TRANSFUSION MEDICINE
Transfusion Medicine Makes its Mark
As more than commitment centers to blood safety and adequacy, transfusion services evolve into the 21st century by redesigning current processes and assessing future prospects.
With sensitized, refined testing techniques, transfusion medicine is not remaining static. In fact, the restructuring of products, services and business operations is part of the new design process for reducing costs, improving productivity and accommodating increased workload capacity.
Rethinking the upcoming challenges in the transfusion sector begins with identifying opportunities for improvement and goals for maximizing the most of your time and money. Whether it’s through redesigning your work processes or acquiring new testing techniques, transfusion medicine is making its mark.
“Understanding the risks and benefits of transfusion medicine is and will continue to be a moving target,” believes Linda Chambers, MD, medical director of Transfusion Services, Children’s Hospital, Columbus, OH.
Work Process Redesign
For a successful centralization of transfusion services, some form of process review, such as Work Process Redesign (WPR), must be implemented. WPR is a procedure that encompasses looking at information, business flow and activities that presently prohibit adding value to the laboratory. By realizing what doesn’t work, you can assemble a project vision that will work.
Whether WPR is instituted in one centralized location or in various laboratory segments, it eliminates redundancy and non-value added steps, thus reducing costs and increasing productivity and capacity.
“WPR provides a structure around which you can identify process improvement opportunities and apply quality improvement principles,” says Susan South, MAOM, MT(ASCP)SBB, consultant, Ortho Diagnostic Systems Inc., Scottsdale, AZ. “It will help you analyze every piece of your business.”
Further, since adding value and decreasing costs cannot occur simultaneously, WPR helps each step of the way. To accomplish the goals of WPR, you should:
* establish a vision,
* determine the end result,
* assess the readiness of the organization and
* establish a timeline.
Sometimes, it’s easier to begin this transition process by bringing in an outside facilitator, whether a consultant or a colleague from another department.
“Collect information in a neutral fashion, questioning everything” says South. “Then review and analyze the activities and information, formulate and implement the changes and measure and monitor the results of the changes made.”
Forming a WPR team will help achieve a form of accountability for the desired outcomes. The end result, however, doesn’t mean that the WPR procedure is finished. Rather, it simply means that you will have a measurement basis for where you want to go next. WPR should be viewed as an on-going process, part of the continuous improvement cycle.
Screening Devices
“To avoid wasting time, choose a testing system up front that best meets your requirements for sensitivity and specificity,” says Dr. Chambers.
Improving testing practices between patient and donor creates greater efficiencies. The key to selecting what technology will best meet your facility’s needs is by identifying several components, including hands-on and hands-off times and total test time. In addition, it’s crucial to examine cost per test, the possibility of automation, the ability to batch and improve patient care. What type of assay you will use largely varies according to what type of laboratory you are overseeing.
Testing for antibodies to red blood cells, platelets, cytomegalovirus (CMV) and syphilis, solid phase assays (Immucor, Norcross, GA) provide the target antigen, which is affixed to the bottom of the microplate stripwell. These assays use either plasma or serum, although plasma is preferred since serum tends to clot the sample. The test plasma or serum and low-ionic strength saline are added and incubated at 37 degrees Celsius. The wells are then washed with pH-buffered isotonic saline, indicator cells are added and the microplates are centrifuged. The indicator cells will form a monolayer of red blood cells if the antibody has attached to the antigen; but if it has not attached, a delineated button will form at the center of the well.1
“Solid phase assays are more sensitive than other technologies so more clinically significant antibodies are detected by this method than by test tubes and gels. Sensitivity and batchability are great pluses,” says Hope Rabinovitz, MS, MT(ASCP)SBB, field technical representative, Immucor.
This testing provides ease of batching and the capability of running multiple specimens in a short period of time. This technology is particularly ideal for donor centers, reference laboratories and high-volume transfusion services with or without liquid handling systems may. For the smaller laboratories, samples can simply be loaded manually with disposable pipettes.
“Usually with solid phase, you can get a lot of information out of a little sample, and the end product is stable for a long period of time,” says Dr. Chambers.
For performing reverse ABO grouping, Rh typing, antibody detection, identification and compatibility testing, gel technology (Ortho Diagnostic Systems, Raritan, NJ) uses prefilled microtubes attached to a plastic card.
The test plasma or serum and red cells are combined in a reaction chamber at the top of the tube and incubated at 37 degrees Celsius. Prior to incubation, the plasma or serum is prevented from entering the gel due to an air bubble; however, following the incubation process, the card is centrifuged and the red cells are driven past the air bubble into the gel. Agglutination will occur if the plasma or serum contains antibodies that are attached to the antigens on the red cells.
FDA-approved gel cards are limited to a buffered gel card, an anti-D card and an anti-IgG card. Reverse ABO grouping is performed using microtubes containing buffered gel and Rh typing is performed using microtubes filled with gel containing anti-D. Antibody detection and identification, as well as compatibility testing, are performed using microtubes filled with gel containing anti-IgG antibodies.1
“With the gel system, you can perform a test at 3 a.m. and review it at 3 p.m. and it won’t change,” says Dr. Chambers. “This has some appeal if you’re trying to run a blood bank with a generalist covering third shift and you want to see the end result when you arrive.”
