Committed to providing the best care for their patients, doctors are eager to take advantage of technologies that make it possible to bring diagnostic testing to the patient’s bedside.
Testing must be done not only quickly, but the results must be accurate and actionable. As a result, the adoption of such convenient, rapid tests grows as their efficacy improves. This is especially true for clinicians tending to patients who have experienced cardiac episodes of some sort.
“Point-of-care for cardiac testing is being driven by the guidelines issued recently by the American College of Cardiology, in conjunction with the European Society of Cardiology,” says Lauren Foohey, who works in business planning in POC testing for Siemens Medical Solutions Diagnostics, Malvern, Pa. “They have issued recommendations that, depending upon the cardiac marker, test results should be back to the physician in 30 to 60 minutes.”
In addition to setting forth a desirable turnaround time, these guidelines, published in 2001, also made specific recommendations on the use of biomarkers for the detection of myocardial infarction, making the detection of cardiac markers the standard for risk-stratifying chest pain patients.
While the markers being sought are the same—CK-MB, myoglobin, troponin—how vendors work to identify them can vary greatly.
Close, Compact, Correct
The Advia Centaur CP System from Siemens is not a true POC testing system, but rather is considered “near-patient” testing.
Intended for use in an emergency department’s stat lab, the analyzer features a small footprint—just 43 inches wide x 29 inches deep—making it ideal for the tight spaces often allocated to these on-site technicians. It also boasts a capacity for 84 samples, and continuous loading in 12-position sample racks.
Because it is derived from the manufacturer’s lab-based Centaur system, the CP, which was released in late 2005, uses the same reagents and consumables. Not only does this create less inventory, but the results are consistent across both analyzers.
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- Advia Centaur CP System
Though the system can also be used for a number of disease-state assay groups, including anemia, fertility, oncology, and infectious disease, cardiac is one of the analyzer’s most complete lines.
“In the cardiac offering, we have four tests: myoglobin, BNP, and CK-MB,” says Foohey. “We also have TnI-Ultra, the first fully automated, high-sensitivity assay released for troponin that satisfies the ESC/ACC guidelines of a
< 10% level of imprecision at the 99th percentile of a healthy population."
Run individually, test results are produced in 15 minutes. Multiple tests can be processed simultaneously, adding only 1 to 2 minutes to the total processing time. “There is a 20-second delay between results, so if all four tests are ordered, results are available in 16 to 17 minutes,” adds Foohey.
Well aware of the increasing pressure from hospitals for true POC cardiac tests, Siemens still chooses to take a “watch and wait” approach.
“We see a trend toward smaller systems and a growing interest from customers, as well as the need for portable systems,” says Arnd Kaldowski, senior vice president of POC for Siemens. “We are exploring those directions, but the most important thing to us is the accuracy of the testing. You still want to be able to closely correlate POC results to what is done in the central lab. If you don’t, all you succeed in is creating headaches.”
Other considerations include developing systems that are intuitive and simple to use, intended for use by nonlab personnel. Siemens is also focused on keeping tests cost effective.
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- Nanogen CardiacStatus
“If they are not, then clinicians have to perform a balancing act between what is the impact of the test versus the cost of running the operation,” says Kaldowski. “So we are looking for different technologies and approaches that can fulfill those requirements. Then it is a natural extension of cardiac testing to be performed closer to the patient, at the point of care.”
Quality: STAT
Nanogen’s POC products fall under the Cardiac Status line of tests, which includes the Cardiac Status Myoglobin, Troponin I, and CK/MB Tandem 3-in-1 test, which will rule in or rule out acute coronary syndrome.
The Cardiac Status Troponin I seeks out the single marker, while the Cardiac Status Myoglobin/Troponin I can be used to diagnose acute myocardial infarction. These FDA-cleared tests provide emergency room staff with results in 15 minutes or less.
