Reliability of bedside ABO testing before transfusion

Digital Microfluidic Hemagglutination Assays for Blood Typing, Donor Compatibility Testing, and Hematocrit Analysis

BACKGROUND

Blood typing, donor compatibility testing, and hematocrit analysis are common tests that are important in many clinical applications, including those found in high-stakes settings such as the trauma center. These tests are typically performed in centralized laboratories with sample batching; the minutes that are lost in this mode can lead to adverse outcomes, especially for critical-care patients. As a step toward providing rapid results at the bedside, we developed a point-of-care hemagglutination system relying on digital microfluidics (DMF) and a unique, automated readout tool, droplet agglutination assessment using digital microfluidics (DAAD).

METHODS

ABO and Rhesus blood grouping, donor crossmatching, and hematocrit assays were developed on a portable DMF platform that allowed for automated sample processing. The result of each assay could be determined by eye or automatically with the DAAD imaging tool.

RESULTS

DMF-DAAD was applied to 109 samples collected from different sources (including commercial samples, pinpricks from volunteers, and a hospital blood bank), with perfect fidelity to gold-standard results. Some of these tests were carried out by a nonexpert in a hospital trauma center. Proof-of-concept results were also collected from smaller sample sets for donor compatibility testing and hematocrit analysis.

CONCLUSION

DMF-DAAD shows promise for delivering rapid, reliable results in a format well suited for a trauma center and other settings where every minute counts.

Red Blood Cell Agglutination for Blood Typing Within Passive Microfluidic Biochips

Pre-transfusion bedside compatibility test is mandatory to check that the donor and the recipient present compatible groups before any transfusion is performed. Although blood typing devices are present on the market, they still suffer from various drawbacks, like results that are based on naked-eye observation or difficulties in blood handling and process automation. In this study, we addressed the development of a red blood cells (RBC) agglutination assay for point-of-care blood typing. An injection molded microfluidic chip that is designed to enhance capillary flow contained anti-A or anti-B dried reagents inside its microchannel. The only blood handling step in the assay protocol consisted in the deposit of a blood drop at the tip of the biochip, and imaging was then achieved. The embedded reagents were able to trigger RBC agglutination in situ, allowing for us to monitor in real time the whole process. An image processing algorithm was developed on diluted bloods to compute real-time agglutination indicator and was further validated on undiluted blood. Through this proof of concept, we achieved efficient, automated, real time, and quantitative measurement of agglutination inside a passive biochip for blood typing which could be further generalized to blood biomarker detection and quantification.

Unreliable patient identification warrants ABO typing at admission to check existing records before transfusion

BACKGROUND AND OBJECTIVES

This study describes patient identification errors leading to transfusional near-misses in blood issued by the Alps Mediterranean French Blood Establishment (EFSAM) to Marseille Public Hospitals (APHM) over an 18-month period. The EFSAM consolidates 14 blood banks in southeast France. It supplies 149 hospitals and maintains a centralized database on ABO types used at all area hospitals. As an added precaution against incompatible transfusion, the APHM requires ABO testing at each admission regardless of whether the patient has an ABO record. The study goal was to determine if admission testing was warranted.

MATERIALS AND METHODS

Discrepancies between ABO type determined by admission testing and records in the centralized database were investigated. The root cause for each discrepancy was classified as specimen collection or patient admission error. Causes of patient admission events were further subclassified as namesake (name similarity) or impersonation (identity fraud).

RESULTS

The incidence of ABO discrepancies was 1:2334 including a 1:3329 incidence of patient admission events. Impersonation was the main cause of identity events accounting for 90.3% of cases. The APHM's ABO control policy prevented 19 incompatible transfusions. In relation to the 48,593 packed red cell units transfused, this would have corresponded to a risk of 1:2526.

CONCLUSION

Collecting and storing ABO typing results in a centralized database is an essential public health tool. It allows crosschecking of current test results with past records and avoids redundant testing. However, as patient identification remains unreliable, ABO typing at each admission is still warranted to prevent transfusion errors.

Wrong blood in tube - potential for serious outcomes: can it be prevented?

'Wrong blood in tube' (WBIT) errors, where the blood in the tube is not that of the patient identified on the label, may lead to catastrophic outcomes, such as death from ABO-incompatible red cell transfusion. Transfusion is a multistep, multidisciplinary process in which the human error rate has remained unchanged despite multiple interventions (education, training, competency testing and guidelines). The most effective interventions are probably the introduction of end-to-end electronic systems and a group-check sample for patients about to receive their first transfusion, but neither of these eradicates all errors. Further longer term studies are required with assessment before and after introduction of the intervention. Although most focus has been on WBIT in relation to blood transfusion, all pathology samples should be identified and linked to the correct patient with the same degree of care. Human factors education and training could help to increase awareness of human vulnerability to error, particularly in the medical setting where there are many risk factors.

