Automation Flashcards
(113 cards)
1
Q
Platelet Function Tests
A
○ Platelet Aggregometers
○ Platelet function Analyzers
○ Flow Cytometry
2
Q
Visual clot-based testing traces back to the
A
18th century
3
Q
Visual clot based initial observation
A
blood clotting from samples taken from
dogs and humans.
4
Q
Visual clot based Advancements
A
Temperature control during clot formation
5
Q
Visual clot based Observation methods
A
passing objects through blood and
using glass tubes evolved.
6
Q
First clot detection instrument
A
1910 - Koagulovis-kosimeter
7
Q
Koagulovis-kosimeter measures what?
A
measured blood viscosity change during clotting.
8
Q
Later development of visual clot based led to
A
thromboelastograph (TEG) and sonar clot detection
9
Q
Plasma coagulation testing began in? With addition of what?
A
1920
Addition of calcium chloride
10
Q
laid the foundation for PT and PTT assays.
A
Grams method
11
Q
Initial testing involved manual methods like ________
A
Tilt-tube technique
12
Q
First coagulometer
A
BBL Fibrometer in 1950s
13
Q
Subsequent developments included _____________ and __________
A
Rolling steel ball and Photo-optical measurements
14
Q
Modern instrumentation integrates
A
clot-based assays,
chromogenic assays
immunoassays for comprehensive testing
15
Q
Assay End–Point Detection Principles
A
Obeservation based
Feel based
16
Q
Utilizes “observation” of clot formation
A
Observation-Based End-Point Detection
17
Q
Commonly used in traditional coagulation instruments
A
Observation-Based End-Point Detection
18
Q
Observation-Based End-Point Detection uses what device?
A
Optical and nephelometric devices
19
Q
Detects clot formation by “feel”
A
Feel-based end-point detection
20
Q
Early instruments primarily relied on mechanical principles
A
Feel-Based End-Point Detection
21
Q
Feel-Based End-Point Detection uses what device
A
Mechanical and viscosity-based devices
22
Q
Technological Advancements
A
● Transition to photo–optical detection
● Fixed wavelength between 500 and 600 nm
● Integration of viscoelastic end–point detection for
specialty testing
23
Q
Modern Instrumentation
A
● Integration of multiple end-point mechanisms
● Incorporation of chromogenic and immunoassay-based testing
● Streamlining laboratory workflows for routine and
specialized testing need
24
Q
Measure a change in conductivity between two metal electrodes in plasma
A
Mechanical Clot End-Point Detection
25
first semi-automated instrument to be used routinely in the coagulation laboratory
BBL fibrometer
26
Has one stationary and one moving electrode
BBL FIBROMETER
27
BBL FIBROMETER Moving electrodes
enters and leaves (breaks the current between the electrodes) the plasma
at regular intervals
28
BBL FIBROMETER PRINCIPLE
○ When a clot forms, the fibrin strand conducts current between the electrodes even when the
moving electrode exits the solution. (stops the timer)
29
Another method that uses magnetic sensors that monitors the movement of a steel ball within the test plasma
Magnetic sensors
30
An electromagnetic field detects the oscillation of a steel ball within the plasma-reagent solution (fibrin formation increases viscosity and slows the movement until the oscillation decreases to a predefined rate — timer stops)
Magnetic sensors
31
MAGNETIC SENSORS
■ A steel ball is________________________. As the well rotates, the ball remains positioned on the incline and is only swept out as fibrin forms. The position is detected by a magnetic sensor. Timer stops as it moves away from the senso
positioned in an inclined well
32
Detect changes in plasma optical density (OD) during the clotting process
Photo-Optical Clot End-Point Detection
33
Light of a specific wavelength passes through the sample, and its intensity (OD) is recorded by a photodetector.
