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1.
Analyst ; 144(12): 3782-3789, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31094378

RESUMO

We investigate the influence of rotational forces on blood dynamics in a microfluidic device. The special confluence of Coriolis force and blood rheology is brought forth by analyzing the flow at different hematocrit (volume fraction of red blood cells) levels and rotational speeds. We further study the effects of channel layout and alignment with regard to the axis of rotation to understand this intricate interplay. We provide a sound basis for efficient designing of a lab on a compact disc (lab on CD) platform by harnessing the effects of Coriolis force at relatively much lower rotational speeds, in sharp contrast with the reported findings where Coriolis effects have been considered to be effective only for exceptionally high rotational speeds. Our results show that over certain intermediate regimes of rotational speeds, the flow profiles for different hematocrit levels are noticeably different. This, in turn, could be harnessed as a possible diagnostic signature of the hematocrit (or equivalently, packed cell volume) level, without necessitating the deployment of chemical consumables, in an energy efficient paradigm.


Assuntos
Sangue , Discos Compactos , Força Coriolis , Hematócrito/métodos , Dispositivos Lab-On-A-Chip , Viscosidade Sanguínea , Hematócrito/instrumentação , Humanos , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Rotação
2.
J Diabetes Sci Technol ; 13(3): 514-521, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30974988

RESUMO

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.


Assuntos
Glicemia/análise , Técnicas de Laboratório Clínico , Diabetes Mellitus/sangue , Equipamentos e Provisões/normas , Acesso à Internet , Artefatos , Automonitorização da Glicemia/instrumentação , Automonitorização da Glicemia/normas , Técnicas de Laboratório Clínico/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Hematócrito/instrumentação , Hematócrito/métodos , Hematócrito/normas , Humanos , Modelos Lineares , Fitas Reagentes/normas , Reprodutibilidade dos Testes
3.
J Diabetes Sci Technol ; 13(3): 568-574, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30623673

RESUMO

Hematocrit is known to influence glucose values obtained on some blood glucose meters, with bias observed especially at low and high hematocrit levels. We evaluated the performance of a meter with hematocrit correction technology alongside 3 other commercially available meters. Capillary blood samples from 100 subjects were analyzed in duplicate and compared to the plasma values obtained by reference laboratory analyzer. Bias, error grid, and sensitivity to hematocrit analyses were performed for each meter. Average percentage bias was similar for all meters, however the evaluated meter performed best with respect to error grid analysis, with 100% of values falling within the "no effect on clinical action" and "no risk" categories and did not display any hematocrit associated bias.


Assuntos
Glicemia/análise , Diabetes Mellitus/sangue , Artefatos , Automonitorização da Glicemia/economia , Automonitorização da Glicemia/instrumentação , Automonitorização da Glicemia/normas , Comércio , Diabetes Mellitus/diagnóstico , Hematócrito/instrumentação , Hematócrito/normas , Humanos , Padrões de Referência , Reprodutibilidade dos Testes , Projetos de Pesquisa , Sensibilidade e Especificidade , Reino Unido
4.
Am J Emerg Med ; 37(6): 1048-1053, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30131206

RESUMO

INTRODUCTION: Blood gas analyzers can be alternatives to laboratory autoanalyzers for obtaining test results in just a few minutes. We aimed to find out whether the results from blood gas analyzers are reliable when compared to results of core laboratory autoanalyzers. MATERIALS AND METHODS: This retrospective, single-centered study examined the electronic records of patients admitted to the emergency department of a tertiary care teaching hospital between May 2014 and December 2017. Excluded from the study were patients under 18 years old, those lacking data, those who had any treatment before the laboratory tests, those whose venous gas results were reported more than 30 minutes after the blood sample was taken and for whom any of the laboratory tests were performed at a different time, and recurrent laboratory results from a single patient. RESULTS: Laboratory results were analyzed from a total of 31,060 patients. The correlation coefficients for sodium, potassium, hemoglobin, hematocrit, and glucose levels measured by a blood gas analyzer and a laboratory autoanalyzer were 0.725, 0.593, 0.982, 0.958, and 0.984, respectively; however, there were no good, acceptable agreement limits for any of the parameters. In addition, these results did not change according to the different pH stages (acidosis, normal pH and alkalosis). CONCLUSION: The two types of measurements showed a moderate correlation for sodium and potassium levels and a strong correlation for glucose, hemoglobin, and hematocrit levels, but none of the levels had acceptable agreement limits. Clinicians should be aware of the limitations of blood gas analyzer results.


