Laboratory Hematology Analyzer Research Articles

Hematocrit Self-Testing in Patients with Polycythemia Vera: A Proof-of-Concept Study Assessing the Accuracy of the Statstrip Xpress ® 2 Hb/Hct Device and Its Impact on Patients' Quality of Life in Clinical Practice

Hematocrit Self-Testing in Patients with Polycythemia Vera: A Proof-of-Concept Study Assessing the Accuracy of the Statstrip Xpress ® 2 Hb/Hct Device and Its Impact on Patients' Quality of Life in Clinical Practice

Neonatal hemoglobin affects the accuracy of whole blood bilirubin measurement on GEM Premier 4000 blood gas analyzers

ObjectivesWhole blood bilirubin measured on blood gas analyzers is accepted by physicians in neonatal hyperbilirubinemia management since it requires a small sample volume. The accuracy of bilirubin measurement on blood gas analyzers is instrument dependent and remains controversial. Design and MethodsBilirubin in adult and umbilical cord whole blood samples, spiked with an unconjugated bilirubin standard, and non-spiked adult plasma samples was measured on a blood gas analyzer (GEM 4000) and a Core Laboratory Chemistry analyzer (Architect c16000) respectively. We also investigated the linear regression for neonatal and adult hemoglobin measured on the blood gas analyzer and the Core Laboratory hematology analyzer (Alinity h-Series). ResultsPlasma bilirubin measured on the blood gas analyzer and the chemistry analyzer was statistically identical. Adult whole blood bilirubin showed slightly increased proportional bias. When umbilical cord whole blood samples were used, the Deming regression showed GEM bilirubin =1.233(Architect) (95% CI 1.199 ~ 1.266)-44.43 ​μmol/L (95% CI -53.6 ​~ ​−35.2). The regression was significantly different from that in plasma (p ​< ​0.001) or adult whole blood (p ​< ​0.001) samples. 36.1% neonatal samples with bilirubin levels >50 ​μmol/L showed that the bias% was above laboratory standards. In addition, the regression of neonatal hemoglobin measurement between the GEM and the Alinity was significantly different from adult hemoglobin (p ​< ​0.01). ConclusionsNeonatal whole blood bilirubin measurement on blood gas analyzers may be affected by neonatal hemoglobin. The method should be validated using neonatal whole blood samples or samples with a similar matrix before the analyzers are implemented into neonatal hyperbilirubinemia management.

Evaluation of automatic mixing versus manual mixing for point of care hemoglobin measurement

ObjectiveWe compared hemoglobin results from manually mixed blood gas (BG) Portex syringes (Smiths Medical) and automatically mixed safePICO BG syringes (Radiometer Medical) measured on the ABL90 FLEX blood gas analyzer at the Point of Care with a laboratory hematology analyzer (XN-series, Sysmex) to determine whether automatic mixing improved the accuracy and precision of hemoglobin measurement relative to the standardized method. MethodsNinety-nine lithium heparin tubes and EDTA tubes were collected simultaneously from selected patients at five participating institutions. The lithium heparin tubes were then split between the Portex ABG syringe and the safePICO aspirator. The Portex syringe was mixed manually according to routine procedures, while the safePICO syringe was mixed automatically on the ABL90 FLEX using the automatic mixing ball. The two syringes were mixed and run on the ABL90 FLEX analyzer by the same lab personnel. Total hemoglobin results obtained from the EDTA tubes on the Sysmex XN hematology analyzer were used as the reference values. ResultsManual mixing demonstrated a larger scatter of hemoglobin values (R2 ​= ​0.515 and Mean diff.: -0.9 ​g/dL) while automatic mixing at the point of care yielded a significantly better correlation (R2 ​= ​0.986 and Mean diff.: -0.2 ​g/dL) when compared to a reference hematology analyzer. ConclusionUsing the safePICO syringe with automatic mixing at the point of care results in a significantly better correlation of hemoglobin with the standardized method.

