Assessing Accuracy and Precision of Hemoglobin Determination in Venous, Capillary Pool, and Single-Drop Capillary Blood Specimens Using three Different HemoCue® Hb Models: The Multicountry Hemoglobin Measurement (HEME) Study.

BACKGROUND: Anemia prevalence estimates reported in population surveys can vary based on the blood specimen source (capillary or venous) and analytic device (hematology autoanalyzers or portable hemoglobinometers) used for hemoglobin (Hb) determination. OBJECTIVES: This study aimed to compare accuracy and precision of Hb measurement in three blood specimen types on three models of hemoglobinometers against the results from venous blood from the same individuals measured on automated analyzers (AAs). METHODS: This multisite (Cambodia, Ethiopia, Guatemala, Lebanon, Nigeria, and Tanzania) study assessed Hb measurements in paired venous and capillary blood specimens from apparently healthy women (aged 15-49 y) and children (aged 12-59 mo) using three HemoCue® Hb models (201+, 301, and 801). Measurements were compared against reference values: venous blood in hematology AA and adjusted via regression calibration or mean difference in HemoCue® Hb. Venous, capillary pool, and single-drop capillary blood specimens were assessed for accuracy and precision. RESULTS: Venous blood measured using HemoCue® Hb 301 exhibited a positive mean error, whereas responses in HemoCue® Hb 201+ and 801 were nondirectional compared with the reference. Adjustment with the reference harmonized mean errors for all devices across study sites to <1.0 g/L using venous blood. Precision was highest for venous blood (±5-16 g/L) in all sites, lowest for single-drop capillary (±9-37 g/L), and intermediate (±9-28 g/L) for capillary pool blood specimen. Imprecision differed across sites, especially with both capillary blood specimens, suggesting different levels of personnel skills. CONCLUSIONS: Findings suggest that venous blood is needed for accurate and precise Hb determination. Single-drop capillary blood use should be discouraged owing to high measurement variability. Further research should evaluate the viability and reliability of capillary pool blood for this purpose. Accuracy of HemoCue® Hb devices can be improved via standardization against results from venous blood assessed using AA.

Comparison of four methods to measure haemoglobin concentrations in whole blood donors (COMPARE): A diagnostic accuracy study.

OBJECTIVE: To compare four haemoglobin measurement methods in whole blood donors. BACKGROUND: To safeguard donors, blood services measure haemoglobin concentration in advance of each donation. NHS Blood and Transplant's (NHSBT) customary method have been capillary gravimetry (copper sulphate), followed by venous spectrophotometry (HemoCue) for donors failing gravimetry. However, NHSBT's customary method results in 10% of donors being inappropriately bled (ie, with haemoglobin values below the regulatory threshold). METHODS: We compared the following four methods in 21 840 blood donors (aged ≥18 years) recruited from 10 NHSBT centres in England, with the Sysmex XN-2000 haematology analyser, the reference standard: (1) NHSBT's customary method; (2) "post donation" approach, that is, estimating current haemoglobin concentration from that measured by a haematology analyser at a donor's most recent prior donation; (3) "portable haemoglobinometry" (using capillary HemoCue); (4) non-invasive spectrometry (using MBR Haemospect or Orsense NMB200). We assessed sensitivity; specificity; proportion who would have been inappropriately bled, or rejected from donation ("deferred") incorrectly; and test preference. RESULTS: Compared with the reference standard, the methods ranged in test sensitivity from 17.0% (MBR Haemospect) to 79.0% (portable haemoglobinometry) in men, and from 19.0% (MBR Haemospect) to 82.8% (portable haemoglobinometry) in women. For specificity, the methods ranged from 87.2% (MBR Haemospect) to 99.9% (NHSBT's customary method) in men, and from 74.1% (Orsense NMB200) to 99.8% (NHSBT's customary method) in women. The proportion of donors who would have been inappropriately bled ranged from 2.2% in men for portable haemoglobinometry to 18.9% in women for MBR Haemospect. The proportion of donors who would have been deferred incorrectly with haemoglobin concentration above the minimum threshold ranged from 0.1% in men for NHSBT's customary method to 20.3% in women for OrSense. Most donors preferred non-invasive spectrometry. CONCLUSION: In the largest study reporting head-to-head comparisons of four methods to measure haemoglobin prior to blood donation, our results support replacement of NHSBT's customary method with portable haemoglobinometry.

