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Clinical Hemorheology and... 2016We investigated whether the concept of hematocrit/viscosity (h/η) ratio explains the "paradox of hematocrit in athletes", by calculating a "theoretical optimal...
We investigated whether the concept of hematocrit/viscosity (h/η) ratio explains the "paradox of hematocrit in athletes", by calculating a "theoretical optimal hematocrit" (i.e., associated with the higher h/η value predicted with Quemada's equation from plasma viscosity, and erythrocyte rigidity index) before and after exercise. 14 rugby players (19-31 yr; weight 65.8-109.2 kg; height 1.7-1.96 m; BMI 21.7-33.1 kg/m2) underwent a standardized submaximal exercise session on cycloergometer corresponding to 225 kjoules over 30 min. The rheologic response to exercise was measured with the MT90 viscometer and the Myrenne aggregometer. After exercise there was an increase in whole blood viscosity (p < 0.05) and hematocrit (p < 0.005) and a decrease in h/η ratio (from 14.7±0.34 to 12.9±0.37, p < 0.005). There was an increase in viscometric RBC rigidity indexes "Tk" and "k" in 9/14 subjects. Predicted and actual h/η are fairly well correlated (preexercise r = 0.998, p < 0.001; postexercise r = 0.985 p < 0.001) but actual h/η was lower than predicted (preexercise p = 0.005; postexercise p = 0.02). This discrepancy between predicted and measured hematocrit was not correlated to dehydration or plasma viscosity but was correlated to red cell rigidity (r = 0.774, p < 0.01) and its exercise-induced change (r = 0.858, p < 0.01). This study suggests that h/η, although it is not directly correlated to parameters of exercise performance, is precisely regulated during exercise according to the classic concept of "viscoregulation", and that the prediction of the theoretical optimal values of h/η and hematocrit by models may help to interpret the actual values of these parameters. However, these models need to be more extendedly tested and improved.
Topics: Adult; Athletes; Blood Viscosity; Erythrocyte Deformability; Exercise; Football; Hematocrit; Hemorheology; Humans; Male; Young Adult
PubMed: 27792003
DOI: 10.3233/CH-168042 -
Clinica Chimica Acta; International... Sep 2021Dried blood spot (DBS) sampling has many advantages over conventionally used blood samples, but is thought to suffer from hematocrit related issues. The aim of our...
BACKGROUND AND AIM
Dried blood spot (DBS) sampling has many advantages over conventionally used blood samples, but is thought to suffer from hematocrit related issues. The aim of our research was to investigate whether reliable results can be obtained without bothering about hematocrit effects in DBS analysis of analytes that are mainly present in the plasma compartment.
MATERIALS AND METHODS
Venous blood samples with variation in hematocrit and spotted volume were prepared. Spot diameter and 25-OH Vitamin D and testosterone concentrations were measured. Moreover, DBS and plasma concentrations of 25-OH Vitamin D, testosterone and hematocrit were determined in random patient samples.
RESULTS
DBS spot size was linearly related to hematocrit. Measured DBS concentrations of 25-OH Vitamin D and testosterone were independent of hematocrit and spotted volume. Determining the relation between plasma and DBS concentration resulted in a factor that can be used to convert DBS concentrations to standardized plasma concentrations.
CONCLUSION
Addressing the hematocrit issue is not necessary for hormones that are mainly present in the plasma compartment. The relation between plasma and DBS concentration can be used to convert DBS concentrations to standardized plasma concentrations which makes interpretation of DBS concentrations easier.
Topics: Dried Blood Spot Testing; Hematocrit; Hormones; Humans; Reference Standards; Tandem Mass Spectrometry
PubMed: 34119531
DOI: 10.1016/j.cca.2021.06.014 -
PloS One 2022Although both the erythrocyte sedimentation rate (ESR) and optically measured erythrocyte aggregation parameters are affected by the hematocrit, this interaction is not...
