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The hybrid laboratory: shifting the focus to the point of care.

Dramatic changes in medical and surgical practice during the 1980s impelled testing to move closer to the patient[1,2] (Figure I). Intensive care expanded to serve increasing numbers of critically ill patients, many with complex multiple-system diseases and others with multiple organ failure. Fast therapeutic turnaround time (from test order to patient treatment[3,4] of two to five minutes was necessary for liver transplantation,[5] a procedure that catapulted to more widespread significance the use of ionized calcium[6.7] and direct whole blood analysis,[8] the concept of a critical care profile,[1,8] and the shift toward trend monitoring.[5]

Figure I

Rationale for national

trends in testing

Changes in hospital practice

* Increased heart and liver transplantation

* Expanded intensive care

* Complex multisystem diseases

* Shift toward trend monitoring

New technologies

* Whole blood biosensors

* Ion-selective electrodes (ISEs)

* Substrate-specific electrodes (SSEs)

* Amperometric and impedance electrodes

Miniaturization

* Microchemistry

* Microelectronics

* Microprocessing

Mobility

* Hand-held

* Portable

* Transportable

Rising expectations of patients and physicians

* Point-of-care testing

* Therapeutic turnaround time

* The hybrid laboratory

Simultaneously, instrument biosensors were developed rapidly and heart transplantation was performed far more frequently. United States cardiac transplant centers, having both the need and the resources, took advantage of new whole blood technologies to project themselves to the vanguard of bedside testing.[1,2] Point-of-care testing, defined as testing that could be done in virtually any hospital area where it is medically indicated, emerged with the advent of portable and hand-held instruments.

By 1989, in cardiac transplant centers, 82% of blood gas laboratories that supplied critical chemistry and hematology tests did so from satellite sites located primarily in operating rooms.[1,2] Other institutions distributed testing, even though nearly two-thirds of such satellite blood gas laboratories were not controlled by pathologists. This was true in general hospitals and in cardiac transplant centers.[1,2] Between 1982 and 1989, the percentage of general hospital blood gas labs performing chemistry testing more than doubled, and, in cardiac transplant centers, nearly tripled.[1,2] Profound shifts in testing caused the expectations of patients and physicians to rise.

Now well established, these trends will continue through the 1990s. Customized services, expanded point-of-care testing, and minimized therapeutic turnaround time will be the hallmark of the hybrid laboratory. This new composite laboratory will unify heterogeneous central, satellite, bedside, point-of-care, and patient monitoring components while serving physicians and patients more intensively and with a tighter focus.

This article will define criteria for evaluation of point-of-care instruments, introduce the axioms and theoretical basis for synthesis of point-of-care testing with conventional laboratory functions, outline strategies to optimize laboratory support for critical care, discuss rapid response planning and implementation, and describe the hybrid laboratory, a conceptual framework for effective decisions and performance.

* Instrument evaluation. Critical care diagnosis, trend monitoring, and therapy demand rapid response. Point-of-care instruments incorporate two practical elements necessary for critical care testing: use of whole blood, which saves time by eliminating the need for centrifugation, and cellular components, which permit specimens of minimal volume to be used. Criteria of particular importance for evaluating whole blood and point-of-care instrumentation are presented in Figure II.

Figure II

Criteria for evaluation of whole

blood instruments

Test menu and point-of-care features

* Appropriateness and completeness

* Specimen volume

* Speed, ease, and security of operation

Accuracy, precision, and linearity on-site

* High and low extremes

* Method consistency

* Biosensor reproducibility and stability

Physician capture

* Professional productivity

* Cost-effectiveness

* Patient outcome

Manufacturer and vendor support

* Quality assurance and quality control

* Training programs

* Point of-care credentials

Future prospects

* Robotics and remote operation

* Artificial intelligence

* Iformation integration

The marriage of blood gases and electrolytes on a single specimen has led to a standard turnaround time of no greater than 5 to 10 minutes for whole blood tests.[1,2] Using whole blood permits direct measurement not only of blood gases and pH but also of ionized calcium,[7] ionized magnesium,[9] glucose,[10] and other analytes with activity-based ion-selective electrodes (ISEs) and substrate-specific electrodes (SSEs).[8] Artifacts due to hyperlipidemia and hyperproteinemia are thus eliminated and clinical accuracy is improved.[11] Whole blood instruments that cannot perform activity-based measurements quickly and directly on anaerobically processed specimens lack these advantages; therefore, they generally are not intended for critical care settings, where rapid response is imperative.

