[Rationale for early rehabilitation of patients with uterine corpus cancer]. / Obosnovanie rannei reabilitatsii bol'nykh rakom tela matki.

OBJECTIVE: To study the dynamics of hemorheologic changes and the frequency of early complications of laparoscopic radical hysterectomy in patients with uterine corpus cancer depending on conducting rehabilitation activities in the early postoperative period. MATERIAL AND METHODS: The number of patients with uterine corpus cancer equal 49 (mean age 54.8±2.2 years), divided into 2 comparable groups, was examined: experimental group - 23 patients, who received local magnetotherapy since the first day after surgery for 5-6 days, and control group - 26 patients without physiotherapy. Comparative group included 24 healthy women. The basic rheological parameters, namely blood viscosity at high and low shear rate, hematocrit, erythrocytes' aggregation and deformability, erythrocytes and platelets electrophoretic mobility, were evaluated in all patients initially, on the 1st and 5th days after surgery and in comparison group. RESULTS: There were changes in the rheological properties of the blood before surgery in patients of both groups: increase of blood viscosity, enhancement of aggregation activity of its formed elements, decrease of erythrocytes' deformability properties. The laparoscopic radical hysterectomy was accompanied by the exacerbation of these disorders. The early magnetotherapy in patients reduced hemorheological abnormalities up to the preoperative parameters (p<0.05) for 5 days, as well as reduced the incidence of early postoperative complications by 2.4 times compared to the control group. CONCLUSION: The application of local low-frequency low-intensity magnetotherapy since the first postoperative day allows to reduce the level of postoperative hemorheological abnormalities up to the level of preoperative parameters, as well as the frequency of early postoperative complications.

Consequence of Red Blood Cells Deformability on Heat Sink Effect of Blood in a Three-Dimensional Bifurcated Vessel.

Several diseases like Sickle Cell Anemia, Thalassemia, Hereditary Spherocytosis, Malaria, and Micro-angiopathic Hemolytic Anemia can alter the normal shape of red blood cells (RBCs). The objective of this study is to gain insight into how a change in RBC deformability can affect blood heat transfer. The heat sink effect in a bifurcated vessel with two asymptotic cases (case 1: deformable and case 2: nondeformable RBCs) is being studied during hyperthermia treatment in a three-dimensional bifurcated vessel, whose wall is being subjected to constant heat flux boundary condition. Euler-Euler multiphase method along with the granular model and Kinetic theory is used to include the particle nature of RBCs during blood flow in the current model. To enhance the efficiency of the numerical model, user-defined functions (UDFs) are imported into the model from the C++ interface. The numerical model used is verified with the experimental results from (Carr and Tiruvaloor, 1989, "Enhancement of Heat Transfer in Red Cell Suspensions In Vitro Experiments," ASME J. Biomech. Eng., 111(2), pp. 152-156; Yeleswarapu et al. 1998, "The Flow of Blood in Tubes: Theory and Experiment," Mech. Res. Commun., 25(3), pp. 257-262). The results indicate that the deformability of RBCs can change both the flow dynamics and heat sink effect in a bifurcated vessel, which subsequently affects the efficacy and efficiency of the thermal ablation procedure. Both spatial and transient Nusselt numbers of blood flow with deformable RBCs are slightly higher compared to the one with nondeformable RBCs.

HIIT serves as an efficient training strategy for basketball players by improving blood fluidity and decreasing oxidative stress.