Improvement in Red Blood Cell Physiology in Children with Sickle Cell Anemia Receiving Voxelotor

Background: Sickle hemoglobin (HbS) under conditions of deoxygenation polymerizes to cause sickling of red blood cells (RBCs) and other rheological abnormalities. Voxelotor has been previously shown in a preclinical model of sickle cell disease (SCD) to increase HbS affinity to oxygen, thus reducing its polymerization and sickling with subsequent increase in the half-life of RBCs. We hypothesized that given this mechanism of action, we would observe improvements in RBC physiology in patients receiving voxelotor. In the Phase 3 GBT HOPE trial, the use of voxelotor in patients with SCD caused a significant reduction in markers of hemolysis and anemia. Ektacytometry is considered the gold standard to study deformability of RBCs with membrane protein disorders. The deformability of RBCs can be assessed using a defined value of shear stress with an increasing osmotic gradient (osmoscan) as well as with a newer technology to subject these cells to gradual deoxygenation (oxygenscan). Both assays can be measured using the Laser Optical Rotational Red Cell Analyzer (LORRCA, RR Mechatronics, NL). In this pilot study, we analyzed samples from patients with SCD receiving voxelotor, before and 12 weeks after starting therapy to assess the benefits of voxelotor on RBC physiology. Methods: Our pilot study obtained whole blood from children ages 4-11 years with SCD, who were enrolled in the IRB approved GBT 440-007 clinical trial (NCT02850406; a study evaluating multiple doses of voxelotor at 1500 mg/day equivalent exposure to adults based on body weight) at Emory University/Children's Healthcare of Atlanta. All participants in this cohort continued their stable, optimal hydroxyurea dose during treatment with voxelotor. The below measurements were performed on the pre-dose and Week 12 visit samples. Deformability of RBCs was performed at a shear stress of 30 Pa and varying osmolality gradients (0-600 mOsm/Kg) for Osmoscan. Omin corresponds to the value of the hypotonic osmolality, where 50% of the cells hemolyze in an osmotic fragility assay and provides information on the initial surface area:volume ratio. Maximal deformability or Elongation Index (EImax) near isotonic osmolality informs us of the RBC cytoskeleton mechanics and Ohyper, the osmolality corresponding to 50% of the Elmax, provides information regarding the cytoplasmic viscosity. Oxygenscan was performed but under controlled deoxygenation using nitrogen. Point of Sickling (POS) is a point on the curve during deoxygenation when sickling begins, and EImin corresponds when sickle RBCs can least elongate. Oxygen dissociation curves were obtained using a HemOx Analyzer (TCS Scientific). Complete blood count parameters were determined on a clinical laboratory hematology analyzer (ADVIA, Siemens). Data was analyzed with Prism using a paired T-test. Results: Both pre-dose and Week 12 visit samples were available for 10 participants. Mean hemoglobin at baseline was 9.0 g/dL (7.6-10.0) and at 12 weeks, 10.3 g/dL (8.2-12.3). Six out of 10 participants had a hemoglobin response at Week 12 (defined as an increase in Hb from baseline by &gt;1 g/dL), of which 5 had hemoglobin over 10 g/dL. Mean % change in percentage of reticulocytes was -17.0%. Significant improvement in EImax on osmoscan was noted at Week 12 (p=0.0147), suggesting RBCs were more deformable with improved cytoskeleton mechanics. In addition, oxygenscan curves shifted upwards towards normal with a significant increase in EImax (p=0.0347) and EImin (p=0.0079). These findings combined with a decrease in POS (p=0.0001) during deoxygenation suggests that at low oxygen tension, voxelotor treated RBCs were more deformable possibly from reduced HbS polymer inside these cells. Significant reductions in P50 (p=0.0011) and P20 (p=0.0001) with a left shift of the oxygen dissociation curve further demonstrates the effect of voxelotor on RBCs. Discussion: Voxelotor therapy in children with HbSS is associated with reductions in anemia and reticulocyte response, and recovery in RBC health as early as 12 weeks of treatment. Voxelotor's ability to inhibit HbS polymerization and RBC sickling is associated with specific modulation in red cell rheology at normoxic and deoxygenating conditions. Left shifted oxygen dissociation curves confirm voxelotor's ability to increase oxygen affinity. These findings suggest that voxelotor improves RBC deformability and anemia and delays the initiation of RBC sickling. Figure Disclosures Chonat: Alexion: Other: advisory board; Agios Pharmaceuticals, Inc.: Other: advisory board. Baratz:Prolong Pharmacuticals: Honoraria; Global Blood Therapeutics: Research Funding. Pochron:Global Blood Therapeutics: Employment, Equity Ownership. Dixon:Global Blood Therapeutics: Employment, Equity Ownership. Tonda:Global Blood Therapeutics: Employment, Equity Ownership. Lehrer-Graiwer:Global Blood Therapeutics: Employment, Equity Ownership. Brown:Pfizer: Research Funding; Novartis, Inc: Research Funding; Imara, Inc: Consultancy, Research Funding; Global Blood Therapeutics, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Archer:AstraZeneca: Research Funding; Prolong Pharmaceuticals: Consultancy; Global Blood Therapeutics: Consultancy, Research Funding.