Comparison of Hemoglobin Measurements by 3 Point-of-Care Devices With Standard Laboratory Values and Reliability Regarding Decisions for Blood Transfusion.

BACKGROUND: We compared the accuracy of 3 point-of-care testing (POCT) devices with central laboratory measurements and the extent to which between-method disagreements could influence decisions to transfuse blood. METHODS: Hemoglobin concentrations [Hb] were measured in 58 adult patients undergoing cardiothoracic surgery using 2 Ilex GEM Premier 3500 blood gas analyzers (BG_A and BG_B) and a HemoCue Hb-201 device (HemoCue). Measurements were compared with our central laboratory's Siemens Advia 2120 flow cytometry system (laboratory [Hb] [Lab[Hb]]), regarded as the gold standard. We considered that between-method [Hb] differences exceeding 10% in the [Hb] range 6-10 g/dL would likely erroneously influence erythrocyte transfusion decisions. RESULTS: The 70 Lab[Hb] measurements ranged from 5.8 to 16.7 g/dL, of which 25 (36%) were <10.0 g/dL. Measurements by all 4 devices numbered 57. Mean POCT measurements did not differ significantly (P > .99). Results of the Bland-Altman analyses revealed statistically significant bias, with predominant underestimations by all 3 POCTs predominating. HemoCue upper and lower limits of agreement (LOA) were narrower, and the 95% confidence intervals (95% CIs) of the LOAs did not overlap with those of BG_A and BG_B. Similarly, a narrow mountain plot demonstrated greater precision for the HemoCue. Comparing BG_A with BG_B revealed no bias and narrow LOA. Error grid analysis within the [Hb] range 6-10 g/dL revealed that 5.3% of HemoCue measurements were beyond the permissible 10.0% error zone in contrast to 19.0% and 16.0% of the blood gas measurements. Possible inappropriate transfusion decisions based on POCT values generally erred toward unnecessary transfusions. Calculations of Cohen κ statistic indicated better chance-corrected agreement between HemoCue and Lab[Hb] regarding erythrocyte transfusions than the blood gas analyzers. CONCLUSIONS: All 3 POCT devices underestimated the Lab[Hb] and cannot be used interchangeably with standard laboratory measurements. BG_A and BG_B can be considered to be acceptably interchangeable with each other. Whereas the HemoCue had little bias and good precision, the blood gas analyzers revealed large bias and poor precision. We conclude that the tested HemoCue provides more reliable measurements, especially within the critical 6-10 g/dL range, with reduced potential for transfusion errors. Decisions regarding erythrocyte transfusions should also be considered in the light of clinical findings.

Assessing the Association Between Blood Loss and Postoperative Hemoglobin After Cesarean Delivery: A Prospective Study of 4 Blood Loss Measurement Modalities.

BACKGROUND: Visual estimation and gravimetric methods are commonly used to quantify the volume of blood loss during cesarean delivery (CD). However, the correlation between blood loss and post-CD hemoglobin (Hb) is poorly studied, and it is unclear whether the correlation varies according to how blood loss is measured. METHODS: After obtaining Institutional Review Board approval, we performed a prospective study of 61 women undergoing CD to assess the relations between post-CD Hb and blood loss measured using 4 modalities: gravimetric blood loss measurement (gBL), visual blood loss estimation by a blinded obstetrician (oBL) and anesthesiologist (aBL), and the Triton System (tBL). Hb was measured preoperatively and within 10 minutes after CD. gBL was quantified as blood volume in a suction canister in addition to the weight of blood-soaked sponges. tBL was measured with the Triton System by photographing blood-soaked sponges and suction canister contents. To assess the relation between blood loss and post-CD Hb, we performed correlation analyses and compared the magnitude of the correlations across the 4 measurement modalities using William t test. A Bonferroni correction was set to identify a statistically significant correlation (P < .0125) and statistically significant differences between correlation coefficients (P < .008). RESULTS: The mean (standard deviation) preoperative Hb was 12 (1.1) g/dL and post-CD Hb was 11.3 (1.0) g/dL. Median (interquartile range) values for gBL, oBL, aBL, and tBL were 672 mL (266-970), 700 mL (600-800), 750 mL (600-1000), and 496 mL (374-729), respectively. A statistically significant but weak correlation was observed between tBL and post-CD Hb (r = -0.33; P = .01). No statistically significant correlations were observed among aBL (r = -0.25; P = .06), oBL (r = -0.2; P = .13), and gBL (r = -0.3; P = .03) with post-CD Hb. We did not detect any significant differences between any 2 correlation coefficients across the 4 modalities. CONCLUSIONS: Given that we observed only weak correlations between each modality with post-CD Hb and no significant differences in the magnitude of the correlations across the 4 modalities, there may be limited clinical utility in estimating post-CD Hb from blood loss values measured with any of the 4 modalities.

