Hematocrit Measurements Research Articles

In vitro performance of a new non‐invasive extracorporeal saturation monitor

I read with interest the study by Bailey at al. measuring the performance of the Spectrum M3 non-invasive extracorporeal saturation monitor (Spectrum Medical LLP, Gloucester, UK) [1]. Being external to the circuit, it is clear that this device could offer significant benefit in the continuous measurement of oxygen saturation, haematocrit and haemoglobin concentration (Hb), whilst avoiding additional turbulence. This would be particularly so in extracorporeal membrane oxygenation (ECMO) circuits, where bypass is maintained for several days. Whilst the agreement between the readings of the new monitor and the gold standard reference is good, with a low level of bias, the experimental conditions under which it was tested raise some questions. I am surprised that the mean (SD) Hb of the test circuit was 15.4 (0.6) g.dl−1. In practice, the circulating Hb of a cardiopulmonary bypass circuit is lower after the addition of priming fluid – in our hospital, 500 ml crystalloid and 1200 ml colloid, aiming for a Hb < 12 g.dl−1. A Hb > 15 g.dl−1 would be undesirable due to the higher viscosity, causing increased haemolysis and potentially impairing microvascular circulation [2], particularly at lower temperatures. Interestingly, the authors do not expand further upon the values of Hb in their experiment, only high, medium, low and very low, and do not present the individual results at these different values. In testing the device’s accuracy at differing temperatures, only three measurement points over a very large range of temperatures (37, 27 and 17 °C) were used. In routine clinical practice, cardiopulmonary bypass is not conducted under deep hypothermic conditions. The device’s accuracy should be tested at hypothermic limits; however, narrower intervals between measurements over the range of temperatures most commonly used clinically, above 30 °C in most cases, particularly if used for ECMO, would better prove its performance. More closely simulating the conditions encountered in clinical practice and further expanding upon the results, especially if considering the device’s use for ECMO, given that these circuits operate under considerably different conditions to those found intra-operatively, would have provided more assurance of this device’s performance.

MPGES-1 deletion potentiates urine concentrating capability after water deprivation

PGE(2) plays an important role in the regulation of fluid metabolism chiefly via antagonizing vasopressin-induced osmotic permeability in the distal nephron, but its enzymatic sources remain uncertain. The present study was undertaken to investigate the potential role of microsomal PGE synthase (mPGES)-1 in the regulation of urine concentrating ability after water deprivation (WD). Following 24-h WD, wild-type (WT) mice exhibited a significant reduction in urine volume, accompanied by a significant elevation in urine osmolality compared with control groups. In contrast, in response to WD, mPGES-1 knockout (KO) mice had much less urine volume and higher urine osmolality. Analysis of plasma volume by measurement of hematocrit and by using a nanoparticle-based method consistently demonstrated that dehydrated WT mice were volume depleted, which was significantly improved in the KO mice. WD induced a twofold increase in urinary PGE(2) output in WT mice, which was completely blocked by mPGES-1 deletion. At baseline, the KO mice had a 20% increase in V(2) receptor mRNA expression in the renal medulla but not the cortex compared with WT controls; the expression was unaffected by WD irrespective of the genotype. In response to WD, renal medullary aquaporin-2 (AQP2) mRNA exhibited a 60% increase in WT mice, and this increase was greater in the KO mice. Immunoblotting demonstrated increased renal medullary AQP2 protein abundance in both genotypes following WD, with a greater increase in the KO mice. Similar results were obtained by using immunohistochemistry. Paradoxically, plasma AVP response to WD seen in WT mice was absent in the KO mice. Taken together, these results suggest that mPGES-1-derived PGE(2) reduces urine concentrating ability through suppression of renal medullary expression of V(2) receptors and AQP2 but may enhance it by mediating the central AVP response.

Spectroscopic and Wireless Sensor of Hematocrit Level

An optical method for hematocrit measurement has been presented. The sensor, designed and developed by authors, consists of spectroscopic set-up controlled by a microcontroller. Measurement results are sent via wireless module. Experiment has confirmed the ability of the sensor to determine the hematocrit with appropriate measurement accuracy.

