Systematic comparison of four point-of-care methods versus the reference laboratory measurement of hemoglobin in the surgical ICU setting: a cross-sectional method comparison study.

BACKGROUND: Transfusion decision during the perioperative period mostly relies on the point-of-care testing for Hb measurement. This study aimed systematically compared four point-of-care methods with the central laboratory measurement of hemoglobin (LHb) regarding the accuracy, precision, and assay practicality to identify the preferred point-of-care method during the perioperative period. METHODS: This cross-sectional method comparison study was conducted in the surgical intensive care unit at Ramathibodi Hospital, Thailand, from September 2015 to July 2016. Four point-of-care methods, i.e., capillary hematocrit (HctCap), HemoCue Hb201+, iSTAT with CG8+ cartridge, and SpHb from Radical-7 pulse co-oximeter were carried out when LHb was ordered. Pearson correlation and Bland-Altman analyses were performed to assess the accuracy and precision, while the workload, turnaround time, and the unit cost were evaluated for the method practicality. RESULTS: Thirty-five patients were enrolled, corresponding to 48 blood specimens for analyses, resulting in the measured hemoglobin of 11.2 ± 1.9 g/dL by LHb. Ranking by correlation (r), mean difference (bias) and 95% limit of agreement (LOA) showed the point-of-care methods from the greater to the less performance as followed, iSTAT-LHb pair (r = 0.941; bias 0.15 (95% LOA; - 1.41, 1.12) g/dL), HemoCue-LHb pair (r = 0.922; bias - 0.18 (95% LOA; - 1.63, 1.28) g/dL), SpHb-LHb pair (r = 0.670; bias 0.13 (95% LOA; - 3.12, 3.39) g/dL) and HctCap-LHb pair (r = 0.905; bias 0.46 (95% LOA; - 1.16, 2.08) g/dL). Considering the practicality, all point-of-care methods had less workload and turnaround time than LHb, but only HemoCue and HctCap had lower unit cost. CONCLUSION: This study identified HemoCue as the suitable point-of-care method for the sole purpose of Hb measurement in the surgical ICU setting, while iSTAT should be considered when additional data is needed.

The value of routine laboratory screening in the neonatal intensive care unit.

BACKGROUND: Healthcare spending is expected to grow faster than the economy over the next decade, and the cost of prematurity increases annually. The aim of this study was to investigate the frequency of intervention after routine laboratory testing in preterm infants. METHODS: This was a retrospective study of preterm infants (≤34 weeks) admitted to the NYU Langone Health NICU from June 2013 to December 2014. Data collected included demographics, results of laboratory tests, and resulting interventions. Intervention after a hemogram was defined as a blood transfusion. Intervention after a hepatic panel was defined as initiation or termination of ursodiol or change in dose of vitamin D. Subjects were stratified into 3 groups based on gestation (<28 weeks, 28-31 6/7 weeks, 32-34 weeks). Chi-square analysis was used to compare the frequency of intervention between the groups. RESULTS: A total of 135 subjects were included in the study. The frequency of intervention after a hemogram was 8.4% in infants <28 weeks, 4.6% in infants 28-31 6/7 weeks, and 0% in infants 32-34 weeks; this difference was found to be statistically significant (p = 0.02). The frequency of intervention after a hepatic panel was 4.2% in infants <28 weeks, 5.7% in infants 28-31 6/7 weeks, and 0% in infants 32-34 weeks, which was not found to be a statistically significant different. CONCLUSION: No interventions were undertaken post-routine laboratory testing in any infant 32-34 weeks and routine testing in this population may be unnecessary. Further studies are needed to elucidate if routine testing affects neonatal outcomes.

Anemia Screening in Naval Aviation: Is Hemoglobin a Better Indicator Than Hematocrit as the Primary Index?

