Hemolytic specimens in complete blood cell count: Red cell parameters could be revised by plasma free hemoglobin

Hemolysis prediction in bio-microfluidic applications using resolved CFD-DEM simulations

BACKGROUND AND OBJECTIVE

Hemolysis, namely hemoglobin leakage from red blood cells (RBCs), is one of the major sources of incorrect results in clinical tests, especially when passive microfluidics is involved. This is due to small characteristic dimensions which could cause strong RBCs deformation. Prediction of hemolysis is essential in the design and optimization of lab-on-a-chip devices for cell sorting and plasma separation. The aim of this work is to provide a numerical simulation tool this purpose applicable to real-scale bio-microfluidic devices with affordable computational cost.

METHODS

Blood is modelled as a suspension of biological cells, mainly RBCs, in liquid plasma assumed as a Newtonian, incompressible carrier fluid. Therefore, the physics of cells and carrier fluid is coupled by means of an immersed boundary concept known as resolved CFD-DEM. In this approach, the Navier-Stokes equations are numerically solved through a finite volume method with an additional penalty term to account for the presence of RBCs. RBCs' positions and velocities are updated by solving Newton and Euler equations for conservation of linear and angular momentum. To model the RBCs deformation, a reduced-order model is employed, where each RBC is represented by a clump of overlapping rigid spheres connected by fictional numerical bonds, whose properties are tuned to reproduce the ones of RBCs viscoelastic membrane. This coupled approach allows access to cell-level information and facilitates the usage of strain-based hemolysis models.

RESULTS

Different micro-channel geometries and blood hematocrits are simulated, to explore the influence of these factors on RBCs damage. Statistical analysis is performed to extract relevant biophysical quantities from numerical simulations such as hemolysis index distribution at the channel exit. Finally, the effect of carrier fluid viscosity is studied in relation to cell-cell interactions.

CONCLUSIONS

Simulation results show that hemolysis occurrence is almost independent of the hematocrit values in the microchannel, implying the possibility to speed up calculation using low hematocrit values. Nevertheless, using whole blood viscosity for the carrier fluid overestimates the value of the hemolysis index by almost one order of magnitude.

Erythrocyte lysis and angle-resolved light scattering measured by scanning flow cytometry result to 48 indices quantifying a gas exchange function of the human organism

Molecular/cell level of gas exchange function assumes the accurate measurement of erythrocyte characteristics and rate constants concerning to molecules involved into the CO₂ /O₂ transport. Unfortunately, common hematology analyzers provide the measurement of eight indices of erythrocytes only and say little about erythrocyte morphology and nothing about rate constants of cellular function. The aim of this study is to demonstrate the ability of the Scanning Flow Cytometer (SFC) in the complete morphological analysis of mature erythrocytes and characterization of erythrocyte function via measurement of lysing kinetics. With this study we are introducing 48 erythrocyte indices. To provide the usability of application of the SFC in clinical diagnosis, we formed four categories of indices which are as follows: content/concentration (9 indices), morphology (26 indices), age (5 indices), and function (8 indices). The erythrocytes of 39 healthy volunteers were analyzed with the SFC to fix the first-ever reference intervals for the new indices introduced. The essential measurable reliability of the presented method is expressed in terms of errors of characteristics of single erythrocytes retrieved from the solution of the inverse light-scattering problem and errors of parameters retrieved from the fitting of the experimental kinetics by molecular-kinetics model of erythrocyte lysis.

Cross-Sectional Associations between Dietary Daily Nicotinamide Intake and Patient-Reported Outcomes in Colorectal Cancer Survivors, 2 to 10 Years Post-Diagnosis

Supplementation with nicotinamide adenine dinucleotide (NAD⁺) precursors including dietary nicotinamide has been found to boost tissue NAD⁺ levels and ameliorate oxidative stress-induced damage that contributes to aging and aging-related diseases. The association between dietary NAD⁺ precursors and patient-reported health-related outcomes in cancer survivors has not been investigated. This study aimed to determine associations of dietary nicotinamide intake with different patient-reported outcomes in colorectal cancer survivors, 2 to 10 years post-diagnosis. A total of 145 eligible participants were recruited into this cross-sectional study. Dietary nicotinamide intake level was calculated based on data from 7-day food diaries. Fatigue was assessed with the Checklist Individual Strength (CIS), which is a subscale of the cancer-specific European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC), and anxiety and depression were assessed with Hospital Anxiety and Depression Scale (HADS). Oxidative stress marker serum protein carbonyl contents and serum NAD⁺ levels were measured. A hierarchical linear regression model with confounder adjustment was performed to analyze the association of nicotinamide intake, serum protein carbonyl contents, and NAD⁺ levels with patient-reported outcomes. The median values of daily nicotinamide intake for male and female participants were 19.1 and 14.4 mg, respectively. Daily dietary nicotinamide intake was associated with a lower level of fatigue (β: -14.85 (-28.14, -1.56)) and a lower level of anxiety and depression (β: -4.69 (-8.55, -0.83)). Subgroup analyses by sex showed that a beneficial association between nicotinamide intake and patient-reported outcomes was mainly found in men. To conclude, our findings suggested that higher dietary NAD⁺ precursor nicotinamide intake was cross-sectionally associated with less patient-reported outcomes in CRC survivors.

Hemolytic specimens in complete blood cell count: Red cell parameters could be revised by plasma free hemoglobin

Introduction

Hemolysis is the main cause of unqualified clinical samples. In this study, we established a method for detecting and evaluating hemolysis in whole blood test. We used a mathematical formula for correcting the influence of hemolysis on complete blood cell count (CBC) so as to avoid re‐venipuncture and obtain more accurate parameters of red blood cell detection, reduce the burden of patients, and improve the efficiency of diagnosis and treatment.

Methods

Hemolytic samples were selected and then corrected using the new formula. Plasma free hemoglobin (fHB) was used as the criterion to determine the degree of hemolysis; the uncertainty of measurement is acceptable as the limit value of deviation between the measured value and the revised value. Hemolysis simulation analysis in vitro and continuous monitoring of clinical patients were used to verify the correction effect.

Results

A total of 83 clinical samples with hemolysis were collected and analyzed; fHB 1.4 g/L was selected as the unacceptable value for clinical hemolysis detection. In hemolytic samples, the red blood cell parameters corrected by formula are significantly different from those uncorrected and had a good consistency with those before hemolysis.

Conclusion

The results show that the hemolysis phenomenon of CBC has a significant impact on routine blood testing. By using the new formula, the influence of hemolysis on erythrocyte and related parameters can be quickly and easily corrected, thus avoiding venipuncture again for re‐examination, reducing diagnostic errors, and saving medical resources.