Determination of hematocrit using on-line conductance cell

Hematocrit has been considered as an important marker of oxygen carrying capacity of the blood associated with whole blood viscosity to assess the mortality risk of both cardiovascular, cerebral, and kidney diseases. The present study developed a new on-line conductivity cell to measure the hematocrit of whole blood using a bipolar square-wave voltage signal at a frequency of 5kHz. By applying such a voltage signal to a blood flowing in a range of 1.2–3.0mL/min, the electrolyte effect of blood plasma, the conductive and capacitive effects of blood cells, and the sedimentation effect of erythrocytes on the conductivity of whole blood could be minimized for an accurate hematocrit measurement. The coefficient of correlation between the present method and conventional microcentrifuge method showed an excellent linear relationship. A new equation between the specific conductance and Hct of whole blood was obtained: C=12.561−0.1527 Hct (P<0.001).

Phosphodiesterase 4 inhibition attenuates plasma volume loss and transvascular exchange in volume expanded mice

Phosphodiesterase 4 inhibition attenuates plasma volume loss and transvascular exchange in volume expanded mice

Laser interference microscopy of amphibian erythrocytes: impact of cell volume and refractive index

This study examined the action of anisosmotic media on the volume of nucleated erythrocytes isolated from Rana temporaria. Elevation of medium osmolarity from 100 to 345 mOsm resulted in attenuation of mean cell volume by more than 3-fold, estimated by hematocrit measurement. By contrast to this 'classic' erythrocyte volume evaluation technique, we did not observe any significant cell volume modulation by examining the 3D reconstruction of erythrocyte interference images obtained by laser interference microscopy. Comparative analysis of mean cell volume, phase height and cell area appraised by laser interference microscopy showed that the lack of visible alterations of phase image geometry was caused by sharp elevation of the average refractive index of the cytoplasm in shrunken cells. Thus, our results show for the first time that laser interference microscopy in combination with a direct method for cell volume measurement may be employed for estimation of the refractory index of intracellular milieu and for assessment of changes of physical chemical properties of the cytoplasm evoked by diverse stimuli including osmotic stress.

Optical Investigation of Hematocrit Level in Human Blood

In this paper use of selected optical methods of a hematocrit measurement has been presented. Elaborated methods have numerous advantages: relatively simple configurations, potentially low cost and high resolution. Investigation confirmed their ability to determine the hematocrit value with appropriate measurement accuracy. Furthermore, simultaneous use of complementary optical methods can substantially increase measurement reliability, because low-coherence interferometric measurement is based on physical (mainly optical) properties of the investigated object, while Raman spectroscopy is based on study of its molecular composition.

Preliminary survey on tsetse flies and trypanosomosis at grazing fields and villages in and around the Nech Sar National Park, Southern Ethiopia

Preliminary survey on tsetse flies and trypanosomosis were conducted between July and August 2007 at grazing fields and villages in and around the Nech Sar national park, with the ultimate intention of forwarding baseline information on the extent of the problem and possible control strategies. . Entomological (Tsetse flies) survey was conducted by deploying a total of 16 geo referenced NGU traps on the grazing fields of cattle. Parasitological (Trypanosomosis) survey and PCV (Packed Cell Volume) measurement were done on randomly selected 202 cattle, of the park neighboring villagers. Glossina pallidipes with mean apparent density of 11.46 ftd (flies per trap per day) were found to be the only prevailing tsetse fly species in the study area. However, the mean apparent density of biting flies was found to be 4.54 ftd. Trypanosomosis with population mean estimated 17.33±5.30 were seen to be a serious problem of cattle in the area. Trypanosoma congolense and T. vivax were the two dominant species encountered in the area. However statistically significant proportion of the cattle (P

QUantitative Imaging of eXtraction of oxygen and TIssue consumption (QUIXOTIC) using venular‐targeted velocity‐selective spin labeling

While oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO(2)) are fundamental parameters of brain health and function, a robust MRI-based mapping of OEF and CMRO(2) amenable to functional MRI (fMRI) has not been established. To address this issue, a novel method called QUantitative Imaging of eXtraction of Oxygen and TIssue Consumption, or QUIXOTIC, is introduced. The key innovation in QUIXOTIC is the use of velocity-selective spin labeling to isolate MR signal exclusively from postcapillary venular blood on a voxel-by-voxel basis. Measuring the T(2) of this venular-targeted blood allows calibration to venular oxygen saturation (Y(v)) via theoretical and experimental T(2) versus blood oxygen saturation relationships. Y(v) is converted to OEF, and baseline CMRO(2) is subsequently estimated from OEF and additional cerebral blood flow and hematocrit measurements. Theory behind the QUIXOTIC technique is presented, and implications of cutoff velocity (V(CUTOFF)) and outflow time parameters are discussed. Cortical gray matter values obtained with QUIXOTIC in 10 healthy volunteers are Y(v) = 0.73 ± 0.02, OEF = 0.26 ± 0.02, and CMRO(2) = 125 ± 15 μmol/100 g min. Results are compared to global measures obtained with the T(2) relaxation under spin tagging (TRUST) technique. The preliminary data presented suggest that QUIXOTIC will be useful for mapping Y(v), OEF, and CMRO(2), in both clinical and functional MRI settings.

Clinical performance of the new glucometer in the nursery and neonatal intensive care unit

Performance of point-of-care (POC) glucometers in newborns have been unsatisfactory in low glucose concentration range and the effects of different hematocrit levels on glucose measurements have also demonstrated in currently used POC glucometers. The aim of this study was to evaluate the performance of the new glucometer (Nova-Statstrip(®) ; Nova Biomedical, Waltham, MA, USA) compared to the reference method. Venous blood specimens of neonates were collected and tested by the two glucometers. Standard reference was performed using the hexokinase method within 10 min of blood collection. Hematocrit and total serum bilirubin measurements were performed simultaneously. One hundred and fifty-one blood specimens were collected and measured by the reference method with plasma glucose concentrations ranging from 12 to 371 mg/dL. Twenty-one specimens had plasma glucose concentrations <45 mg/dL. At plasma glucose concentrations less than 75 mg/dL, the Statstrip(®) achieved 93% in the tests for discrepancy < 15 mg/dL. At a glucose concentration more than 75 mg/dL, 97% of the Statstrip(®) readings were within 20% of the reference values. The mean difference (±2SD) of the Statstrip(®) was 2.8 (-14.1, 19.7) mg/dL. At a hypoglycemic level (<45 mg/dL), it showed a sensitivity of 95.2%. No significant interference of hematocrit or total serum bilirubin was found on the mean bias of the Statstrip(®) . The new glucometer (Nova-Statstrip(®) ) could be used for point-of-care blood glucose measurement in neonates as it showed a narrow margin of error and had no hematocrit or bilirubin interference.

Overexpression of thioredoxin 2 does not affect hypoxia‐induced right ventricular hypertrophy

Pulmonary hypertension (PH) is characterized by increased pulmonary vascular resistance and vasoconstriction that can result in right ventricular hypertrophy. Studies suggest that mitochondrial reactive oxygen species (ROS) may play a role in right ventricular hypertrophy and PH pathogenesis. The present study examines the effects of overexpression of Thioredoxin 2 (Trx2), a mitochondrial ROS scavenger, in the development of hypoxia-induced right ventricular hypertrophy. Western blot analysis was used to confirm Trx2 overexpression in transgenic mice. Wild-type (WT) and Trx2 transgenic (Tg) mice were exposed to normoxic or hypoxic conditions for three weeks. Blood was collected for hematocrit measurement and hearts removed to assess right ventricular hypertrophy using right ventricle/left ventricle plus septum (RV/LV+S) weight ratios. Trx2 Tg mice have increased Trx2 expression in the lung. Hypoxia exposure significantly elevated hematocrit in both WT and Trx2 Tg mice relative to normoxic animals (p<0.05). Similarly, hypoxia increased RV/LV+S weight ratios for WT and Trx2 Tg mice when compared to WT normoxic conditions (p<0.05). These results suggest that increased expression of Trx2 in pulmonary tissue does not affect the progression of hypoxia-induced right ventricular hypertrophy. Funding by: VA Research Service Award DK074518 and Toxicology Training Grant 5T32ES012870-07.