The impact of analytical variation of hemoglobin measurement on blood donors' hemoglobin and deferral rates.

BACKGROUND: Donors' hemoglobin (Hb) level must be tested before blood donation. Low Hb is the leading reason for donor deferral. Many donor-related and external factors associated with low Hb are known, but no studies have been conducted concerning the effects of analytical variation on donor Hb measurements and deferrals. STUDY DESIGN AND METHODS: The effects of donors' age, the seasonal and daily distribution of donations, and batch-to-batch variation in HemoCue Hb 201+ cuvettes on donors' capillary Hb (cHb) measurements and deferrals were analyzed for more than 1.7 million donor visits in 2010 to 2016 at a national blood establishment. Furthermore, approximately 3.1 million cHb measurements from the years 2000 to 2009 were included in analyses to correlate measured cHb value and Hb deferral rate. RESULTS: A significant correlation between the mean annual cHb and Hb deferral rate was observed in both women and men. The season of the donation was the strongest explanatory factor for the monthly variation of predonation cHb (explaining 25 and 31% of the variation in women and men, respectively). Batch-to-batch variation in HemoCue cuvettes explained 6.8% of monthly variation in women and 7.4% in men. Monthly changes in donors' age distribution explained 2.5% of monthly variation in women and 2.4% in men. CONCLUSION: Small and, in most clinical settings, negligible analytical variation in Hb measurement methods can have significant consequences when used for Hb screening of blood donors. This should be minimized by using methods in which analytical variation is under control and kept as low as possible.

New approach to accurate interpretation of sickle cell disease newborn screening by applying multiple of median cutoffs and ratios.

BACKGROUND: The main goal of newborn screening (NBS) for sickle cell disease (SCD) is to detect affected neonates so that specific preventive care can be implemented. High-performance liquid chromatography (HPLC) used for NBS has high sensitivity and specificity, but we lack guidelines for quantitative hemoglobin (Hb) fraction interpretation. The purpose of this study was to determine cutoff values to standardize quantitative interpretation in SCD NBS for different clinical situation such as, red blood cell transfusion or beta-thalassemia, which can be real screening pitfalls. METHODS: Retrospective study of 75,026 samples from the neonatal screening program analyzed in our laboratory. Precise HbA and HbS percentages at birth were recorded and median values established for each gestational age, allowing percentage results to be expressed in normal gestation-specific multiples of the median (MoM). Three threshold values of clinical interest were determined. RESULTS: High levels of HbA (>2.5 MoM) allowed identification of newborns who received transfusions. Low levels of HbS (≤0.7 MoM) allowed detection of the association between HbS and other mutations of the beta-globin gene (i.e., HbHope, ß0-thalassemia, etc.). An HbA/HbS ratio <0.5 to distinguish healthy carriers from SCD with S/ß+-thalassemia. The screening accuracy for each threshold was established. The screening accuracy of low-level HbA, which is determinant in identifying the subgroup of patients at risk of ß-thalassemia, will be determined prospectively. CONCLUSIONS: This new approach introduces tools for a quantitative interpretation in SCD NBS by HPLC methods and could allow standardization of interpretation between centers.

Hemoglobin S monitoring on TOSOH G8 in hemoglobin A1c mode in case of urgent red blood cell exchange.