Assuntos
Autoanálise/normas , Gasometria/normas , Adulto , Idoso , Autoanálise/instrumentação , Autoanálise/estatística & dados numéricos , Gasometria/instrumentação , Gasometria/estatística & dados numéricos , Feminino , Glucose/análise , Hematócrito/instrumentação , Hematócrito/normas , Hemoglobinas/análise , Humanos , Masculino , Pessoa de Meia-Idade , Sistemas Automatizados de Assistência Junto ao Leito/normas , Sistemas Automatizados de Assistência Junto ao Leito/estatística & dados numéricos , Potássio/análise , Estudos Retrospectivos , Sódio/análise
5.
Diabetes Care ; 41(8): 1681-1688, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29898901

RESUMO

OBJECTIVE: Cleared blood glucose monitors (BGMs) for personal use may not always deliver levels of accuracy currently specified by international and U.S. regulatory bodies. This study's objective was to assess the accuracy of 18 such systems cleared by the U.S. Food and Drug Administration representing approximately 90% of commercially available systems used from 2013 to 2015. RESEARCH DESIGN AND METHODS: A total of 1,035 subjects were recruited to have a capillary blood glucose (BG) level measured on six different systems and a reference capillary sample prepared for plasma testing at a reference laboratory. Products were obtained from consumer outlets and tested in three triple-blinded studies. Each of the three participating clinical sites tested a different set of six systems for each of the three studies in a round-robin. In each study, on average, a BGM was tested on 115 subjects. A compliant BG result was defined as within 15% of a reference plasma value (for BG ≥100 mg/dL [5.55 mmol/L]) or within 15 mg/dL (0.83 mmol/L) (for BG <100 mg/dL [5.55 mmol/L]). The proportion of compliant readings in each study was compared against a predetermined accuracy standard similar to, but more lenient than, current regulatory standards. Other metrics of accuracy included the overall compliance proportion; the proportion of extreme outlier readings differing from the reference value by >20%; modified Bland-Altman analysis including average bias, coefficient of variation, and 95% limits of agreement; and proportion of readings with no clinical risk as determined by the Surveillance Error Grid. RESULTS: The different accuracy metrics produced almost identical BGM rankings. Six of the 18 systems met the predetermined accuracy standard in all three studies, 5 systems met it in two studies, and 3 met it in one study. Four BGMs did not meet the accuracy standard in any of the three studies. CONCLUSIONS: Cleared BGMs do not always meet the level of analytical accuracy currently required for regulatory clearance. This information could assist patients, professionals, and payers in choosing products and regulators in evaluating postclearance performance.


Assuntos
Glicemia/análise , Diabetes Mellitus/sangue , Equipamentos e Provisões/normas , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Automonitorização da Glicemia/instrumentação , Automonitorização da Glicemia/normas , Comércio , Método Duplo-Cego , Feminino , Hematócrito/instrumentação , Hematócrito/normas , Humanos , Masculino , Pessoa de Meia-Idade , Cooperação do Paciente , Estado Pré-Diabético/sangue , Valores de Referência , Reprodutibilidade dos Testes , Estados Unidos , United States Food and Drug Administration , Adulto Jovem
6.
J Cardiovasc Magn Reson ; 20(1): 19, 2018 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-29544519