Modelling of cardiovascular response to graded orthostatic stress: role of capillary filtration

Of the many possible factors that may contribute to orthostatic intolerance, the loss of circulating blood because of capillary filtration is one of the few that can explain the gradual decline of arterial pressure during stand tests. This study used a computer model to investigate the relative importance of haemodynamic parameters, including capillary filtration, as potential contributors to orthostatic intolerance. Simulated orthostatic tolerance times were compared to previous experiments combining head-up tilt and lower body negative pressure graded orthostatic stress, which provided haemodynamic data, in particular haematocrit measurements that allowed subject-specific modelling of capillary transport. The cardiovascular system was simulated using a seven-compartment model with measured heart rate, stroke volume, total peripheral resistance, mean arterial pressure and haematocrit data for 12 subjects. Simulations were controlled by decreasing the total blood volume at the measured rates of capillary filtration until cerebral pressure dropped below a threshold for consciousness. Predicted times to syncope were compared to actual times to presyncope, and sensitivity of arterial pressure and cardiac output to independent system parameters were determined. There was no statistical difference in modelled times to syncope and actual times to presyncope. Both arterial pressure and cardiac output were most sensitive to total blood volume and least sensitive to caudal compliance parameters. The feasibility of subject-specific simulations of cardiovascular response to orthostatic stress was demonstrated, providing stronger evidence that capillary filtration is a prominent mechanism in causing orthostatic intolerance. These results may have clinical and spaceflight applications.

RELATIONSHIP BETWEEN OBESITY, PSA, AND PROSTATE VOLUME IN PATIENTS WITH BPH WITHOUT URINARY RETENTION

Objective: To study the relationship between obesity, prostate specific antigen (PSA) level, and prostate volume in patients with benign prostate hyperplasia (BPH) without urinary retention.Material &amp; Method: Twenty two BPH patients without urinary retention were enrolled in this study. Patients were classified into 2 groups based on body mass index (BMI). The first group consisted of 11 patients with obesity (BMI ≥ 27 kg/m2), the second group consisted of 11 non obese patients (BMI &lt; 27 kg/m2). Each patient underwent measurement of PSA, prostate volume and hematocrit. We performed tests for correlation between all variables in both groups. Results: From correlation testing there was a significant relationship between obesity and PSA. With increasing BMI, a lower PSA level was observed (p&lt; 0,05). There was no significant relationship between prostate volume and hematocrit (p &gt; 0,05).Conclusion: There is a significant negative correlation between obesity and PSA in BPH patients without urinary retention

AO-38. Point of care measurement of hemoglobin and hematocrit in newborn infants using a blood gas analyzer

Objective: To assess the reliability of measuring hemoglobin (Hb) and hematocrit (Hct) in neonates using a point of care blood gas analyzer. Methods: Hb and Hct results were compared between the point of care blood gas analyzer (OMNI-S, Roche) and laboratory values on 131 paired blood samples, collected from 67 newborns. The bias and limits of agreement were assessed with the Bland Altman method. Paired results were classified in four therapeutic groups according to the Canadian Pediatric Society (CPS) guidelines for blood transfusion; the percent of agreement and weighed kappa were calculated. Results: The mean difference between paired samples was – 0.14 g/dl (± 1.4) and -0.11% (± 8.8) for Hb and Hct respectively; 97% of Hb and 77.4% of Hct values fell within the acceptable limits of the Clinical Laboratories Improvement Amendment. The correlation coefficient between the paired results was 0.95 (P 0.0005) and 0.84 (P 0.0005) respectively. The data distribution in the four CPS groups showed a high level of agreement for Hb (86.3%) and less for Hct (65%) corresponding to a weighted kappa of 0.75 and 0.45 respectively. The disagreement between the Hb and Hct pairs modified the clinical indication of blood transfusion in 2.3% and 3.2% respectively. Conclusion: Our data showed a high level of agreement between paired Hb values measured by the blood gas analyzer and the laboratory permitting its routine use in the point of care setting. The wide limits of agreement between Hct values hinder its clinical use.

