Transcript Aucun titre de diapositive - Infomed, Portal de Salud de Cuba

Point-of-Care Testing: What does is really
mean today and is it relevant to the local
situation ?
Patrick St.Louis
Département de biochimie
Hôpital Ste-Justine et Université de Montréal
Montréal, Canada
SCPC, Havane, 2004
Point-of-Care Testing (POCT)  the analysis of
(biochemical) parameters at or near the patient’s bedside.
A new name for satellite lab testing ? ER, OR, ICU
Clinical benefit of POCT  reduces the time interval
between the decision to order the test and the clinical
action based on the test result (total turn-around time;
TAT)
test needed/request  specimen  lab  test/result  report
One classification of POCT
• in vitro (traditional)
 manual: urinalysis, occult blood
 instrumented: glucose meters, ACT, gases
• in vivo
 invasive e.g. pulmonary artery catheter
 non-invasive e.g. transcutaneous bilirubin, pulse
oximetry (transcutaneous)
• ex vivo
 in-line sensors; through an extracorporeal circuit
some examples
The present scope of POCT: Tests possible in the ER
• Blood gases, electrolytes, creatinine, lactate
• hemglobin/hematocrit
• cardiac markers: myoglobin, troponin, BNP - NPV for
Dx of CHF = 98%; precludes the need for echocardiography
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Coagulation: PT/INR, ACT, D-dimer
glucose
urinalysis, urine pregnancy test
hemoccult/gastroccult/pH
drugs screens
rapid HIV
How is POCT used and what are its advantages?
1. POCT for glucose:
• improves response time for
 high risk neonates with hypoglycemia,
 diabetics in hyperglycemia
 patients in Tight Glycemic Control protocols
• decreases iatrogenic blood loss - l of capillary blood
2.
Clinical applications of anticoagulation therapy
• OR - cardiac surgery, interventional cardiology and
radiology (heparin)
• critical care
• satellite sites: dialysis, ECMO, anticoagulation clinic
• Patients on coumadin/warfarin therapy
Monitoring anticoagulation therapy
treament
monitor with
• heparin (intrinsic pathway)
ACT, aPTT
• coumadin/warfarin
(extrinsic pathway)
• direct thrombin inhibitors
(common pathway)
• Thrombolytics (clot)
PT/INR
???
TT, fibrinogen
• POC coagulation testing for monitoring patient status
post-thoracic/cardiovascular surgery; studies have
shown that this permits the evaluation and
management of microvascular bleeding:
 complications
- blood loss
- need for blood and blood products
- re-operations (repeat surgery)
 overall cost of care
 satisfaction
Patients on coumadin/warfarin therapy:
• Monitor using PT/INR testing
• Patient self-testing a major direction with clear
advantages
There are Advantages and Problems related to the use of
instrumented POCT:
POSITIVES
 for the most part these POCT devices are robust and
easy to use; require minimal maintenance
 testing process is generally simple
 results are usually reliable
• Data management in instrumented POCT systems
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calibration curves, AMR
QC: lot information, automated QC
material information: strip lot numbers, parameters
identifiers: operator, patient
results: tests, QC, unique event time stamp
lock-out: operator and patient ID, QC demanded,
prohibits use of expired reagents
– have comment codes, response protocols
– notices and messages
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Issues with POCT devices
method characteristics : AMR (measuring range),
linearity, precision  usually not as good as central lab
sample type in relation to normal (reference) intervalsblood glucose: capillary/venous blood
plasma/whole blood
QC; operator attitude to QC
results and charting; ensuring that the information gets
to the Laboratory Information System and into the
patient chart - Connectivity
POSSIBLE CAUSES OF POOR PERFORMANCE
• novel technologies
– transcutaneous bilirubin: interferences, calibration
– hematocrit determination by conductivity
• interferences
– gel separator tubes
– drugs in patient samples
– Extraneal (icodextrin; a dialysis solution)- GDH-PQQ-based glucose
meters
• patient-related
– high hematocrit in neonatal samples for glucose
THE COST FACTOR
No standardised manner of calculating costs for POCT
Generally the cost/patient result is higher than the
corresponding central laboratory cost
Some factors:
•
reagent costs: the single-use disposable strip or cassette or
multi-test packs versus standard laboratory reagent packaging
in hundreds of tests; the incremental effects of utilisation on
costs  more costs less
• equipment costs: additional to central lab system
• labour costs: operators, coordinators,
• other: QC, training, re-certification, regulatory requirements
Cost can also be affected by the total number of tests;
demand for confirmation, correlations.