INTRODUCTION: Because of the rigorous mental and physical health requirements for Naval Aviation, all applicants and designated personnel must meet physical standards, including initial and periodic screening for anemia. Most standards, including for accession to the U.S. Navy, use hemoglobin as the standard marker to screen for anemia. Moreover, previous literature generally supports the assertion that hemoglobin is more reliable and accurate than hematocrit. However, the U.S. Navy Aeromedical Reference and Waiver Guide uses a hematocrit standard for anemia screening. The purpose of this study was to determine whether hemoglobin or hematocrit correlates better with clinical anemia and evaluate which index is a more accurate indicator for anemia screening in Naval Aviation personnel. MATERIALS AND METHODS: This is a retrospective cross-sectional study of Naval Aviation applicants (N = 95) who were evaluated by the Human Performance and Aeromedical Qualifications department at Naval Aerospace Medical Institute Clinic in Pensacola, Florida, from January 1, 2015 to September 30, 2018. Data were collected from electronic medical records in a de-identified manner that included demographics, class designations, labs results, diagnoses, and final disposition. Logistic regression was used to analyze whether hemoglobin (using the U.S. Navy standard of 13.5 g/dL for men and 12.0 g/dL for women) or hematocrit (using the Naval Aviation standard of 40% for men and 37% for women) predicted the diagnosis of anemia for subjects having at least one lab sample (1-sample) and for those having three samples (3-samples). Sensitivity and specificity values were calculated for hemoglobin and hematocrit as tools to predict a diagnosis of anemia using the same standards in the 1-sample and 3-sample groups. RESULTS: Data were collected for 95 subjects, 53 of whom had three sets of paired hemoglobin/hematocrit values. Using logistic regression, hemoglobin was found to be a statistically significant predictor of anemia for both the 1-sample group (odds ratio 3.4, confidence interval [1.130-10.196], P < 0.05) and the 3-sample group (odds ratio 10.5, confidence interval [1.776-62.580], P < 0.01). Hematocrit was not a significant predictor in either group. Hemoglobin was 80% sensitive and 52.3% specific for a diagnosis of anemia in the 1-sample group and 91.3% sensitive and 50.0% specific in the 3-samples group. Hematocrit was 86.7% sensitive and 35.4% specific for a diagnosis of anemia in the 1-sample group and 91.3% sensitive and 23.3% specific in the 3-samples group. CONCLUSIONS: This study found that hemoglobin correlates better with the diagnosis of anemia than hematocrit. When three samples are analyzed, hemoglobin is equally sensitive and more specific than hematocrit. Based on these results and the U.S. Navy accession standards using hemoglobin as the standard index for anemia, the U.S. Navy Aeromedical Reference and Waiver Guide should consider using hemoglobin instead of hematocrit to screen for anemia. Future research should focus on prospective research to determine whether hemoglobin or hematocrit is a better indicator of anemia in screening military personnel.

ASSESSMENT OF A VISUAL SCORING SYSTEM FOR IDENTIFYING AND QUANTIFYING ANEMIA IN MALE EASTERN BOX TURTLES ( TERRAPENE CAROLINA CAROLINA).

The North Carolina State University College of Veterinary Medicine Turtle Rescue Team (TRT) regularly admits wild eastern box turtles (EBT) ( Terrapene carolina carolina) for treatment and rehabilitation. Adult males of this species generally have an impressive red coloration of the iris, a feature commonly used to differentiate them from their brown-eyed female conspecifics. Male EBTs that present often display marked pallor of the eyes, which has accompanied clinical anemia. The aim of this study was to examine the relationship between eye color and packed cell volume (PCV) in adult male EBTs, and to assess the accuracy of using eye color to predict PCV. Eye-color scoring cards were created using Adobe Creative Cloud Photoshop®. Each card was composed of blocks displaying progressively lighter tints of a red hue, with a number (score) assigned to each block. Five-block, six-block, and nine-block scoring cards were prepared, with lower numbers (scores) corresponding to lighter hues. To determine the variation in subjective color scores assigned by different human observers, 85 individuals were asked to score EBT eye color in three animals using each of the three scoring cards. Eye color of adult male EBTs that presented to the TRT ( n = 18) and those housed at the North Carolina Museum of Natural Sciences ( n = 6) were scored using each of the three cards, immediately preceding venipuncture of the occipital sinus for determination of PCV. All animals were scored by at least two individuals. Turtles with low scores (pale eyes) using all three scoring cards consistently had lower PCVs. The five- and six-block scorecards had a positive predictive value (PPV) of 100% while the nine-block score card had a PPV of 71.4%. This specific and noninvasive method for estimating PCV of male EBTs is clinically desirable in both rehabilitation and hospital settings.