The effect of low molecular weight heparin (enoxaparin) on enhanced coagulation induced by crystalloid haemodilution*

The purpose of this study was to establish whether a low molecular weight heparin (enoxaparin) attenuated or abolished the enhanced coagulation induced by crystalloid fluid therapy. Twenty young, healthy male volunteers were injected subcutaneously with either enoxaparin 40 mg or saline on two separate occasions one week apart, in a randomised, blinded study. Twelve hours later, a blood sample was taken for thrombelastography analysis and haematocrit. Saline 14 ml.kg⁻¹ was then infused over thirty minutes and thrombelastography and haematocrit measurements repeated. There was a significant post-dilutional difference in the alpha angle (p = 0.002) and k-time (p = 0.001) between the two groups. There was a trend towards reduced shortening of r-time in the enoxaparin group compared to the saline control (p = 0.18). The findings suggest that enoxaparin diminished acceleration of clot formation due to haemodilution.

Agreement between Erythrocyte Sedimentation Rate and C-Reactive Protein in Hospital Practice

Background Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are frequently prescribed jointly. The usefulness of this practice is uncertain. Methods All patients with ESR and CRP measured at the same time in an academic tertiary hospital during a 1-year period were included. Concomitant measures of serum creatinine, hematocrit, and anti-Xa activity were recorded to study noninflammatory cause of increased ESR. Level of agreement between ESR and CRP was assessed with kappa coefficient, and their accuracy was determined in a medical chart review of 99 randomly selected patients with disagreement between both markers. Results Among 5777 patients, 35% and 58% had an elevated CRP and ESR, respectively. ESR and CRP were in agreement in 67% of patients (both elevated in 30%, both normal in 37%). A disagreement was observed in 33% (elevated ESR/normal CRP in 28%, normal ESR/elevated CRP in 5%). The kappa coefficient showed poor agreement (k = 0.38) between both markers. Review of medical chart showed that 25 patients with elevated CRP and normal ESR had an active inflammatory disease (false-negative ESR). Conversely, 74 patients had elevated ESR and normal CRP—32% had resolving inflammatory disorders, 28% disclosed a variable interfering with the ESR measure (false-positive ESR), 32% had unexplained discrepancies, and 8% had an active inflammatory disease (false-negative CRP). Conclusion In hospital practice, joint measurement of ESR and CRP is unwarranted. Because of slow variation and frequent confounding, ESR is frequently misleading in unselected patients. When an inflammatory disorder is suspected, priority should be given to CRP.

Diagnostic performance of Baveno IV criteria in cirrhotic patients with upper gastrointestinal bleeding: Analysis of the F7 liver-1288 study population

The definition of failure to control bleeding agreed upon at the Baveno IV consensus meeting, included the Adjusted Blood Requirement Index [ABRI: number of blood units/(final-initial hematocrit+0.01)]. ABRI ≥0.75 denotes failure. However, timing for hematocrit measurements was not defined. The aims of this study were: (1) to assess the Baveno IV criteria performance to classify treatment success or failure to control bleeding at 5 days, (2) to determine the appropriate timing for hematocrit. Two hundred and forty-two cirrhotic patients with gastrointestinal bleeding were independently classified by three clinical experts according to the Baveno IV criteria, by analysis of the database of a randomized trial. ABRI was calculated by using the closest hematocrit to the 5 day time point from the first trial product administration (ABRI-1) or after the latest transfusion within the 5-day period (ABRI-2). The gold standard for success/failure for 5-day control of bleeding was the clinical judgment of the three independent observers based on all the clinical and follow-up data. Inter-observer agreement for the final outcome assessment was 0.82 and a final consensus was obtained in 236/242 patients. Inter-observer agreement on patient classification with Baveno IV criteria was 0.70 with ABRI-1 and 0.84 with ABRI-2. c-statistics for correct patients classification were 0.86 for ABRI-1, 0.84 for ABRI-2, and 0.88 for Baveno IV criteria without ABRI. ABRI-1 caused misclassification of 27 patients and ABRI-2 of 39. Baveno IV criteria are accurate to assess outcome of patients with variceal bleeding. There is a substantial observer variability linked to timing of hematocrits for ABRI calculation. With the current definition ABRI does not add to the performance of the other criteria.