Non-Invasive Method to Estimate Red Blood Cell in Blood.

This work proposes a non-invasive method to estimate the number of red blood cells in the blood. To achieve the development of this research, first, a photosensitive device was designed, which is formed by a phototransistor with a transparent casing allowing the red light coming from a red LED to penetrate the sensor. This means, that when the intensity of the light varies, the amount of current flowing through the sensor also changes. In consequence, this variation in electric current causes a variation on the voltage drop across the connections of a resistor, which is read by a microcontroller that calculates the number of red blood cells. Second, some formulas were established to represent the relationship between the extreme points of a data set obtained during a sampling process. Finally, to verify the device operation, a sampling process was performed in volunteer patients (range 18-84years) with venous blood samples run on a laboratory hematology analyzer, a total 68 measurements were made to people of different ages and genders, of which 34 are females and 34 are males.

USING SIX SIGMA TO EVALUATE ANALYTICAL PERFORMANCE OF HEMATOLOGY ANALYZER

Background: Many medical decisions in hospital are based on hematology examination results. We must be aware about their method performance. Sigma-metric is an excellent way to evaluate analytical performance quality. We will display the performance of our laboratory hematology analyzer, Cell Dyne Ruby, by sigma-metric analysis.Method: sigma analysis was calculated by a formula, sigma = (TEa – CV)/ Bias. Total Error Allowable (TEa) was specified by the CLIA proficiency testing criteria. The coefficien of variant (CV) and bias data were supplied from analyzer running three levels of control low (L), normal (N), and high (H) include following analytes: hemoglobin (Hb), Red Blood Cell count (RBC), Hematocrit (HCT), White Blood Cell count (WBC), and Platelet count (PLT).Results : Sigma value as follows Hb(L:4,33 N:6,68 H:2,62), RBC(L:3,43 N:3,84 H:3,46), HCT(L:2,52 N:1,73 H:2,27), WBC (L:7,14 N:8,44 H:6,38),and PLT (L:2,46 N:8,75 H:7,84). Average sigma value for all parameters were 4,75. Minimum sigma value for any business or manufacturing process was 3. More than 6 sigma value was world class performance.Conclusion: Hematology Analyzer Cell Dyne Ruby provides "Good” performance by sigma-metric.

Post marketing study of hemodynamic and hematological noninvasive readings in a blood bank.