Clinical Experience of Autologous Blood Transfusion in Neurosurgery: Prospective Study in Central India.

OBJECTIVE: To evaluate the benefits of intraoperative autologous blood transfusion in intracranial procedures and to conserve precious homologous blood due to shortage of donor and associated complications. METHODS: This was a prospective study performed at Bansal Hospital, Bhopal. Predetermined autologous blood was collected in a well-labeled bag containing citrate phosphate dextrose adenine solution after induction of general anesthesia. Then appropriate amount of crystalloid solution was transfused in to the body. All collected autologous blood was transfused back to the patient at the end of the surgery or during the surgery if excessive blood loss occurred. Demographic data, hemodynamic changes (mean arterial pressure, heart rate) before and after donation, complications, and any additional homologous blood requirement were noted. Pre- and postoperative hemoglobin and hematocrit values were compared. RESULTS: In total, 32 patients were included in this study. In our study, mean age was 48.87 years; male-to-female ratio was 1:1.4. The mean amount of autologous blood collected was 461 mL, and the mean amount of blood loss during surgery was 1048 mL. In our study, there was no statistically significant difference was found in mean arterial pressure and heart rate before and after autologous blood collection (P > 0.05). When we compared pre- and postoperative mean hemoglobin and hematocrit levels, there was a statistically significant difference present (P < 0.05); this was due to the fact that many patients had meningiomas (15 of 32). Additional homologous blood was required only in 25% of cases (8/32). Of 8 patients, 5 were again cases of deep-seated meningiomas. No complications were observed during or after autologous blood collection. CONCLUSIONS: Autologous blood transfusion is a safe, effective, and affordable method of blood transfusion in patients undergoing intracranial surgery. Complications associated with homologous blood transfusion can be avoided with autologous blood transfusion.

Simultaneous assessment of blood coagulation and hematocrit levels in dielectric blood coagulometry.

BACKGROUND: In a whole blood coagulation test, the concentration of any in vitro diagnostic agent in plasma is dependent on the hematocrit level but its impact on the test result is unknown. OBJECTIVE: The aim of this work was to clarify the effects of reagent concentration, particularly Ca2+, and to find a method for hematocrit estimation compatible with the coagulation test. METHODS: Whole blood coagulation tests by dielectric blood coagulometry (DBCM) and rotational thromboelastometry were performed with various concentrations of Ca2+ or on samples with different hematocrit levels. DBCM data from a previous clinical study of patients who underwent total knee arthroplasty were re-analyzed. RESULTS: Clear Ca2+ concentration and hematocrit level dependences of the characteristic times of blood coagulation were observed. Rouleau formation made hematocrit estimation difficult in DBCM, but use of permittivity at around 3 MHz made it possible. The re-analyzed clinical data showed a good correlation between permittivity at 3 MHz and hematocrit level (R2=0.83). CONCLUSIONS: Changes in the hematocrit level may affect whole blood coagulation tests. DBCM has the potential to overcome this effect with some automated correction using results from simultaneous evaluations of the hematocrit level and blood coagulability.

Time Dependent Assessment of Morphological Changes: Leukodepleted Packed Red Blood Cells Stored in SAGM.

Usually packed red blood cells (pRBCs) require specific conditions in storage procedures to ensure the maximum shelf life of up to 42 days in 2-6°C. However, molecular and biochemical consequences can affect the stored blood cells; these changes are collectively labeled as storage lesions. In this study, the effect of prolonged storage was assessed through investigating morphological changes and evaluating oxidative stress. Samples from leukodepleted pRBC in SAGM stored at 4°C for 42 days were withdrawn aseptically on day 0, day 14, day 28, and day 42. Morphological changes were observed using scanning electron microscopy and correlated with osmotic fragility and hematocrit. Oxidative injury was studied through assessing MDA level as a marker for lipid peroxidation. Osmotic fragility test showed that extended storage time caused increase in the osmotic fragility. The hematocrit increased by 6.6% from day 0 to day 42. The last 2 weeks show alteration in the morphology with the appearance of echinocytes and spherocytes. Storage lesions and morphological alterations appeared to affect RBCs during the storage period. Further studies should be performed to develop strategies that will aid in the improvement of stored pRBC quality and efficacy.

