Improved accuracy from point-of-care heparin tests
Promise medical technicians ease of use and better results from testing supplies, and promise administrators they can expand services because of it and you’re on to a surefire winner of a performance improvement (PI) project. That’s just what happened at Tulane University Hospital and Clinic in New Orleans when staff there tried a new point-of-care heparin management test. The new test improved accuracy reduced testing variation from ±25% to ±10%. It also was easy to use, easy to train operators in, and allowed the 353-bed hospital to open a new clinic based on the point-of-care tests.
In the past, the hospital used several instruments from different companies — among them Medtronic and ITC — to monitor activated clotting time (ACT), explains Gale Gelston, MPH, assistant lab director and point-of-care coordinator at the hospital. But inconsistent results created difficulties in meeting proficiency tests. Gelston obtained a demonstration unit of the Rapidpoint Coag, manufactured by Bayer Diagnostics in Walpole, MA. She found that the consistency of the results provided by the new unit is substantially higher than what had been achieved in the past.
Another advantage, according to Gelston, is that the unit’s ease of use makes it possible to place units throughout the hospital and easily train new operators. Indeed, training took just 30 minutes, with no resistance from the staff.
"All the users love it, and have from the moment they saw how easy it was to use," says Gelston. "And we have confidence that our results are accurate and repeatable and no longer have difficulty passing proficiency tests. This makes it possible to provide immediate feedback that can have a major positive impact on patient outcomes."
Consistency and accuracy are key
The instruments used in the past were based on ACT analysis methods that are performed on whole blood and measure the time to clot using either celite or kaolin as an activating agent. They were located in the extra corporeal membrane oxygenation (ECMO) area, the cardiac catheterization laboratory, the surgical intensive care unit, and the critical care unit. Technicians used a cuvette containing magnetic rod, baffle, and a contact activator for the blood. The blood was added and a timer was started. The tube was heated while slowly being rotated. The formation of a clot constrains the magnet and signals the end of the test at which point the time is recorded.
Tulane used two instruments from different manufacturers, and had difficulty correlating the results of the instruments to each other and to standards. The problem is that operator technique, temperature, hemodilutions, and coagulation abnormalities — among other factors — can cause the results to vary. For that reason, the instruments were highly dependent on the skill and consistency of the operators, especially in the way that they prepared the samples for analysis.
Using an internal standard, Gelston found that results varied about 25% from day to day. The previous instruments also required a considerable amount of skill to operate, about 15 minutes to prepare the samples for these tests, and another five minutes or so to run the test. To minimize problems, operators went through a lengthy training process with the goal of increasing the consistency of the sample preparation process. Operators that had not used the instrument for a few months went through a refresher course. The cost of operating the analyzers was increased by the fact that quality control tests frequently had to be re-run because they didn’t pass the first test.
Gelston says she was concerned about the accuracy of the instruments used in the past. She earlier had spearheaded the establishment of a point-of-care committee that included the lab administrative director, the pathologist, nurses from adult and pediatric critical-care units, the emergency department nurse coordinator, a clinic nurse, and the respiratory therapy manager. The committee met monthly to determine what new point of care tests to bring in, whether any methods needed changing, and how to handle problems that arose in point-of-care areas.
It was while working on this committee that Gelston suggested seeking out an instrument that could increase accuracy while being easy enough to use that it could be located at the point of patient care.
While she had read articles about the Rapidpoint Coag, and had requested information from Bayer about it, Gelston didn’t know anyone who had used it. "But I did phone some users to get their opinions." She was impressed with the reported ease of use.
How it works
The system is based on a novel dry-chemistry method in which paramagnetic iron oxide particles move in response to an oscillating magnetic field. The paramagnetic iron oxide particles are combined with test reagents for clotting assays and formulated as dry reagents within a capillary test chamber located on the surface of a disposable test card. The card is first passed through the magnetic code reader to transfer the test information to the analyzer and then is placed on the instrument, where it is maintained at 37ºC. A drop — which doesn’t need to be precisely measured — of blood or plasma is placed into a sample well on the test card. The sample is drawn into the reaction chamber by capillary action. The sample dissolves the reagent, and the paramagnetic iron oxide particles begin to oscillate. This movement is monitored by the analyzer, which automatically measures the time period that clotting occurs.
The committee was an easy sell on the new technology, Gelston says. She also had to convince the chief nursing officer to go with the Bayer unit, and reports that she easily was able to do so.
Reducing variability
The Bayer technical representative came in and trained the staff members in the use of the instruments, which were provided on a demonstration basis. "It was immediately clear that much less training was required to operate the instrument, and also that there is lot less room for human error," Gelston says. "The process of sample preparation has been essentially eliminated. All the operator has to do is swipe their test card, insert the test card into the instrument, enter their operator ID, select the sample type, enter patient ID, add a sample drop, and walk away until they hear a tone that indicates the results are ready."
She says the use of the test card eliminates the variability that previously entered into the analysis, such as how much sample was used, how well the sample was mixed with the reagents, and whether the mixing was done with the cuvette in the vertical position.
"Right from the very beginning, we saw that everyone who tried the instrument was able to get very consistent results, whether or not they had a lab background," Gelston says. "Our correlations studies on 32 samples were also satisfactory, even though they were hampered by variability in the older instruments. All in all, we felt that the Rapidpoint analyzer was the right instrument to move us forward into the future."
Tulane University Hospital installed eight of the new devices in the cardiac catheterization lab, critical care unit, surgical intensive care unit, dialysis, ECMO, and two in the operating room. One instrument remains in the point-of-care lab for training purposes.
The most important advantage has been the improved performance internal test and CAP proficiency tests — results have been within +10% in every case so far. The simplified operation of the new instruments has made it possible for the main operator to train every nurse in the areas where they are used, a total of 75 people so far. Operators now have no difficulty using the instrument, even if it has been a while since their last use.
Tulane saves money because there is no longer any need to re-run the QC testing. The laboratory staff perform quality control testing of dry chemistry instruments daily with a special electronic quality control test card. For quality control of the analyzer and test cards, wet testing is performed upon receipt of each new batch of test cards.
The ability of the Rapidpoint Coag analyzer to handle a variety of test cards also is making it possible for Tulane to measure prothrombin time (PT) in a new coumadin clinic it is about to open with the same instrument. Traditionally, PTs are performed in the laboratory on conventional laboratory instrument/reagent systems.
Central laboratory testing generally is batched, resulting in longer turnaround times for specific test results. Patients have to schedule follow-up visits for dose adjustment and re-test if necessary. In the mean time, the patient continues taking what may be an inappropriate dose. The Rapidpoint will provide PT results within a matter of minutes, making it possible to adjust patients’ coumadin dosage if required, while they still are at the clinic.
Tulane’s coumadin clinic will focus on maintaining each patient’s target level of anticoagulation in order to prevent adverse events caused by clotting such as strokes, heart attacks, and blood clots in the legs, while at the same time avoiding hemorrhages. Recent studies have shown that adverse effects, such as incidence of thromboembolism and major hemorrhage, were significantly reduced with patients monitored by anticoagulation clinics.
Patients monitored by anticoagulation clinics also had anticoagulant levels within the therapeutic range for a significantly longer time, representing better management of anticoagulation levels, says Gelston. "We expect that our coumadin clinic will help our patients to avoid many emergency room visits."
[For more information, contact:
- Gale Gelston, MPH, MT(ASCP)SC, Assistant Administrative Director-Laboratory, Tulane University Hospital & Clinic HC49, 1415 Tulane Ave., New Orleans, LA 70112. Telephone: (504) 584-1788.]
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