BACKGROUND: A challenge for coaches and athletes is to find the best combination of exercises during training. Considering its favorable effects, HIIT has been very popular recently. OBJECTIVE: The goal of this study was to investigate anthropometric features, performance, erythrocyte deformability, plasma viscosity (PV) and oxidative stress in response to acute and long-term (6 weeks) HIIT in adolescent basketball players. METHODS: 22 sportsmen between the ages of 14-16 were included. Tabata protocol was applied to the HIIT group in addition to their routine training program 3 days/week, for 6 weeks. Erythrocyte deformability was determined using an ectacytometer (LORCA), PV with a rotational viscometer. Total oxidant status (TOS), total antioxidant status (TAS) were measured by kits. RESULTS: HIIT for 6 weeks induced an improvement in performance tests and waist circumference. 6 weeks of HIIT resulted in a decrement, while the last exercise session yielded an increment in RBC deformability. PV and TOS of HIIT groups were decreased on the 6th week. CONCLUSIONS: Our results demonstrate that, HIIT in addition to the routine exercise program is beneficial for improving performance and blood fluidity as well as decreasing oxidative stress in basketball players. Therefore, HIIT seems as an efficient training strategy for highly-trained individuals.

The RoxyScan is a novel measurement of red blood cell deformability under oxidative and shear stress.

Exposure to both oxidative and shear stress, a condition that the red blood cell (RBC) continuously experiences in the circulation in vivo can be mimicked in a Couette type viscometer and monitored by ektacytometry. RBCs maintain their deformation and orientation under shear stress and oxidative stress until a threshold is reached at which these conditions appear to overwhelm the elaborate and complex pathways that maintain a proper redox environment in the cell. Oxidative stress under shear alters the ability of the cell to deform, changes cell morphology, its orientation in the shear stress field, and appears to alter intracellular and membrane characteristics. The application of the RoxyScan technology allows the comparison of oxidant effects and the role of antioxidant systems. This provides the opportunity to study the ability of RBC to deal with oxidative stress in various conditions, including RBC disorders such as sickle cell disease (SCD).

Rheological properties of blood in multiple myeloma patients.

Multiple myeloma (MM) is considered to be one of the hematological malignancies formed by excessive and abnormal proliferation of plasmocytes. Among other parameters, several blood tests are used to diagnose multiple myeloma. The hemorheological profile in multiple myeloma is not widely studied. Hemorheology includes the study of measuring the deformability and aggregation of erythrocytes, blood viscosity, and sedimentation rate. The degree of deformability of blood cells is necessary to maintain proper vital functions. Proper deformability of red blood cells ensures proper blood circulation, tissue oxidation and carbon dioxide uptake. The aim of the study was to compare morphology and blood rheology parameters in patients with MM and healthy individuals. The study included 33 patients with MM, and 33 healthy subjects of the same age. The hematological blood parameters were evaluated using ABX MICROS 60 hematology analyzer. The LORCA Analyzer to study erythrocyte aggregation and deformability. Patients with MM had lower red blood cells count (RBC) (9.11%) (p < 0.001) and half time of total aggregation (T1/2) (94.29%) (p < 0.001) values and higher mean corpuscular volume (MCV) (5.50%) (p < 0.001), aggregation index (AI) (68.60%) (p < 0.001), total extent of aggregation (AMP) (87.92%) (p < 0.001) values than the healthy control group. Aggregation in patients with MM is different compared to healthy individuals. It was observed that the percentage of cell aggregation is almost 50% higher than in the control group. The study of morphology, aggregation and deformability of erythrocytes in patients with suspected MM may be helpful in making clinical decisions.

Decreased erythrocyte aggregation in Glenn and Fontan: univentricular circulation as a rheologic disease model.