Accuracy and precision evaluation of Thai plastic microhematocrit tubes: the first product from Thailand.

BACKGROUND: In Thailand, the spun microhematocrit method is usually performed using glass microhematocrit tubes even though broken glass tube during use may result in a risk of injury and blood-borne infection. The main reason is that the safer product alternatives such as plastic microhematocrit tubes are more expensive. Now, plastic tubes for hematocrit determination can be produced in Thailand at a much cheaper price. However precision and accuracy studies are necessary before being able to use them. OBJECTIVE: To compare the accuracy and precision of Thai plastic microhematocrit tubes against the routinely used glass microhematocrit tubes and imported plastic microhematocrit tubes using spun microhematocrit method. MATERIALS AND METHOD: One hundred residual EDTA blood samples from the Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand along with the three level hematology control materials were measured with spun microhematocrit values using three different types of plastic microhematocrit tubes. This was compared to the routinely used glass microhematocrit tubes as a gold standard. RESULTS: The repeated measures one-way ANOVA found no significant difference between the hematocrit values from each type of tubes with an F(1,99) = 0.667 and p-value = 0.574. Intraclass correlation coefficient (ICC) between four types of microhematocrit tubes ranged from 0.996-0.998 (p-value < 0.001). Correlation coefficients (r) between four types of microhematocrit tubes ranged from 0.996-0.998 (p-value < 0.05). Coefficient of variation (CV) for precision of both within run and between run of Thai plastic microhematocrit tubes ranged from 1.44 to 2.17% compared to 1.39 to 4.01% of the imported plastic microhematocrit tubes. CONCLUSION: The hematocrit values determined by all plastic microhematocrit tubes can be considered relatively equivalent to those of glass microhematocrit tubes in terms of accuracy and precision. The Thai plastic microhematocrit tubes are economical and with the cost-benefit over other plastic tubes of about 12 to 16 times. Therefore, the Thai plastic microhematocrit tubes should be the choice for glass tube replacement.

Estimation of indocyanine green concentration in blood from fluorescence emission: application to hemodynamic assessment during hemodialysis.

There is considerable interest in assessing cardiovascular function noninvasively in patients receiving hemodialysis. A possible approach is to measure the blood concentration of bolus-injected indocyanine green dye and to apply the dye-dilution method for estimating cardiac output and blood volume. Blood ICG concentration can be derived from a measurement of the ICG fluorescence through the dialysis tubing if a simple and unique calibration relationship can be established between transmural fluorescence intensity and blood ICG concentration. We investigated this relationship using Monte Carlo simulations of light transport in blood with varying hematocrit and ICG concentrations and performed empiric measurements of optical absorption and ICG fluorescence emission to confirm our findings. The ICG fluorescence intensity measured at the blood surface, as well as the light intensity remitted by the blood, varied as hematocrit changes modified the absorption and scattering characteristics of the blood. Calibration relationships were developed between fluorescence intensity and ICG concentration that accounted for hematocrit changes. Combining the backreflected fluorescence and the reflected light measured near the point of illumination provided optimal signal intensity, linearity, and robustness to hematocrit changes. These results provide a basis for developing a noninvasive approach to derive optically circulating blood ICG concentration in hemodialysis circuits.

Absolute transmitted light plethysmography for assessment of dental pulp vitality through quantification of pulp chamber hematocrit by a three-layer model.

