Download Point-of-Care Testing: Millennium Technology for Critical Care

CE UPDATE—POINT OF CARE III
Richard F. Louie
Zuping Tang, MD
David G. Shelby, MT
Gerald J. Kost, MD, PhD
Point-of-Care Testing:
Millennium Technology
for Critical Care
ABSTRACT Point-of-care testing (POCT) is an important
diagnostic tool used in various locations in the hospital,
especially in critical care settings such as the intensive care
unit (ICU), the operating room (OR), and the emergency
department (ED).
This is the third article in a 4-part continuing education series on point-of-care
testing. After reading this article, the reader will be able to define POCT, identify its
advantages and disadvantages, explain its benefits in critical care settings,
understand key features in current point-of-care instruments, identify when a pointof-care test may be inaccurate, and recognize important quality management
features of point-of-care instruments.
From Point-of-Care
Testing Center for
Teaching and
Research
(POCT•CTR), School
of Medicine,
University of
California, Davis.
Address
correspondence to:
Mr Richard F. Louie,
Medical Pathology,
3453 Tupper Hall,
School of Medicine,
University of
California, Davis,
Davis, CA 95616.
E-mail:
[email protected]
402
Laboratory test results are often pivotal to critical care
decisions.1 Testing provides physicians with valuable
knowledge about the criticality of the patient so that
appropriate therapeutic interventions can be made
quickly. There has been growing interest in decentralized laboratory testing, especially point-of-care testing (POCT) in critical care settings (eg, ICU, OR, ED)
where rapid therapeutic turnaround time is
needed.2,3 However, some types of POCT are controversial because of concern about the accuracy and
performance of instruments when used with critically ill patients (ie, glucose meter testing).4,5
Point-of-Care Testing Defined
Point-of-care testing is defined as “testing at or
near the site of patient care whenever the medical
care is needed.”6 The purpose of POCT is to provide immediate information to physicians about
the patient’s condition, so that this information
can be integrated into appropriate treatment decisions that improve patient outcomes, that is,
reduce patients’ criticality, morbidity, and mortality. Point-of-care testing can be performed in different environments, such as in the hospital, at
home, or at other locations.
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Types of Point-of-Care Instruments
Point-of-care instruments vary widely and can be categorized as “transportable,” “portable,” or “handheld,”
based on the format. Some are capable of testing specific analytes, while others are capable of performing
an array of tests (eg, electrolytes and blood gases).
Tables 1 and 2 list test parameters and specifications of
the latest whole-blood analyzer/biosensor platforms
and handheld/portable glucose meters, respectively.
Point-of-care instruments differ by their
method of testing. For example, whole-blood glucose meters are categorized as “electrochemical
biosensor,” “reflectance
photometry,”
or
“absorbance photometry.” These instruments are
further differentiated by the type of chemistry used
to measure the glucose: either glucose oxidase or
glucose dehydrogenase enzymes.
Advantages of Point-of-Care Testing
Table 3 summarizes some of the advantages of
POCT. The first advantage of POCT is the short
therapeutic turnaround time of patient sample testing.7,8 The average turnaround time expected by
critical care physicians is 5 to 15 minutes.1 Stat tests
are frequently requested in critical care units.
Depending on the instrument used, the type of test,
and the number of tests performed, the analysis time
of a whole-blood sample can vary from 15 seconds
to 2 minutes 20 seconds (Tables 1 and 2). Delays
could yield results that do not reflect the patient’s
current condition. One benefit of rapid therapeutic
turnaround time is that it allows physicians to begin
implementing appropriate treatment early, especially
for those patients in critical care units where delays
can adversely affect patient outcomes.
