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 between a laser lancing device and lancet for capillary blood sampling, capillary blood hemoglobin measurement, and blood typing.

BACKGROUND: Blood donor screening includes tests using capillary blood, which is usually obtained by finger pricking using a lancet; however, the lancet has some shortcomings, such as skin puncture pain and needle stick injury. Recently, laser lancing devices for finger-prick sampling have been developed. We compared capillary blood Hb (cHb) levels and blood typing results obtained using a laser lancing device with those obtained using a lancet. STUDY DESIGN AND METHODS: cHb levels, blood typing results, and skin puncture pain scores were assessed in 191 participants. Finger-prick sampling was performed using LMT-1000 (LaMeditech, Seoul, Korea) and a lancet on the same finger on different hands. Paired venous Hb (vHb) levels were assessed in 103 participants using an automated hematology analyzer and compared with the cHb levels obtained using both lancing devices. RESULTS: The paired cHb results obtained with the laser lancing device and lancet showed a strong correlation (r = 0.927, p < .001) without any significant difference (p = .113) and a substantial agreement (κ = 0.654) for the identification of participants with a low Hb level (<12.5 g/dl). cHb levels were significantly higher than vHb levels with both lancing devices (mean differences: 0.27-0.43 g/dl). The results of blood typing using the laser lancing device showed 100% accuracy. Use of the laser lancing device showed significantly lower skin puncture pain scores (p < .001). CONCLUSION: Use of a laser lancing device for capillary Hb measurement and blood typing showed accurate results, with significantly reduced skin puncture pain. Laser lancing devices could be feasible for donor screening tests.

Validation of Two Point of Care Devices for Hemoglobin Estimation in Blood Donors.

Hemoglobin (Hb) estimation is a critical investigation in prospective blood donors. There are numerous techniques for Hb estimation, choosing an appropriate method is essential. Point of care devices (POC) have made quantification of Hb possible even in the field or community settings. Validation against a standard measure is necessary before implementing it for routine practice. With this background, we aimed to validate two new POC devices against a standard hematology analyzer for Hb estimation. An observational study on 100 donor venous blood samples was conducted. Hemoglobin was estimated using a Sysmex Hematology Analyzer (reference method) along with POC devices (CompoLab TM and True Hb Hemometer). Three statistical techniques were applied to validate Hb by the two POC devices. CompoLab TM measures 0.4 units more than the reference method and True Hb measures 0.4 units less than the reference method. Measures of Hb obtained from both the equipment showed moderate agreement with that of reference method (CompoLab TM ICC-0.74 and True Hb ICC-0.72). There were no systematic or proportional differences in the comparison of the two POC devices with the reference method. Within the limitations of this study, both the devices can be used for Hb estimation, as there was a substantial agreement of the measurements with the reference method. Other factors such as cost, turnaround time (TAT), ease of utilization should be considered to decide on the choice of equipment to be used.

Comparison of visual estimation of intra-operative blood loss with haemoglobin estimation in patients undergoing caesarean section.

BACKGROUND: Obstetrical haemorrhage is a potentially preventable cause of maternal morbidity and mortality; and measurements of surgical blood loss (BL) are often inaccurate. Accurate BL estimation is paramount as it may substantially alter the timing of interventions to control haemorrhage. The study compares the assessment of intra-operative BL by visual estimation with BL calculated from haemoglobin estimation using the HemoCue®201+. MATERIALS AND METHODS: A total of 60 pregnant patients at term undergoing elective caesarean section under spinal anaesthesia were enrolled into the study. In the theatre, the patients' haemoglobin level was determined before and after the surgery using the HemoCue®201+; and a modified Gross formula was used to calculate the BL. BL was also visually estimated and documented by counting the blood-soaked abdominal mops and gauze pieces and multiplying them by the estimated volume of blood each would hold; fixed size mops and gauzes were used. Statistical analysis was performed to compare both methods using SPSS Version 17. To compare BL assessment, Pearson's correlation and the Bland and Altman's method of assessing agreement between two methods of clinical measurement were used. RESULTS: The mean visually estimated BL (EBL) and HemoCue calculated BL (CBL) were 470 ± 221 ml and 563 ± 204 ml, respectively (P = 0.125). The bias (mean difference between both methods) was negligible (45.25 ml), and the limit of agreement between both methods was -222.20-275.43 ml. The discrepancy between the two methods increased when BL was ≥500 ml. CONCLUSION: This study showed that visually EBL was closely related to HemoCue CBL when the quantity of BL was <500 ml.