Photo-Optical Clot End-Point Detection
34
OD depends on
specimen color and clarity
35
Photo-Optical Clot End-Point Detection principle
Formation of fibrin strands causes light to scatter → less light to fall on the photodetector → increase in OD
● Timer stops when the OD rises to a predetermined variance from the baseline
Collim. l
36
Used to detect clot formation in the past and is still used today in particular instruments for whole blood clotting
Viscoelastic Clot Detection
37
Viscoelastic clot detection
Information can be obtained on:
○ The time of clot
○ Kinetics of whole blood clot formation
○ Clot strength
○ Fibrinolytic activity
38
Uses a synthetic small peptide substrate (three amino acids that matches the factor) conjugated to a chromophore
Chromogenic end-point detection
39
Chromogenic End-Point Detection uses what?
Para-nitroaniline or pNA
40
Measures the activity of a specific coagulation factor (exploits the factor’s enzymatic properties)
Chromogenic End-Point Detection
41
The factor cleaves the chromogenic substrate at the site binding the oligopeptide to the pNA, freeing the pNA
Chromogenic End-Point Detection
42
Colors
Free pNa
Bound pNa
Yellow
Clear
43
chromogenic End-Point Detection
● The OD of the solution is proportional to protease activity and is measured by a photodetector at
405 nm
44
OD is proportional to the activity of the analyte being measured
Direct chromogenic assay
45
Direct chromogenic assay example
Protein C activity
46
Protein or analyte being measured inhibits a target enzyme (has the activity toward the chromogenic
substrate)
Indirect chromogenic assay
47
○ OD is inversely proportional to the concentration or activity of the substance being measured
Indirect chromogenic assay
48
Indirect Chromogenic Assay: example
Anti-factor Xa assay
49
Chromogenic assay application
○ Measure specific coagulation factors’ activity
○ Assess inhibitors and quantitative substances like heparin
50
Chromogenic assay benefits
○ High specificity and sensitivity
○ Quantitative assessment of coagulation factors
○ Enables precise diagnosis and monitoring of coagulation disorders
51
Is a modification of photo-optical end-point detection in which 90-degree or forward-angle light scatter rather than OD is measured
Nephelometric End–Point Detection
52
Nephelometric End–Point Detection
A ______________ produces incident light at approx. ________, and a ___________ detects variations in light scatter at 90 degrees (side) and 180 degrees (forward)
Light-emitting diode 600 nm
Photodetector
53
Nephelometric End–Point Detection principle
Formation of fibrin polymers causes side and forward-angle scatter to rise. Timer stops as it reaches a predetermined intensity
54
Continuous readings throughout the clotting period
produce a clot curve or signature
Nephelometric End–Point Detection
55
Provides a quantitative assay of coagulation factors
Nephelometric End–Point Detection
56
Are based on antigen–antibody coagulation testing
Immunologic Light Absorbance End-Point
Detection
57
Uses light absorbance to detect an end-point
Immunologic Light Absorbance End-Point
Detection
58
Latex microparticles are coated with antibodies directed against the selected antigen, forming agglutinates that absorb light that is proportional to the antigen levels.
Immunologic Light Absorbance End-Point
Detection
59
Immunologic Light Absorbance End-Point
Detection principle
The increased in light absorbance is proportional to the size of the agglutinates, which in turn is proportional to the antigen level
60
Are useful to evaluate specimens from patients who have circulating inhibitors or who are on treatment
Chromogenic
61
Is isolated to the specific chemical (enzymatic) reaction in question rather than the entire coagulation cascade
Chromogenic
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specific than clot–based assays
Chromogenic
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Not affected by icterus or lipemia
Mechanical clot end–based methods
64
Able to detect weak clots (low fibrinogen or factor XIII deficiency)
Mechanical clot end–based methods
65
May be confounded by icterus or lipemia
Photo-optical clot end-point detection
66
All reagents and specimens are transferred manually by the operator.
Manual and semiautomated
67
Temperature is maintained by a water
bath or heat block;
Manual
68
external measurement by operator may be required.
Manual
69
End-point is determined visually by the operator.
Manual
70
Timer is initiated and stopped by the operator.
Manual
71
Manual example
Tilt tube
Wire loop
72
Instrument usually contains a device
for maintaining constant 37° C temperature.
Semiautomated
73
Analyzer may internally monitor temperature.
Semiautomated
74
Instrument has a mechanism to initiate a timing device automatically on addition of final reagent and a mechanism for detecting clot formation and stopping the timer.