BACKGROUND: In the Fontan palliation for single ventricle heart disease (SVHD), pulmonary blood flow is non-pulsatile/passive, low velocity, and low shear, making viscous power loss a critical determinant of cardiac output. The rheologic properties of blood in SVHD patients are essential for understanding and modulating their limited cardiac output and they have not been systematically studied. We hypothesize that viscosity is decreased in single ventricle circulation. METHODS: We evaluated whole blood viscosity, red blood cell (RBC) aggregation, and RBC deformability to evaluate changes in healthy children and SVHD patients. We altered suspending media to understand cellular and plasma differences contributing to rheologic differences. RESULTS: Whole blood viscosity was similar between SVHD and healthy at their native hematocrits, while viscosity was lower at equivalent hematocrits for SVHD patients. RBC deformability is increased, and RBC aggregation is decreased in SVHD patients. Suspending SVHD RBCs in healthy plasma resulted in increased RBC aggregation and suspending healthy RBCs in SVHD plasma resulted in lower RBC aggregation. CONCLUSIONS: Hematocrit corrected blood viscosity is lower in SVHD vs. healthy due to decreased RBC aggregation and higher RBC deformability, a viscous adaptation of blood in patients whose cardiac output is dependent on minimizing viscous power loss. IMPACT: Patients with single ventricle circulation have decreased red blood cell aggregation and increased red blood cell deformability, both of which result in a decrease in blood viscosity across a large shear rate range. Since the unique Fontan circulation has very low-shear and low velocity flow in the pulmonary arteries, blood viscosity plays an increased role in vascular resistance, therefore this work is the first to describe a novel mechanism to target pulmonary vascular resistance as a modifiable risk factor. This is a novel, modifiable risk factor in this patient population.

Unraveling the motion and deformation characteristics of red blood cells in a deterministic lateral displacement device.

Deterministic Lateral Displacement (DLD) device has gained widespread recognition and trusted for filtering blood cells. However, there remains a crucial need to explore the complex interplay between deformable cells and flow within the DLD device to improve its design. This paper presents an approach utilizing a mesoscopic cell-level numerical model based on dissipative particle dynamics to effectively capture this complex phenomenon. To establish the model's credibility, a series of numerical simulations were conducted and the numerical results were validated with nominal experimental data from the literature. These include single cell stretching experiment, comparisons of the morphological characteristics of cells in DLD, and comparison the specific row-shift fraction of DLD required to initiate the zigzag mode. Additionally, we investigate the effect of cell rigidity, which serves as an indicator of cell health, on average flow velocity, trajectory, and asphericity. Moreover, we extend the existing theory of predicting zigzag mode for solid spherical particles to encompass the behavior of red blood cells. To achieve this, we introduce a new concept of effective diameter and demonstrate its applicability in providing highly accurate predictions across a wide range of conditions.

High-throughput single-cell assay for precise measurement of the intrinsic mechanical properties and shape characteristics of red blood cells.

The intrinsic physical and mechanical properties of red blood cells (RBCs), including their geometric and rheological characteristics, can undergo changes in various circulatory and metabolic diseases. However, clinical diagnosis using RBC biophysical phenotypes remains impractical due to the unique biconcave shape, remarkable deformability, and high heterogeneity within different subpopulations. Here, we combine the hydrodynamic mechanisms of fluid-cell interactions in micro circular tubes with a machine learning method to develop a relatively high-throughput microfluidic technology that can accurately measure the shear modulus of the membrane, viscosity, surface area, and volume of individual RBCs. The present method can detect the subtle changes of mechanical properties in various RBC components at continuum scales in response to different doses of cytoskeletal drugs. We also investigate the correlation between glycosylated hemoglobin and RBC mechanical properties. Our study develops a methodology that combines microfluidic technology and machine learning to explore the material properties of cells based on fluid-cell interactions. This approach holds promise in offering novel label-free single-cell-assay-based biophysical markers for RBCs, thereby enhancing the potential for more robust disease diagnosis.

High-throughput quantification of red blood cell deformability and oxygen saturation to probe mechanisms of sickle cell disease.

The complex, systemic pathology of sickle cell disease is driven by multiple mechanisms including red blood cells (RBCs) stiffened by polymerized fibers of deoxygenated sickle hemoglobin. A critical step toward understanding the pathologic role of polymer-containing RBCs is quantifying the biophysical changes in these cells in physiologically relevant oxygen environments. We have developed a microfluidic platform capable of simultaneously measuring single RBC deformability and oxygen saturation under controlled oxygen and shear stress. We found that RBCs with detectable amounts of polymer have decreased oxygen affinity and decreased deformability. Surprisingly, the deformability of the polymer-containing cells is oxygen-independent, while the fraction of these cells increases as oxygen decreases. We also find that some fraction of these cells is present at most physiologic oxygen tensions, suggesting a role for these cells in the systemic pathologies. Additionally, the ability to measure these pathological cells should provide clearer targets for evaluating therapies.