Detailed view on slow sinusoidal, hemodynamic oscillations on the human brain cortex by Fourier transforming oxy/deoxy hyperspectral images.

Slow sinusoidal, hemodynamic oscillations (SSHOs) around 0.1 Hz are frequently seen in mammalian and human brains. In four patients undergoing epilepsy surgery, subtle but robust fluctuations in oxy- and deoxyhemoglobin were detected using hyperspectral imaging of the cortex. These SSHOs were stationary during the entire 4 to 10 min acquisition time. By Fourier filtering the oxy- and deoxyhemoglobin time signals with a small bandwidth, SSHOs became visible within localized regions of the brain, with distinctive frequencies and a continuous phase variation within that region. SSHOs of deoxyhemoglobin appeared to have an opposite phase and 11% smaller amplitude with respect to the oxyhemoglobin SSHOs. Although the origin of SSHOs remains unclear, we find indications that the observed SSHOs may embody a local propagating hemodynamic wave with velocities in line with capillary blood velocities, and conceivably related to vasomotion and maintenance of adequate tissue perfusion. Hyperspectral imaging of the human cortex during surgery allow in-depth characterization of SSHOs, and may give further insight in the nature and potential (clinical) use of SSHOs.

Predicting changes in hemoglobin S after simple transfusion using complete blood counts.

BACKGROUND: Hemoglobin S percentages are used in the management of patients who have sickle cell disease. However, hemoglobin S measurements often are not routinely or rapidly performed. Rapid and accurate methods to estimate hemoglobin S levels after simple transfusion may improve the care of patients with sickle cell disease. STUDY DESIGN AND METHODS: A comprehensive review of the electronic medical record identified 24 stable patients with sickle cell disease who received simple red blood cell transfusions and had hemoglobin S measurements before and after the transfusion that were less than 72 hours apart. Examination of these patients identified 62 separate transfusions that met our criteria. Three simple equations that utilized complete blood count values and readily available information from the medical record were used to predict the post-transfusion hemoglobin S level after transfusion (Equation 1: predicted post-transfusion hemoglobin = pre-transfusion hemoglobin S × [pre-transfusion hemoglobin/post-transfusion hemoglobin]; Equation 2: predicted post-transfusion hemoglobin S = pre-transfusion hemoglobin S × [pre-transfusion hematocrit/post-transfusion hematocrit]; and Equation 3: predicted post-transfusion hemoglobin S = pre-transfusion hemoglobin S × total pre-transfusion hemoglobin/[total pre-transfusion hemoglobin + (red blood cell volume × 20)]). RESULTS: The predicted hemoglobin S values for all three equations showed a highly significant correlation with the measured post-hemoglobin S value. The coefficient of determination (R2 ) for Equations 1, 2, and 3 was 0.95, 0.92, and 0.97, respectively. Predicting the post-transfusion hemoglobin S value using estimates of the patient's total hemoglobin and the transfused hemoglobin (Equation 3) was the most precise. CONCLUSION: Reductions in hemoglobin S values in patients with sickle cell disease who receive simple red blood cell transfusions can be reliably predicted using complete blood cell measurements and simple arithmetic equations.

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.

In Vitro Evaluation of a Novel Image Processing Device to Estimate Surgical Blood Loss in Suction Canisters.