After confirming that the gingival circulation had little effect on transmitted light plethysmography measurement in the upper central incisor in both in vivo experiments and numerical Monte Carlo simulation studies, a three-layer model comprising of a pulp chamber sandwiched between two dentin layers has been introduced to quantify the pulp chamber hematocrit (Hctp) from the measured optical density. Two-flux theory was utilized to derive a mathematical equation for transmitted intensity in terms of tooth dimensions, Hctp, and light-source wavelength. Each layer was assumed homogeneous so as to represent its optical properties by the bulk absorption and scattering constants. The mean error between the Hctp estimate based on the three-layer-model equation and the Hctp actual in the extracted model tooth was -0.00115 with standard deviation (SD) of 0.00733 at 522 nm wavelength, while for 810 nm +0.09157 and 0.02493. The Hctp estimate of the upper central incisor in 10 young volunteers at 522 nm using the three-layer model ranged from 0.002 to 0.061 with the mean of 0.032. The Hctp change reflects blood volume shift in the pulp microcirculation to possibly indicate dental pulp vitality.

Single-step centrifugal hematocrit determination on a 10-$ processing device.

We present a novel concept to process human blood on a spinning polymer disk for the determination of the hematocrit level by simple visual inspection. The microfluidic disk which is spun by a macroscopic drive unit features an upstream metering structure and a downstream blind channel where the centrifugally enforced sedimentation of the blood is performed. The bubble-free priming of the blind channel is governed by centrifugally assisted capillary filling along the sloped hydrophilic side-wall and the lid as well as the special shape of the dead end of the two-layer channel. The hematocrit is indicated at the sharp phase boundary between the plasma and the segregated cellular pellet on a disk-imprinted calibrated scale. This way, we conduct the hematocrit determination of human blood within 5 min at a high degree of linearity (R(2) = 0.999) and at a high accuracy (CV = 4.7%) spanning over the physiological to pathological working range. As all processing steps including the priming, the metering to a defined volume as well as the centrifugation are executed automatically during rotation, the concept is successfully demonstrated in a conventional PC-CDROM drive while delivering the same performance (R(2) = 0.999, CV = 4.3%).

Determination of optical properties of human blood in the spectral range 250 to 1100 nm using Monte Carlo simulations with hematocrit-dependent effective scattering phase functions.

The absorption coefficient mu(a), scattering coefficient mu(s), and anisotropy factor g of diluted and undiluted human blood (hematocrit 0.84 and 42.1%) are determined under flow conditions in the wavelength range 250 to 1100 nm, covering the absorption bands of hemoglobin. These values are obtained by high precision integrating sphere measurements in combination with an optimized inverse Monte Carlo simulation (IMCS). With a new algorithm, appropriate effective phase functions could be evaluated for both blood concentrations using the IMCS. The best results are obtained using the Reynolds-McCormick phase function with the variation factor alpha = 1.2 for hematocrit 0.84%, and alpha = 1.7 for hematocrit 42.1%. The obtained data are compared with the parameters given by the Mie theory. The use of IMCS in combination with selected appropriate effective phase functions make it possible to take into account the nonspherical shape of erythrocytes, the phenomenon of coupled absorption and scattering, and multiple scattering and interference phenomena. It is therefore possible for the first time to obtain reasonable results for the optical behavior of human blood, even at high hematocrit and in high hemoglobin absorption areas. Moreover, the limitations of the Mie theory describing the optical properties of blood can be shown.

The cost of a specific immune response in young guinea pigs.

The specific immune system is a protective mechanism that detects infection and fights it by production of antibodies. Newborns are especially susceptible to infections because their immune system is not yet as fully developed as that of adults. This has been well established in altricial mammals. Fighting infection is associated with costs (metabolic rate, protein synthesis) potentially affecting other developmental processes. We investigated the specific immune response in a precocial mammal, by testing the response of 3 and 7 day old young guinea pigs (Cavia aperea f. porcellus) against a non-pathogenic antigen (KLH) and determined the effect of the immune response on growth and metabolic rate. Challenged young produced a substantial specific immune response (IgG). The efficiency of the immune response was almost identical in 3 and 7 day old young, but lower than in adult females. Antibody titres achieved by actively immunised young pups were as high as titres transferred transplacentally by mothers immunised on day 40 and 47 of pregnancy. In comparison to a control group, the immune response did not influence growth and metabolic rate measured on day 4 after each immune challenge and was not reflected by changes in hematocrit value. We discuss whether the weaker immune response of pups is caused by reduced allocation of limited resources in growing young or by the immature immune system of young animals.