A second advantage to POCT is potential reduction of preanalytic and postanalytic errors. Traditional methods of laboratory testing involve multiple
preparatory steps. With increased process steps, there
is an increased possibility of introducing preanalytic
Table 1. Characteristics of Whole-Blood Analyzers
Sample
mL)
Volume (m
65 or 95
Analysis Time
(seconds)
Test Analytes (measured)
90-140
pO2, pCO2, pH, Na+, K+, Ca++,
Cl-, Hct, urea nitrogen, glucose,
lactate, creatinine
Manufacturer
Abbott Diagnostics,
Abbott Park, IL
Type
Handheld
AVL Scientific,
Roswell, GA
Transportable
40-161
60-90
pO2, pCO2, pH, Na+, K+,
Ca++, Cl-, Hct, Hb, urea nitrogen,
glucose, lactate, creatinine
AVL OPTI
AVL Scientific
Portable
125
<120
pO2, pCO2, pH, Na+, K+, Ca++, Cl-, Hb
Rapid Lab 800
series †
Bayer Diagnostics,
Norwood, MA
Transportable
140-175
85
pO2, pCO2, pH, Na+, K+, Ca++, Cl-,
glucose, lactate
IRMA SL
(series 2000)
Agilent Technologies,
St Paul, MN
Portable
125
90
pO2, pCO2, pH, Na+, K+, Ca++, Hct
HemoCue
B-Hemoglobin
HemoCue,
Mission Viejo, CA
Portable
10
45-60
Hb
Gem Premier
3000, 3001§
Instrumentation
Laboratory
Lexington, MA
Portable
135
<120
pO2, pCO2, pH, Na+, K+, Ca++, Hct,
glucose, lactate
AVL OMNI
†‡
Stat profile pHOX
SO2%, Hct, Hb
Nova Biomedical,
Waltham, MA
Transportable 40-70
Stat Profile
M/M7†
Nova Biomedical
Transportable
78-108
pO2, pCO2, pH, SO2%, Na+, K+, Ca++,
Mg++, Cl-, Hct, urea nitrogen, glucose,
lactate, creatinine
Nova series
(16)
Nova Biomedical
Transportable
85
Na+, K+, Cl-, Hct, TCO2, Hct, urea
nitrogen, glucose, creatinine
ABL 700
series †
Radiometer,
Westlake, OH
Transportable
55-195
80-135
pO2, pCO2, pH, Na+, K+, Ca++, Cl-,
glucose, lactate
ABL 70
Series
Radiometer
Portable
<180
<60
pO2, pCO2, pH, Na+, K+, Ca++, Hct
YSI 2300
Stat Plus
Yellow Springs
Instrument, Yellow
Springs, OH
Transportable
25
45
Glucose, lactate
85-190
385
45
pO2, pCO2, pH,
Portable indicates easily carried, usually with a built-in handle; transportable, equipment usually carried on a cart; pO2, blood oxygen tension; pCO2,
blood carbon dioxide tension; SO2%, oxygen saturation; TCO2, total carbon dioxide in blood; Na+, sodium; K+, potassium; Ca++, ionized calcium; Mg++,
magnesium; Cl-, chloride; Hct, hematocrit; Hb, hemoglobin.
* i-STAT test cluster capability is cartridge dependent.
†Co-oximetry available as a modular add-on.
‡AVL OMNI test cluster is instrument-model dependent.
§3100 includes optimal modular prothrombin time (PT), activated partial thromboplastin time (aPTT), and activated clotting time (ACT) tests.
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4
Point-of-care testing is convenient for clinicians,
because it can be performed quickly, and results are
readily available. As point-of-care test menus
expand, we will find that based on real-time clinical
need, POCT drives diagnostic testing. Current
point-of-care instruments are user friendly, which
allows nontechnically oriented or nonlaboratory
professionals to operate instruments. Many pointof-care devices are self-contained with on-screen
instructions, which promote ease of use. Several
point-of-care devices are low maintenance because
they are self-contained, use disposable test cartridges, and the test cartridges are readily replaced.
Finally, POCT is advantageous because of the
small sample volume required to perform a test.
Patients potentially lose 25 to 125 mL of blood each
day, or up to 944 mL of blood per hospital stay
through phlebotomy for traditional centralized laboratory testing.8-10 Oftentimes, in the OR, ICU, and
Section
errors.1 Some common preanalytic and postanalytic
errors associated with traditional laboratory testing
are listed in Table 4. Delays in specimen processing
and testing may allow samples to degrade. The subsequent testing may yield results that do not represent the actual status of the patient. This is especially
true when blood gases, pH, and glucose are tested.
Performing tests immediately at the bedside minimizes both preanalytic and postanalytic errors,
because bedside testing eliminates time delays due to
specimen transportation and multiple persons handling a patient specimen. Postanalytic errors can be
minimized because results from bedside testing are
immediately available to the clinical team and can be
printed out or stored in memory by the instrument.
Furthermore, the results are recorded directly onto
the patient’s chart.