BACKGROUND: Clinicians are tasked with monitoring surgical blood loss. Unfortunately, there is no reliable method available to assure an accurate result. Most blood lost during surgery ends up on surgical sponges and within suction canisters. A novel Food and Drug Administration-cleared device (Triton system; Gauss Surgical, Inc, Los Altos, CA) to measure the amount of blood present on sponges using computer image analysis has been previously described. This study reports on performance of a complementary Food and Drug Administration-cleared device (Triton Canister System; Gauss Surgical, Inc, Los Altos, CA) that uses similar image analysis to measure the amount of blood in suction canisters. METHODS: Known quantities of expired donated whole blood, packed red blood cells, and plasma, in conjunction with various amounts of normal saline, were used to create 207 samples representing a wide range of blood dilutions commonly seen in suction canisters. Each sample was measured by the Triton device under 3 operating room lighting conditions (bright, medium, and dark) meant to represent a reasonable range, resulting in a total of 621 measurements. Using the Bland-Altman method, the measured hemoglobin (Hb) mass in each sample was compared to the results obtained using a standard laboratory assay as a reference value. The analysis was performed separately for samples measured under each lighting condition. It was expected that under each separate lighting condition, the device would measure the various samples within a prespecified clinically significant Hb mass range (±30 g per canister). RESULTS: The limits of agreement (LOA) between the device and the reference method for dark (bias: 4.7 g [95% confidence interval {CI}, 3.8-5.6 g]; LOA: -8.1 g [95% CI, -9.7 to -6.6 g] to 17.6 g [95% CI, 16.0-19.1 g]), medium (bias: 3.4 g [95% CI, 2.6-4.1 g]; LOA: -7.4 g [95% CI, -8.7 to -6.1 g] to 14.2 g [95% CI, 12.9-15.5 g]), and bright lighting conditions (bias: 4.1 g [95% CI, 3.2-4.9 g]; LOA: -7.6 g [95% CI, -9.0 to -6.2 g] to 15.7 g [95% CI, 14.3-17.1 g]) fell well within the predetermined clinically significant limits of ±30 g. Repeated measurements of the samples under the various lighting conditions were highly correlated with intraclass correlation coefficient of 0.995 (95% CI, 0.993-0.996; P < .001), showing that lighting conditions did not have a significant impact on measurements. Hb mass bias was significantly associated with hemolysis level (Spearman ρ correlation coefficient, -0.137; P = .001) and total canister volume (Spearman ρ correlation coefficient, 0.135; P = .001), but not ambient illuminance. CONCLUSIONS: The Triton Canister System was able to measure the Hb mass reliably with clinically acceptable accuracy in reconstituted blood samples representing a wide range of Hb concentrations, dilutions, hemolysis, and ambient lighting settings.

Clinical Experience with the Implementation of Accurate Measurement of Blood Loss during Cesarean Delivery: Influences on Hemorrhage Recognition and Allogeneic Transfusion.

OBJECTIVE: This article compares hemorrhage recognition and transfusion using accurate, contemporaneous blood loss measurement versus visual estimation during cesarean deliveries. STUDY DESIGN: A retrospective cohort study using visually estimated blood loss (traditional, n = 2,025) versus estimates using a mobile application that photographs sponges and canisters and calculates their hemoglobin content (device, n = 756). RESULTS: Blood loss > 1,000 mL was recognized in 1.9% of traditional visual estimation patients, while measured blood loss of > 1,000 mL occurred in 8.2% of device patients (p < 0.0001). In both groups, this was accompanied by a greater decrease in transfusion-adjusted hemoglobin levels than occurred in patients without hemorrhage (p < 0.0001). Despite similar transfusion rates (1.6% in both groups), fewer red cell units were given to transfused patients in the device group (1.83 ± 0.58 versus 2.56 ± 1.68 units; p = 0.038). None of the patients in the device group received plasma or cryoprecipitate. Seven patients in the traditional group received these products (p = 0.088). Device use was associated with shorter hospital stays (4.0 ± 2.3 versus 4.4 ± 2.9 days; p = 0.0006). CONCLUSION: The device identified hemorrhages more frequently than visual estimation. Device-detected hemorrhages appeared clinically relevant. Blood product transfusion was reduced possibly due to earlier recognition and treatment, although further studies are needed to verify the conclusion.

Real-time evaluation of an image analysis system for monitoring surgical hemoglobin loss.

Monitoring blood loss is important for management of surgical patients. This study reviews a device (Triton) that uses computer analysis of a photograph to estimate hemoglobin (Hb) mass present on surgical sponges. The device essentially does what a clinician does when trying to make a visual estimation of blood loss by looking at a sponge, albeit with less subjective variation. The performance of the Triton system is reported upon in during real-time use in surgical procedures. The cumulative Hb losses estimated using the Triton system for 50 enrolled patients were compared with reference Hb measurements during the first quarter, half, three-quarters and full duration of the surgery. Additionally, the estimated blood loss (EBL) was calculated using the Triton measured Hb loss and compared with values obtained from both visual estimation and gravimetric measurements. Hb loss measured by Triton correlated with the reference method across the four measurement intervals. Bias remained low and increased from 0.1 g in the first quarter to 3.7 g at case completion. The limits of agreement remained narrow and increased proportionally from the beginning to the end of the cases, reaching a maximum range of -15.3 to 22.7 g. The median (IQR) difference of EBL derived from the Triton system, gravimetric method and visual estimation versus the reference value were 13 (74), 389 (287), and 4 (230) mL, respectively. Use of the Triton system to measure Hb loss in real-time during surgery is feasible and accurate.

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.

Effects of indigo carmine intravenous injection on noninvasive and continuous total hemoglobin measurement with using the Revision L sensor.