RESUMO

BACKGROUND: Calculation of cardiovascular magnetic resonance (CMR) extracellular volume (ECV) requires input of hematocrit, which may not be readily available. The purpose of this study was to evaluate the diagnostic accuracy of ECV calculated using various noninvasive measures of hematocrit compared to ECV calculated with input of laboratory hematocrit as the reference standard. METHODS: One hundred twenty three subjects (47.7 ± 14.1 years; 42% male) were prospectively recruited for CMR T1 mapping between August 2016 and April 2017. Laboratory hematocrit was assessed by venipuncture. Noninvasive hematocrit was assessed with a point-of-care (POC) device (Pronto-7® Pulse CO-Oximeter®, Masimo Personal Health, Irvine, California, USA) and by synthetic derivation based on the relationship with blood pool T1 values. Left ventricular ECV was calculated with input of laboratory hematocrit (Lab-ECV), POC hematocrit (POC-ECV), and synthetic hematocrit (synthetic-ECV), respectively. Statistical analysis included Wilcoxon signed-rank test, Bland-Altman analysis, receiver-operating curve analysis and intra-class correlation (ICC). RESULTS: There was no significant difference between Lab-ECV and POC-ECV (27.1 ± 4.7% vs. 27.3 ± 4.8%, p = 0.106), with minimal bias and modest precision (bias - 0.18%, 95%CI [- 2.85, 2.49]). There was no significant difference between Lab-ECV and synthetic-ECV (26.7 ± 4.4% vs. 26.5 ± 4.3%, p = 0.084) in subjects imaged at 1.5 T, although bias was slightly higher and limits of agreement were wider (bias 0.23%, 95%CI [- 2.82, 3.27]). For discrimination of abnormal Lab-ECV ≥30%, POC-ECV had good diagnostic performance (sensitivity 85%, specificity 96%, accuracy 94%, and AUC 0.902) and synthetic-ECV had moderate diagnostic performance (sensitivity 71%, specificity 98%, accuracy 93%, and AUC 0.849). POC-ECV had excellent test-retest (ICC 0.994, 95%CI[0.987, 0.997]) and inter-observer agreement (ICC 0.974, 95%CI[0.929, 0.991]). CONCLUSIONS: Myocardial ECV can be accurately and reproducibly calculated with input of hematocrit measured using a noninvasive POC device, potentially overcoming an important barrier to implementation of ECV. Further evaluation of synthetic ECV is required prior to clinical implementation.


Assuntos
Cardiopatias/diagnóstico por imagem , Hematócrito/instrumentação , Imagem Cinética por Ressonância Magnética , Oximetria/instrumentação , Sistemas Automatizados de Assistência Junto ao Leito , Testes Imediatos , Adulto , Estudos de Casos e Controles , Desenho de Equipamento , Feminino , Cardiopatias/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Valor Preditivo dos Testes , Estudos Prospectivos , Reprodutibilidade dos Testes
8.
Perfusion ; 32(2): 126-132, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27591743

RESUMO

BACKGROUND: HemoSep® is a commercial ultrafiltration and haemoconcentration device for the concentration of residual bypass blood following surgery. This technology is capable of reducing blood loss in cardiac and other types of "clean site" procedures, including paediatric surgery. Clinical feedback suggested that the device would be enhanced by including a sensor technology capable of discerning the concentration level of the processed blood product. We sought to develop a novel sensor that can, using light absorption, give an accurate estimate of packed cell volume (PCV). MATERIALS AND METHODS: A sensor-housing unit was 3D printed and the factors influencing the sensor's effectiveness - supply voltage, sensitivity and emitter intensity - were optimised. We developed a smart system, using comparator circuitry capable of visually informing the user when adequate PCV levels (⩾35%) are attained by HemoSep® blood processing, which ultimately indicates that the blood is ready for autotransfusion. RESULTS: Our data demonstrated that the device was capable of identifying blood concentration at and beyond the 35% PCV level. The device was found to be 100% accurate at identifying concentration levels of 35% from a starting level of 20%. DISCUSSION: The sensory capability was integrated into HemoSep's® current device and is designed to enhance the user's clinical experience and to optimise the benefits of HemoSep® therapy. The present study focused on laboratory studies using bovine blood. Further studies are now planned in the clinical setting to confirm the efficacy of the device.


