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No description available.

No description available.

No description available.

No description available.

Background: Glucocorticoids (GCs) may cause leukocytosis via several mechanisms. This study was conducted to examine the impact of a single dose of systemic GCs on total white blood cell count (WBC), absolute neutrophilic count (ANC), and absolute lymphocytic count (ALC) in hospitalized adults without bacterial infections. Methods: This retrospective cohort study was carried out in a university hospital. Hospitalized patients 18 years of age or older who received a single dose of a systemic GC were included. Baseline blood cell counts prior to GC administration were required for subjects to be included in the study. Glucocorticoids included in this study were oral or intravenous methylprednisolone and hydrocortisone and oral prednisone. Results: A total of 99 patients were included in the study. After the administration of a single GC dose, ALC began to drop significantly as early as the interval of 0 - <6 hours [median (IQR), 0.90 (0.60-1.10), P=0.011]. ANC increased significantly as early as the interval of 6 - <12 hours [median (IQR), 6.22 (4.45-7.33), P=0.049] and continued to be significantly increased from baseline up to 42 hours from GC administration. Total WBC counts significantly decreased in the 6 - <12 hours interval [median(IQR), 6.90 (5.15-8.85) P=0.03] and then increased significantly in the12 - <18 hours interval [median(IQR), 8.80 (6.50-11.95), P= 0.002]. This effect on total WBC count continued to be significant until the 36 - <42 hours interval [median (IQR), 10.55 (7.23-13.03), P<0.001] Conclusion: ANC, followed by WBC count increase significantly after a single dose administration of GC in hospitalized patients within 12 hours of a single GC dose. Variability in timing and extent of leukocyte and ANC elevation was seen. A decrease in WBC and ALC was seen within the first few hours of GC dose. High doses of GC and autoimmune disease were associated with greater elevation in WBC counts.

Hemodialysis is a renal replacement therapy that removes waste solutes from the blood stream using concentration gradients across a membrane. In order to overcome several shortcomings and increase the waste removal rate, a new dialyzer (filter) design is proposed in this study. In the new dialyzer design, the blood concurrently flows with a sheath fluid in a micro-fluidic channel. Because the blood stream directly contacts the sheath stream, it is important to prevent blood cell migration from the blood stream to the sheath stream while providing enough time for the waste solutes to diffuse into the sheath stream. This research was intended to understand the migration behavior of red blood cells (RBC) and platelets in non-uniform suspension flow, where the blood and sheath flows in direct contact, and apply the results to identify the feasible design space of the proposed dialyzer. The effect of different flow conditions and channel geometry on the blood cell extraction ratios (ER), the ratio of cells lost into the sheath stream, in non-uniform suspension flows was parametrically studied using Lattice Boltzmann and Spectrin Link (LB-SL) method based direct numerical simulation (DNS). Analyzing ER over the flow distance showed that the channel size and the area ratio of sheath to channel are the main variables that affect the ER. Based on the relationship found, a meta-model of RBC ER was created, although platelet ERs showed only a general trend. Based on the study, feasible conditions that will retain blood cells in the blood stream were identified. Then, the DNS results of blood cell ER were used with a molecule diffusion model and a hemodialysis system model to study the feasibility of the proposed dialyzer design that maximizes middle molecule filtration with limited blood cell and protein loss. No feasible design was found in the studied range suggesting that relying purely on the diffusion based on the direct contact for the removal of middle molecules is not a feasible solution with the small channel size (~700 µm) due to the loss of protein. It suggested that in order to increase the middle molecule removal while maintain the protein level, clearance ratio of middle molecule to protein should be increased using large channel size, small sheath stream thickness, long tubule length, and slow blood flow velocity. The intellectual merit of this research lies in understanding the migration behavior of blood cells in a non-uniform suspension. This knowledge helped to establish the feasibility of the proposed dialyzer design and can be applied in a variety of applications for the manipulation of cells in a micro-fluidic channel.

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Red blood cells are commonly administered during the perioperative period, however our understanding of available guidance informing transfusion decisions as well as appropriateness of current practice is not well understood. Blood transfusions are associated with post-operative morbidity and possibly worse long-term outcomes. Furthermore, they are a costly and limited resource. They should therefore be used sparingly. The objective of this thesis was to further our understanding of guidance available for administration of intraoperative red blood blood cell transfusion, as well as conduct an audit of the appropriateness of transfusions administered during the perioperative period. This thesis is composed of both a systematic review as well as a retrospective review of a prospectively maintained database. The systematic review of identified 10 guidelines published between 1992-2018 that included indications for intraoperative transfusions. Six provided objective clearly defined criteria for transfusion based on hemoglobin triggers (range 60-100g/L) or hematocrit (<30%); one stated a specific clinical situation for which transfusion would be appropriate (ST changes). The evidence supporting intraoperative recommendations was extrapolated primarily from the non-operative setting. Retrospective review of a single centre revealed 19% of patients underging liver resection were transfused a mean of 2.6 units during the perioperative period. A total of 22% to 63% of transfusions administered during the intraoperative period were considered inappropriate based on the application of three different instruments. In contrast, 38% to 67% of transfusions administered during the postoperative period were considered inappropriate. Patients considered to have been inappropriately transfused during the intraoperative period were at increased risk of developing a major postoperative adverse event (Clavien-Dindograde 3) compared to those who did not receive a transfusion (OR 4.2; 95% CI 1.1-15.6). In conclusion, this thesis demonstrates evidence-based, practitioner oriented, intraoperative transfusion guidance for clinicians is lacking. Furthermore, a significant proportion of patients continue to be exposed to unnecessary transfusion. Further work in this area is warranted to clarify indications for intraoperative transfusion and subsequently minimize the administration of unnecessary transfusion.

An investigation of red blood cell interactions with contacting foreign surfaces is reported. The purpose of the study was to provide evidence to test the hypothesis that red cell membrane related deposit occurs when a suspension of red cells are exposed to a foreign surface. This membrane derived deposit is speculated to inhibit fibrinogen and albumin adsorption to glass and polyethylene (1,2). Experiments consisted of flowing suspensions of washed human red cells through a column packed with spherical glass beads. The column is then washed to remove suspended cells and eluted using a mild detergent solution. The red cells were observed to have retained their biconcave shape after passage through the column. The eluates are examined by UV-visible spectroscopy and SDS-PAGE, and are found to contain cell membrane components. It is therefore concluded that membrane material had been deposited on the bead surface. The SDS-PAGE data show that membrane skeleton proteins are missing from the eluate, while SEM examination indicates the presence of filamentous deposits on the bead surfaces. These data suggest that cell-surface interactions may occur through a tether-type mechanism involving extrusion of part of the red cell membrane. A 3 level, 3 factor fractional factorial design was used to quantitatively investigate the deposition in the column and to assess the effect of experimental variables on the phenomenon. The three factors studied were hematocrit, surface shear rate, and the presence of plasma in the suspending medium. Statistical analysis of the data generated indicates a positive correlation between hematocrit and the amount of surface deposit. However no correlation for the effects of shear rate or plasma content could be established In summary, red cell membrane components on contacting foreign surfaces were identified and a preliminary description of the phenomenon involved obtained. The deposit of membrane material is discussed in relation to Uniyal's "red cell effect" (1), and in the context of foreign surface induced thrombosis. It is hoped that this work will promote greater respect for the red cell as an important element in blood biomaterials interactions, and will prompt continued investigation on Uniyal's and other potential "red cell effects". / Thesis / Master of Engineering (ME)