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Why testing is being moved to the site of patient care.

Although we continue to talk about the "diagnostic laboratory," most lab tests now performed on hospitalized patients are used to monitor the course of treatment for known conditions. In medical intensive care units, more than three-quarters of admissions may be for monitoring rather than for immediate major therapeutic interventions.|1~ In many inpatient units, the great majority of tests are done to assess the status of patients undergoing relatively few procedures, largely to monitor cardiorespiratory status, red cell mass, and fluid and electrolyte balance.

* Changes in medical practice. Increased acuity and severity of illness in hospitalized patients and the resulting higher costs associated with managing such patients have intensified institutional pressures to achieve clinical efficiency. The advent of the prospective payment system for Medicare patients in the United States has significantly changed the pattern of hospital admissions. The dual result has been hospital admission of fewer patients with nonacute conditions and a higher proportion of patients admitted for major therapeutic interventions that require more intensive support systems. This change in patient mix has been accompanied by increased pressures to decrease both the length of hospital stays and the use of certain high-cost resources such as intensive care beds.

These pressures upon clinical units for increased efficiency are translated to the clinical laboratory as requests to improve service levels by decreasing turnaround time. Although many laboratories have struggled to meet these clinical needs within the framework of existing centralized laboratories, others have established satellite laboratories, particularly to support operating rooms and intensive care units. Even satellite laboratories, however, may have difficulties in meeting the changing requirements for clinical management. Substantial delays can occur in transporting and processing specimens. Delays take place even when electronic communication of results dramatically reduces the lag phase: transfer of information to clinical units.

Similar pressures for improved laboratory turnaround times should be anticipated for ambulatory care. The rapid growth of centers for ambulatory surgery has essentially transferred many preoperative laboratory workups to an outpatient setting, with patients arriving an hour before the procedure for premedication and last-minute evaluation. In ambulatory medical practice, the costs in both time and money of prolonged diagnostic testing and repetitive monitoring--in diabetic patients and in those receiving anticoagulant therapy, for example--will increase pressures for more selective use of tests with rapid turnaround. The goal is to reduce the number of repeat patient visits and to prevent delays in therapeutic decisions.

As the nature of laboratory testing of inpatients has changed during the last two decades, the technologies involved in these tests have continued to evolve in several important ways. First, increased automation has heightened the precision of many commonly used tests. The principles applied to costly high-volume chemistry analyzers, for example, can be applied to modest and less-expensive equipment designed to bear smaller workloads. As an example, the development of ion-selective electrodes for measuring most electrolytes has made possible the production of self-contained analytical systems that measure blood gases and electrolytes.|2~

Another important step in the evolution of inpatient laboratory testing involves the development of technologies for solid-state stabilized reagents. This advance has permitted the production of chemistry analyzers using dry multilayer thin-film reagent systems that can be highly automated.|3~ Initially developed for high-volume instrumentation, these methods have since been modified for use in small desktop analyzers. Because antibodies used in immunochemical systems can also be stabilized in solid-state systems, low concentrations of hormones in urine or serum--chorionic gonadotropin in single-test configurations, for example---can now be measured.|4~ A final way in which technologic innovation has affected testing is the astonishing speed of development in microcomputers and microelectronics.

* Growth of point-of-care testing. The combination of technologic innovations and increased pressures for more rapid turnaround of laboratory test results has made the performance of many procedures possible at the point of care, whether that point is an operating room, an emergency room, a critical care unit, an office practice, or the patient's home.|5~

In the care of critically ill patients, substantial changes have occurred regarding both the location and the technologies of laboratory testing.|6~ The development of automated analyzers that use whole blood, rather than serum or plasma obtained after centrifugation, has permitted turnaround times of five minutes or less not only for blood gases but also for sodium, potassium, ionized calcium, and glucose. These analyzers are located predominantly in satellite laboratories. The recent development of self-contained analyzers with autocalibration features has made possible point-of-care testing of critically ill patients.|7~

Almost all primary-care physicians in the United States have access to an office laboratory.|8~ The procedures performed in most office laboratories have traditionally involved simple manual tests such as urinalysis. Changes in the practice of ambulatory medicine and in the available technology, however, have substantially increased the menu of tests that can be rapidly performed in the setting of ambulatory medical practice.