BACKGROUND: Pre- and post-transfusion hemoglobin S (HbS) levels are used to document the efficacy of red blood cell exchange (RCE) in patients with sickle cell disease (SCD). In case of urgent RCE a 24/7 short turn-around time (STAT) analysis, with the ability to identify and quantify HbS, is warranted. The use of TOSOH G8 (Tosoh Europe) is evaluated for this purpose, using the variant HbA1c mode. METHODS: Analytical performance of the HbS analysis on TOSOH G8 in variant HbA1c mode was evaluated, including assessment of imprecision and linearity for HbS. In addition, a comparison study between TOSOH G8 and Minicap Flex Piercing (FP) system CZE (Sebia) using 32 HbS samples (HbS range: 9%-93%) was carried out to evaluate analytical and clinical concordance. RESULTS: Total HbS imprecision was 1.77% and 0.31% for a sickle cell trait and a sickle cell anemia sample, respectively. An acceptable linearity (HbS range: 6%-88%) was observed (R2  > .99). Passing-Bablok regression analysis showed a significant proportional bias; however, a good analytical concordance (r > .95) was found. Our results suggested that TOSOH G8 underestimated HbS results compared with those of Minicap FP system (mean difference: -3.54%), especially in samples with a high HbS concentration. CONCLUSION: Hemoglobin S results obtained with TOSOH G8 in variant HbA1c mode are clinically acceptable to monitor urgent RCE. The observed underestimation will not alter clinical decision-making.

Analysis of HbA1c on an automated multicapillary zone electrophoresis system.

Hemoglobin A1c (HbA1c) is a frequently requested laboratory test and there is thus a need for high throughput instruments for this assay. We evaluated a new automated multicapillary zone electrophoresis instrument (Capillarys 3 Tera, Sebia, Lisses, France) for analysis of HbA1c in venous samples. Routine requested HbA1c samples were analyzed immunologically on a Roche c6000 instrument (n = 142) and then with the Capillarys 3 Tera instrument. The Capillarys 3 Tera instrument performed approximately 70 HbA1c tests/hour. There was a strong linear correlation between Capillarys 3 Tera and Roche Tina-Quant HbA1c Gen 3 assay (y = 1.003x - 0.3246 R2 = .996). The total CV for the 12 capillaries varied between 0.8 and 2.2% and there was a good agreement between duplicate samples (R2 = .997). In conclusion, the Capillarys 3 Tera instrument has a high assay capacity for HbA1c. It has a good precision and agreement with the Roche Tina-Quant HbA1c method and is well suited for high volume testing of HbA1c.

Can the Afinion HbA1c Point-of-Care instrument be an alternative method for the Tosoh G8 in the case of Hb-Tacoma?

BACKGROUND: Hb-variant interference when reporting HbA1c has been an ongoing challenge since HbA1c was introduced to monitor patients with diabetes mellitus. Most Hb-variants show an abnormal chromatogram when cation-exchange HPLC is used for the determination of HbA1c. Unfortunately, the Tosoh G8 generates what appears to be normal chromatogram in the presence of Hb-Tacoma, yielding a falsely high HbA1c value. The primary aim of the study was to investigate if the Afinion HbA1c point-of-care (POC) instrument could be used as an alternative method for the Tosoh G8 when testing for HbA1c in the presence of Hb-Tacoma. METHODS: Whole blood samples were collected in K2EDTA tubes from individuals homozygous for HbA (n = 40) and heterozygous for Hb-Tacoma (n = 20). Samples were then immediately analyzed with the Afinion POC instrument. After analysis, aliquots of each sample were frozen at -80 °C. The frozen samples were shipped on dry ice to the European Reference Laboratory for Glycohemoglobin (ERL) and analyzed with three International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and National Glycohemoglobin Standardization Program (NGSP) Secondary Reference Measurement Procedures (SRMPs). The Premier Hb9210 was used as the reference method. RESULTS: When compared to the reference method, samples with Hb-Tacoma yielded mean relative differences of 31.8% on the Tosoh G8, 21.5% on the Roche Tina-quant Gen. 2 and 16.8% on the Afinion. CONCLUSIONS: The Afinion cannot be used as an alternative method for the Tosoh G8 when testing for HbA1c in the presence of Hb-Tacoma.

Guidance for faecal occult blood testing: quantitative immunochemical method (FIT-HB) in colorectal cancer screening programmes. / Guida per la determinazione del sangue occulto fecale: metodo immunochimico quantitativo (FIT-HB) nei programmi di screening per il carcinoma colorettale