A third technology, affinity column (Gamma Biologicals, Houston), is appropriate for traditional testing needs, such as antiglobulin phase. This technology detects IgG-coated red cells without using anti-human globulin. Plasma or serum and red cells are combined at the top of the card in a reaction chamber. A barrier is then formed to prevent the plasma or serum from entering the gel before it can react with the red cells. After the mixture incubates at 37 degrees Celsius, the card is centrifuged to push the red cells past the barrier into the matrix. Depending on the distance the red cells travel in the matrix, the test’s endpoint is interpreted as either strong positive, positive or negative.1
According to Neil Blumberg, MD, director, Transfusion Medicine Unit and Blood Bank, professor, Pathology and Laboratory Medicine, University of Rochester (NY) Medical Center, “These techniques will lead to improved accuracy, in addition to the potential of lowered costs and a reduction in transcription errors.”
Automation
Beginning to make its niche in transfusion medicine, automated equipment will be the trend within the next few years.
“A typical transfusion service can become more like chemistry and hematology with loading and walkaway features,” says Rabinovitz.
Immucor’s ABS-2000 performs ABO grouping and Rh typing by hemagglutination and antibody screens and crossmatches using solid phase technology. This system, designed for use in transfusion services, is currently available in Canada and Europe and has proven to be effective in improving efficiencies with some facilities processing greater than 90 percent of samples on the ABS 2000. This system is expected to be released in the United States within the next few months. The ABS-2000 includes a bar code scanner, a robotic liquid handling system, an analyzer, an optical reader and a computer for monitoring the process and compiling results. For donor centers, reference laboratories and high-volume transfusion services, the DIASPlus System is currently available to perform ABO and Rh testing by hemagglutination and antibody screening, CMV and syphilis testing by solid phase.1
Automated instrumentation for gel testing is being used in Europe. Semi-automated technology for gel testing, which is suited for large-volume operations located in transfusion sevice or donor center settings, is available in the United States. For affinity column technology, automation is under development.
Many laboratorians, however, feel skeptical about the impact of automation, sensing that it will force downsizing. According to Rabinovitz, this isn’t the case.
“Technologists will still play a vital role,” she says. “They will need to remain a resource to identify and interpret results and identify and resolve discrepancies. Automation will just eliminate the routine work for them, which represents about 80 percent of their workflow.”
Michelle L. Paquette is an assistant editor.
Reference
Walker P. New technologies in transfusion medicine. Laboratory Medicine. April 1997;28(4):258-262.
Identifying Underreported Incidences
A national surveillance system for the measurement of bacterial contamination in the U.S. blood supply doesn’t exist. However, over the last 10 years, 20 contamination cases have been reported from the Yersinia enterocolitica organism alone. It’s suspected that the morbidity of other organisms are much higher.
To assess the exact rates of bacterial contamination of blood components associated with the transfusion reaction of patients, a year-long collaborative study, which began in November 1997, has been instituted. This study, the BaCon study, has joined the forces of several leading governmental bodies, including the American Association of Blood Banks (AABB), American Red Cross (ARC), Centers for Disease Control and Prevention (CDC) and Department of Defense (DoD).
One of the biggest problems, according to CDC epidemiologist Matthew J. Kueknert, MD, is that there are no standard definitions for transfusion reactions potentially due to bacterial contamination.
The intention of the study is to quantify the risk of bacterial contamination in the blood supply. The study will require nationwide cooperation from transfusion services and blood collection facilities. Materials distributed to each of these entities include pocket-sized data cards that list definitions for significant transfusion reactions and outline the protocol for proper workup for clinical services; BaCon Adverse Reaction Forms to be completed by the clinical services, transfusion services and blood collection facilities, and educational materials, including a descriptive slide set for blood bank and clinical personnel.
“Hospitals need to be aware and report suspected cases of bacterial contamination,” says Mark Popovsky, MD, chief executive officer and chief medical officer, New England Region, ARC, Dedham, MA.
He adds, “This study could prove advantageous in the assessment of these contaminants. One of the dilemmas is that we don’t know all the incidences of bacterial contamination, but we do know that when it happens it can be fatal.”
Another attempt to improve the blood supply’s safety is through an antigenic conversion technology for converting A and B blood groups to group O. ABO mismatches account for the vast majority of fatal hemolytic transfusion reactions today. The conversion would occur as soon as the patient’s blood type is identified, and the storage life is anticipated to be the maximum of 42 days.
“It’s been estimated that at least 12 people die each year due to ABO incompatibilities,” says Dr. Popovsky. “Many more cases occur that are not reported.”
Antigenically converted units will group as type O blood. The conversion involves the use of purified, recombinantly derived enzymes that cleave the terminal sugars of group B and group A blood cells. It makes such cells antigenically and functionally Group O. This conversion technology provides for the possibility of having an all type O inventory, which would prove beneficial as type O is the universal blood type. The vast majority of patients would be able to be transfused with these blood units without difficulty.
With an all Type O stock on hand, cost should also be driven down because the manner in which blood is collected, distributed and inventoried as well as cross-matched would change.
“Antigenic conversion should, theoretically, virtually eliminate the need to crossmatch all together,” says Dr. Popovsky. “It’s possible this technology could be commercially available by 1999.”
—Michelle L. Paquette