The increased size of group practices provides a larger patient base for testing, with higher volumes of routine tests and a potentially broader range of tests. Development of small desktop analyzers that use whole blood|9~ has allowed outpatient testing by nontechnical personnel to be performed with satisfactory accuracy and precision.|10~

Laboratory testing by patients themselves has been a feature of the consumer revolution as patients become more involved in their own care.|11~ The growth of self-testing is best illustrated by the number of diabetic patients who monitor their own blood glucose levels with portable devices.|12~

The articles in this special supplement to MLO will concentrate upon the changing environment for care of critically ill patients, the impact of new technologies for laboratory support of this care, and alternative strategies for the introduction and management of these technologies.

I believe it is appropriate to concentrate upon laboratory support of critically ill patients for several reasons. First, the increased complexity of case mix and supportive measures will apply to patients in the hospital setting who are not in critical care units. Second, the pressures for improved turnaround time of laboratory information are more clear-cut for critically ill patients. Third, the technological response of the laboratory is better defined for critically ill patients than for other areas of point-of-care testing. Fourth, the health care community has exhibited increased acceptance of the need for point-of-care testing for critically ill patients.

* Important issues. Senior laboratory professionals who recognize the clinical need for point-of-care testing and who support its intelligent application have warned that "like all new technologies, its apparent simplicity often belies its complexity and masks the need for attention to detail in order to achieve optimum effects and avoid disasters."|13~

Features essential for reliable point-of-care testing fall into three major categories: instrumentation, staff, and operations.

Improving the quality of point-of-care testing depends heavily on engineering controls of instrumental systems, making them less dependent upon the technical skill of the operator and more rugged under conditions of actual use. Technological innovations in the formulation of reagents such as stabilized solid-phase components can be combined with built-in software capability for quality control activities and the detection of instrument malfunction.

Even with so-called "black box" technologies, which appear to be relatively foolproof, operator error may significantly degrade the performance of the test. A number of studies have documented the difficulties experienced by nontechnical staff, for example, in using glucose reflectance meters. The most common problem identified has been lack of adequate training of staff in operating the instrument and practicing appropriate quality control techniques.

Programs designed to certify nontechnical users have been successfully implemented.|14~ Because staff turnover in inpatient units tends to be rapid, all users of a point-of-care laboratory system must receive adequate initial instruction, followed by periodic retraining that places particular emphasis on quality control techniques and understanding of instrument malfunction.

Assessing technology that provides point-of-care testing typically involves comparing new instrument systems with those currently in operation. Clinical laboratory staff should be actively involved in this assessment, not only to provide correlative data but also to help identify potential pitfalls in the use of new systems and to design training programs for nontechnical users.

Documentation of laboratory procedures is required for point-of-care testing as much as it is for centralized laboratory operations. It is particularly important to provide occasional users with procedure manuals. One approach that deserves wider use is to build in the software capability for prompting users in the sequence of operations. The availability of inexpensive LED screens should help this enhancement to proliferate.

QC procedures developed for central clinical laboratories can be adapted for point-of-care testing. The design of instrumentation that incorporates periodic calibration cycles and the introduction of QC specimens is probably the most effective approach. Lack of adequate quality control procedures, a widespread problem in many point-of-care settings,|15~ may account for poor performance of certain procedures.

The reporting of results from point-of-care testing has received little attention. That gap is surprising in view of the emphasis on rapid turnaround of information as the principal justification for moving tests to the point of care. Providing hard copies as well as electronic results is essential for medical record keeping and to reduce errors in result transcription. In the case of critically ill patients, the large volume of test results generated over short periods of time will have to be integrated into the clinical record, ideally as a component of a computer-based clinical information system.

The contributors to this special issue have a wide variety of clinical backgrounds and professional experiences. The symposium begins with articles outlining recent developments in the clinical settings for critical care medicine, continues with reviews of the changing technologies that have been developed to meet these new clinical needs, and concludes with several articles focusing on selected issues in implementing new technologies and integrating them into these rapidly evolving areas of clinical medicine.