Objectives:This validation test was conducted in the Fujisan Blood Bank, Fortaleza, Brazil and evaluated the noninvasive TensorTip MTX (MTX, Cnoga Medical Ltd.) readings of hemoglobin, hematocrit, red blood cells, blood pressure, and heart rate compared to reference lab device readings. Generally, these parameters are measured from venous or capillary blood samples run on a laboratory analyzer or handheld invasive testing devices. Needle sticks are inconvenient to blood donors with relatively high exposure risks. To our vision, noninvasive determination would be of benefit to blood contributors and medical professional teams; it would be fast and painless.Methods:A total of 334 subjects were included in the Fujisan blood bank validation (65% male, 35% female). Hemoglobin, hematocrit, and red blood cells, as well as blood pressure and heart rate, were measured noninvasively using the MTX device and were compared to venous blood samples run on two laboratory hematology analyzers (Horiba ABX Micros60 and Siemens blood count analyzer), to digital sphygmomanometer (OMRON BP786) and to manual auscultation. The noninvasive measurement with the appropriate virtual arm cuff setting was performed simultaneously with the blood sample extraction of the reference devices measurement.Results:There was no statistically significant difference (p > 0.05, paired, two-tailed t-test) between the average daily hemoglobin, hematocrit, and red blood cells measurements provided by the MTX device and the laboratory hematology analyzer. In addition, there was no significant difference between the daily blood pressure and heart rate results provided by the MTX device and the digital and manual sphygmomanometers. The error calculated between the MTX and the reference device was found to be sufficiently accurate according to the relevant standards.Conclusion:The MTX accuracy of noninvasive hemoglobin, hematocrit, red blood cells, blood pressure, and heart rate measurements satisfies the industrial standards; therefore, the device enables more accurate, efficient, and effective patient care.

The Efficacy of Noninvasive Hemoglobin Measurement by Pulse CO-Oximetry in Neonates

To evaluate clinical applicability of noninvasive hemoglobin (Hb) measurement with a pulse CO-oximeter in neonates. Prospective comparison study. Neonatal ICU. Fifty-six preterm and term infants with median age = 20 days (range = 1-98 days) and median weight = 1,440 g (range = 530-4,230 g). Hb measurements by Pulse CO-Oximetry (Masimo Radical-7) were recorded immediately prior to venous samplings. The collected data were compared with the corresponding venous Hb level obtained in laboratory testing, and a total of 137 data pairs were analyzed. Noninvasive Hb values measured with a pulse CO-oximeter were significantly correlated with the venous Hb levels (correlation coefficient, r = 0.758; p < 0.001). Hb values measured with a pulse CO-oximeter were higher than those measured with a laboratory hematology analyzer (13.3 ± 2.6g/dL vs. 12.5 ± 3.1g/dL). In terms of the agreement between the laboratory analyzer and the pulse CO-oximeter, 94.8% of the measurements fell within two standard deviations of the mean difference. Noninvasive Hb measurements with Pulse CO-Oximetry provide clinically acceptable accuracy, and they were significantly correlated with laboratory Hb measurement in neonates. In terms of the clinical applicability, noninvasive Hb monitoring with a pulse CO-oximeter could be useful in the early detection of Hb changes in neonates.

Considerations for Evaluating the Accuracy of Hemoglobin Monitoring

Considerations for Evaluating the Accuracy of Hemoglobin Monitoring

Accuracy of Noninvasive and Invasive Point-of-Care Total Blood Hemoglobin Measurement in an Outpatient Setting

Objective: The purpose of this study was to determine the accuracy of noninvasive hemoglobin measurement using pulse CO–oximetry (Pronto® SpHb®, Masimo Corp.) and a commonly used, invasive, point–of–care, automated spectrophotometer (HemoCue 201+®, HemoCue, Inc.), in comparison with hemoglobin measurements obtained from a laboratory hematology analyzer (measuring total blood hemoglobin) in the outpatient setting. Methods: Adult patients presenting to an outpatient research clinic were tested for total blood hemoglobin measurement by 3 methods: noninvasive pulse CO–oximetry (SpHb®), finger–stick blood sample on a point–of–care device, and venous sample on a laboratory hematology analyzer (reference device). Bias and standard deviation (SD) of SpHb® and HemoCue 201+® compared with the values obtained with the laboratory hematology analyzer were calculated and Bland–Altman graphs were generated. Results: Samples from 152 subjects were assessed (average age, 46 years; 69% female). The bias ± SD compared with the reference method was −0.5 ± 1.0 g/dL for SpHb® and 0.3 ± 1.0 g/dL for HemoCue 201+®. The Bland–Altman plots assessing agreement of the test methods to the reference method had limits of agreement of +2.5 to 1.5 g/dL for SpHb® and +1.7 to 2.3 g/dL for HemoCue 201+®. A noninvasive measurement could not be obtained in 4 subjects after 2 attempts (2.5% failure rate), whereas the HemoCue 201+® measurements were obtained for all subjects. Conclusion: Noninvasive SpHb® testing had bias and SD similar to those of HemoCue 201+®. Because SpHb® measurement is noninvasive, it may offer additional patient and provider benefits.

