The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Chen Wang - One of the best experts on this subject based on the ideXlab platform.
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Microfluidic measurement of RBC bending stiffness changes in Blood Storage
2017 19th International Conference on Solid-State Sensors Actuators and Microsystems (TRANSDUCERS), 2017Co-Authors: Zhensong Xu, Huayan Pu, Chen WangAbstract:In transfusion medicine, the deformability of stored red Blood cells (RBCs) changes during Storage in Blood banks. Compromised red Blood cell (RBC) deformability can lower the transfusion efficiency or intensify transfusion complications such as sepsis. The controversial results in present literature are caused by the differences in the mode of RBC deformation and the metrics for indicating RBC deformability. This paper reports microfluidic mechanical measurement of stored RBCs under the physiological deformation mode (i.e., bending). Instead of using phenomenological metrics of deformation or elongation indices (DI or EI), RBCs' bending stiffness, a flow velocity independent parameter, is for the first time defined and used to evaluate the mechanical degradation of RBCs during Storage. Fresh RBCs and RBCs stored up to six weeks in the Blood bank were measured, revealing that the bending stiffness of RBCs increases over the Storage process. RBCs stored for one week already started to show significantly higher stiffness than fresh RBCs, and stored RBC stiffness degraded faster in the last three weeks than in the first three weeks.
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characterization of red Blood cell deformability change during Blood Storage
Lab on a Chip, 2014Co-Authors: Yi Zheng, Jun Chen, Nadine Shehata, Chen WangAbstract:Stored red Blood cells (RBCs) show progressive deformability changes during Blood banking/Storage. Their deformability changes over an 8 weeks' Storage period were measured using a microfluidic device. Hydrodynamic focusing controls the orientation and position of individual RBCs within the microchannel. High-speed imaging (5000 frames s−1) captures the dynamic deformation behavior of the cells, and together with automated image analysis, enables the characterization of over 1000 RBCs within 3 minutes. Multiple parameters including deformation index (DI), time constant (shape recovery rate), and RBC circularity were quantified. Compared to previous studies on stored RBC deformability, our results include a significantly higher number of cells (>1000 cells per sample vs. a few to tens of cells per sample) and, for the first time, reveal deformation changes of stored RBCs when traveling through human-capillary-like microchannels. Contrary to existing knowledge, our results demonstrate that the deformation index of RBCs under folding does not change significantly over Blood Storage. However, significant differences exist in time constants and circularity distribution widths, which can be used to quantify stored RBC quality or age.
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Characterization of red Blood cell deformability change during Blood Storage
2014 IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS), 2014Co-Authors: Yi Zheng, Jun Chen, Nadine Shehata, Chen WangAbstract:Stored red Blood cells (RBCs) show progressive deformability change during Blood banking/Storage. Their deformability change over an 8 weeks' Storage period was measured in this work using a microfluidic device and high-speed imaging. Multiple parameters including deformation index (DI), time constant (shape recovery rate), and RBC circularity were quantified. Compared to previous RBC deformability studies reported in the literature, our results include a significantly higher number of cells (>1,000 cells/sample vs. a few to tens of cells/sample) and, for the first time, reveal deformation changes of stored RBCs when they travel through human-capillary-like microchannels. The correlation between deformability and morphology of stored RBCs is also presented.
Yi Zheng - One of the best experts on this subject based on the ideXlab platform.
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characterization of red Blood cell deformability change during Blood Storage
Lab on a Chip, 2014Co-Authors: Yi Zheng, Jun Chen, Nadine Shehata, Chen WangAbstract:Stored red Blood cells (RBCs) show progressive deformability changes during Blood banking/Storage. Their deformability changes over an 8 weeks' Storage period were measured using a microfluidic device. Hydrodynamic focusing controls the orientation and position of individual RBCs within the microchannel. High-speed imaging (5000 frames s−1) captures the dynamic deformation behavior of the cells, and together with automated image analysis, enables the characterization of over 1000 RBCs within 3 minutes. Multiple parameters including deformation index (DI), time constant (shape recovery rate), and RBC circularity were quantified. Compared to previous studies on stored RBC deformability, our results include a significantly higher number of cells (>1000 cells per sample vs. a few to tens of cells per sample) and, for the first time, reveal deformation changes of stored RBCs when traveling through human-capillary-like microchannels. Contrary to existing knowledge, our results demonstrate that the deformation index of RBCs under folding does not change significantly over Blood Storage. However, significant differences exist in time constants and circularity distribution widths, which can be used to quantify stored RBC quality or age.