* Critical care profiles. Point-of-care test menus[8] should fulfill patient and physician goals assessed in concert with the clinical team. Figure III summarizes vital functions and their diagnostic pivots or physiologic indicators (discussed elsewhere [12]). Historically, a key technical advance propelling the concept of a critical care profile was the simultaneous measurement of electrolytes and hematocrit (or hemoglobin) with blood gases and pH.[1,2] Several whole blood instruments now supply appropriate critical care profiles of tests listed in Figure III, of which ionized calcium ([iCa.sup.++]) and ionized magnesium ([iMg.sup.++]) are fundamentally new measurements.

Figure III

Critical care profile
Vital function Diagnostic pivots
Energy Glucose, Hgb, Hct, [pO.sub.2], [O.sub.2]
 saturation
Conduction [K.sup.+], [Na.sup.+], [iMg.sup.++], [iCa.sup.++]
Contraction [iCa.sup.++], [iMg.sup.++]
Perfusion Lactate
Acid-base pH, [pCO.sub.2], [TCO.sub.2], [HCO.sub.3]
Osmolality Osm, 1.86([[Na.sup.+]] + [[K.sup.+]])
 + [Glucose]/18
Hemostasis PT, PTT, platelets
Homeostasis [P.sub.i], [Cl.sup.-], Creat., BUN, WBC


Biosensors for [HCO.sub.3.sup.-] (direct bicarbonate) and [P.sub.i] (inorganic phosphorus) also will become available. Access to rapid response hemostasis and hematology testing will advance beyond the sodium-corrected impedance method for hematocrit and the spectrophotometric method for hemoglobin currently available. Interchangeable modular biosensor arrays will allow selection of several test menus on one instrument platform. Therefore, the flexible selection of test menus will be an increasingly important criterion for instrument purchase, since cluster effectiveness of tests in a critical care profile affects patient outcome (to be discussed).

* Point-of-care designs. The design of a point-of care instrument should be ergonomic. Ease of operation and speed in the intended clinical setting are essential. For example, in an emergency the operator should be able to interrupt an automatic two-point calibration to save time. The one-point calibration cycle should be short. Calibration drift should be minimal. Throughput must match clinical input, especially during emergencies. Hand-held and portable instruments should be efficient, reliable, durable, compact, and light, with streamlined requirements for reagents, maintenance, biohazard disposal, and quality control.

Deployed in a clinical unit, these portable instruments can defray laboratory personnel costs. Programmability, self-diagnostics, data management, and security make it safer for operators with different levels of experience to perform measurements. Similarly, the biosensor systems should not be sensitive to operator technique.

Instrument systems should include a smart printer, magnetic storage, and interfacing capability. For example, an instrument stand for a portable unit could include an infrared transmitter/receiver, a printer, and an RS-232 port. In the future, patient results will be communicated to a base station by radio telemetry, fiber optics, or local area networks (LANs). At present, communications are facilitated by the appropriate of facsimile machines, electronic mall, beepers, two-way radios, and cellular telephones.

In the 1980s, small bench instruments were often used in satellite laboratories located in operating rooms, emergency departments, and intensive care units.[1,2] These instruments allow flexible selection of test menus and tend to be interfaced easily with computerized laboratory information systems. Significant progress has been made with bar coding, reagent efficiency, and menu-driven touch screens. Less well developed to date are integration of bedside testing results, interlinking of satellite sites, and comprehensive quality assurance protocols.[13]

One must cautiously balance the use of instruments that offer portability and those offering transportability. The operation of an instrument from a carefully placed satellite laboratory, bedside workstation, or mobile cart is highly effective, whether transportable or portable models are selected. The trend in miniaturization will undoubtedly continue, resulting in increased availability of smaller and modular instrument formats.