Amplitude-Modulated Electrodeformation to Evaluate Mechanical Fatigue of Biological Cells.

Red blood cells (RBCs) are known for their remarkable deformability. They repeatedly undergo considerable deformation when passing through the microcirculation. Reduced deformability is seen in physiologically aged RBCs. Existing techniques to measure cell deformability cannot easily be used for measuring fatigue, the gradual degradation in cell membranes caused by cyclic loads. We present a protocol to evaluate mechanical degradation in RBCs from cyclic shear stresses using amplitude shift keying (ASK) modulation-based electrodeformation in a microfluidic channel. Briefly, the interdigitated electrodes in the microfluidic channel are excited with a low voltage alternating current at radio frequencies using a signal generator. RBCs in suspension respond to the electric field and exhibit positive dielectrophoresis (DEP), which moves cells to the electrode edges. Cells are then stretched due to the electrical forces exerted on the two cell halves, resulting in uniaxial stretching, known as electrodeformation. The level of shear stress and the resultant deformation can be easily adjusted by changing the amplitude of the excitation wave. This enables quantifications of nonlinear deformability of RBCs in response to small and large deformations at high throughput. Modifying the excitation wave with the ASK strategy induces cyclic electrodeformation with programmable loading rates and frequencies. This provides a convenient way for the characterization of RBC fatigue. Our ASK-modulated electrodeformation approach enables, for the first time, a direct measurement of RBC fatigue from cyclic loads. It can be used as a tool for general biomechanical testing, for analyses of cell deformability and fatigue in other cell types and diseased conditions, and can also be combined with strategies to control the microenvironment of cells, such as oxygen tension and biological and chemical cues.

Deformability of mouse erythrocytes in different diluents measured using optical tweezers.

Optical tweezers are widely used to measure the mechanical properties of erythrocytes, which is crucial to the study of pathology and clinical diagnosis of disease. During the measurement, the blood sample is diluted and suspended in an exogenous physiological fluid, which may affect the elastic properties of the cells in vitro. Here, we investigate the effect of different diluents on the elastic properties of mouse erythrocytes by quantitatively evaluating their elastic constants using optical tweezers. The diluents are plasma extracted from mouse blood, veterinary blood diluent (V-52D), Dulbecco's modified Eagle's medium (DMEM), phosphate-buffered saline (PBS), and normal saline (NS). To create an environment that closely resembles in vivo conditions, the experiment is performed at 36.5 °C. The results show that the spring constant of mouse erythrocytes in plasma is 6.23 ± 0.41 µN m-1. The elasticity of mouse erythrocytes in V-52D and DMEM is 8.21 ± 0.91 and 6.95 ± 0.85 µN m-1, which are higher than that in plasma extracted from blood, whereas, the elasticity in PBS and NS is 4.23 ± 0.85 and 4.68 ± 0.79 µN m-1, which are less than that in plasma extracted from blood. At last, we observe the size and circularity of erythrocytes in different diluents, and consider that the erythrocyte diameter and circularity may affect cell deformability. Our results provide a reference of the diluent choice for measuring the mechanical properties of erythrocytes in vitro.

Low-Dose Dietary Fish Oil Improves RBC Deformability without Improving Post-Transfusion Recovery in Mice.