Assuntos
Técnicas Biossensoriais/métodos , Hematócrito/métodos , Ultrafiltração/métodos , Animais , Técnicas Biossensoriais/instrumentação , Células Sanguíneas/citologia , Perda Sanguínea Cirúrgica/prevenção & controle , Ponte Cardiopulmonar/métodos , Bovinos , Separação Celular/métodos , Desenho de Equipamento , Hematócrito/instrumentação , Humanos , Impressão Tridimensional
9.
Lab Chip ; 16(19): 3689-94, 2016 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-27604182

RESUMO

The quantification of blood cells provides critical information about a patient's health status. Sophisticated analytical equipment, such as hematology analyzers, have been developed to perform these measurements, but limited-resource settings often lack the infrastructure required to purchase, operate, and maintain instrumentation. To address these practical challenges, paper-based microfluidic devices have emerged as a platform to develop diagnostic assays specifically for use at the point-of-care. To date, paper-based microfluidic devices have been used broadly in diagnostic assays that apply immunoassay, clinical chemistry, and electrochemistry techniques. The analysis of cells, however, has been largely overlooked. In this communication, we demonstrate a paper-based microfluidic device that enables the controlled transport of red blood cells (RBCs) and the measurement of the hematocrit-the ratio of RBC packed cell volume to total volume of whole blood. The properties of paper, device treatment, and device geometry affect the overall extent and reproducibility of transport of RBCs. Ultimately, we developed an inexpensive (US$0.03 per device) thermometer-styled device where the distance traveled by RBCs is proportional to the hematocrit. These results provide a foundation for the design of paper-based microfluidic devices that enable the separation and detection of cells in limited-resource settings.


Assuntos
Hematócrito/instrumentação , Dispositivos Lab-On-A-Chip , Papel , Desenho de Equipamento , Eritrócitos/citologia , Humanos , Plasma/citologia
10.
Ethiop J Health Sci ; 26(3): 251-8, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27358546

RESUMO

BACKGROUND: Prompt and accurate diagnosis is needed to prevent the untoward effects of anaemia on children. Although haematology analyzers are the gold standard for accurate measurement of haemoglobin or haematocrit for anaemia diagnosis, they are often out of the reach of most health facilities in resource-poor settings thus creating a care gap. We conducted this study to examine the agreement between a point-of-care device and haematology analyzer in determining the haematocrit levels in children and to determine its usefulness in diagnosing anaemia in resource-poor settings. METHODS: EDTA blood samples collected from participants were processed to estimate their haematocrits using the two devices (Mindray BC-3600 haematology analyzer and Portable Mission Hb/Haemotocrit testing system). A pairwise t-test was used to compare the haematocrit (PCV) results from the automated haematology analyzer and the portable haematocrit meter. The agreement between the two sets of measurements was assessed using the Bland and Altman method where the mean, standard deviation and limit of agreement of paired results were calculated. RESULTS: The intraclass and concordance correlation coefficients were 0.966 and 0.936. Sensitivity and specificity were 97.85% and 94.51% respectively while the positive predictive and negative predictive values were 94.79% and 97.73%. The Bland and Altman`s limit of agreement was -5.5-5.1 with the mean difference being -0.20 and a non-ignificant variability between the two measurements (p = 0.506). CONCLUSION: Haematocrit determined by the portable testing system is comparable to that determined by the haematology analyzer. We therefore recommend its use as a point-of-care device for determining haematocrit in resource-poor settings where haematology analyzers are not available.