BACKGROUND: in Italy, colorectal cancer screening is included as part of the Italian National Health Service - SSN (Servizio Sanitario Nazionale) Essential Levels of Care - LEA (Livelli Essenziali Assistenziali) and the European Guidelines, which specify quantitative FIT-Hb testing as the best strategy for organised screening programmes. To ensure consistent operating standards in Member States, European regulations require the implementation of certification and accreditation requirements for diagnostic and care-related processes. The requirement, based on ISO 17021 accreditation standards, includes ISO 9001 certification for systems and ISO 15189:2012 accreditation for laboratories. METHODOLOGY: various phases of the analytical process (pre-test, test, post-test) were evaluated in detail and provided operational guidelines for adjusting analytical and managerial procedures using: (a) feedback from members of GISCoR screening labs; (b) performance data obtained via a systematic review of the literature and the Osservatorio Nazionale Screening (ONS) Survey; (c) recommendations for laboratory practice issued by the World Endoscopy Organization "FIT for Screening" Working Group; (d) selected guidelines from the National Guidelines Clearinghouse database; and (e) Canadian, Australian and European screening programme websites. With respect to ISO 15189:2012 standards for accreditation of medical laboratories, GISCoR's guidance has been re-evaluated and revised by auditors from the Italian certification body (ACCREDIA) to assess its compliance and completeness with the aim of finalising operating procedures. CONCLUSIONS: the implementation and maintenance of operational standards required by complex systems (e.g. screening programmes) involving constant interaction between facilities and the supporting organisational structure are not easy to achieve. The guide aims to provide laboratories with the necessary guidance for proper process management.

Complete blood count at the ED: preanalytic variables for hemoglobin and leukocytes.

OBJECTIVE: The objective of this study is to determine the ways in which preanalytic factors related to physiologic status can affect the complete blood cell count (CBC) in patients referring to an emergency department (ED). METHODS: Over a 1-year period, the results of hemoglobin (Hb) level and white blood cell (WBC) counts of the first CBC tests undertaken in consecutive patients (n = 11487) referring to the ED were compared with those obtained in the same patients at a second test undertaken within 24 hours of admission. A prospective evaluation of the same differences was made in another group (group 2) of 1025 consecutive ED patients, several clinical characteristics being taken into consideration. RESULTS: Mean Hb concentrations were higher in the first (range, 8.0-15.9 g/dL) than in the second test results (median overestimation, 0.4-0.8 g/dL; P < .0001). At multivariate analysis of results in group 2 patients, fluid administration (>0.5 L) and the presence of edema played a significant role in the initial overestimation of Hb level (P = .001 and P = .045, respectively). The comparison between leukocyte counts (WBC) showed that values from the first were higher than those in the second test (median overestimation ranging from 0.42 to 3.63 × 10(9)/L cells, in the range counts from 4.0 to 30.0 × 10(9)/L). None of the clinical factors studied appeared to have affected this overestimation. CONCLUSIONS: On interpreting CBC results in patients admitted to the ED, physicians must consider the effect of physiologic variables on Hb level (mainly hydration status) and WBC count (mental and physical stress).

Trending and accuracy of noninvasive hemoglobin monitoring in pediatric perioperative patients.

BACKGROUND: Rainbow Pulse CO-Oximetry technology (Masimo Corporation, Irvine, CA) provides continuous and noninvasive measurement of arterial hemoglobin concentration (SpHb). We assessed the trending and accuracy of SpHb by this innovative monitoring compared with Hb concentration obtained with conventional laboratory techniques (Hb) in children undergoing surgical procedures with potential for substantial blood loss. METHODS: Hb concentrations were recorded from Pulse CO-Oximetry and a conventional hematology analyzer. Regression analysis and 4-quadrant plot were used to evaluate the trending for changes in SpHb and Hb measurements (ΔSpHb and ΔHb). Bias, precision, and limits of agreement of SpHb and of in vivo adjusted SpHb (SpHb - first bias to HB) compared with Hb were calculated. RESULTS: One hundred fifty-eight SpHb-Hb data pairs and 105 delta pairs (ΔSpHb and ΔHb) from 46 patients aged 2 months to 17 years with Hb ranging from 16.7 to 7.9 g/dL were collected. To evaluate trending, the delta pairs (ΔSpHb and ΔHb) were plotted, which revealed a positive correlation (ΔSpHb = 0.022 + 0.76ΔHb) with correlation coefficient r = 0.76, 95% CI [confidence interval] = 0.57-0.86. The bias and precision of SpHb to Hb and in vivo adjusted SpHb were 0.4 ± 1.3 g/dL and 0.1 ± 1.2 g/dL, respectively; the limits of agreement were -2.0 to 3.2 g/dL before in vivo adjustment and -2.4 to 2.2 g/dL after in vivo adjustment (P value = 0.04). The mean percent bias (from the reference Hb concentration) decreased from 4.1% ± 11.9% to 0.7% ± 11.3% (P value = 0.01). No drift in bias over time was observed during the study procedure. Of patient demographic and physiological factors tested for correlation with the SpHb, only perfusion index at sensor site showed a weak correlation. CONCLUSIONS: The accuracy of SpHb in children with normal Hb and mild anemia is similar to that previously reported in adults and is independent of patient demographic and physiological states except for a weak correlation with perfusion index. The trending of SpHb and Hb in children with normal Hb and mild anemia showed a positive correlation. Further studies are necessary in children with moderate and severe anemia.