The implementation of point-of-care testing will be most successful when laboratory professionals with technological experience work with clinical users who require these services. The authors of articles in this issue bring together the changing needs of clinical care and the advances in laboratory technology that make point-of-care testing a logical step in the evolution of laboratory medicine.

1. Thibault, G.E.; Mulley, A.G.; Barnett, G.O.; et al. Medical intensive care: Indications, interventions, and outcomes. N. Engl. J. Med. 302:938-942, 1980.

2. Meyerhoff, M.E. New in vitro analytical approaches for clinical chemistry measurements in critical care. Clin. Chem. 36: 1567-1572, 1990.

3. Curme, H.G.; Columbus, R.L.; Dappen, G.M.; et al. Multilayer film elements for clinical analysis: General concepts. Clin. Chem. 24: 1335-1342, 1978.

4. Valkirs, G.E., and Barton, R. ImmunoConcentration: A new format for solid-phase immunoassays. Clin. Chem. 31: 1427-1431, 1985.

5. Rock, R.C. "Distributed technology: Managing decentralized clinical biochemistry," chap. 24 pp. 222-236. In: Marks. V., and Albert, K.G.M.M., eds. "Clinical Biochemistry Nearer the Patient." London, Churchill Livingstone, 1985.

6. Kost, G.J., and Shirey, T.L. New whole-blood testing for laboratory support of critical care at cardiac transplant centers and U.S. hospitals. Arch. Pathol. Lab. Med. 114: 865-868, 1990.

7. Zaloga, G.P.; Hill, T.R.; Strickland, R.A.; et al. Bedside blood gas and electrolyte monitoring in critically ill patients. Crit. Care Med. 17: 920-925. 1989.

8. Fischer, P., and Addison, L.A. The office laboratory director's guide. JAMA 254: 2941-2945, 1985.

9. Schultz, S.G.; Holen, J.T.; Donohue, J.P.; et al. Two-dimensional centrifugation for desk-top clinical chemistry. Clin. Chem. 31: 1457-1463, 1985.

10. Nanji, A.A.; Poon, R.; and Hinberg, I. Quality of laboratory test results obtained by non-technical personnel in a decentralized setting. Am. J. Clin. Pathol. 89: 797-801, 1988.

11. Sobel, D.S., and Ferguson, T. "The People's Book of Medical Tests," pp. 434-438. New York, Summit Books, 1985.

12. McCall, A.L., and Mullin, C.J. Home monitoring of diabetes mellitus: A quiet revolution. Clin. Lab. Med. 6: 215-239, 1986.

13. Marks, V. Essential considerations in the provision of near-patient testing facilities. Ann. Clin. Biochem. 25: 220-225, 1988.

14. Leroux, M.L., and Desjardins, P.R.E. Establishment and maintenance of a hospital glucose meter program. Lab. Med. 20: 97-99, 1989.

15. Burrin, J.M., and Fyffe, J.A. Diagnostic equipment outside the laboratory. J. Clin. Pathol. 41: 925-928, 1988.

Figure I Recent changes in medical practice

Shift of diagnostic testing to ambulatory care

Increased clinical needs of inpatients




Ambulatory practice

Freestanding walk-in and "surgicenter" units

Larger group practices

Managed care

Patients' expectations

Figure II

Technologic innovations that feed point-of-care testing

Solid-phase reagent systems

Ion-selective electrodes

Microcomputers and microelectronics

Figure III

Essentials of point-of-care testing

Instrumentation ("engineering controls")

* Self-contained

* Stable reagent systems

* Hardware reliability

* Software capability


* Initial credentialing

* Continuing education

* Troubleshooting


* Technology assessment

* Documentation

* Quality control

* Reporting

* Laboratory networks

Robert C. Rock is director of the department of laboratory medicine at the Johns Hopkins Hospital, Baltimore, Md.
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No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991 Gale, Cengage Learning. All rights reserved.

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Title Annotation:MLO Special Issue: Point-of-Care Testing
Author:Rock, Robert C.
Publication:Medical Laboratory Observer
Date:Sep 1, 1991
Previous Article:The role of the laboratorian on the critical care team.
Next Article:Monitoring versus testing technologies: present and future.

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