Assessment of body composition and breast milk volume in lactating mothers in pastoral communities in Pokot, Kenya, using deuterium oxide.

BACKGROUND: In sub-Saharan Africa, the practice of breast-feeding infants is common. Records documenting the intake of breast milk amongst infants are limited. This study evaluated the association between maternal body composition and the intake of breast milk in infants from the pastoral communities within Pokot, Kenya. METHODS: The study was conducted in 10 lactating mothers who were participating in a longitudinal study aimed at determining maternal body composition, iron stores and vitamin A status during the third trimester pregnancy and four months after they had given birth. Maternal and infant anthropometric measurements were made, and maternal blood samples were taken to determine serum retinol and ferritin levels. Infant milk intake and maternal fat-free mass (FFM) and percent body fat (% BF) were measured using 'the dose to the mother method'. A measured deuterium oxide ((2)H(2)O) dose was given to the mother. Urine and breast milk from the mother, and saliva samples from the infant, were collected on days 1, 8 and 14 after dosing. RESULTS: The mean (+/- SD) maternal mid upper arm circumference (MUAC) and body mass index (BMI) were 21.8 (0.9) cm and 18.6 (1.0) kg/height (m(2)), respectively. Infant weight and weight/age Z score were 4.956 (0.874) kg and -1.750 (0.77), respectively. Throughout the study, the infants gained 20 (4) g/day in body weight and had a milk intake of 555 (22) ml/day. The energy intake of the infant was 1,602 (148) kJ/day and was lower (p < 0.05) than the 2,404 (423) kJ/day estimated requirement by the FAO/WHO/UNU. The maternal FFM, %BF, Hb, Hct, ferritin and retinol were 32.8 (3.1) kg, 17.24 (7.0), 11.5 (1.3) g/dl, 33.9 (4.9), 16.2 (0.1) microg/l and 0.894 (0.16) micromol/l, respectively. Infant milk intake was significantly and positively correlated to maternal pregnancy triceps (r = 0.679) p < 0.05) and pregnancy MUAC (r = 0.725) p < 0.05). Maternal pregnancy MUAC was an important predictor of infant breast milk intake. CONCLUSION: Data on volume of breast milk consumed by the infants suggests, at least for this group of infants, that adequate growth may not be achieved. There is a possibility that lactating mothers practicing exclusive breast-feeding and living under harsh conditions may experience periods of low breast milk volume. Body composition and biochemical findings among this group of Pokot mothers indicate dietary inadequacies that require nutritional intervention.

Evaluación del desempeño de contadores hematológicos / Performance assessment of blood cells analyzers

El objetivo de esta presentación es brindar, en forma didáctica y actualizada, una orientación para la evaluación de contadores hematológicos. Primeramente se hace referencia a los niveles de evaluación, la información preliminar referida al instrumento sobre requerimientos de espacio y servicios y al manual de instrucción. En cuanto a las etapas de evaluación se tratan: a) la planificación técnica que incluye acuerdos previos con el fabricante y la planificación de recursos internos; b) calibración, calibradores y materiales de control; c) reactivos; d) muestras: su manipulación y registros de datos; e) ensayo preliminar: normas de seguridad (mecánicas, eléctricas, microbiológicas, químicas, ambientales) e instalación y mantenimiento; f) evaluación del desempeño: efecto de la dilución, coincidencia, precisión intra e interensayo, deriva, evaluación del arrastre, comparabilidad con datos obtenidos por procedimientos de rutina, exactitud, efecto del envejecimiento de la muestra, sensibilidad para muestras anormales, interferencias, análisis de datos y utilidad clínica; g) evaluación de la eficiencia. Finalmente, se sacan conclusiones sobre la base de un ejemplo de evaluación de un equipo de apertura-impedancia