Scientific Communications
Instrument
i-STAT*
403
Table 2. Characteristics of Glucose Monitoring Devices
Instrument*
HemoCue B-Glucose
Manufacturer
HemoCue, Mission Viejo, CA
mL)
Sample Volume (m
5
Analysis Time (seconds)
< 90, if [Glu] < 140 mg/dL
< 240, if [Glu] < 400 mg/dL
Precision PCx‡
Precision G
Abbott Diagnostics, Bedford, MA
3.5
20
Abbott Diagnostics
3.5
20
Precision QID
Abbott Diagnostics
3.5
20
SureStepPro
LifeScan, Milpitas, CA
10
15-45
One Touch Hospital
LifeScan
10
45
FastTake
LifeScan
2.5
15
Glucometer Elite
Bayer, Elkhart, IN
5
30
Accu-Chek Advantage H
Roche Diagnostics, Indianapolis, IN
9-14
45
Accu-Chek Comfort Curve
Roche Diagnostics
4
45
* Systems use handheld meters and glucose test strips, except the HemoCue B-Glucose, which is a portable analyzer that uses a
cuvette and photometric absorbance to measure glucose. The SureStepPro and One Touch Hospital test strips use photometric
reflectance. Test strips for the other systems incorporate electrochemical (amperometric) biosensors for glucose measurement.
GO indicates glucose oxidase; GD, glucose dehydrogenase. Test limitations are those provided by the manufacturers and list the
recommended test conditions to yield the optimal results.
ED, there is demand for frequent serial whole-blood
testing. Serial testing of patients with respiratory failure or distress, acid-base imbalance, or surgery provides useful trend monitoring, which is helpful when
determining whether current therapy is effective. Serial
whole-blood testing may be as frequent as every 15 to
30 minutes during open heart surgery. Such frequent
laboratory testing results in extensive blood loss, which
could lead to unwarranted transfusions as well to
unforeseen health complications (eg, transfusionacquired illness, infections, and iatrogenic anemia). In
the treatment of critically ill patients, minimizing
blood loss is of utmost importance.8,11,12 Point-of-care
instruments are capable of providing a cluster of tests
with minimal blood loss (as low as 40 µL), depending
on the instrument used and the test performed. Current point-of-care instruments can provide up to 14
simultaneously measured test parameters (Table 2).
This strategy conserves blood and minimizes health
complications and unnecessary transfusions.12
Disadvantages of Point-of-Care Testing
Table 3 summarizes some of the disadvantages of
POCT. A concern that arises with POCT is the accuracy and performance of the instrument when used
in critical care settings. One important question is
whether interfering substances in the specimen can
affect instrument performance. This concern is
especially true in critical care, where changes in
blood gases, pH, glucose, and medication levels can
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pose a potential problem to whole-blood biosensors. Although studies13,14 have documented the
accuracy of point-of-care test results compared with
that of laboratory test results, the accuracy of smallerformat devices remains controversial (eg, bedside
glucose testing with handheld devices). Recent studies4,5,15,16 have documented the potential effects of
high or low blood oxygen tension, hematocrit, and
pH levels, which could cause handheld glucose
meters to report higher or lower glucose values.
Because the responsibility of POCT in critical care
is usually assigned to nonlaboratory professionals,2,17
another concern with POCT is whether measurements by nonlaboratory professionals (eg, nurses,
physicians) are accurate compared to measurements
by laboratory professionals. Studies have reported
that measurements obtained by nonlaboratory professionals with the proper training can be as accurate
as those obtained by laboratory professionals.14,18
Measurements generally are accurate if operators
have been properly trained in quality assurance and
instruments are properly maintained.