Assuntos
Anemia/diagnóstico , Países em Desenvolvimento , Hematócrito/métodos , Testes Imediatos , Anemia/sangue , Pré-Escolar , Feminino , Recursos em Saúde , Hematócrito/instrumentação , Humanos , Lactente , Masculino , Nigéria , Projetos Piloto , Sensibilidade e Especificidade
11.
Anal Chem ; 88(12): 6538-46, 2016 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-27206105

RESUMO

Dried blood spot (DBS) sampling is recognized as a valuable alternative sampling strategy both in research and in clinical routine. Although many advantages are associated with DBS sampling, its more widespread use is hampered by several issues, of which the hematocrit effect on DBS-based quantitation remains undoubtedly the most widely discussed one. Previously, we developed a method to derive the approximate hematocrit from a nonvolumetrically applied DBS based on its potassium content. Although this method yielded good results and was straightforward to perform, it was also destructive and required sample preparation. Therefore, we now developed a nondestructive method which allows to predict the hematocrit of a DBS based on its hemoglobin content, measured via noncontact diffuse reflectance spectroscopy. The developed method was thoroughly validated. A linear calibration curve was established after log/log transformation. The bias, intraday and interday imprecision of quality controls at three hematocrit levels and at the lower and upper limit of quantitation (0.20 and 0.67, respectively) were less than 11%. In addition, the influence of storage and the volume spotted was evaluated, as well as DBS homogeneity. Application of the method to venous DBSs prepared from whole blood patient samples (n = 233) revealed a good correlation between the actual and the predicted hematocrit. Limits of agreement obtained after Bland and Altman analysis were -0.076 and +0.018. Incurred sample reanalysis demonstrated good method reproducibility. In conclusion, mere scanning of a DBS suffices to derive its approximate hematocrit, one of the most important variables in DBS analysis.


Assuntos
Teste em Amostras de Sangue Seco/instrumentação , Hematócrito/instrumentação , Análise de Variância , Calibragem , Desenho de Equipamento , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Análise Espectral/instrumentação
12.
Methods Mol Biol ; 1428: 297-306, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27236808

RESUMO

In vitro-transcribed (IVT) mRNA encoding therapeutic protein has the potential to treat a variety of diseases by serving as template for translation in the patient. To optimize conditions for such therapy, reporter protein-encoding mRNAs are usually used. One preferred reporter is erythropoietin (EPO), which stimulates erythropoiesis and leads to an increase in hematocrit. Measurement of hematocrit is a fast and reliable method to determine the potency of the in vitro-transcribed EPO mRNA. However, frequent blood draw from mice can increase hematocrit due to blood loss. Therefore, instead of using conventional hematocrit capillary tubes, we adapted glass microcapillaries for hematocrit measurement. Daily monitoring of mice can be accomplished by drawing less than 20 µL of blood, thus avoiding blood loss-related hematocrit increase. Due to the small volume of the withdrawn blood the hematocrit remains the same for mice injected with control mRNA, whereas significant hematocrit increase is measured between day 4 and 20 postinjection for those injected with pseudouridine-modified EPO mRNA. Following hematocrit measurement the microcapillaries are snapped easily to recover plasma for further analyses, including EPO measurement by ELISA.


Assuntos
Eritropoetina/genética , Hematócrito/instrumentação , RNA Mensageiro/administração & dosagem , Animais , Eritrócitos/metabolismo , Eritropoetina/metabolismo , Humanos , Técnicas In Vitro , Camundongos , Camundongos Endogâmicos BALB C
13.
Anal Chim Acta ; 924: 1-8, 2016 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-27181638