HemoCue Hb-801 Provides More Accurate Hemoglobin Assessment in Blood Donors Than OrSense NBM-200.

Hemoglobin levels are commonly assessed to prevent causing or worsening of anemia in prospective blood donors. We compared head-to-head the accuracy of different technologies for measuring hemoglobin suitable for use in mobile donation units. We included 144 persons donating platelets at the Central Institute for Blood Transfusion and Immunology in Innsbruck, Austria. Hemoglobin levels were measured in venous blood using the portable hemoglobinometer HemoCue Hb-801 and noninvasively using OrSense NBM-200, and compared to values obtained with the Sysmex XN-430, an automated hematology analyzer employing the sodium lauryl sulphate method, which is broadly used as reference method in everyday clinical practice. Mean age of participants was 34.2 years (SD 13.0); 34.0% were female. Hemoglobin values measured with HemoCue were more strongly correlated with the Sysmex XN-430 (r = 0.90 [95% CI: 0.87-0.93]) than measured with OrSense (r = 0.49 [0.35-0.60]). On average, HemoCue overestimated hemoglobin by 0.40 g/dL (0.31-0.48) and OrSense by 0.75 g/dL (95% CI: 0.54-0.96). When using OrSense, we found evidence for higher overestimation at higher hemoglobin levels (proportional bias) specifically in females but not in males (Pdifference = .003). Sensitivity and specificity for classifying donors according to the hemoglobin donation thresholds were 99.2% (95% CI: 95.3%-100.0%) and 43.8% (23.1%-66.8%) for HemoCue vs 95.3% (89.9%-98.0%) and 12.5% (2.2%-37.3%) for OrSense. Areas under the receiver operating characteristic curves were higher using HemoCue vs OrSense both in females (0.933 vs 0.547; P = .044) and males (0.948 vs 0.628; P < .001). HemoCue Hb-801 measures hemoglobin more accurately than OrSense NBM-200 in the setting of mobile blood donation units. Our findings are particularly relevant for females, having in mind that anemia is more prevalent in females than in males.

Accuracy of determining hemoglobin level using occlusion spectroscopy in patients with severe gastrointestinal bleeding.

BACKGROUND: In patients presenting with severe hemorrhage, the authors conducted an equivalence trial that compared noninvasive occlusion spectroscopy and the capillary blood method to determine hemoglobin level. METHODS: This prospective observational study included patients admitted to their intensive care unit for gastrointestinal bleeding. A ring-shaped sensor, connected to a NBM-200MP (OrSense, Nes Ziona, Israel), was fitted onto the patient's thumb to intermittently measure hemoglobin (SotHb). During the first 24 h after admission, venous hemoglobin level, considered as the reference method, was determined at the laboratory every 8 h and was compared to SotHb and the capillary blood method. The primary endpoint was the proportion of inaccurate measurements, defined as greater than 15% difference compared with reference values or their unavailability for any technical reason. RESULTS: The study was scheduled to include 68 patients but was stopped prematurely after an interim analysis of 34 patients. The proportion of inaccuracies revealed that SotHb could not be considered equivalent to the capillary blood method (47% [95% CI, 43-51] and 24% [95% CI, 20-28]). Considering venous hemoglobin level as a reference method, the mean biases for SotHb (n = 133) and the capillary blood method (n = 135) were, respectively, -0.4 ± 2.0 and 0.8 ± 1.2 g/dl (P < 0.05). SotHb was associated with an increased incidence of failed transfusion. The inaccuracy of SotHb tended to be increased in patients receiving vasopressor agents. CONCLUSIONS: Noninvasive determination of hemoglobin level based on occlusion spectroscopy lacks accuracy in patients presenting with severe gastrointestinal bleeding and cannot be considered equivalent to the capillary-based method. This inaccuracy seems to be moderately influenced by the infusion of vasopressor agents.