The effects of intravenous injection of indigo carmine on noninvasive and continuous total hemoglobin (SpHb) measurement were retrospectively evaluated with the Revision L sensor. The subjects were 18 patients who underwent elective gynecologic surgery under general anesthesia. During surgery, 5 mL of 0.4 % indigo carmine was injected intravenously, and changes in SpHb concentrations between before and after the injection were evaluated. The mean age was 52.4 ± 12.8 years. Before injection, the median SpHb level was 10.1 (range, 6.8-13.4) g/dL. The results demonstrated no change in SpHb concentration between before and after indigo carmine injection as detected by the Revision L sensor. SpHb measurements as determined with the Revision L sensor were not affected, even after the intravenous injection of indigo carmine.

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.

Point-of-Care Hemoglobin/Hematocrit Testing: Comparison of Methodology and Technology.

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.

Comparison of the accuracy of hemoglobin point of care testing using HemoCue and GEM Premier 3000 with automated hematology analyzer in emergency room.

The laboratory analysis provides accurate, but time consuming hemoglobin level estimation especially in the emergency setting. The reliability of time-sparing point of care devices (POCT) remains uncertain. We tested two POCT devices accuracy (HemoCue®201+ and Gem®Premier™3000) in routine emergency department workflow. Blood samples taken from patients admitted to the emergency department were analyzed for hemoglobin concentration using a laboratory reference Beckman Coulter LH 750 (HBLAB), the HemoCue (HBHC) and the Gem Premier 3000 (HBGEM). Pairwise comparison for each device and HbLAB was performed using correlation and the Bland-Altman methods. The reliability of transfusion decision was assessed using three-zone error grid. A total of 292 measurements were performed in 99 patients. Mean hemoglobin level were 115 ± 33, 110 ± 28 and 111 ± 30 g/l for HbHC, HbGEM and HbLAB respectively. A significant correlation was observed for both devices: HbHC versus HbLAB (r2 = 0.93, p < 0.001) and HBGEM versus HBLAB (r2 = 0.86, p < 0.001). The Bland-Altman method revealed bias of -3.7 g/l (limits of agreement -20.9 to 13.5) for HBHC and HBLAB and 2.5 g/l (-18.6 to 23.5) for HBGEM and HBLAB, which significantly differed between POCT devices (p < 0.001). Using the error grid methodology: 94 or 91 % of values (HbHC and HbGEM) fell in the zone of acceptable difference (A), whereas 0 and 1 % (HbHC and HbGEM) were unacceptable (zone C). The absolute accuracy of tested POCT devices was low though reaching a high level of correlation with laboratory measurement. The results of the Morey´s error grid were unfavorable for both POCT devices.

Sildenafil Increases the p50 and Shifts the Oxygen-Hemoglobin Dissociation Curve to the Right.

INTRODUCTION: Sildenafil (Viagra®) is a selective phosphodiesterase type 5 (PDE5) inhibitor that block the breakdown of cyclic guanyl monophosphate (cGMP) leading to relaxation of the smooth muscles of the corpus cavernous and an increase in blood flow resulting in penile erection. It is hypothesized that sildenafil will increase the release of oxygen from erythrocytes and shift the oxygen-hemoglobin curve to the right. AIM: The aim of this study was to investigate the effect of varying doses of sildenafil on the p50 of the oxygen-hemoglobin dissociation curve in blood samples from eight (8) healthy adult male volunteers with normal hemoglobin HbAA. METHOD: The hemox-analyzer was used to generate the p50 and the oxygen-hemoglobin dissociation curves. MAIN OUTCOME MEASURES: The effect of different doses of sildenafil on the p50 values and shift of the oxygen-hemoglobin curve were the main outcome measures. RESULT: Sildenafil caused a statistically significant increase in the p50 values and rightward shift of the oxygen-hemoglobin dissociation curve. CONCLUSION: Sildenafil caused a dose-dependent increase in the release of oxygen from the erythrocytes as shown by the increased p50 values and rightward shift of the oxygen-hemoglobin dissociation curve. Ellis SS and Pepple DJ. Sildenafil increases the p50 and shifts the oxygen-hemoglobin dissociation curve to the right.

A novel method based on two cameras for accurate estimation of arterial oxygen saturation.