RESUMO

Hematocrit (HCT) measurements are important clinical diagnostic variables that help physicians diagnose and treat various medical conditions, ailments, and diseases. In this work, we present the HCT Disc, a centrifugal microdevice fabricated by a Print, Cut and Laminate (PCL) method to generate a 12-sample HCT device from materials costing <0.5 USD (polyester and toner or PeT). Following introduction from a drop of blood (finger stick), whole blood metering and cell sedimentation are controlled by centrifugal force, only requiring a CD player motor as external hardware and, ultimately, a cell phone for detection. The sedimented volume from patient blood in the HCT Disc was analyzed using a conventional scanner/custom algorithm for analysis of the image to determine a hematocrit value, and these were compared to values generated in a clinical laboratory, which correlated well. To enhance portability and assure simplicity of the HCT measurement, values from image analysis by a cell phone using a custom application was compared to the scanner. Fifteen samples were analyzed with cell phone image analysis system and were found to be within 4% of the HCT values determined in the clinical lab. We demonstrate the feasibility of the PeT device for HCT measurement, and highlight its uniquely low cost (<0.5 USD), speed (sample-to-answer <8 min), multiplexability (12 samples), low volume whole blood requirement (<3 µL), rotation speeds (<4000 rpm) needed for effective measurement as well as the direct finger-to-chip sample loading capability.


Assuntos
Hematócrito/instrumentação , Poliésteres/química , Telefone Celular , Centrifugação/instrumentação , Desenho de Equipamento , Hematócrito/economia , Humanos , Processamento de Imagem Assistida por Computador , Fatores de Tempo
14.
J Trop Pediatr ; 62(4): 316-23, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-26995011

RESUMO

BACKGROUND: Sub-Saharan Africa has the largest burden and worst outcome of sickle cell disease (SCD). This gloomy outlook has been attributed to the lack of use of simple and cost-effective measures for diagnosis and treatment of the disease. Although haematology analysers are the gold standard for accurate measurement of haemoglobin (Hb) concentration, they are often out of reach of most health facilities in resource-poor settings, thus creating a care gap. We conducted this study to examine the agreement between a point-of-care device and haematology analyser for determining the Hb concentration in children with SCD and its usefulness in resource-poor settings. METHODS: Ethylenediaminetetraacetic acid blood samples collected from participants were processed to estimate their Hb concentration using two devices (Sysmex KX21N haematology analyser and portable mission Hb device). The agreement between the two sets of measurements was assessed by the Bland and Altman method. RESULTS: The intraclass and concordance correlation coefficients were 0.854 and 0.936, respectively. Sensitivity and specificity were 84.2% and 98.6%, respectively. The positive and negative predictive values were 94.1% and 96.0%, respectively. The Bland and Altman's limit of agreement was -2.3 to 1.6 and the mean difference was -0.34 with non-significant variability between the two measurements (p = 0.949). CONCLUSION: Hb concentration determined by the portable testing system is comparable with that determined by the haematology analyser. We recommend its use as a point-of-care device for determining Hb concentration of SCD children in resource-poor settings where haematology analysers are not available.


Assuntos
Anemia Falciforme/sangue , Anemia Falciforme/diagnóstico , Hematócrito/instrumentação , Testes Imediatos , Feminino , Hematócrito/métodos , Hospitais de Ensino , Humanos , Masculino , Nigéria , Sistemas Automatizados de Assistência Junto ao Leito , Estudos Prospectivos , Sensibilidade e Especificidade , Traço Falciforme/sangue , Traço Falciforme/diagnóstico
15.
J Cardiothorac Vasc Anesth ; 30(2): 352-62, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27013121