Noninvasive hemoglobin monitoring: how accurate is enough?

Evaluating the accuracy of medical devices has traditionally been a blend of statistical analyses, at times without contextualizing the clinical application. There have been a number of recent publications on the accuracy of a continuous noninvasive hemoglobin measurement device, the Masimo Radical-7 Pulse Co-oximeter, focusing on the traditional statistical metrics of bias and precision. In this review, which contains material presented at the Innovations and Applications of Monitoring Perfusion, Oxygenation, and Ventilation (IAMPOV) Symposium at Yale University in 2012, we critically investigated these metrics as applied to the new technology, exploring what is required of a noninvasive hemoglobin monitor and whether the conventional statistics adequately answer our questions about clinical accuracy. We discuss the glucose error grid, well known in the glucose monitoring literature, and describe an analogous version for hemoglobin monitoring. This hemoglobin error grid can be used to evaluate the required clinical accuracy (±g/dL) of a hemoglobin measurement device to provide more conclusive evidence on whether to transfuse an individual patient. The important decision to transfuse a patient usually requires both an accurate hemoglobin measurement and a physiologic reason to elect transfusion. It is our opinion that the published accuracy data of the Masimo Radical-7 is not good enough to make the transfusion decision.

Accuracy of noninvasive haemoglobin measurement by pulse oximetry depends on the type of infusion fluid.

CONTEXT: Measurement of blood haemoglobin concentration by pulse oximetry could be of value in determining when erythrocytes should be transfused during surgery, but the effect of infusion fluids on the results is unclear. OBJECTIVE: To study the effect of crystalloid and colloid fluid on the accuracy (bias) and precision of pulse oximetry haemoglobin estimation to indicate the venous haemoglobin concentration in volunteers. DESIGN: Open interventional crossover study. SETTING: Single university hospital. PARTICIPANTS: Ten male volunteers aged 18-28 (mean 22) years. INTERVENTIONS: Each volunteer underwent three infusion experiments on separate days and in random order. The infusions were Ringer's acetate (20 ml kg), hydroxyethyl starch 130/0.4 (10 ml kg) and a combination of both. RESULTS: At the end of the infusions of Ringer's acetate, pulse oximetry haemoglobin concentration had decreased more than the true haemoglobin concentration (15 vs. 8%; P < 0.005; n = 10) whereas starch solution decreased pulse oximetry haemoglobin concentration less than true haemoglobin concentration (7 vs. 11%; P < 0.02; n = 20). The same differences were seen when the fluids were infused separately and when they were combined. The overall difference between all 956 pairs of pulse oximetry haemoglobin concentration and true haemoglobin concentrations (the bias) averaged only -0.7 g l whereas the 95% prediction interval was wide, ranging from -24.9 to 23.7 g l. In addition to the choice of infusion fluid, the bias was strongly dependent on the volunteer (each factor, P < 0.001). CONCLUSION: The bias of measuring haemoglobin concentration by pulse oximetry is dependent on whether a crystalloid or a colloid fluid is infused. TRIAL REGISTRATION: ClinicalTrials identifier: NCT01195025.

Validation and implementation of a new hemoglobinometer for donor screening at Canadian Blood Services.

BACKGROUND: Hemoglobin (Hgb) determination is an essential part of donor qualification. We assessed and implemented a new spectrophotometer for donor Hgb determination. STUDY DESIGN AND METHODS: Precision, accuracy, and ease of use were assessed on a prototype DiaSpect analyzer (DiaSpect Medical, GmBH, Sailauf, Germany). A protocol to qualify the analyzer was developed and executed preimplementation. Samples were developed for periodic quality control (QC). Postimplementation performance was assessed based on QC results and trending of deferral rates. RESULTS: Precision was excellent, with a coefficient of variation of 0.53%-1.14% per sample. The correlation coefficient between capillary DiaSpect and venous laboratory autoanalyzer measurements was 0.736. After 169 out of 223 analyzers failed to qualify on our initial protocol, all were successfully qualified with the use of a modified protocol, adjusted to avoid sources of variability. Because commercial controls proved inadequate, in-house samples were developed for periodic QC. Postimplementation, all analyzers had adequate QC results. Deferral rates decreased from 10.1 to 8.1% (p < 0.0001) for female donors and from 0.8 to 0.6% for male donors (p < 0.0001). The system was faster and easier to use compared with our previous two-step process. CONCLUSION: We successfully implemented a new spectrophotometer, which resulted in greater efficiency, improved ease of use, and decreased deferrals.