Accuracy and Precision of the Pronto-7 for Noninvasive Hemoglobin Testing in An Outpatient Setting

Abstract 3147 IntroductionInvasive blood draw and laboratory analysis for determination of total hemoglobin concentration (tHb) is routine in the outpatient setting. However, the method is time consuming, uncomfortable for the patient, and exposes caregivers to risks associated with needle sticks and blood exposure. In contrast, hemoglobin determination with Pulse CO-Oximetry (SpHb) allows for noninvasive and quick estimation of hemoglobin with a spectrophotometric finger sensor. Continuous SpHb has been validated in the ICU [1], surgery[2], and volunteers undergoing hemodilution, [3] but the accuracy of “spot check” SpHb devices has not been validated in the outpatient setting. Our objective was to compare spot-check SpHb and invasive point-of-care (POC) hemoglobin testing to tHb measurements from a laboratory hematology analyzer. MethodsStudy subjects were adult and pediatric subjects presenting to two outpatient clinics and one health screening event. A noninvasive hemoglobin test device (Pronto-7, software version 2.19, Masimo Corp. Irvine CA) and reusable finger clip sensor (rainbow 4D) was placed on the patient's non-dominant ring finger. The sensor was covered with an opaque shield to prevent optical interference. Two consecutive SpHb readings were obtained from each subject, detaching and reattaching the sensor between each measurement. Testing was conducted while patients were quiet and sitting upright. A venous blood sample was obtained by venipuncture of the median cubital vein of the non-dominant arm and a capillary sample was obtained by finger stick according to the manufacturer's directions for use. The venous sample was analyzed for reference tHb with a laboratory hematology analyzer (LH 780, Beckman Coulter, USA). The capillary sample was analyzed immediately following the finger stick with a POC device (HemoCue 201+, Hemocue, Cypress CA). The SpHb and POC tHb were compared to the laboratory tHb. Bias, standard deviation, and coefficient of variation (precision) were calculated. ResultsA total of 474 subjects (37% male, 39 +/− 17 years of age) were enrolled, 431 (91%) from outpatient clinics and 43 (9%) from a community screening event. Subjects consisted of 246 (52%) healthy volunteers and 228 (48%) with one or more of the following conditions: high blood pressure, diabetes, high cholesterol, chronic obstructive pulmonary disease, or pregnancy. A total of 399 (84%) had light pigmentation, 71 (15%) medium pigmentation, and 3 (1%) had dark pigmentation. Reference tHb ranged from 8.6 to 17.4 g/dL. There were 877 SpHb measurements, 443 POC tHb measurements, and 473 reference tHb measurements. The mean bias and standard deviation of SpHb was −0.1 +/− 1.1 g/dL and of POC tHb was -0.1 and 1.6 g/dL. Using the first and second SpHb measurements, the precision of SpHb was 4.1%. ConclusionNoninvasive hemoglobin testing with the Pronto-7 had acceptable accuracy with similar bias and lower standard deviation than a widely available, POC tHB test device. The Pronto-7 has the potential to enhance patient care and caregiver safety in the outpatient setting. Disclosures:Shah:Masimo Corp.: Consultancy, Honoraria, Speakers Bureau. Martinez:Masimo Corp.: Research Funding. Osea:Masimo Corp.: Research Funding.