RESUMO

OBJECTIVE: Point-of-care (POC) testing allows rapid assessment of hemoglobin (Hgb) and hematocrit (Hct) values. This study compared 3 POC testing devices--the Radical-7 pulse oximeter (Radical-7, Neuchȃtel, Switzerland), the i-STAT (Abbott Point of Care, Princeton, NJ), and the GEM 4000 (Instrumentation Laboratory, Bedford, MA)--to the hospital reference device, the UniCel DxH 800 (Beckman Coulter, Brea, CA) in cardiac surgery patients. DESIGN: Prospective study. SETTING: Tertiary care cardiovascular center. PARTICIPANTS: Twenty-four consecutive elective adult cardiac surgery patients. INTERVENTIONS: Hgb and Hct values were measured using 3 POC devices (the Radical-7, i-STAT, and GEM 4000) and a reference laboratory device (UniCel DxH 800). Data were collected simultaneously before surgery, after heparin administration, after heparin reversal with protamine, and after sternal closure. Data were analyzed using bias analyses. POC testing data were compared with that of the reference laboratory device. MEASUREMENTS AND MAIN RESULTS: Hgb levels ranged from 6.8 to 15.1 g/dL, and Hct levels ranged from 20.1% to 43.8%. The overall mean bias was lowest with the i-STAT (Hct, 0.22%; Hgb 0.05 g/dL) compared with the GEM 4000 (Hct, 2.15%; Hgb, 0.63 g/dL) and the Radical-7 (Hgb 1.16 g/dL). The range of data for the i-STAT and Radical-7 was larger than that with the GEM 4000, and the pattern or slopes changed significantly with the i-STAT and Radical-7, whereas that of the GEM 4000 remained relatively stable. The GEM 4000 demonstrated a consistent overestimation of laboratory data, which tended to improve after bypass and at lower Hct/Hgb levels. The i-STAT bias changed from overestimation to underestimation, the latter in the post-cardiopulmonary bypass period and at lower Hct/Hgb levels. By contrast, the Radical-7 biases increased during the surgical procedure and in the lower ranges of Hgb. CONCLUSION: Important clinical differences and limitations were found among the 3 POC testing devices that should caution clinicians from relying on these data as sole determinants of when or when not to perform transfusion in patients. Even though a low bias might support the use of POC data, further analysis of the bias plots demonstrates pattern changes during the surgical procedure and across the range of Hct/Hgb data.


Assuntos
Hematócrito/métodos , Hemoglobinometria/métodos , Hemoglobinas/análise , Sistemas Automatizados de Assistência Junto ao Leito , Adulto , Idoso , Idoso de 80 Anos ou mais , Transfusão de Sangue/estatística & dados numéricos , Procedimentos Cirúrgicos Cardíacos , Feminino , Hematócrito/instrumentação , Hemodiluição , Hemoglobinometria/instrumentação , Humanos , Masculino , Pessoa de Meia-Idade , Oximetria , Perfusão , Estudos Prospectivos , Garantia da Qualidade dos Cuidados de Saúde
17.
Analyst ; 140(19): 6619-24, 2015 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-26332369

RESUMO

Besides being a crucial parameter for surgery and clinical diagnosis, hematocrit tends to affect the analytical results of point-of-care analytical devices. Therefore, an accurate and quick method for measuring hematocrit was developed on the basis of screen-printed carbon electrodes (SPCE). An impulse DC voltage of 3.0 V was imposed on ferricyanide-coated SPCE to induce hemolysis, and the released hemoglobin reduced the ferricyanide, generating a higher oxidation current for estimating hematocrit. Hematocrit ranging from 10 to 70% can be determined in 5 s by linear sweep voltammetry (r(2) = 0.9907) or 0.8 s by 3 V of potential step voltammetry (r(2) = 0.9833).