Although both the erythrocyte sedimentation rate (ESR) and optically measured erythrocyte aggregation parameters are affected by the hematocrit, this interaction is not considered by the method used to estimate ESR that considers aggregation parameters. In this study, we investigated the relationship between the ESR obtained by the Westergren method and that obtained with an aggregation parameter, namely, the aggregation index (AI) of multiple hematocrit values and fibrinogen-spiked samples with an analysis time of 5-60 s, and attempted to develop a rapid and accurate ESR estimation method. The AIs obtained from 5- and 10-s optical measurements with a fixed hematocrit were highly correlated with the erythrocyte sedimentation velocity. Furthermore, the rate of the AI increase with an increasing hematocrit was not significantly affected by the fibrinogen concentration at these measurement times. On the basis of these results, we defined the hematocrit-corrected aggregation index (HAI). The exponential function of the HAI obtained from the 5-s measurement agreed well with the sedimentation velocity calculated to eliminate the effect of hindered settling, and the HAI and hematocrit could be used to calculate the time constant of the sedimentation curve with a linear regression equation. The ESR value at 1 h was calculated based on the modified Stokes' law and the HAI obtained from the 5-s measurement and showed an excellent correlation (R = 0.966) with the ESR value obtained by the Westergren method over a wide range of hematocrit and fibrinogen concentrations.
Topics: Blood Sedimentation; Erythrocyte Aggregation; Erythrocytes; Fibrinogen; Hematocrit
PubMed: 35819942
DOI: 10.1371/journal.pone.0270977 -
California Medicine Jan 1953Clinical diagnosis of subperitoneal hemorrhage can be made in a substantial percentage of cases by recognition of a quite constant syndrome-provided the possibility of...
Clinical diagnosis of subperitoneal hemorrhage can be made in a substantial percentage of cases by recognition of a quite constant syndrome-provided the possibility of bleeding is considered. Progressive anemia, as indicated by repeated counts of erythrocytes in the blood or by hematocrit determinations, is confirmation of the diagnosis. The majority of patients recover spontaneously under conservative management.Surgical intervention is indicated if repeated episodes of hemorrhage occur or if the volume of circulating blood cannot be maintained by repeated transfusions of whole blood.
Topics: Abdomen; Abdominal Neoplasms; Anemia; Blood Transfusion; Erythrocytes; Hematocrit; Hemorrhage; Humans; Neoplasms
PubMed: 13009511
DOI: No ID Found -
Archives of Disease in Childhood Apr 1970
Topics: Acid-Base Equilibrium; Blood Viscosity; Hematocrit; Humans; Infant, Newborn; Infant, Newborn, Diseases; Polycythemia; Umbilical Cord
PubMed: 5419999
DOI: 10.1136/adc.45.240.273-a -
Revista Medica Del Instituto Mexicano... Jul 2022Usually hemoglobin and hematocrit are obtained from peripheral venous blood samples processed in equipment for hematic biometry. These parameters can also be determined...
BACKGROUND
Usually hemoglobin and hematocrit are obtained from peripheral venous blood samples processed in equipment for hematic biometry. These parameters can also be determined from arterial samples processed on blood gas equipment. Its variability when using arterial samples and this equipment is unknown, in addition, if the lack of knowledge of this variability affects clinical decisions.
OBJECTIVE
To know the variability of hemoglobin and hematocrit from arterial blood samples processed in blood gas equipment.
MATERIAL AND METHODS
Analytic cross design. Consecutive subjects with stable cardiopulmonary disease were blindly studied. The samples were obtained at the same time for analysis in both equipments. Variability was analyzed with Bland-Altman descriptive statistic and its magnitude with the intraclass correlation coefficient.
RESULTS
Two hundred of blood samples from 50 patients were studied, 31 (62%) women, age 62 ± 14 years old, body mass index 30.11 ± 5.69 Kg/m2. The main comparison was peripheral venous blood sample processed in laboratory equipment (SYSMEX) vs. arterial sample on blood gas equipment (GEM). The mean difference (bias) and intraclass correlation coefficient for hemoglobin were: 0.12 (-1.45, 1.23) and 0.95 (0.91, 0.97); for the hematocrit -4.4 (-0.4, 8.54), and 0.72 (0.51, 0.84).
CONCLUSIONS
The mean difference and bias for hemoglobin was close to 0; the hematocrit was higher. Hemoglobin from arterial samples processed in blood gas equipment can be used to make clinical decisions.
Topics: Aged; Blood Gas Analysis; Female; Hematocrit; Hemoglobins; Humans; Male; Middle Aged
PubMed: 35816622
DOI: No ID Found -
NeuroImage Jun 2021Cerebrovascular reactivity (CVR) reflects the capacity of the brain to meet changing physiological demands and can predict the risk of cerebrovascular diseases. CVR can...