There is additional concern that nonlaboratory
professionals may not have adequate understanding
or appreciation of the significance of quality control
and quality assurance for testing devices.2,17 Nonlaboratory professionals may not take adequate responsibility for quality management and performance
enhancement, thereby potentially affecting patient
results. Therefore, it is important that the hospital
team (ie, physicians, nurses, medical technologists,
Test Limitations
Linearity (mg/dL) †
0-400
Chemistry
GO
Hct (%)
None
pO2 (mmHg)
None
None
20-600
GO
20-70
None
20-600
GO
20-70
None
20-600
GO
20-70
None
0-600
GO
25-60, adults
25-65, neonates
None
0-600
GO
25-60, adults
25-76, neonates
25-76, [Glu] ≤ 150mg/dL§
> 60, [Glu] < 150 mg/dL §
< 45, [Glu] > 150 mg/dL
20-600
GO
30-55
None
20-600
GO
20-60
> 55, [Glu] < 300 mg/dL
None
10-600
GD
20-65, [Glu] < 200 mg/dL
20-55, [Glu] > 200 mg/dL
None
10-600
GD
20-65, [Glu] < 200 mg/dL
20-55, [Glu] > 200 mg/dL
None
† The
Table 3. Advantages and Disadvantages of Point-of-Care Testing
Advantages
Reduced therapeutic turnaround time of diagnostic testing
Rapid data availability
Reduced preanalytic and postanalytic testing errors
Self-contained and user-friendly instruments
Small sample volume for a large test menu
Shorter patient length of stay
Convenience for clinicians
Ability to test many types of samples (ie, capillary, saliva, urine)
Disadvantages
Concerns about inaccuracy, imprecision, and performance
(ie, potential interfering substances)
Bedside laboratory tests performed by poorly trained
nonlaboratorians
Quality management/assurance issues and responsibilities
not defined
Cost of point-of-care testing compared with traditional
laboratory testing
Quality of testing is operator-dependent
Difficulty in integrating test results with hospital information
system (HIS) or laboratory information system (LIS)—
lack of connectivity
Narrower measuring range for some analytes
Improvement Amendments of 1988 (CLIA ’88).
Compliance with the Joint Commission on Accreditation of Healthcare Organizations (JCAHO, Oakbrook Terrace, IL) or College of American
Pathologists (CAP, Northfield, IL) regulations is voluntary. All medical institutions must comply with
state laws. These laboratory testing regulations help
to ensure the high-quality performance of the
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respiratory therapists, and pathologists) know the
proper operating procedures and limitations of their
point-of-care testing instruments, whether they are
testing for glucose, electrolytes, blood gases, cardiac
markers, coagulation indices, or other analytes. Hospital staff working with these instruments should be
familiar with and responsible for quality management of their instruments, to ensure the reliability of
the patient test results.
Administrative staff (ie, nurse managers, coordinators of point-of-care testing programs, and managers of quality assurance programs) should keep
up-to-date with proficiency testing of operators of
point-of-care instruments at their facility as well as be
able to train new operators and assess operators’
competence. Quality management deals with measures taken by operators of point-of-care instruments
to ensure that instruments are accurate and performing optimally. Compromising the accuracy and precision for expeditious testing is not recommended.
Each medical institution should have its own quality
assurance committee that is responsible for the competence of operators and for decisions about
expected performance standards of the entire testing
cycle. Additionally, operators must take necessary
measures to comply with regulations.
To regulate the performance of laboratory testing
(including point-of-care testing), the federal government requires that each medical institution meet the
standards established by the Clinical Laboratory
4
§
equation to convert to SI units is: mmol/L = mg/dL 3 0.05551.
Handheld device for measurement of glucose and ketones planned.
Hematocrit limits apply to neonate samples only.
Section
‡
405
Table 4. Preanalytic and Postanalytic Errors
Preanalytic errors
Mishandling and/or mislabeling of patient specimen
Contamination of specimen
Degradation of specimen due to delays in specimen
processing/testing and/or arrival at central laboratory
Postanalytic errors
Misreporting patient test results
Recording wrong patient test results
Lost data
Delayed reporting of critical results
Table 5. Cost Factors in Point-of-Care Testing
Supplies (eg, reagents, disposable cartridges, test
strips) and equipment
Training and retraining of instrument operators
Maintenance of instruments, including replacing
defective instruments
Additional labor on the part of nonlaboratorians
(eg, nurses) to run patient tests
New software that enables patient results to be entered
into hospital/laboratory information systems (HIS/LIS)
Troubleshooting instruments
Consultation services for instrumentation problems
Performing comparison studies of new instruments
and methodologies with existing instruments
Accreditation and proficiency testing fees
Duplication, repeated tests, verification, and validation
instruments as well the proper practice of diagnostic testing by
the operators.
Quality control compliance is one of the many quality
management monitors used routinely with POCT devices.
The Figure illustrates documentation of QC compliance rates
of critical-care operators and all other operators of point-ofcare devices at the University of California, Davis, Health System (UCDHS). As part of the quality assurance and
performance-improvement program at UCDHS, an e-mail
progress report is issued monthly to nurse supervisors of each
department by the pathology POCT manager. The report
provides an assessment of the overall QC compliance rate of
that department and compares the department’s performance
to the rest of the hospital. If the department compliance rate
falls below the rest of the hospital, a message in the e-mail
emphasizes the necessity for improvement to meet JCAHO
and CLIA guidelines. Performance has improved steadily with
the electronic broadcast approach.