Semiautomated
75
All reagents are automatically pipetted by the instrument.
Automated
76
Specimens may or may not be automatically pipetted.
Automated
77
Analyzer contains monitoring devices and an internal mechanism to maintain and monitor constant 37° C temperature throughout the testing sequence.
Automated
78
Timers are initiated and clot formation is detected automatically.
Automated
79
Automated coagulometers offer random access testing, allowing a variety of tests to be run in any order.
Random access training
80
● Visual methods necessitated duplicate testing to reduce the coefficient of variation, often exceeding 20%
● Fully automated instruments have significantly enhanced precision, eliminating the need for duplicate testing
● Coefficients of variation of less than 5% are typically achieved, reducing material and reagent costs by half.
Improved Accuracy and Precision
81
Previous analyzers required batching, limiting the number of assays that could be run simultaneously
Random Access Testing
82
Random access training
Current analyzers can run multiple tests limited only by _________________ and ____________________ methodologies
reagent storage capacity and end-point detection
83
Random acess training benefits
improved turnaround times, reduced errors, and decreased labor costs.
84
Reduced reagent and specimen volumes
Improved Reagent Handling
85
The ability to select reagents independently of the analyzer is a high priority
Open regent system
86
Keep records of reagent lot numbers and expiration dates, on–board monitoring of reagent volumes with flagging systems, and reagent barcoding
Reagent tracking
87
Open reagent system and reagent tracking belongs to what?
Improved Reagent Handling
88
Improved specimen anage is composed of
Primary tube sampling
closed tube sampling
Automatic dilutions
89
Eliminates the need to separate the plasma into the secondary tube
Primary tube sampling
90
Placement of the primary blood collection tube without removing the blue stopper (the cap is pierced by a needle in the instrument that
aspirates plasma)
Closed-tube sampling
91
Instruments often accommodate multiple tube sizes
Primary tube sampling
92
Eliminates cross-over between specimens
Closed-tube sampling
93
Significant time savings occur
Primary tube sampling
94
Reduces the risk to the staff of specimen exposure
Closed-tube sampling
95
Eliminates the need for the operator to perform tasks manually
Automatic dilutions
96
Expanded computer capabilities
Data storage and retrieval
Programming flexibility
Instrument interfacing
97
Quality control files stored, eliminating manual logging
Data Storage and Retrieval
98
Multiple calibration curves accessible
Data Storage and Retrieval
99
Quality control files stored, eliminating manual logging
Data Storage and Retrieval
100
Easily changeable testing parameters
Programming Flexibility
101
Preprogrammed test protocols
Programming Flexibility
102
User–programmable additional tests for enhanced flexibility
Programming Flexibility
103
Integration with laboratory information systems
Instrument Interfacing
104
Specimen bar coding for efficient tracking
Instrument Interfacing
105
Bidirectional interfaces for streamlined workflow
Instrument Interfacing
106
Alert operator when preset criteria have been exceeded for instrument performance and specimen quality
Flagging
107
Quality Features of Automated Assay
Performance
Flagging
Reflex testing
Kinetics of clot formtion
108
Is the automatic ordering of tests based on preset parameters or the results of prior tests
Reflex testing
109
final result does not need to wait for review by the operator before follow up action is initiated by the instrument
Reflex testing
110
graphing for enhanced analysis and
troubleshooting
Kinetics of clot formation
111
Specimen Quality Set Points
● Lipemia: will falsely prolong clotting time
● Icterus: will falsely prolong clotting time
● Abnormal clot formation: will falsely prolong clotting time
● Clotted: will falsely shorten clotting time
● Hemolysis: will falsely shorten clotting time
● No end-point detection: consider alternative testing methods
112
Selection of Coagulation Instrumentation
● Considerations for cost-effectiveness, testing capabilities, and standardization
● Identify testing needs based on patient population
● Collaboration with medical staff for test appropriateness
● Match instrument to anticipated workload
● Consider sending out esoteric or low-volume tests to reference laboratories
● Throughput of routine coagulation tests
● Additional features prioritization
● Specialized features consideration for advantageous capabilities
113