Cerebrovascular reactivity (CVR) reflects the capacity of the brain to meet changing physiological demands and can predict the risk of cerebrovascular diseases. CVR can be obtained by measuring the change in cerebral blood flow (CBF) during a brain stress test where CBF is altered by a vasodilator such as acetazolamide. Although the gold standard to quantify CBF is PET imaging, the procedure is invasive and inaccessible to most patients. Arterial spin labeling (ASL) is a non-invasive and quantitative MRI method to measure CBF, and a consensus guideline has been published for the clinical application of ASL. Despite single post labeling delay (PLD) pseudo-continuous ASL (PCASL) being the recommended ASL technique for CBF quantification, it is sensitive to variations to the arterial transit time (ATT) and labeling efficiency induced by the vasodilator in CVR studies. Multi-PLD ASL controls for the changes in ATT, and velocity selective ASL is in theory insensitive to both ATT and labeling efficiency. Here we investigate CVR using simultaneous O-water PET and ASL MRI data from 19 healthy subjects. CVR and CBF measured by the ASL techniques were compared using PET as the reference technique. The impacts of blood T1 and labeling efficiency on ASL were assessed using individual measurements of hematocrit and flow velocity data of the carotid and vertebral arteries measured using phase-contrast MRI. We found that multi-PLD PCASL is the ASL technique most consistent with PET for CVR quantification (group mean CVR of the whole brain = 42±19% and 40±18% respectively). Single-PLD ASL underestimated the CVR of the whole brain significantly by 15±10% compared with PET (p<0.01, paired t-test). Changes in ATT pre- and post-acetazolamide was the principal factor affecting ASL-based CVR quantification. Variations in labeling efficiency and blood T1 had negligible effects.
Topics: Adult; Aged; Blood Flow Velocity; Brain; Cerebrovascular Circulation; Cerebrovascular Disorders; Female; Hematocrit; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Oxygen Radioisotopes; Positron-Emission Tomography; Spin Labels; Time Factors; Water
PubMed: 33716155
DOI: 10.1016/j.neuroimage.2021.117955 -
NMR in Biomedicine May 2022Dynamic susceptibility contrast (DSC) MRI is clinically used to measure brain perfusion by monitoring the dynamic passage of a bolus of contrast agent through the brain....
Dynamic susceptibility contrast (DSC) MRI is clinically used to measure brain perfusion by monitoring the dynamic passage of a bolus of contrast agent through the brain. For quantitative analysis of the DSC images, the arterial input function is required. It is known that the original assumption of a linear relation between the R relaxation and the arterial contrast agent concentration is invalid, although the exact relation is as of yet unknown. Studying this relation in vitro is time-consuming, because of the widespread variations in field strengths, MRI sequences, contrast agents, and physiological conditions. This study aims to simulate the R versus contrast concentration relation under varying physiological and technical conditions using an adapted version of an open-source simulation tool. The approach was validated with previously acquired data in human whole blood at 1.5 T by means of a gradient-echo sequence (proof-of-concept). Subsequently, the impact of hematocrit, field strength, and oxygen saturation on this relation was studied for both gradient-echo and spin-echo sequences. The results show that for both gradient-echo and spin-echo sequences, the relaxivity increases with hematocrit and field strength, while the hematocrit dependency was nonlinear for both types of MRI sequences. By contrast, oxygen saturation has only a minor effect. In conclusion, the simulation setup has proven to be an efficient method to rapidly calibrate and estimate the relation between R and gadolinium concentration in whole blood. This knowledge will be useful in future clinical work to more accurately retrieve quantitative information on brain perfusion.
Topics: Contrast Media; Gadolinium DTPA; Hematocrit; Humans; Magnetic Fields; Magnetic Resonance Imaging
PubMed: 34816501
DOI: 10.1002/nbm.4653 -
Kidney International Feb 2001Anemia is a known complication of renal insufficiency, but the relationship between level of renal function and magnitude of reduction in hematocrit is not well defined....
BACKGROUND
Anemia is a known complication of renal insufficiency, but the relationship between level of renal function and magnitude of reduction in hematocrit is not well defined. Men have higher hematocrit and absolute glomerular filtration rate (GFR) than women; however, it is unknown whether the level of clearance associated with decreased hematocrit is the same in men and women.