Comparison of gel column, card, and cartridge techniques for dog erythrocyte antigen 1.1 blood typing

OBJECTIVE

To compare accuracy and ease of use of a card agglutination assay, an immunochromatographic cartridge method, and a gel-based method for canine blood typing.

SAMPLE

Blood samples from 52 healthy blood donor dogs, 10 dogs with immune-mediated hemolytic anemia (IMHA), and 29 dogs with other diseases.

PROCEDURES

Blood samples were tested in accordance with manufacturer guidelines. Samples with low PCVs were created by the addition of autologous plasma to separately assess the effects of anemia on test results.

RESULTS

Compared with a composite reference standard of agreement between 2 methods, the gel-based method was found to be 100% accurate. The card agglutination assay was 89% to 91% accurate, depending on test interpretation, and the immunochromatographic cartridge method was 93% accurate but 100% specific. Errors were observed more frequently in samples from diseased dogs, particularly those with IMHA. In the presence of persistent autoagglutination, dog erythrocyte antigen (DEA) 1.1 typing was not possible, except with the immunochromatographic cartridge method.

CONCLUSIONS AND CLINICAL RELEVANCE

The card agglutination assay and immunochromatographic cartridge method, performed by trained personnel, were suitable for in-clinic emergency DEA 1.1 blood typing. There may be errors, particularly for samples from dogs with IMHA, and the immunochromatographic cartridge method may have an advantage of allowing typing of samples with persistent autoagglutination. The laboratory gel-based method would be preferred for routine DEA 1.1 typing of donors and patients if it is available and time permits. Current DEA 1.1 typing techniques appear to be appropriately standardized and easy to use.

Challenges and opportunities to prevent transfusion errors: a Qualitative Evaluation for Safer Transfusion (QUEST)

BACKGROUND

One of the most frequent causes of transfusion-associated morbidity or mortality is the transfusion of the wrong blood to the wrong patient. This problem persists in spite of the incorporation of numerous procedures into the pretransfusion checking process in an effort to improve patient safety. A qualitative study was undertaken to understand this process from the perspective of those who administer blood products and to identify concerns and suggestions to improve safety.

STUDY DESIGN AND METHODS

Twelve focus group discussions and seven individual interviews were conducted at six hospitals in five countries (n = 72 individuals). Health care professionals from a variety of clinical areas participated. Data analysis identified common themes using the constant comparison method.

RESULTS

Five major themes emerged from the analysis: the pretransfusion checking process, training, policy, error, and monitoring. Findings include the following: staff were aware and appreciative of the seriousness of errors and were receptive to continuous monitoring, the focus was on checking the bag label with the paperwork rather than the bag label with the patient at the bedside, training methods varied with most perceived to have minimal effectiveness, and access to policies was challenging and keeping up to date was difficult. Other factors that could contribute to errors included high volume of workload distractions and interruptions and familiarity or lack of familiarity with patients.

CONCLUSIONS

Multiple factors can contribute to errors during the pretransfusion checking limiting the effectiveness of any individual intervention designed to improve safety. Areas of further research to improve safety of blood administration were identified.

Comparison of five blood-typing methods for the feline AB blood group system

Objective-To compare the ease of use and accuracy of 5 feline AB blood-typing methods: card agglutination (CARD), immunochromatographic cartridge (CHROM), gel-based (GEL), and conventional slide (SLIDE) and tube (TUBE) agglutination assays. Sample Population-490 anticoagulated blood samples from sick and healthy cats submitted to the Transfusion or Clinical Laboratory at the Veterinary Hospital of the University of Pennsylvania. Procedures-Sample selection was purposely biased toward those from anemic, type B, or type AB cats or those with autoagglutination. All blood samples were tested by use of GEL, SLIDE, and TUBE methods. Fifty-eight samples were also tested by use of CARD and CHROM methods. The presence of alloantibodies in all cats expressing the B antigen as detected by use of any method was also assessed. Results-Compared with the historical gold-standard TUBE method, good to excellent agreement was achieved with the other typing tests: CARD, 53 of 58 (91% agreement); CHROM, 55 of 58 (95%); GEL, 487 of 490 (99%); and SLIDE, 482 of 487 (99%; 3 samples were excluded because of autoagglutination). Four of the samples with discordant test results originated from cats with FeLV-related anemia. Conclusions and Clinical Relevance-Current laboratory and in-clinic methods provide simple and accurate typing for the feline AB blood group system with few discrepancies. Retyping after in-clinic typing with the GEL or TUBE laboratory methods is recommended to confirm any type B or AB cats.