Assuntos
Equipamentos Descartáveis , Eletroquímica/instrumentação , Hematócrito/instrumentação , Hemólise , Gasometria , Humanos
18.
Electrophoresis ; 36(7-8): 978-85, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25640582

RESUMO

Hematocrit (HCT) tests are widely performed to screen blood donors and to diagnose medical conditions. Current HCT test methods include conventional microhematocrit, Coulter counter, CuSO4 specific gravity, and conductivity-based point-of-care (POC) HCT devices, which can be either expensive, environmentally inadvisable, or complicated. In the present work, we introduce a new and simple microfluidic system for a POC HCT determination. HCT was determined by measuring current responses of blood under 100 V DC for 1 min in a microfluidic device containing a single microchannel with dimensions of 180 µm by 70 µm and 10 mm long. Current responses of red blood cell (RBC) suspensions in PBS or separately plasma at HCT concentrations of 10, 20, 25, 30, 35, 40, 45, 50, 55, 60, and 70 vol% were measured to show feasibility of the microfluidic system for HCT determination. Key parameters affecting current responses included electrolysis bubbles and irreversible RBC adsorption; parameters were optimized via addition of nonionic surfactant Triton X-100 into sample solution and carbonizing electrode surfaces. The linear trend line of current responses over a range of RBC concentrations were obtained in both PBS and plasma. This work suggested that a simple microfluidic device could be a promising platform for a new POC HCT device.


Assuntos
Hematócrito/instrumentação , Hematócrito/métodos , Eletrodos , Desenho de Equipamento , Contagem de Eritrócitos , Eritrócitos/efeitos dos fármacos , Humanos , Dispositivos Lab-On-A-Chip , Octoxinol/farmacologia
19.
IEEE Trans Biomed Eng ; 62(2): 708-16, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25347870

RESUMO

A first approach to a portable and compact device for point-of-care (PoC) early instantaneous detection of anemia is described. This device works directly with whole blood samples relying on hematocrit analysis by means of impedance analysis. This device consists of a custom electronic instrumentation, postprocessing software and plug-and-play disposable sensor. The designed electronics are connected to a remote computer, which allows control of the instrumentation and results displaying with a user friendly software panel. The disposable sensor is based on a low-cost label-free three gold electrode commercial sensor for 50-µL volume samples. Forty-eight whole blood samples, randomly collected from hospitalized patients in Hospital Clínic, were used to validate the device capability for anemia detection. Whole blood samples were distributed in two groups: 10 samples for system calibration, and 38 samples for system validation. To calibrate the device, a complete EIS experiment has been performed to get a full impedance spectrum analysis, defining an accurate frequency working range for hematocrit detection. Afterward, we developed a protocol for instant impedance detection to determine the system detection accuracy, sensitivity, and coefficient of variation. As a result, impedance variations between different samples have been detected with less than 2% accuracy error for both impedance magnitude and phase. A hematocrit detection algorithm, relying on impedance analysis, has been developed based on the previous studies. The response, effectiveness, and robustness of the portable PoC device to detect anemia have been proved with an accuracy error of 1.75% and a coefficient of variation of less than 5%.


Assuntos
Anemia/sangue , Anemia/diagnóstico , Coleta de Amostras Sanguíneas/instrumentação , Condutometria/instrumentação , Diagnóstico por Computador/métodos , Hematócrito/instrumentação , Algoritmos , Técnicas Biossensoriais/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
20.
Anat Histol Embryol ; 44(4): 317-20, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25181932

RESUMO

Plastic hematocrit tubes (PHTs) are convenient tools for electron microscopy (EM) of peripheral blood buffy coats, and the PHT-EM technique is expected to be a practical method for veterinary clinical medicine. In this study, fixatives composed of various concentrations of sucrose, glutaraldehyde, and phosphate buffer (PB) were tested for preparing canine and feline buffy coats. The highest quality images were obtained using a fixative consisting of 2.5% glutaraldehyde in 0.1 m PB, and it was concluded that this method allows clinicians who are inexperienced in histological techniques can conveniently transport buffy coat samples to diagnostic laboratories for analysis by EM.


Assuntos
Buffy Coat/ultraestrutura , Gatos/sangue , Cães/sangue , Microscopia Eletrônica/veterinária , Animais , Fixadores , Glutaral , Hematócrito/instrumentação , Hematócrito/veterinária , Microscopia Eletrônica/instrumentação , Microscopia Eletrônica/métodos
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