Validity and reliability of haemoglobin colour scale and its comparison with clinical signs in diagnosing anaemia in pregnancy in Ahmedabad, India.

This study compared the validity of the haemoglobin colour scale (HCS) and clinical signs in diagnosing anaemia against Sahli's haemoglobinometer method as the gold standard, and assessed the reliability of HCS. The sample comprised 129 pregnant women recruited from 6 urban health centres in Ahmedabad. The prevalence of anaemia was 69.8% by Sahli's method, 78.3% by HCS and 89.9% by clinical signs; there was no statistically significant difference between Sahli's method and HCS whereas there was between Sahlis method and clinical signs. The mean haemoglobin level by Sahli's method and HCS differed significantly. The sensitivity, specificity, positive predictive value and negative predictive value of HCS was 83.3%, 33.3%, 74.3% and 46.4% respectively and that of clinical signs was 91.1%, 12.8%, 70.7% and 38.5% respectively. Interobserver agreement for HCS was moderate (K = 0.43). Clinical signs are better than HCS for diagnosing anaemia. HCS can be used in the field provided assessors are adequately trained.

Status of hemoglobin A1c measurement and goals for improvement: from chaos to order for improving diabetes care.

BACKGROUND: The Diabetes Control and Complications Trial (DCCT) and United Kingdom Prospective Diabetes Study (UKPDS) established the importance of hemoglobin A(1c) (Hb A(1c)) as a predictor of outcome in patients with diabetes mellitus. In 1994, the American Diabetes Association began recommending specific Hb A(1c) targets, but lack of comparability among assays limited the ability of clinicians to use these targets. The National Glycohemoglobin Standardization Program (NGSP) was implemented in 1996 to standardize Hb A(1c) results to those of the DCCT/UKPDS. CONTENT: The NGSP certifies manufacturers of Hb A(1c) methods as traceable to the DCCT. The certification criteria have been tightened over time and the NGSP has worked with the College of American Pathologists in tightening proficiency-testing requirements. As a result, variability of Hb A(1c) results among clinical laboratories has been considerably reduced. The IFCC has developed a reference system for Hb A(1c) that facilitates metrological traceability to a higher order. The NGSP maintains traceability to the IFCC network via ongoing sample comparisons. There has been controversy over whether to report Hb A(1c) results in IFCC or NGSP units, or as estimated average glucose. Individual countries are making this decision. SUMMARY: Variability among Hb A(1c) results has been greatly reduced. Not all countries will report Hb A(1c) in the same units, but there are established equations that enable conversion between different units. Hb A(1c) is now recommended for diagnosing diabetes, further accentuating the need for optimal assay performance. The NGSP will continue efforts to improve Hb A(1c) testing to ensure that clinical needs are met.

Performance evaluation of a noninvasive hemoglobin monitoring device.

STUDY OBJECTIVE: Hemoglobin measurement is a routine procedure, and a noninvasive point-of-care device may increase the quality of care. The aim of the present study is to compare hemoglobin concentration values obtained with a portable totally noninvasive device, the Masimo Labs Radical-7 Pulse CO-Oximeter, with the results obtained by the ADVIA 2120 in the laboratory. METHODS: This was a prospective monocentric open trial enrolling patients consulting in the emergency department of a university hospital from June 16 to December 17, 2009. The main outcome measure was the agreement between both methods and evaluation of the percentage of potential decision error for transfusion. RESULTS: Samples from 300 consecutive patients were assessed. Hemoglobin concentration could not be obtained with the new device for 24 patients. In others, the mean bias, the lower and the upper limits of agreement between the 2 methods, was 1.8 g/dL (95% estimated confidence interval [CI] 1.5 to 2.1 g/dL), -3.3 g/dL (95% CI -3.8 to -2.8 g/dL), and 6.9 g/dL (95% CI 6.4 to 7.4 g/dL), respectively. The intraclass correlation coefficient was 0.53 (estimated 95% CI 0.10 to 0.74). The number of potential errors about transfusion decision was 38 (13% of patients). The peripheral oxygen saturation and the true value of hemoglobin concentration were independently associated with the bias. CONCLUSION: Results from this widely available noninvasive point-of-care hemoglobin monitoring device were systematically biased and too unreliable to guide transfusion decisions.