* Accuracy, precision, and linearity. Accuracy and precision must be excellent in the near-normal ranges, acceptable in the high and low extremes, and congruent for the same measurement performed on different instruments. Critical test results arise frequently during medical emergencies and in the operating room, intensive care unit, and emergency room. One can estimate the linear range that is necessary to span critical results from published tables of critical limits.[ 14,15]

For example, in adults the glucose low critical limit mean is 46 (with a standard deviation of 7) mg/dl (2.6 [0.4] mmol/L), aud the glucose high critical limit mean is 484 (144) mg/dl (26.9 [8.0] mmol/L).[14] In children, the low is 46 (9) mg/dl (2.6 [0. 5] mmol/L) and the high is 445 (161) mg/dl (24.7 [8.9] mmol/L).[15] In newborns, the low is 33 (8) mg/dl (1.8 [0.4] mmol/L) and the high is 327 (65) mg/dl (18.2 [3.6] mmol/L).[15] Glucose is the most commonly encountered critical limit at United States medical centers[14] and children's hospitals.[15] Hence, critical limit frequencies suggest test priorities. Accuracy of point-of-care results is often more integral to treatment (such as insulin dose) than to diagnosis (diabetes).

* On-site performance. Instrument performance depends on biosensor stability and reproducibility. A challenge for point-of-care instruments is to provide accuracy and precision at several different clinical or laboratory sites. If feasible, using the identical biosensor technology in all clinical units of a given facility from the start will help achieve consistency of methods. A designated reference instrument (on a mobile cart, if necessary) can be moved on-site for side-by-side comparisons to initiate use of new instruments. It is inadvisable to split, transport, and then analyze anaerobic whole blood specimens for comparison studies performed at distant sites.

The decision to implement different types of instruments at an institution depends upon documented performance under fire. Essential elements include individual instrument histories, tracking records, and quality control. The relative performance of operators and instruments can be assessed with pattern recognition techniques[13] using aqueous control materials, blind samples, and whole blood clinical specimens.

* Physician capture. One objective of point-of-care testing is physician capture-immediate availability of test results to the physician-thus providing sufficient time for effective thought and action in the clinical unit immediately. Physicians are willing to wait for test results before proceeding if they know they will arrive swiftly. This facilitates rapid diagnosis, speeds treatment, and eliminates unnecessary delays. The result is to make physicians less likely to feel pressed to order therapies that may increase morbidity, prolong stays, or cause costs to escalate.[16-18] A focus on patient outcome affects bottom-line hospitalization expenses and produces savings that offset costs incurred by implementing bedside testing.[18]

To build physicians' enthusiasm about the prospect of a point-of-care program, the facility must buy enough instruments to satisfy their testing needs and to achieve physician capture in the most important critical care areas. As part of this effort, manufacturers and vendors should work to, reduce the direct costs of equipment and supplies and should support on-site training programs for point-of-care operators. Some hospitals have developed videotapes to educate operators with different backgrounds and to explain documentation requirements for quality assurance. In fact, it should be established from the outset that videotaped instruction programs will be provided and plans made for operator training that will satisfy accreditation requirements.

* Integrating information. As tasks expand, clinical lab staff will continue to shrink, providing an opportune situation for implementing robotics, remote operation, and artificial intelligence. Instruments should be designed for rapid information exchange with the laboratory information system (LIS), the hospital information system (HIS), or a Stat local area network (LAN). The risk of miscommunicating potentially actionable results during a fast-paced code is great. The data stream of results flows so quickly that assimilation into the patient record, a legal necessity, often lags behind real-time care.

Test results may be inconsistent due to instrument specific normal reference intervals or measurement inaccuracies. These inconsistencies become visible as unexpected shifts that confound accurate and swift diagnosis, and occur, for example, as the patient is transferred from the emergency department to the operating room and subsequently to the intensive care unit. Seamless information processing, diagnostic fingerprints revealed by computer graphics, and pattern recognition techniques[13] can help eliminate inconsistencies and improve the quality of care.