Finally, there is growing debate about the cost-effectiveness
of POCT. It has been argued that the cost for POCT compared
to centralized laboratory testing may be less, more, or may
show no difference.19,20,21 Table 5 lists some factors that contribute to the costs of POCT. While it appears that POCT may
be more expensive than laboratory testing, some argue that the
benefits of POCT—the small sample volume12 and short therapeutic turnaround time7—could shorten the length of
patient stay or offset the costs of POCT—or both. POCT in the
operating room is cost-effective for hemostasis evaluation and
transfusion management.22 In some cases, such as rapid
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parathyroid hormone (PTH) testing for parathyroid surgery,
speed alone is crucial in saving operating room time and
reducing the length of hospitalization.23 Recent studies
demonstrated that point-of-care testing can reduce the length
of hospital stay24 and time in the emergency department,25 but
further study is needed to validate these results.
Technology of Whole-Blood Biosensors
Whole-blood analyzers currently use both electrochemical
sensors and other methods (ie, optical sensors) for specimen
analysis. Electrochemical sensors are categorized as either
potentiometric or amperometric and include the ion-selective
electrode (ISE) and substrate-specific electrode (SSE). The
electrical conductance (impedance) sensor (ECS) is used to
measure hematocrit indirectly. Optical sensor technology
includes spectrophotometry, absorbance photometry, and
reflectance photometry. Table 6 lists analytes commonly tested
with these methods. Ion-selective electrodes operate by determining the electrical potential (relative to the reference electrode potential) established by ions across selectively
permeable membranes. The difference in potential across the
membrane is logarithmically proportional to the specific ion
concentration (activity) in the blood.
The operation of a substrate-specific electrode is illustrated
when testing for glucose using the YSI 2300 Stat Glucose/Lactate
Analyzer. Glucose is oxidized with the catalysis of glucose oxidase
to form gluconic acid and hydrogen peroxide. Hydrogen peroxide subsequently becomes oxidized, and a platinum electrode
measures the current that forms. The current formed is proportional to the glucose (substrate) concentration (molality). The
electrical conductance sensor operates by measuring the impedance of the current flow in the sample. The impedance of the
current is measured by applying an alternating voltage across 2
or more electrodes in contact with the blood sample.
Features of Current Whole-Blood Point-of-Care
Analyzers and Glucose Meters
Notable features of point-of-care instruments include
expanded test options, shortened analysis time, reduced sample
test volume, and automated quality management. Current
instruments are able to measure up to 14 different tests per
sample of blood, compared to the 8 to 11 tests in previous generations. Many of the current instruments require a small
blood volume to perform a test—as little as 2.5 µL for a single
measurement on a handheld glucose meter, or as little as 40 µL
for 1 or 2 measurements, such as glucose and lactate, on a
whole-blood analyzer. The analysis time can be as rapid as 15
seconds for a single measurement, or 45 seconds for a multipleparameter test; hence, shortening the therapeutic turnaround
time. The latest whole-blood analyzers have the capability of
providing selective testing; that is, the operator may select the
tests to be performed, thereby eliminating unnecessary tests,
which can generate financial losses and waste patient blood.
100
90
80
Compliance Rate (%)
70
60
50
40
30
All critical care units
All hospital areas
20
10
Sep 99
Jul 99
Aug 99
Jun 99
Apr 99
May 99
Feb 99
Mar 99
Jan 99
Dec 98
Oct 98
Nov 98
Sep 98
Jul 98
Aug 98
Jun 98
Apr 98
May 98
Feb 98
Mar 98
Jan 98
0
Dec 97
Month/Year
Quality control (QC) compliance rates. QC compliance rates are shown as a
function of time for critical care settings and all hospital areas at the University of
California, Davis, Health System from January 1998 through September 1999. The
line for all critical care units is based on 14 different critical care settings, including
intensive care units, the operating room, and the emergency department. The line
for all hospital areas is based on 57 settings. The graph shows progressive
performance enhancement after instituting electronic mail broadcasting.
thus ensuring proper usage of the instrument. Some
instruments require that proper patient identification
be entered before testing can proceed. This action
ensures proper documentation of test results.