BACKGROUND: Photoplethysmographic imaging (PPGi) that is based on camera allows acquiring photoplethysmogram and measuring physiological parameters such as pulse rate, respiration rate and perfusion level. It has also shown potential for estimation of arterial oxygen saturation (SaO2). However, there are some technical limitations such as optical shunting, different camera sensitivity to different light spectra, different AC-to-DC ratios (the peak-to-peak amplitude to baseline ratio) of the PPGi signal for different portions of the sensor surface area, the low sampling rate and the inconsistency of contact force between the fingertip and camera lens. METHODS: In this paper, we take full account of the above-mentioned design challenges and present an accurate SaO2 estimation method based on two cameras. The hardware system we used consisted of an FPGA development board (XC6SLX150T-3FGG676 from Xilinx), with connected to it two commercial cameras and an SD card. The two cameras were placed back to back, one camera acquired PPGi signal from the right index fingertip under 660 nm light illumination while the other camera acquired PPGi signal from the thumb fingertip using an 800 nm light illumination. The both PPGi signals were captured simultaneously, recorded in a text file on the SD card and processed offline using MATLAB®. The calculation of SaO2 was based on the principle of pulse oximetry. The AC-to-DC ratio was acquired by the ratio of powers of AC and DC components of the PPGi signal in the time-frequency domain using the smoothed pseudo Wigner-Ville distribution. The calibration curve required for SaO2 measurement was obtained by linear regression analysis. RESULTS: The results of our estimation method from 12 subjects showed a high correlation and accuracy with those of conventional pulse oximetry for the range from 90 to 100%. CONCLUSIONS: Our method is suitable for mobile applications implemented in smartphones, which could allow SaO2 measurement in a pervasive environment.

Clinical evaluation of a novel technology for non-invasive and continuous measurement of plasma haemoglobin concentration.

We undertook the first clinical evaluation of a novel, non-invasive device for the continuous measurement of plasma haemoglobin concentration in 25 patients undergoing elective cardiac surgery. At four pre-determined intervals, samples of blood were taken for plasma haemoglobin estimation on a blood gas analyser and a laboratory device and were compared with the plasma haemoglobin estimation on the novel device using the Bland-Altman method. The 95% limits of agreement for estimation of plasma haemoglobin concentration for the device vs. laboratory, the device vs. the blood gas analyser and the blood gas analyser vs. the laboratory were 101.3 g.l(-1) , 103.1 g.l(-1) and 14.5 g.l(-1) , respectively. The bias (mean difference) in each case was 27.4 g.l(-1) , 25.1 g.l(-1) and 2.4 g.l(-1) , respectively. We conclude that the novel device in its current form is not a suitable replacement for more invasive methods of determining plasma haemoglobin concentration in patients in the setting of cardiac surgery; however, lessons learnt from the study will help to improve the device's future performance.

Evaluation of two-step haemoglobin screening with HemoCue for blood donor qualification in mobile collection sites.

BACKGROUND AND OBJECTIVES: Inaccuracy of fingerstick haemoglobin compromises donor's health and losses blood donations. We evaluated the benefit of double haemoglobin screening with HemoCue. STUDY DESIGN AND METHODS: Blood donors underwent fingerstick screening by HemoCue and were driven for donation if capillary haemoglobin was within the regulatory range. Those failing were drawn venous blood and donated if their venous haemoglobin determined with HemoCue was acceptable. RESULTS: Of 276 605 donor clinic visits, 10 011 (3·6%) were assessed by two-step haemoglobin screening using HemoCue, because of low (n = 9444) or high (n = 567) capillary haemoglobin. Among these, 2561 (25·6%) were deemed eligible [recovered donations]. The recovery rate was 23·8% and 55·0% among donors presenting with low and high capillary haemoglobin, respectively. In both categories of attempted donations, capillary and venous haemoglobin with HemoCue correlated significantly in recovered donors (R(2)  ≈ 0·5-0·7) but not in deferred visits (R(2)  < 0·15). Venous haemoglobin with HemoCue and by haematological analyzer significantly correlated in all donations attempts (R(2)  ≈ 0·7). Donors presenting with low capillary haemoglobin showed small bias between capillary and venous haemoglobin by HemoCue (-2·4 ± 6·2 g/l), fingerstick haemoglobin and venous haemoglobin with counter (1·3 ± 7·3 g/l), and venous haemoglobin with HemoCue and counter (3·7 ± 3·9 g/l). This bias was slightly greater in donors with high capillary haemoglobin (-7·5 ± 7·8, 13·7 ± 7·5, and 6·2 ± 7·5, respectively). Double haemoglobin screening by HemoCue reached an accuracy of 87·3% for qualifying donors presenting with low fingerstick haemoglobin. CONCLUSIONS: Double haemoglobin measurement with HemoCue [fingerstick and venous blood if required] is feasible and allows a significant recovery of blood donations.