* Theoretical basis for point-of-care testing. Results from investigators[1,2,5,16-19] who have implemented point-of-care testing support the four principles below. For clarity, performance variables are limited to diagnostic efficiency ([epsilon.sub.d]). therapeutic efficiency ([epsilon.sub.t]), cluster effectiveness [e.sub.c]), response time ([t.sub.r]) analysis time [t.sub.a]), and transit time ([t.sub.t]). For discrete tests, t, depends on the distance, x, of the measurement from the patient; ([t.sub.a]) signifies instrument measurement time; and ([t.sub.r]) is equivalent to turnaround time. For continuous monitors, ([t.sub.r]) approaches ([t.sub.a]). The equations illustrate relations among performance variables. The symbol f is read as "function of."

[paragraph] Axiom 1. Patient outcome ([OMEGA]) depends fundamentally on optimization of decisions ([D.sub.i]) and performance variables ([P.sub.ij]) affected by those decisions, including financial ones:

[Mathematical Expression Omitted]

[paragraph] Axiom 2. Morbidity and mortality (M) decrease as diagnostic and therapeutic efficiency increase:

M = [f.sub.2] ([epsilon.sub.d], [epsilon.sub.t)

[paragraph] Axiom 3. Diagnostic efficiency increases as the cluster effectiveness of tests or other diagnostic procedures increases and response time decreases:

[epsilon.sub.d] = [f.sub.3]([e.sub.c], [t.sub.r])

[paragraph] Axiom 4. For a critical care profile, optimum response time is met when the combination of analysis time and transit time, including the physical distance of the measurement from the patient, is minimized:

[Mathematical Expression Omitted]

The purpose of these axioms is to aid intelligent objectivity. For example, those who are about to dismiss the idea of obtaining point-of-care testing for their institutions simply because they feel startup costs will be too high should first evaluate the potential impact of such a program on performance variables and patient outcome. A strictly centralized laboratory may worsen patient outcome through confusion over test priorities and degradation of transit and analysis times, despite the lower marginal costs of tests performed in the centralized laboratory.

How well results from sets of necessary tests separate (rule in or rule out) differential diagnoses or motivate physicians to alter (start or stop) therapies is described in the term "cluster effectiveness." Morbidity and mortality decrease when diagnostic tests are clustered shrewdly and when results are received rapidly enough to speed diagnosis and therapeutic intervention.

Physician capture and getting results to physicians quickly reduce unnecessary tests, blind chases of insignificant abnormalities, and costly patient relapses. The axioms on the preceding page, although most pertinent to critical care, apply broadly to the hybrid laboratory, as will be discussed. Envision, perhaps 100 years from now, virtually immediate diagnosis and treatment permitted by the provision of continuous noninvasive biochemical data in vivo. Ask yourself how long you would want an emergency room physician to wait for critical test results if you arrived unconscious with no diagnosis.

* Strategies to optimize lab support for critical care. In the 1980s, satellite laboratories began to be placed in the operating rooms, emergency departments, and intensive care units (in order of decreasing frequency) of cardiac transplant centers and general medical centers.[1,2] These locations served surgery, trauma, and critically ill patients with benchtop whole blood instruments. Liver transplantation, which demands the most rigorous turnaround time (two to five minutes), was best served by either a workstation at the patient's bedside or a satellite laboratory near the transplant suite.[5]

The time required to transport a specimen is a major factor slowing overall turnaround time (Figure IV). Salem and coworkers[19] showed in data published in 1991 that bedside testing reduced turnaround time to one to five minutes and conserved patient blood volume. Other investigators,[1- 5,16-18,20] have shown that proximity of testing to patients dramatically decreases response time, facilitates immediate liability of results, increases diagnostic and therapeutic efficiency, and decreases morbidity.

Figure IV

Transportation time

versus analysis time

Transportation time was much longer than analysis time in each case shown, as revealed by turnaround times for blood gases and pH; potassium and sodium; and hematocrit. An incremental increase in the analysis time for electrolytes and hematocrit caused total turnaround time to rise more than turnaround time for blood gases and pH. These inefficiencies can be alleviated by implementing a critical care profile with a whole blood specimen analyzed at the point of care.