METHODS
We conducted a cross-sectional study of 12,055 adult ambulatory patients. General linear models were used to analyze the relationship between hematocrit and Cockcroft-Gault equation estimated creatinine clearance (C(Cr); mL/min) and Modification of Diet in Renal Disease (MDRD) formula estimated the GFR indexed to body surface area (mL/min/1.73 m(2)).
RESULTS
The hematocrit decreased progressively below estimated C(Cr) 60 mL/min in men and 40 mL/min in women. Compared with subjects with C(Cr)> 80 mL/min, men with C(Cr) 60 to 50 mL/min, 50 to 40 mL/min, 40 to 30 mL/min, 30 to 20 mL/min, and < or =20 mL/min had mean hematocrits that were lower by 1.0, 2.4, 3.7, 3.5, and 10.0%, respectively; the corresponding reductions in women with C(Cr) 40 to 30 mL/min, 30 to 20 mL/min, and < or =20 mL/min were 1.7, 2.9, and 6.3% (all P < 0.05). This between-sex difference diminished when renal function measurement was indexed to body size. Compared with subjects with GFR> 80 mL/min/1.73 m(2), men with GFR 50 to 40 mL/min/1.73 m(2), 40 to 30 mL/min/1.73 m(2), 30 to 20 mL/min/1.73 m(2), and < or =20 mL/min/1.73 m(2) had mean hematocrits that were lower by 2.0, 4.4, 5.3, and 9.4%; the corresponding reductions in women with GFR 50 to 40 mL/min/1.73 m(2), 40 to 30 mL/min/1.73 m(2), 30 to 20 mL/min/1.73 m(2) and < or =20 mL/min/1.73 m(2) were 0.6, 1.6, 3.8, and 5.3% (all P < 0.05).
CONCLUSIONS
A decrease in hematocrit is apparent even among patients with mild to moderate renal insufficiency. At any given level of renal function below estimated C(Cr) 60 mL/min, men have a larger decrease in hematocrit than women.
Topics: Adult; Aged; Anemia; Creatinine; Cross-Sectional Studies; Female; Glomerular Filtration Rate; Hematocrit; Humans; Kidney; Male; Middle Aged; Models, Biological; Prevalence; Renal Insufficiency; Sex Characteristics
PubMed: 11168955
DOI: 10.1046/j.1523-1755.2001.059002725.x -
Journal of Diabetes Science and... May 2019In recent clinical trials, use of the MyGlucoHealth blood glucose meter (BGM) and electronic diary was associated with an unusual reporting pattern of glycemic data and...
BACKGROUND
In recent clinical trials, use of the MyGlucoHealth blood glucose meter (BGM) and electronic diary was associated with an unusual reporting pattern of glycemic data and hypoglycemic events. Therefore, the performance of representative BGMs used by the patients was investigated to assess repeatability, linearity, and hematocrit interference in accordance with regulatory guidelines.
METHOD
Ten devices and 6 strip lots were selected using standard randomization and repeatability procedures. Venous heparinized blood was drawn from healthy subjects, immediately aliquoted and adjusted to 5 target blood glucose (BG) ranges for the repeatability and 11 BG concentrations for the linearity tests. For the hematocrit interference test, each sample within 5 target BG ranges was split into 5 aliquots and adjusted to hematocrit levels across the acceptance range. YSI 2300 STAT Plus was used as the laboratory reference method in all experiments.
RESULTS
Measurement repeatability or precision was acceptable across the target BG ranges for all devices and strip lots with coefficient of variation (CV) between 3.4-9.7% (mean: 5.7%). Linearity was shown by a correlation coefficient of .991; however, a positive bias was seen for BG <100 mg/dL (86% measurements did not meet ISO15197:2015 acceptance criteria). Significant hematocrit interference (up to 20%) was observed for BG >100 mg/dL (ISO15197:2015 acceptance criteria: ±10%), while the results were acceptable for BG <100 mg/dL.
CONCLUSIONS
The BGM met repeatability requirements but demonstrated a significant measurement bias in the low BG range. In addition, it failed the ISO15197:2015 criteria for hematocrit interference.
Topics: Artifacts; Blood Glucose; Blood Glucose Self-Monitoring; Clinical Laboratory Techniques; Diabetes Mellitus; Equipment Design; Equipment Failure Analysis; Equipment and Supplies; Hematocrit; Humans; Internet Access; Linear Models; Reagent Strips; Reproducibility of Results
PubMed: 30974988
DOI: 10.1177/1932296819841357