Future of Point-of-Care
Instruments and Testing
An important issue to address now about POCT is
the accuracy, performance, and reliability of these
Scientific Communications
Advanced quality management features also
appear on the latest instruments. Most wholeblood analyzers are equipped with automatic internal 1- and 2-point calibrations at various time
intervals ranging from every 15 minutes to every 2
hours. Some instruments have automatic or electronic QC (EQC). Automatic QC ensures that QC
testing is performed routinely at regular intervals.
The purpose of EQC is to test the electronics; that
is, the internal and analyte circuits of the instrument. However, EQC doesn’t validate the performance of the test cartridges or of the operator. EQC
can help generate cost savings because it is convenient, can be completed quickly, is reagentless,
requires only a reusable EQC card, and is a beneficial feature that assesses the electronic measurement cycle of the instrument. It is important to
realize that manufacturers of instruments with the
EQC feature do not recommend substituting EQC
for aqueous QC. Aqueous and electronic QC
should both be performed.
A QC “lockout” feature, when enabled, does not
allow the operator to perform any patient testing
unless quality control testing has been performed and
has satisfied the vendor-specified QC ranges. Other
lockout and security features include a password
option, which must be entered by a certified operator
before the instrument can be used for patient testing,
Table 6. Methods for Analyte Measurements
Substrate-Specific
Electrode (SSE)
No
Mg++
Yes
No
K+
Yes
No
No
No
Cl–
Yes
No
No
No
No
Analyte-Specific Optical
Sensor (ASOS)
No
No
Na++
Yes
No
No
No
pH
PCO2
Yes
CO2-sensitive buffer,
with pH electrode
No
No
No
No
Yes
Yes
pO2
No
Amperometric
No
Yes
Glucose
No
Yes
No
No
Lactate
No
Yes
No
No
Urea Nitrogen
No
Yes
No
No
Creatinine
No
Yes
No
No
Hematocrit
No
No
Yes
No
Hemoglobin
No
No
No
Multiwavelength
reflectance
Acid displacement,
CO2-sensitive buffer,
with pH electrode
No
No
No
No
No
Optical reflectance
Total CO2
O2 saturation
No
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Analyte
Ca++
Section
Method
Electrical Conductance
Sensor (ECS)
No
Ion-Selective
Electrode (ISE)
Yes
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instruments for patient testing in the critical care setting. More study is needed to examine the limitations of these instruments and to resolve any
potential error sources (eg, interfering substances)
that may affect instrument performance. However, in regard to short-term advances with pointof-care technology, we will see continued
expansion of test menus, shorter analysis time,
and reduced sample volume. For example, several
devices are now available for hemostasis testing at
the point of care,26 for other point-of-care analytes not listed in Table 1 (eg, ß-hydroxybutyrate,
therapeutic drugs, and drugs of abuse), and for
cardiac-injury markers (eg, troponin I, CK-MB,
and myoglobin). Several additional point-of-care
analytes are under development.
Additionally, POCT will be “connected” in the
near future. Test results will be downloaded and
recorded readily into the hospital and laboratory
information system (HIS/LIS). The first meeting of
the Connectivity Industry Consortium (CIC) on
POCT was held October 20, 1999, in Redwood City,
CA, to facilitate this process. The CIC members set a
goal of writing and publishing connectivity standards
for near-patient and point-of-care instruments by
the end of the year 2000.
Point-of-care testing undoubtedly will take a more
active role in critical care settings. It will be used more
for on-site diagnostic testing and trend monitoring of
patient conditions, due in part to the increasing percentage of critically ill patients in hospitals, the need for
shorter therapeutic turnaround time, and bidirectional
connectivity of transportable, portable, and handheld
devices. While POCT may not necessarily replace centralized laboratory testing, it is becoming an important
modality for improving patient care and outcomes.l
Acknowledgments
The authors would like to acknowledge Joan Bullock for her
contribution of information and insights into the Quality
Assurance Program at the University of California, Davis,
Health System, and thank the vendors for providing information on their products.
References
1. Harvey MA. Point-of-care laboratory testing in critical
care. Am J Crit Care. 1999;8:72-83.
2. Lamb LS, Parrish RS, Goran SF, et al. Current nursing practice of point-of-care laboratory diagnostic testing in critical
care units. Am J Crit Care. 1995;4:429-434.
3. Kost GJ, Ehrmeyer SS, Chernow B, et al. The laboratory-clinical interface: point-of-care testing. Chest. 1999;115:1140-1154.