Because satellite laboratories, tube transport systems, and specimen couriers can influence response time, it is important to assess their relative efficiency when evaluating new systems. Specimen collection and transport were considered vital factors to emergency department laboratory turnaround time in a sample of 700 hospitals in the 1990 Q-probes report by the College of American Pathologists.[20] Satisfying clinicians' goals required a satellite laboratory if specimen transport time exceeded five minutes. A tube transport system improved efficiency; unless it optimally connected the clinical unit and the instrument site, however, the transit time achieved did not surpass that of directly controlled specimen collection and courier transport.

Median turnaround times from collection or ordering to receipt of results for potassium testing were 38, 31, and 23 minutes for serum (n = 474 hospitals), plasma (n = 216), and whole blood (n = 10), respectively.[20] Whole blood analysis, used by only 10 of the hospitals that were noted in the CAP study, was the fastest method.

The axioms, theory, and evidence presented above suggest strategies to optimize laboratory support for critical care (Figure V). A critical care profile[1,8] increases cluster effectiveness ([e.sub.c]) of tests by combining indicators that pivot differential diagnoses efficiently and guide crucial therapies. For example, high-quality trend monitoring of [K.sup.+], [Na.sup.+], [iCa.sup.+], [iMg.sup.++] glucose, hematocrit, [pO.sub.2], [pCO.sub.2], and pH is essential to intraoperative treatment during open heart surgery, while for an outpatient with renal failure, point-of-care results for [Na.sup.+], [K.sup.+], urea, and creatinine might save a day of routine dialysis.

Figure V

Strategies to optimize laboratory

support for critical care

Establish a critical care profile

* Fulfill clinical objectives

* Combine tests to improve efficiency

* Monitor vital functions

Select instruments designed for critical care

* Use direct whole blood measurement

* Conserve blood

* Eliminate centrifugation

Minimize response time

* Create patient proximity

* Reduce specimen transit time

* Report results immediately

In each case, whole blood instruments (minimum [t.sub.a]) close to patients (minimum [t.sub.r]) provide highly important tests faster (optimum [t.sub.r]). Whole blood measurement eliminates multiple sampling for blood gas and main laboratories and reduces preanalytical errors due to transport, centrifugation, splitting, and distribution of specimens to several instruments. Additionally, direct activity-based biosensor measurement improves accuracy. For new point-of-care testing programs, one cost-effective way to improve performance is to select a few key sites to create patient proximity, reduce specimen transit time, and report results immediately, thus facilitating physician capture. The net effect is increased diagnostic and therapeutic efficiency ([epsilon.sub.d], [epsilon.sub.t] leading to decreased morbidity and mortality (M) and improved patient outcome ([OMEGA]) with attendant economic benefits.

* Rapid response planning and implementation. Strategic planning of diagnostic testing must now focus on the patient,[21] respond to needs, and be site-specific. A critical care profile[1,8] targets clinical priorities that are determined by the rapid response team. Bedside testing provides higher-quality trend monitoring, faster treatment decisions, and lower hospitalization costs.[16-18] Turnaround time provides a very important indicator for continuous quality improvement.

An on-site licensed clinical laboratory technologist (medical technologist) must be on call continuously to back up point-of-care instrument operators, although some state statutes explicitly require licensed personnel to verify each result. The appropriateness of using clinical personnel to operate point-of-care instruments can be determined by consultation with the risk management team. Common sense dictates that licensure issues ultimately will be resolved in favor of the interests of the patient.

Initiating new bedside workstations, satellite laboratories, and interdepartmental services requires a management philosophy based on trust. Point-of-care testing is not only well established in cardiac transplant and many general medical centers,[1,2,19] but also probably inevitable for hospitals in which it has not yet been introduced. The need to consolidate disparate testing sites can give rise to disputes over changes related to management, staffing, and fiscal issues. Administrators can help by equitably distributing instruments, revenues, and staff and by recognizing that the costs of bedside testing should be weighed against the benefits of improved patient outcome.