Accuracy of a continuous noninvasive hemoglobin monitor in intensive care unit patients*

To determine whether noninvasive hemoglobin measurement by Pulse CO-Oximetry could provide clinically acceptable absolute and trend accuracy in critically ill patients, compared to other invasive methods of hemoglobin assessment available at bedside and the gold standard, the laboratory analyzer. Prospective study. Surgical intensive care unit of a university teaching hospital. Sixty-two patients continuously monitored with Pulse CO-Oximetry (Masimo Radical-7). None. Four hundred seventy-one blood samples were analyzed by a point-of-care device (HemoCue 301), a satellite lab CO-Oximeter (Siemens RapidPoint 405), and a laboratory hematology analyzer (Sysmex XT-2000i), which was considered the reference device. Hemoglobin values reported from the invasive methods were compared to the values reported by the Pulse CO-Oximeter at the time of blood draw. When the case-to-case variation was assessed, the bias and limits of agreement were 0.0±1.0 g/dL for the Pulse CO-Oximeter, 0.3±1.3g/dL for the point-of-care device, and 0.9±0.6 g/dL for the satellite lab CO-Oximeter compared to the reference method. Pulse CO-Oximetry showed similar trend accuracy as satellite lab CO-Oximetry, whereas the point-of-care device did not appear to follow the trend of the laboratory analyzer as well as the other test devices. When compared to laboratory reference values, hemoglobin measurement with Pulse CO-Oximetry has absolute accuracy and trending accuracy similar to widely used, invasive methods of hemoglobin measurement at bedside. Hemoglobin measurement with pulse CO-Oximetry has the additional advantages of providing continuous measurements, noninvasively, which may facilitate hemoglobin monitoring in the intensive care unit.

The Accuracy of Noninvasive Hemoglobin Measurement by Multiwavelength Pulse Oximetry After Cardiac Surgery

In March 2008, a new multiwavelength pulse oximeter, the Radical 7 (Rad7; Masimo Corp., Irvine, CA), was developed that offers noninvasive measurement of hemoglobin concentration. Accuracy has been established in healthy adults and some surgical patients, but not in cardiac surgery intensive care patients, a group at high risk of postoperative bleeding events and anemia in whom early diagnosis could improve management. In this prospective, observational study conducted in a cardiovascular intensive care unit, we compared hemoglobin concentrations shown by the Rad7 with arterial hemoglobin concentrations determined by an automated hematology analyzer, XE-2100 (Roche, Neuilly sur Seine, France). Two software versions of Rad7 (V 7.3.0.1 [42 points of comparison in 14 patients] and the updated V 7.3.1.1 [61 points of comparison in 27 patients]) were studied during two 1-week periods. Bias, defined as the difference between the 2 methods (Masimo SpHb-XE-2100 laboratory hemoglobin), was calculated. A negative bias indicated that the Masimo underestimated hemoglobin compared with the laboratory analyzer. Correlation between the perfusion index given by Rad7 and the hemoglobin bias was also studied. Correlations between Rad7 and XE-2100 were weak for both software versions (R2=0.11 for V 7.3.0.1 and R2=0.27 for V 7.3.1.1). Mean bias was -1.3 g/dL for V 7.3.0.1 and -1.7 g/dL for V 7.3.1.1, with wide 95% prediction intervals for the bias (respectively, -4.6 to 2.1 g/dL and -5.7 to 2.3 g/dL). The absolute hemoglobin bias tended to increase when the perfusion index decreased. For the V 7.3.0.1 software, the average absolute bias was 1.9 g/dL for perfusion index<2 and 0.8 g/dL for perfusion index>2 (P=0.03). For V 7.3.1.1, the mean absolute bias was 2.1 g/dL when the perfusion index was <2, and 1.6 g/dL when the perfusion index was >2 (P=0.26). Our study demonstrates poor correlation between hemoglobin measured noninvasively by multiwavelength pulse oximetry and a laboratory hematology analyzer. The difference was greater when the pulse oximetry perfusion index was low, as may occur in shock, hypothermia, or vasoconstriction patients. The multiwavelength pulse oximetry is not sufficiently accurate for clinical use in a cardiovascular intensive care unit.