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Characterization of red Blood cell deformability change during Blood Storage
2014 IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS), 2014Co-Authors: Yi Zheng, Jun Chen, Nadine Shehata, Chen WangAbstract:Stored red Blood cells (RBCs) show progressive deformability change during Blood banking/Storage. Their deformability change over an 8 weeks' Storage period was measured in this work using a microfluidic device and high-speed imaging. Multiple parameters including deformation index (DI), time constant (shape recovery rate), and RBC circularity were quantified. Compared to previous RBC deformability studies reported in the literature, our results include a significantly higher number of cells (>1,000 cells/sample vs. a few to tens of cells/sample) and, for the first time, reveal deformation changes of stored RBCs when they travel through human-capillary-like microchannels. The correlation between deformability and morphology of stored RBCs is also presented.
Nancy M Heddle - One of the best experts on this subject based on the ideXlab platform.
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effect of short term vs long term Blood Storage on mortality after transfusion
The New England Journal of Medicine, 2016Co-Authors: Nancy M Heddle, Richard J Cook, Donald M Arnold, Rebecca Barty, Mark Crowther, P J DevereauxAbstract:BackgroundRandomized, controlled trials have suggested that the transfusion of Blood after prolonged Storage does not increase the risk of adverse outcomes among patients, although most of these trials were restricted to high-risk populations and were not powered to detect small but clinically important differences in mortality. We sought to find out whether the duration of Blood Storage would have an effect on mortality after transfusion in a general population of hospitalized patients. MethodsIn this pragmatic, randomized, controlled trial conducted at six hospitals in four countries, we randomly assigned patients who required a red-cell transfusion to receive Blood that had been stored for the shortest duration (short-term Storage group) or the longest duration (long-term Storage group) in a 1:2 ratio. Only patients with type A or O Blood were included in the primary analysis, since pilot data suggested that our goal of achieving a difference in the mean duration of Blood Storage of at least 10 days wo...
Walter H Dzik - One of the best experts on this subject based on the ideXlab platform.
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tissue oxygenation by transfusion in severe anemia with lactic acidosis total a prospective randomized non inferiority trial of Blood Storage duration
Blood, 2015Co-Authors: Aggrey Dhabangi, Christine Csertigazdewich, Brenda Ainomugisha, Henry Ddungu, Dorothy Kyeyune, Ezra Musisi, Robert O Opoka, Christopher P Stowell, Walter H DzikAbstract:Each year approximately 100 million units of Blood are transfused worldwide. Current regulations allow RBCs to be stored in approved solutions for up to five or six weeks. Regulatory agencies use cell survival studies and in vitro markers of hemolysis, rather than measures of oxygen delivery, to establish the maximal duration of Blood Storage. During Storage, RBCs undergo cumulative structural, biochemical, and enzymatic changes that collectively might impair the ability of erythrocytes to deliver oxygen to tissues and contribute to adverse patient outcomes. Study design and Methods: We conducted a prospective, randomized, controlled, clinical trial comparing short-Storage versus longer-Storage RBCs for tissue oxygen delivery as measured by reduction in Blood lactate levels in severe anemia. We studied 290 patients presenting to a university hospital urgent care facility with a hemoglobin ≤5g/dL and lactate ≥5mM. Patients were children, age 6 to 60 months, whose lactic acidosis was due to severe anemia and who did not have shock, trauma, impaired cardiac function, refractory hypoxia, need for pressors, liver disease or tissue injury. Subjects were randomly assigned to receive leukoreduced RBCs stored 1-10 days (n=145) versus 25-35 days (n=145). All patients received 10mL/kg of RBCs during hours 0-2; and, if indicated per protocol, an additional 10mL/kg during hours 4-6. The study was conducted in Kampala, Uganda and registered as #NCT01586923 at clinicaltrials.gov. Results: Hour 0 was the start of transfusion.We measured Blood