Contributions by medical technologists toward assuaging anxiety include their technical leadership, training, credentials, and experience in providing quality assurance, workstation maintenance, and test selection. Ideally, point-of-care management recognizes the professional expertise of each speciality.

Whether internal agreement on responsibilities for point-of-care services should be sealed with a pact, letter of intent, memorandum of understanding, or contract depends on the hospital and setting. A pact is an earnest exchange of promises based on mutual trust. At the other extreme, a contract is written in such explicit terms as to be enforceable by law. Division of labor is stimulated by restrictions placed on testing by the Federal government and demands for documented quality assurance by accrediting agencies. Regardless of the hospital setting, for example, laboratorians tend to be comfortable with the evaluation of new instruments and extremely qualified to manage the comprehensive quality assurance program needed for point-of-care testing. Authorization of QA functions may require nothing more than extending protocols across interdepartmental lines.

A written document signed by laboratory directors, clinical department heads, and hospital executives can be used to formalize agreement regarding important factors listed in Figure VI. Funding for equipment, staff support, and testing privileges should be agreed upon at the outset. The term of the agreement also should be specified.

Figure VI

Factors on which hospital

leadership must reach consensus

Clinical objectives

* Critical care priorities

* Sites for point-of-care workstations

* Hybrid laboratory implementation

Strategic plan

* Testing and monitoring privileges

* Funding and accountability

* Space instruments, and staff

Administration

* Authority and responsibility

* Supervision and budgeting

* Accreditation and regulations

Continuous quality improvement

* Proficiency testing

* Performance indicators

* Clinical research

Participants include department heads, the directorship, and task forces representing physicians and administration. Although sophisticated techniques such as network planning and the critical path method can be used for implementing point-of-care testing,[22,23] management by objective[24] (MBO) is adequate. MBO can be defined as the setting of objectives and appraising them by results.[24] The MBO slate identifies the task as well as its status and deadline. MBO, which encourages participation, communication, and the tracking and updating of progress, is readily understood. Operations management can be tailored to the needs of the individual hospital by addressing essential factors listed in Figure VII.

Figure VII

Essential factors to address related

to operations management

Instrumentation

* Mobility, maintenance, and backup

* Point-of-care operator protocols

* "FAST QC" pattern recognition

Education

* Resources and documentation

* Clinician certification courses

* Annual renewal plan

Patient results

* Verification and reporting

* Communication and computerization

* Notification of critical results

Critical path analysis

* Transport systems

* Response times

* Emergency preparedness

JCAHO addresses three basic requirements: what instruments are used where, when, and how; who performs the tests; and documentation that written procedures, including quality assurance, are being carried out, and by whom. Policies regarding Federal, CAP, and state regulations should be communicated explicitly to avoid any unauthorized point-of-care testing.

* The hybrid laboratory. The goal of the hybrid laboratory is to improve patient outcome by reducing morbidity and mortality. The hybrid laboratory synthesizes diagnostic modalities from in vivo patient monitoring to remote test analyses to achieve better patient focus and efficiency.

Technological advances push testing closer to the patient, while rising expectations pull it in the same direction. Therefore, the hybrid laboratory is dynamic, operating from a well-placed foundation of satellite laboratories, bedside workstations, point-of-care instruments, patient monitoring, and the main laboratory; however, it is tempered by consolidated interdisciplinary management, consistent technical performance, comprehensive quality assurance, and the competence of those individuals who operate the instruments.

Point-of-care instruments will become smaller and smarter, eventually incorporating artificial intelligence, FAST QC (an acronym for Fingerprint-Analysis, Systems-testing Quality Control[13]) and three-dimensional graphics, to speed patient management as well as to verify instrument operation. As with the personal computer, access to testing is growing easier and less expensive. An objective of the hybrid laboratory is to guide this blossoming of technology while facing fiscal realities and the demands of accreditation, agencies.

The strategic plan for critical care testing in the hybrid laboratory calls for two identical whole blood instruments in each satellite site and two additional instruments in the main laboratory: one available for immediate replacement of an instrument with prolonged down time and one for technical validation of other instruments. The dual equipment provides local backup, flexibility, and continuity. Initially, critical care profiles can be established by extrapolating test needs from the historical trends described above, by satisfying clinical objectives established with unit directors, and by monitoring performance variables (indicators).