“Our rapid tests can all be performed on our reader, the i-Lynx, which is portable,” says Suzanne Clancy, PhD, senior manager of corporate communications for Nanogen, San Diego. “It provides a qualitative yes/no answer about whether or not someone is having a myocardial infarct.”
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- Nanogen StatusFirst CHF
A handheld reader designed to capture and analyze the results of the Cardiac Status products, along with other rapid test strips, the i-Lynx connects with any existing laboratory data management systems, making it possible for results to be automatically included in the patient’s record. The feature also aids in the billing process, improving speed and accuracy.
Nanogen is also developing a test to measure chronic congestive heart failure. “This would not be a lab test, but rather a point-of-care test for use throughout the health care enterprise, not necessarily just the emergency room,” adds Clancy. “This is a test that will measure the levels of NT-pro BNP, which will aid a physician in identifying patients who are experiencing the chronic condition of cardiac stress.”
The test, called StatusFirst CHF NT-proBNP, has been FDA cleared for use with plasma.
Providing Testing Choices
Biosite is currently working on creating a version compatible for use with whole blood. The company offers clinicians options—not just in what types of markers they search for, but also in how those tests are performed. Available assays consist of troponin I, myoglobin, CK-MB, BNP, and D-dimer. The products are available in the form of a panel, with BNP and D-dimer also available as stand-alone tests. Results from all tests are produced in approximately 15 minutes.
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- Biosite’s Triage Meter Pro
The Triage Cardiac Panel is an immunoassay for the quantitative determination of CK-MB, myoglobin, and troponin I and can be used with either whole blood or plasma. A true POC test, the unit is compact and portable, with built-in quality control features.
Biosite’s Triage CardioProfiler is a panel test that can help emergency room professionals diagnose acute myocardial infarction, as well as perform risk stratification of patients with acute coronary syndromes. The test combines high-sensitivity troponin I, CK-MB, myoglobin, and BNP to provide results in whole blood and plasma.
Making use of highly sensitive fluorescence immunoassay technology, the Triage D-Dimer Test is used for patients believed to have disseminated intravascular coagulation or thromboembolic events such as pulmonary embolism or deep-vein thrombosis.
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- Biosite’s D-dimer
The company also offers two Triage BNP tests—one designed for the Triage Meter and the other for the Beckman analyzers. These immunoassays possess 98% diagnostic accuracy1 in initial studies, versus all other clinical findings in patients with or without disease history.
At home in emergency departments, Biosite’s tests are also finding their way into physician’s office laboratories.
“In the doctor’s office, the tests are used for acute conditions. In many of these cases, the patients go to family physicians rather than to the emergency department,” says Faranak Atrzadeh, product director, point-of- care for Biosite. “It is also a chance for the physicians to identify a problem in a patient who is asymptomatic or may not be acutely presenting, but may have some of the other symptoms of heart failure, such as fatigue, that tend to be overlooked in the elderly. It is one more thing for clinicians to have in their tool kits, to be able to help their patients.”
Another such test is the Triage CardioProfiler Shortness of Breath (SOB) Panel, which also identifies troponin I, CK-MB, and myoglobin. Designed to help physicians determine the cause of a patient’s breathing problems in about 15 minutes, the test provides information on BNP and D-dimer, in addition to the three primary cardiac necrosis markers. Built-in calibration and internal quality controls ensure accuracy.
Looking ahead, Biosite will continue to provide tools for physicians performing POC testing at the patient’s bedside.
“In terms of growth, there are a couple of areas that will remain a focus for us, because the demand for point-of-care testing and innovation from the industry is going to continue,” says Atrzadeh.
“Advancements include menu enhancements, diversification and expansion of menus, the need for rapid, more accurate results, as well as connectivity to the main laboratory or hospital information systems.”
Dana Hinesly is a contributing writer for CLP.
Reference
- Dao Q, Krishnaswamy P, Kazanegra R, et al. Utility of B-type natriuretic peptide in the diagnosis of congestive heart failure in an urgent-care setting. J Am Coll Cardiol. 2001;37(2):379-385.