Long-chain polyunsaturated fatty acids (LC-PUFAs) are important modulators of red blood cell (RBC) rheology. Dietary LC-PUFAs are readily incorporated into the RBC membrane, improving RBC deformability, fluidity, and hydration. Female C57BL/6J mice consumed diets containing increasing amounts of fish oil (FO) ad libitum for 8 weeks. RBC deformability, filterability, and post-transfusion recovery (PTR) were evaluated before and after cold storage. Lipidomics and lipid peroxidation markers were evaluated in fresh and stored RBCs. High-dose dietary FO (50%, 100%) was associated with a reduction in RBC quality (i.e., in vivo lifespan, deformability, lipid peroxidation) along with a reduced 24 h PTR after cold storage. Low-dose dietary FO (6.25-12.5%) improved the filterability of fresh RBCs and reduced the lipid peroxidation of cold-stored RBCs. Although low doses of FO improved RBC deformability and reduced oxidative stress, no improvement was observed for the PTR of stored RBCs. The improvement in RBC deformability observed with low-dose FO supplementation could potentially benefit endurance athletes and patients with conditions resulting from reduced perfusion, such as peripheral vascular disease.

New erythrocyte parameters derived from the Coulter principle relate with red blood cell properties-A pilot study in diabetes mellitus.

In routine hematological instruments, blood cells are counted and sized by monitoring the impedance signals induced during their passage through a Coulter orifice. However, only signals associated with centered paths in the aperture are considered for analysis, while the rejected measurements, caused by near-wall trajectories, can provide additional information on red blood cells (RBC), as recent publications suggest. To assess usefulness of two new parameters in describing alterations in RBC properties, we performed a pilot study to compare blood samples from patients with diabetes mellitus (DM), frequent pathological condition associated with impairment in RBC deformability, versus controls. A total of 345 blood samples were analyzed: 225 in the DM group and 120 in the control group. A diagram of [Formula: see text] and [Formula: see text], the two new parameters derived from the analysis of impedancemetry pulses, was used to compare distribution of RBC subpopulations between groups. To discriminate RBC from DM and control individuals, based on our multiparametric analysis, we built a score from variables derived from [Formula: see text] matrix which showed good performances: area under the receiving operating characteristic curve 0.948 (0.920-0.970), p<0.0001; best discriminating value: negative predictive value 94.7%, positive predictive value was 78.4%. These results seem promising to approach RBC alterations in routine laboratory practice. The related potential clinically relevant outcomes remain to be investigated.

Red Blood Cell Deformability Is Expressed by a Set of Interrelated Membrane Proteins.

Red blood cell (RBC) deformability, expressing their ability to change their shape, allows them to minimize their resistance to flow and optimize oxygen delivery to the tissues. RBC with reduced deformability may lead to increased vascular resistance, capillary occlusion, and impaired perfusion and oxygen delivery. A reduction in deformability, as occurs during RBC physiological aging and under blood storage, is implicated in the pathophysiology of diverse conditions with circulatory disorders and anemias. The change in RBC deformability is associated with metabolic and structural alterations, mostly uncharacterized. To bridge this gap, we analyzed the membrane protein levels, using mass spectroscopy, of RBC with varying deformability determined by image analysis. In total, 752 membrane proteins were identified. However, deformability was positively correlated with the level of only fourteen proteins, with a highly significant inter-correlation between them. These proteins are involved in membrane rafting and/or the membrane-cytoskeleton linkage. These findings suggest that the reduction of deformability is a programmed (not arbitrary) process of remodeling and shedding of membrane fragments, possibly mirroring the formation of extracellular vesicles. The highly significant inter-correlation between the deformability-expressing proteins infers that the cell deformability can be assessed by determining the level of a few, possibly one, of them.

Tubulin-mediated anatomical and functional changes caused by Ca2+ in human erythrocytes

In previous research, we observed that tubulin can be found in three fractions within erythrocytes, i.e., attached to the membrane, as a soluble fraction, or as part of a structure that can be sedimented by centrifugation. Given that its differential distribution within these fractions may alter several hemorheological properties, such as erythrocyte deformability, the present work studied how this distribution is in turn affected by Ca2+, another key player in the regulation of erythrocyte cytoskeleton stability. The effect of Ca2+ on some hemorheological parameters was also assessed. The results showed that when Ca2+ concentrations increased in the cell, whether by the addition of ionophore A23187, by specific plasma membrane Ca2 + _ATPase (PMCA) inhibition, or due to arterial hypertension, tubulin translocate to the membrane, erythrocyte deformability decreased, and phosphatidylserine exposure increased. Moreover, increased Ca2+ was associated with an inverse correlation in the distribution of tubulin and spectrin, another important cytoskeleton protein. Based on these findings, we propose the existence of a mechanism of action through which higher Ca2+ concentrations in erythrocytes trigger the migration of tubulin to the membrane, a phenomenon that results in alterations of rheological and molecular aspects of the membrane itself, as well as of the integrity of the cytoskeleton. (AU)