lactate levels at time 0, 2, 4, 6, 8 and 24 hours following transfusion. The primary outcome was the proportion of patients achieving a lactate ≤3mM at 8 hours. Other measures included cerebral tissue oxygen saturation measured non-invasively, clinical and laboratory changes following transfusion, survival, and 30-day follow-up. At presentation, the mean hemoglobin was 3.7 ±1.3g/dL and mean lactate was 9.3 ±3.4mM. RBC Storage averaged 7.8 ±2.1 days in the shorter-Storage arm and 31.6 ±2.8 days in the longer-Storage arm without overlap. See Fig 1A. The proportion achieving a lactate ≤3mM at 8 hours was 0.58 (95% CI, 0.49-0.66, shorter-Storage) versus 0.61 (95% CI, 0.52-0.69, longer-Storage), p=0.72, a result meeting the pre-specified margin of non-inferiority. Mean lactate levels were not statistically different between the two arms at 2, 4, 6, 8 or 24 hours. See Fig 1B. Kaplan-Meier analysis and global non-linear regression revealed no difference in lactate clearance between the shorter-Storage and longer-Storage groups. Clinical assessment, serial measurements of hemoglobin concentration, cerebral tissue oxygen saturation, and electrolyte abnormalities improved to the same degree in the two groups following transfusion. Adverse events, survival, and 30-day recovery were not significantly different between the two groups. Pre-specified sub-group analysis among patients receiving 20mL/kg of RBCs revealed no significant differences in outcomes. Given the severity of anemia, transfusions represented 60% to 90% of the patients9 pre-transfusion red cell mass. Conclusion and Relevance: This is the first major randomized trial specifically testing whether prolonged Storage RBCs deliver oxygen as well as short-Storage RBCs. We tested the two extremes of Blood Storage duration and found that longer-Storage RBCs were not inferior to shorter-Storage RBCs for oxygen delivery as measured by reduction of elevated Blood lactate levels, improved cerebral oxygen saturation, clinical outcomes, laboratory results, or adverse events. The results carry relevance for health policy decisions regarding the acceptable duration of RBC Storage worldwide. Disclosures No relevant conflicts of interest to declare.
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the effect of Blood Storage age on treatment of lactic acidosis by transfusion in children with severe malarial anaemia a pilot randomized controlled trial
Malaria Journal, 2013Co-Authors: Aggrey Dhabangi, Edison Mworozi, Irene R Lubega, Christine Csertigazdewich, Albert Maganda, Walter H DzikAbstract:Background Severe malarial anaemia requiring Blood transfusion is a life-threatening condition affecting millions of children in sub-Saharan Africa. Up to 40% of children with severe malarial anaemia have associated lactic acidosis. Lactic acidosis in these children is strongly associated with fatal outcomes and is corrected by Blood transfusion. However, it is not known whether the Storage age of Blood for transfusion affects resolution of lactic acidosis. The objective of this pilot study was to evaluate the effect of Blood Storage age on resolution of lactic acidosis in children with severe malarial anaemia and demonstrate feasibility of conducting a large trial.
Olav Gaute Helleso - One of the best experts on this subject based on the ideXlab platform.
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squeezing red Blood cells on an optical waveguide to monitor cell deformability during Blood Storage
Analyst, 2015Co-Authors: Balpreet Singh Ahluwalia, Peter Mccourt, Ana Oteiza, J S Wilkinson, Thomas R Huser, Olav Gaute HellesoAbstract:Red Blood cells squeeze through micro-capillaries as part of Blood circulation in the body. The deformability of red Blood cells is thus critical for Blood circulation. In this work, we report a method to optically squeeze red Blood cells using the evanescent field present on top of a planar waveguide chip. The optical forces from a narrow waveguide are used to squeeze red Blood cells to a size comparable to the waveguide width. Optical forces and pressure distributions on the cells are numerically computed to explain the squeezing process. The proposed technique is used to quantify the loss of Blood deformability that occurs during Blood Storage lesion. Squeezing red Blood cells using waveguides is a sensitive technique and works simultaneously on several cells, making the method suitable for monitoring stored Blood.