Mobile workstations should be used as needed to provide testing for emergency resuscitation, transplantation, or special procedures. Portable and hand-held instruments in different clinical units are overseen by the unified management team, which also oversees education, credentials, and quality assurance. It is best to introduce point-of-care workstations incrementally,[24] while developing a multidisciplinary hybrid staff and expanding QA to include new testing sites.

* A university hospital paradigm. Proximity to the patient is the most crucial factor reducing turnaround time in the paradigm of a university hospital setting, illustrated with a schematic drawing in Figure VIII. Each of the three satellite sites shown contains two or more whole blood instruments. Two more such instruments will be used as mobile workstations, backup, and technical reference. A flexible transport system should link key sites where the action is to improve efficiency, distribute workflow, and keep the number of satellite laboratories to a minimum. The combination of point-of-care testing, satellite laboratories, and a main laboratory, along, with the collaboration of several clinical departments, typifies the organization inherent in the hybrid laboratory. Such a laboratory includes staff from different disciplines, each of whom brings appropriate training and credentials to the performance of point-of-care tests.

Figure VIII

Paradigm for the layout

A new Stat laboratory on Level 2, contiguous with the transplant center and adjacent to the intensive care units, will provide-of-care testing in two to five minutes. General Stat services, on Level 2 above the ED, will move o the Stat lab when available. Whole blood instruments in satellite laboratories on Level 3 next to the intensive care nursery,[25] on Level 2 next to the operating rooms, and on Level 1 in the ED will, with the help of fast courier service, provide critical care profiles with a 10- to 12- minute average turnaround time throughout the 475-bed hospital (University of California, Davis, Medical Center). Other clinical laboratory departments are in a new building 600 yards from the main hospital.

* Conclusions. Advances in technology and point-of-care testing have driven the patient-focused hybrid laboratory to take the place of the strictly centralized laboratory, now obsolete (Figure IX). At the bedside, a critical care profile can be executed on a single high-priority whole blood specimen. Conventional methods are being selectively replaced by more accurate direct activity-based biosensor measurements. including fundamentally new measurements such as ionized calcium and ionized magnesium. Speed and conservation of blood volume necessitate the use of whole blood. Fewer, more important tests are available to physicians more quickly.

Figure IX

The hybrid laboratory: Emergence

and characteristics
Conventional Hybrid laboratory
laboratory (1980s) (1990s)
Centralized Patient-focused
Separate samples Critical care profile
Confusion Whole blood priority
Slow, high-volume Fewer, more important
panels tests faster
Data overload Diagnostic synthesis
Laboratory turnaround Therapeutic
time turnaround time
Cost analysis by Cost-effectiveness
function from patient outcome


No longer burdened by having too many results too late, physicians can synthesize a diagnosis and treat the patient within a realistic therapeutic turnaround time. Fundamental axioms providing a theoretical basis for the hybrid laboratory relate conventional laboratory functions to point-of-care testing. They predict, for example, that immediate availability of point-of-care test results will decrease mortality due to cardiac arrest.[26] Eventually, in vivo bio-chemical monitoring and real-time biosensor telemetry[27,28] will replace discrete sampling.

What appears extraordinary today will be ordinary tomorrow. By breaking through to advanced frontiers of quality and clinical responsiveness, the hybrid laboratory will improve patient outcome in significant ways.

