três modelos de bombas de roletes disponíveis no mercado brasileiro. MÉTODOS: A oclusão dos roletes foi feita por medidas de velocidade de queda e calibração dinâmica. Foram utilizados dois diferentes diâmetros de tubos de silicone (3/8 x 1/16 e 1/2 x 3/32 polegadas). RESULTADOS: Os perfis apresentaram diferenças em suas variâncias. P<0,01 para medidas de velocidade de queda e P<0,0001 para medidas de calibração dinâmica. Foram encontradas diferenças nas variações de pressão entre as bombas analisadas (P<0,002). CONCLUSÃO: As medidas de oclusão são dependentes da forma do leito rígido e comparações envolvendo bombas de rolete devem ser feitas com cautela. Testes com sangue deveriam ser realizados para verificar a influência das variações de pressão na hemólise.

OBJECTIVE: Among the equipments used in cardiopulmonary bypass the roller pumps have great importance with various models available from several manufacturers. The calibration is an important factor in hemolysis rates and its potential is different in each. Researchers do not always approach details on the pump bed profiles assuming that the standardized calibration settings ensure equal and comparable values for all models of roller pumps. We have mainly two methods for calibration of pumps which also interferes on the hemolytic potential. In both of them, the characteristics of fluid impulsion defined by the pump bed design are not considered. The aim of this study is to compare the hydrodynamic profile of three models of roller pumps available in the Brazilian market. METHODS: The rollers occlusion was performed by measures of drop and dynamic calibration. Two different silicone diameter tubes were used (3/8 x 1/16 and 1/2 x 3/32 inches). RESULTS: The profiles showed differences in their variances, P<0.01 for drop rate measures and P<0.0001 for dynamic calibration. Different changes in pressure were found between the pumps analyzed (P<0.002). CONCLUSION: The measures of occlusion are dependent on the design of the pump bed and comparisons involving roller pumps should be performed with caution. Blood tests should be performed to verify the influence of changes in hemolysis pressure.

Relationship between cognitive impairment and arterial stiffness in elderly patients / 中华老年医学杂志

Objective To explore the relationship between cognitive impairment and arterial stiffness in elderly patients. Methods A total of 142 elderly patients were enrolled. Cognitive function was assessed by mini-mental state examination (MMSE) and arterial stiffness was assessed by pulse wave velocity (PWV). A full score on the MMSE was 30, and cognitive impairment was defined as a score less than 24. All subjects underwent the measurement of PWV and MMSE . The subjects were divided into 2 groups: 93 were assigned to the normal cognitive function group (MMSE score 24), and the remainders (n=49) were assigned to the cognitive impairment group (MMSE score 24). Results The PWV was significantly increased in the cognitive impairment group than in the normal cognitive function group [(13.3±2.4) m/s vs. (11.8±2.2) m/s, t=3. 775, P=0. 000]. Logistic regression analysis showed that the PWV was also independently and significantly associated with the MMSE score. Conclusions The increase of arterial stiffness is an important risk factor for impaired cognitive function in elderly patients.