Cell-free layer development and spatial organization of healthy and rigid red blood cells in a microfluidic bifurcation.

Bifurcations and branches in the microcirculation dramatically affect blood flow as they determine the spatiotemporal organization of red blood cells (RBCs). Such changes in vessel geometries can further influence the formation of a cell-free layer (CFL) close to the vessel walls. Biophysical cell properties, such as their deformability, which is impaired in various diseases, are often thought to impact blood flow and affect the distribution of flowing RBCs. This study investigates the flow behavior of healthy and artificially hardened RBCs in a bifurcating microfluidic T-junction. We determine the RBC distribution across the channel width at multiple positions before and after the bifurcation. Thus, we reveal distinct focusing profiles in the feeding mother channel for rigid and healthy RBCs that dramatically impact the cell organization in the successive daughter channels. Moreover, we experimentally show how the characteristic asymmetric CFLs in the daughter vessels develop along their flow direction. Complimentary numerical simulations indicate that the buildup of the CFL is faster for healthy than for rigid RBCs. Our results provide fundamental knowledge to understand the partitioning of rigid RBC as a model of cells with pathologically impaired deformability in complex in vitro networks.

Zinc improved erythrocyte deformability and aggregation in patients with beta-thalassemia: An in vitro study.

BACKGROUND: Thalassemia patients have reduced red cell deformability and decreased plasma zinc levels in their blood. OBJECTIVE: This study aimed to evaluate the effects of zinc (Zn) on the hemorheological parameters and antioxidant enzyme activities in ß-thalassemia major (TM) and healthy volunteers (HV). METHODS: Hemorheological parameters were measured using LORCA (laser-assisted optical rotational cell analyzer) after adjusting the hematocrit to 40%. Zinc sulfate (ZnSO4.7H2O) was used for Zn incubation with a concentration of 0.5µg/dl. Oxidative stress and antioxidant status were determined using commercial kits. RESULTS: Data showed that after Zn incubation, EImax, the area under the EI-osmolarity curve (Area), and Omax decreased in TM. However, no significant difference was observed in the osmotic deformability parameters of HV. The increased elongation index was obtained at different shear stresses for TM and HV, and SS1/2 decreased in both groups. The AMP and aggregation index (AI) decreased in TM, and the required time for half of the maximum aggregation (t1/2) increased in HV. However, Zn did not affect oxidative parameters in both groups. CONCLUSIONS: This study showed that Zn incubation increased deformability and decreased aggregation in thalassemic erythrocytes. It means that Zn supplementation will contribute to microcirculation in thalassemia patients.

Effect of Cell Age and Membrane Rigidity on Red Blood Cell Shape in Capillary Flow.

Blood flow in the microcirculatory system is crucially affected by intrinsic red blood cell (RBC) properties, such as their deformability. In the smallest vessels of this network, RBCs adapt their shapes to the flow conditions. Although it is known that the age of RBCs modifies their physical properties, such as increased cytosol viscosity and altered viscoelastic membrane properties, the evolution of their shape-adapting abilities during senescence remains unclear. In this study, we investigated the effect of RBC properties on the microcapillary in vitro flow behavior and their characteristic shapes in microfluidic channels. For this, we fractioned RBCs from healthy donors according to their age. Moreover, the membranes of fresh RBCs were chemically rigidified using diamide to study the effect of isolated graded-membrane rigidity. Our results show that a fraction of stable, asymmetric, off-centered slipper-like cells at high velocities decreases with increasing age or diamide concentration. However, while old cells form an enhanced number of stable symmetric croissants at the channel centerline, this shape class is suppressed for purely rigidified cells with diamide. Our study provides further knowledge about the distinct effects of age-related changes of intrinsic cell properties on the single-cell flow behavior of RBCs in confined flows due to inter-cellular age-related cell heterogeneity.