Simplified spectraphotometric method for the detection of red blood cell agglutination

Human error is the most significant factor attributed to incompatible blood transfusions. A spectrophotometric approach to blood typing has been developed by examining the spectral slopes of dilute red blood cell (RBC) suspensions in saline, in the presence and absence of various antibodies, offering a technique for the quantitative determination of agglutination intensity [Transfusion39, 1051, 1999TRANAT0041-113210.1046/j.1537-2995.1999.39101051.x]. We offer direct theoretical prediction of the observed change in slope in the 660-1000 nm range through the use of the T-matrix approach and Lorenz-Mie theory for light scattering by dilute RBC suspensions. Following a numerical simulation using the T-matrix code, we present a simplified sensing method for detecting agglutination. The sensor design has been prototyped, fully characterized, and evaluated through a complete set of tests with over 60 RBC samples and compared with the full spectrophotometric method. The LED and photodiode pairs are found to successfully reproduce the spectroscopic determination of red blood cell agglutination.

Evaluation of Four Bedside Test Systems for Card Performance, Handling and Safety

SUMMARY: OBJECTIVE: Pretransfusion ABO compatibility testing is a simple and required precaution against ABO-incompatible transfusion, which is one of the greatest threats in transfusion medicine. While distinct agglutination is most important for correct test interpretation, protection against infectious diseases and ease of handling are crucial for accurate test performance. Therefore, the aim of this study was to evaluate differences in test card design, handling, and user safety. DESIGN: Four different bedside test cards with pre-applied antibodies were evaluated by 100 medical students using packed red blood cells of different ABO blood groups. Criteria of evaluation were: agglutination, labelling, handling, and safety regarding possible user injuries. Criteria were rated subjectively according to German school notes ranging from 1 = very good to 6 = very bad/insufficient. RESULTS: Overall, all cards received very good/good marks. The ABO blood group was identified correctly in all cases. Three cards (no. 1, no. 3, no. 4) received statistically significant (p < 0.008) prominence (mean values shown) concerning clearness of agglutination (1.7-1.9 vs. 2.4 for no. 2). Systems with dried antibodies (no. 2, no. 4) outmatched the other systems with respect to overall test system performance (2.0 vs. 2.8-2.9), labelling (1.5 vs. 2.2-2.4), handling (1.9-2.0 vs. 2.5), and user safety (2.5 vs. 3.4). Analysis of card self-explanation revealed no remarkable differences. CONCLUSION: Despite good performance of all card systems tested, the best results when including all criteria evaluated were obtained with card no. 4 (particularly concerning clear agglutination), followed by cards no. 2, no. 1, and no. 3.

Visible/Near-infrared spectrophotometric blood typing sensor for automated near-patient testing

Automation in near-patient ABO testing has been prohibitive due to cost. Recently, a spectrophotometric approach to blood typing has been developed by examining the spectral slopes of RBC suspensions in saline, in the presence and absence of various antibodies. In this paper, we present a simplified method and a sensor that can replace the spectral imaging component of the diode-array spectrophotometer with a discrete array of LED/IRED and photodiode pairs within the 660nm-1000nm wavelength range of interest. An experimental sensor has been designed and evaluated for the reproduction of results recorded on an HP8453 diode-array spectrophotometer. The LED and photodiode pairs are found to successfully reproduce the spectroscopic determination of red blood cell agglutination, as supported by Mie scattering theory examined herein.

Real-time blood cross-matching sensor for intelligent management of transfusion safety

Blood transfusion errors are not uncommon. In some cases the error is fatal. This is primarily due to lack of an automated system at the point of application and over-reliance on bar-coding and paperwork to catch these critical errors. In emergency situations, human errors contribute to transfusion and transplantation of incompatible blood types and organs resulting in rejection and possible fatality. We present a sensing concept that will monitor blood compatibility between the patient and the transfusion bag before allowing the valve to open for transfusion to take place. This will eliminate all transfusion errors and provide 100% safe transfusions automatically. The operating principle of the sensor is based on the light scattering characteristics of dilute blood and the effect of agglutination on scattering. The device proposed is an optical system based on spectrophotometric methods. The device configuration, and results from several tests with combinations of known blood samples will be presented.