1. POCT for glucose; central laboratory volume (6 months):
pre-POCT = 20406; post-POCT = 24028; figures were not
related to bed occupancy or to patient mix; do not include
glucose meter (POC) testing (Lum, 1997)
Similar results from a recent study at HSC, Toronto
2. HSJ Glucometer program
projected annual workload:
40,000
actual year 2000:
patients = 35,459
controls = 22,931
actual total 58,390
QC and QA in POCT
Quality Control
POCT, like all laboratory testing, demands regular QC
testing to assure acceptable performance (CAP Qprobes)
 For single-use reagent test strips or cassettes - lot validation
 Instrumented, multitest systems - traditional QC procedures
 Electronic QC: these are simulators designed to monitor the
performance of the hardware/reader part of the system; they do
not evaluate the chemistry/reagent part of the system.
 iQM: used in the IL GEM 3000; FDA approved; a complex
algorithm using the same liquid material for QC and calibration
• Just as in traditional central laboratory testing, QA is
important in POCT; there are however some
different issues
With POCT
 variable number of individual devices; multiple sites;
 many operators; training?
 need clear protocols
 ensure appropriate QC practices; resistance to QC
 assure proper storage of reagents, supplies
 eliminate use of expired reagents, cassettes, slides, etc
 verify error-free operator and patient ID
 results: documentation and reporting
meters
September
no. of
ID # (%)
patients
October
no. of
ID # (%)
patients
November
no. of
ID # (%)
patients
2
95
71 (75%) 206
151 (73%) 163
142 (87%)
4
204
127 (62%) 208
119 (57%) 154
94 (61%)
1
68
45 (66%) 142
112 (79%) 157
129 (82%)
4
165
132 (80%) 488
384 (79%) 453
359 (79%)
1
12
3 (25%)
8
3 (38%)
10
9 (90%)
patient tests
control
ratio p/c
405
1466
1375
841
56
898
930
1090
1652
213
563
657
281
873
493
351
17
858
832
258
525
479
787
854
1,4
1,7
2,8
2,4
3,3
1,0
1,1
4,2
3,1
0,4
0,7
0,8
10146
6608
1.54
HOW CAN YOU OPTIMALLY USE POCT?
• manual tests are already used
• Common instrumented POCT types
 glucose meters
 blood gas analysers (electrolytes, creatinine, lactate)
 coagulation analysers
 cardiac marker systems
 urinalysis instruments
glucose meters
• personal or hospital type; relative complexity and
costs of instruments
• lack of QC and data handling capacity in P types
• reliability of results for close clinical management;
American Diabetic Association and NCCLS
guidelines  neither should be used for diagnosis.
• cost of strips; cost of QC material;
• Validation of instrument performance; NCCLS
guidelines for POCT performed outside lab support
• Blood gases; single use i-STAT and IRMA
• multi cassette ABL700 series
• GEM Premier series; more tests; reliable, less costly
on a per/test basis; wastage; how portable?
• co-oximetry: O2 sats, Hb and Hct assays, technology
Trends in POCT
MUCH OF POCT IS NO LONGER ACUTE
The introduction of new clinical standards is motivating
physicians to demand testing be done closer to the patient. (Dr. R.
Christenson, U. of Maryland)
Out-patient and specialty clinics
EVIDENCE BASED LABORATORY MEDICINE
NACB/AACC project for POCT  impact on patient outcomes;
looking at all areas gases, electrolytes, glucose, creatinine, coagulation, fertility, perinatal testing (fetal scalp pH, fern testing, pH testing for ruptured
membranes), transcutaneous bilirubin, cardiac markers, etc
CONCLUSIONS
Like the “Core Lab” concept, POCT is here to stay
? Is it more cost-effective?
? Better patient care
? more satisfaction: patient and caregiver
Newer paradigms
? is POCT now physician driven; is this any different
from the past?
Trends in evidence-based POCT