Simultaneous measurement of RBC velocity, flux, hematocrit and shear rate in vascular networks

Not all tumor vessels are equal. Tumor-associated vasculature includes immature vessels, regressing vessels, transport vessels undergoing arteriogenesis and peritumor vessels influenced by tumor growth factors. Current techniques for analyzing tumor blood flow do not discriminate between vessel subtypes and only measure average changes from a population of dissimilar vessels. We have developed methodologies for simultaneously quantifying blood flow (velocity, flux, hematocrit and shear rate) in extended networks at single capillary resolution in vivo. Our approach relies on deconvolution of signals produced by labeled red blood cells as they move relative to the scanning laser of a confocal or multiphoton microscope and provides fully-resolved three-dimensional flow profiles within vessel networks. Using this methodology, we show that blood velocity profiles are asymmetric near intussusceptive tissue structures in tumors in mice. Furthermore, we show that subpopulations of vessels, classified by functional parameters, exist in, around a tumor and in normal brain.

Blood sugar measurement in zebrafish reveals dynamics of glucose homeostasis.

The adult zebrafish has the potential to become an important model for diabetes-related research. To realize this potential, small-scale methods for analyzing pancreas function are required. The measurement of blood glucose level is a commonly used method for assessing beta-cell function, but the small size of the zebrafish presents challenges both for collecting blood samples and for measuring glucose. We have developed methods for collecting microsamples of whole blood and plasma for the measurement of hematocrit and blood glucose. We demonstrate that two hand-held glucose meters designed for use by human diabetics return valid results with zebrafish blood. Additionally, we present methods for fasting and for performing postprandial glucose and intraperitoneal glucose tolerance tests. We find that the dynamics of zebrafish blood glucose homeostasis are consistent with patterns reported for other omnivorous teleost fish.

Stability of Hemoglobin Mass During a 6-Day UCI ProTour Cycling Race

Blood doping in endurance sport is a growing problem. The purpose of this study was to determine the reliability of total hemoglobin mass (Hb(mass)) measurement in the field and to establish the variability of Hb(mass) during a cycling race, to assess its viability as an additional antidoping detection parameter. Control-matched longitudinal study. International Cycling Union's (UCI) ProTour stage race. Six professional cyclists and 5 recreationally active controls. Seventy-two Hb(mass) tests using the optimized carbon monoxide rebreathing method were performed over 7 consecutive days, before and throughout the tour. Fasted venous blood was obtained for measurement of hematocrit (Hct) and hemoglobin concentration [Hb] in the morning before stages 1, 3, and 6 (D1, D3, and D6). Reliability of Hb(mass) measurement was established using typical error calculated from 2 baseline measures. Individual change scores and coefficients of variation were used to assess stability during racing. Typical error for Hb(mass) was 1.3% [95% confidence limits (CL): 0.9%, 2.5%]. Calculated 95% and 99.99% CL for percent change in Hb(mass) were +/-3.6% and +/-7.2%, respectively. Mean Hb(mass) remained within +/-1.9% of baseline in cyclists and +/-0.5% in controls. In all cases, individual change scores for both cyclists and controls fell within the 95% CL. There was a decrease in Hct (8.1% +/- 2.8%) and [Hb] (9.7% +/- 3.2%) throughout the tour in cyclists but not in controls. We demonstrate that Hb(mass) can be measured reliably via CO-rebreathing during a cycling tour. Unlike [Hb] and Hct, Hb(mass) remains stable over 6 days of racing in professional cyclists and may have potential in an antidoping context.