Disposable integrated microfluidic biochip for blood typing by plastic microinjection moulding

Blood typing is the most important test for both transfusion recipients and blood donors. In this paper, a low cost disposable blood typing integrated microfluidic biochip has been designed, fabricated and characterized. In the biochip, flow splitting microchannels, chaotic micromixers, reaction microchambers and detection microfilters are fully integrated. The loaded sample blood can be divided by 2 or 4 equal volumes through the flow splitting microchannel so that one can perform 2 or 4 blood agglutination tests in parallel. For the purpose of obtaining efficient reaction of agglutinogens on red blood cells (RBCs) and agglutinins in serum, we incorporated a serpentine laminating micromixer into the biochip, which combines two chaotic mixing mechanisms of splitting/recombination and chaotic advection. Relatively large area reaction microchambers were also introduced for the sake of keeping the mixture of the sample blood and serum during the reaction time before filtering. The gradually decreasing multi-step detection microfilters were designed in order to effectively filter the reacted agglutinated RBCs, which show the corresponding blood group. To achieve the cost-effectiveness of the microfluidic biochip for disposability, the biochip was realized by the microinjection moulding of COC (cyclic olefin copolymer) and thermal bonding of two injection moulded COC substrates in mass production with a total fabrication time of less than 20 min. Mould inserts of the biochip for the microinjection moulding were fabricated by SU-8 photolithography and the subsequent nickel electroplating process. Human blood groups of A, B and AB have been successfully determined with the naked eye, with 3 microl of the whole sample bloods, by means of the fabricated biochip within 3 min.

Detection of a new weak A blood-group allele (Aw11)

BACKGROUND AND OBJECTIVES

Weak ABO variants may escape tests using unlicensed sera.

MATERIALS AND METHODS

Prior to transfusion, ABO grouping was performed using an automated system and in-house diluted sera, and manual and bedside test techniques. Genotyping and sequencing were performed using standard methods.

RESULTS

Initially, the red blood cells (RBC) of the first-time blood donor were typed as B, but pretransfusion testing carried out using the bedside test indicated the presence of an additional A phenotype. Serological re-examination confirmed the bedside test results, and the allele in question was identified, by genotyping, as a new weak A variant (Aw11).

CONCLUSIONS

The use of CE-marked and licensed antisera is recommended to avoid ABO mistyping.

Failure of bedside ABO testing is still the most common cause of incorrect blood transfusion in the Barcode era

BACKGROUND AND OBJECTIVES

ABO-incompatible red blood cell (RBC) transfusions are a major risk in transfusion medicine. Identification of factors leading to this hazard is important to improve transfusion safety.

MATERIAL AND METHODS

All consecutive erroneous ABO-incompatible transfusions occurring from January 1997 to December 2004 at the Charité University Hospital in Berlin, Germany were analysed.

RESULTS

A total of 343,432 RBC units were transfused, and eight patients erroneously received 13 ABO-incompatible RBC concentrates. The most frequent error was incorrect bedside testing (n=7). Intensive care treatment was required in two cases, but there were no fatal mistransfusions. Four patients had no or only mild reactions.

CONCLUSION

Mistransfusions are still a considerable risk in transfusion medicine despite quality control systems and electronic data processing. An increase in transfusion safety may require the introduction of further systems, e.g. radio-frequency identification (RFID) tags.

[Diversity of bedside pretransfusion ABO compatibility devices in metropolitan France]

To prevent the occurrence of the ABO incidental incompatibility, the bedside pretransfusion ABO control is mandatory in France since 37 years. If the quality of the reagents is regularly controlled, no technical specification exists concerning the type of support. To describe the different types of devices used by the French hospitals, a brief questionnaire was sent, from December 2000 to March 2001, to each hemovigilance correspondent working in the 1782 hospitals with transfusion activity in 1999. Every participant had to send back the device used in his establishment. The rate of replies was 29.4%, varying from a region to another. The devices distributed by laboratories were the most used (67.4%) vs. 25.6% for the devices provided by the regional establishments of the French Establishment of Blood and 6.7% for the devices manufactured by hospitals. The presence in the region of a local office of the French Establishment of Blood providing some devices was the only factor determining the choice of the device type (p < 10(-8)). Almost half of the hospitals (46.8%) declared to have renewed their devices after 1996, most often in favor of a device provided by a laboratory (p < 10(-8)). We evaluated 30 different devices taking into account the general presentation, the available information on the device. The results of this survey showed a large disparity and heterogeneity in the quality of the devices used by the French hospitals in the context of a lack of standardization.