[1.] 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. [2] Kost. G. J. Role of new whole blood analytical techniques in critical care. Clin. Chem. 35: 1232-1233, 1989, [3.] Kost, G.J. The impact of whole-blood testing on response time: A challenge for the new College of American Pathologists Q-Probes program. Arch. Pathol Lab. Med 114:921-922, 1990. [4.] Kost, G.J. New stat laboratory instrumentation: We can and should satisfy clinicians' demands for rapid response. Am. J Clin. Pathol. 94: 522 523, 1990. [5.] Kost, G. J.; Jammal, M.A.; Ward, R.E., et al. Monitoring of ionized calcium during human hepatic transplantation: Critical values and their relevance to cardiac and hemodynamic management Am. J. Clin Pathol. 86: 61-70, 1986. [6.] Kost, G.J. The challenges of ionized calcium: Cardiovascular management and critical limits. Arch. Pathol. Lab. Med. 111: 932-934, 1987. [7.] Kost, G.J. lonized calcium: Cardiac significance, critical limits and clinical challenges (abstract). Clin. Chem. 38(6):926-927, 1992. [8.] Kost, G.J. Wiese, D.A.; and Bowen, T.P. New whole blood methods and instruments: Glucose measurement and test menus for critical care J. Int. Fed. Clin. Chem. 3:160-172, 1991. [9.] Kost, G.J. Ionized magnesium: Measurement and clinical indications National Meeting Roundtable, American Association for Clinical Chemistry, Chicago, July 1992. [10.] Fogh-Anderson, N.. Wimberley, P.D.; Thode, J.; et al. Direct reading glucose electrodes detect the molality of glucose in plasma and whole blood. Clin. Chim. Acta 189: 33-38, 1990. [11.] Kost. G.J. Accurate and efficient diagnosis of hyperosmolar coma. Audio-Digest Int. Med. 38(10), May 22, 1991. [12.] Kost, G.J. New whole-blood analyzers and their impact on cardiac and critical care. Crit. Rev. Clin. Lab. Sci. (in preparation). [13.] Kost, G J. Evans, B.D. Biltz, J.H. et al. Pattern recognition ("finger-printing") for continuous quality improvement of point-of-care whole blood testing. Proceedings of the Oak Ridge Conference on Analytical Concepts for the Clinical Laboratory, San Diego, April 1992. [14.] Kost. G.J. Critical limits for urgent clinician notification at U.S. medical centers JAMA 263: 704-707, 1990. [15.] Kost G.J. Critical limits for emergency clinician notification at United States children's hospitals. Pediatrics 88: 597-603, 1991. [16.] 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. [17.] Zaloga, G.P. Evaluation of bedside testing options for the critical care unit Chest 97S: 185S-190S, 1990. [18.] Zaloga, G.P. Monitoring versus testing technologies: Present and future. MLO 23(9S): 20-31, September 1991. [19.] Salem, M.; Chernow, B.. Burke, R., et al. Bedside diagnostic testing: Its accuracy rapidity, and utility in blood conservation. JAMA 266: 382 389, 1991. [20.] Cembrowski, G.S., and Steindel, S. Emergency department turn around-time Q-probes 90-13A, pp. 1-11, and Preliminary Report of Results, pp. 1-20. Northfield, Ill., College of American Pathologists, 1990. [21.] Sazama, K. Stat testing in the new CLIA era. MLO 3(12): 22-24, December 1991. [22.] Kost. G.J. Theory of network planning for laboratory research and development. Am. J. Clin. Pathol. 79: 353-359, 1983. [23.] Kost, G J. Application of Program Evaluation and Review Technic (PERT) to laboratory research and development planning. Am. J. Clin Pathol. 86: 186-192, 1986. [24.] Kost, G.J. Management by objectives for the academic medical center Am. J. Clin Pathol. 86: 738 744, 1986. [25.] Fletcher. A.B. The essential role of the laboratory in the optima care of the sick neonate J. Int. Fed Clin. Chem. 2: 166-172, 1990. [26.] Bedell. S.E., Dietz, D.C.; Leeman, D.; et al. Incidence and characteristics of preventable iatrogenic cardiac arrests. JAMA 265: 2815-2820, 1991. [27.] Halbert, S.A. Intravascular monitoring: Problems and promise Clin. Chem. 36: 1581-1584, 1990. [28.] Rolfe, P. In vivo chemical sensors for intensive-care monitoring. Med. Biol. Eng Comp. 28: B34-B46, 1990.
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Title Annotation:Special Supplement: Point-of-Care Testing
Author:Kost, Gerald J.
Publication:Medical Laboratory Observer
Date:Sep 1, 1992
Words:5404
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