4. Kost GJ, Vu H, Lee JH, et al. Multicenter study of oxygeninsensitive handheld glucose point-of-care testing in critical
care/hospital/ambulatory patients in the United States and
Canada. Crit Care Med. 1998; 26:581-590.
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5. Louie RF, Tang Z, Sutton DV, et al. Point-of-care testing:
effects of critical care variables, influence of reference instruments, and a modular glucose meter design. Arch Pathol Lab
Med. 2000;124:257-266.
6. Kost GJ. Guidelines for point-of-care testing: improving
patient outcomes. Am J Clin Pathol. 1995;104(suppl 1):S111S127.
7. Kilgore ML, Steindel SJ, Smith JA. Evaluating stat testing
options in an academic health center: turnaround time and
staff satisfaction. Clin Chem. 1998;44:1597-1603.
8. Chernow B, Salem M, Sacey J. Blood conservation: a critical care imperative. Crit Care Med. 1991;19:313-314.
9. Zimmerman JE, Seveff MG, Sun X, et al. Evaluating laboratory usage in the intensive care unit: patient and institutional
characteristics that influence frequency of blood sampling. Crit
Care Med. 1997;25:737-748.
10. Peruzzi WT, Parker MA, Lichtenthal PR, et al. A clinical
evaluation of a blood conservation device in medical intensive
care unit patients. Crit Care Med. 1993;21:501-506.
11. Chernow B. Blood conservation in critical care: the evidence accumulates. Crit Care Med. 1993;21:481-482.
12. Salem M, Chernow B, Burke, et al. Bedside diagnostic
testing: its accuracy, rapidity, and utility in blood conservation.
JAMA. 1991;266:382-389.
13. Wahr JA, Lau W, Tremper KK, et al. Accuracy and precision of a new, portable, handheld blood gas analyzer, the
IRMA. J Clin Monit. 1996;12:317-324.
14. Zaloga GP, Roberts PR, Black K, et al. Hand-held blood
gas analyzer is accurate in the critical care setting. Crit Care
Med. 1996;24:957-962.
15. Tang Z, Lee JH, Louie RF, et al. Effects of different hematocrits on glucose measurements with handheld meters for
point-of-care testing. Arch Pathol Lab Med. In press.
16. Tang Z, Du X, Louie RF, et al. Effects of pH on glucose
measurements with handheld glucose meters and portable glucose analyzer for point-of-care testing. Arch Pathol Lab Med.
2000;124:577-582.
17. Lamb LS. Responsibilities in point-of-care testing: an institutional perspective. Arch Pathol Lab Med. 1995;119:886-889.
18. Zaloga GP, Dudas L, Roberts P, et al. Near-patient blood
gas and electrolyte analyses are accurate when performed by
non-laboratory-trained individuals. J Clin Monit.
1993;9:341-346.
19. Kilgore ML, Steindel SJ, Smith JA. Cost analysis for decision support: the case of comparing centralized versus distributed methods for blood gas testing. Journal of Healthcare
Management. 1999;44:207-215.
20. Halpern MT, Palmer CS, Simpson KN, et al. The economic and clinical efficiency of point-of-care testing for critically ill patients: a decision-analysis model. Am J Medical Qual.
1998;13:3-12.
21. De Cresce RP, Phillips DL, Howanitz PJ. Financial justification of alternate site testing. Arch Pathol Lab Med.
1995;119:898-901.
22. Depotis GJ, Santoro SA, Spitznagel E, et al. Prospective
evaluation and clinical utility of on-site monitoring of coagulation in patients undergoing cardiac operation. J Thorac Cardiovasc Surg. 1994;107:271-279.
23. Scott MG. Is faster better? An outcomes approach to
POCT implementation decisions. In: Managing Your POCT
Program for Success. Washington, DC: American Association
for Clinical Chemistry. Audio Conference, January 20, 2000.
24. Collinson PO. The need for a point of care testing: an evidence-based appraisal. Scand J Clin Lab Invest. 1999;59(suppl
230):67-73.
25. Murray RP, Leroux M, Sabga E, et al. Effects of point of
care testing on length of stay in an adult emergency department. J Emerg Med. 1999;17:811-814.
26. Kost GJ. Point-of-care testing. In: Meyer RA, ed. Encyclopedia of Analytical Chemistry: Instruments and Applications.
New York, NY: John Wiley and Sons; 2000, chap 540. In press.