The effect of sulfur baths on hemorheological properties of blood in patients with osteoarthritis.

Balneotherapy is an effective treatment method in various diseases and commonly used treatment modality among patients with musculoskeletal disorders. Sulfur baths are known for healing properties however effect on rheological properties is unstudied. Thus the aim of our study was to determine the effect of sulfur balneotherapy on hemorheological blood indices. A total of 48 patients with osteoarthritis were enrolled to the study. Blood samples were collected twice, before and after 3-week time period. We evaluated complete blood count, fibrinogen, hs-CRP and blood rheology parameters such as elongation index (EI), half-time of total aggregation (T1/2) and aggregation index (AI) analyzed with the Lorrca Maxis. Mean age of studied cohort was 67 ± 5 years. After sulfur baths WBC count was significantly decreased is studied group (p = 0.021) as well as neutrophile count (p = 0.036). Red blood cell EIs were statistically higher after sulfur baths in shear stress ranging from 8.24 to 60.30 Pa. T1/2 was significantly higher (p = 0.031) and AI lower (p = 0.003) compared to baseline. No significant changes in fibrinogen and hs-CRP were observed. It is the first study that evaluate effect of sulfur balneotherapy on rheologic properties of blood. Sulfur water baths may improve erythrocyte deformability and aggregation parameters.

Hyperbaric oxygenation improve red blood cell deformability in patients with acute or chronic inflammation.

INTRODUCTION: Red blood cells (RBC) are one of the key elements of the microcirculation. Their ability to pass through capillaries and to deliver oxygen to cells is due to their large degree of deformability linked to the characteristics of the RBC membrane. Alterations in RBC deformability as a result of membrane damage, linked in part to increased synthesis of reactive oxygen species (ROS), can be observed in several diseases, such as sepsis, and may contribute to the altered microcirculation observed in these pathologies. Hyperbaric oxygen therapy (HBOT), with inhalation of 100 % oxygen, has been proposed in several acute or chronic pathologies, including carbon monoxide poisoning. OBJECTIVE: We investigated the effects of HBOT on oxidative stress from ROS produced by myeloperoxidase (MPO) and on RBC deformability in patients with acute or chronic inflammation (n = 10), in patients with acute carbon monoxide poisoning (n = 10), and in healthy volunteers (n = 10). METHODS: RBC deformability was evaluated before and after HBOT in the various populations using the ektacytometry technique (Laser-assisted Optical Rotational Red Cell Analyzer - LORRCA). Deformability was determined by the elongation index (EI) in relation to the shear stress (SS) over a range of 0.3 to 50 Pa. Oxidative stress was estimated through changes in proteins (chlorotyrosine and homocitrulline) induced by MPO activity measured by liquid chromatography-tandem mass spectrometry analysis. RESULTS: Before HBOT, EI was significantly lower in patients with acute or chronic inflammation than in healthy volunteers and patients with acute carbon monoxide poisoning for the majority of SS values studied. After one session of HBOT, the EI was significantly higher than before HBOT for SS values of 1.93 Pa or higher in patients with acute or chronic inflammation. This effect remains constant after 10 sessions. There were no differences before and after HBOT in protein or amino acid oxidation due to ROS generation mediated by MPO in the three populations. CONCLUSIONS: Our results confirm altered RBC deformability in patients with acute and chronic conditions associated with an underlying inflammatory process. HBOT improves deformability only after one session and therefore may improve microcirculation in this population. According to our results, this improvement does not seem mediated by the ROS pathway via MPO. These results need to be confirmed in a larger population.