coag pt.1 Flashcards
(150 cards)
1
Q
Who described a procedure called Prothrombin Time (PT) Test in the mid-1930s?
A
Dr. Armand Quick
2
Q
HISTORY:
DATE - PERSON/S - CONTRIBUTION
A
1905 - Paul Morawitz - comprehensive explanation of theory of coagulation
1913 - Dr. Roger Lee and Paul White - Lee and White Whole Blood Clotting Time
1930s - Dr. Armand Quick - Prothrombin Time
1950s - Blood from hemophiliacs (Normal PT, Inability to clot) - Partial Thromboplastin Time
3
Q
What is Prothrombin Time (PT) Test used for?
A
Evaluating the Extrinsic Coagulation System
4
Q
What test was developed in the 1950s as a result of studying blood from hemophiliacs?
A
Partial Thromboplastin Time (PTT) test
5
Q
CAPILLARY BLOOD METHODS: Intrinsic and Common Pathway and Optimal Coagulation time (Reference Range)
A
- Slide Method (2-6 minutes)
- Capillary Tube Method (2-6 minutes)
- Dale and Laidlaw Method (1-3)
6
Q
Explain the process of Dale and Laidlaw Method
A
- finger puncture
- record time
- allow blood to flow into capillary tube with lead bead
- incubate (water bath) @ 37C
- tilt tube until bead adhere to fibrin clot
- record time (stop time)
7
Q
Outcome/ Result of Dale and Laidlaw Method
A
Fibrin threads
8
Q
VENOUS BLOOD METHODS: Intrinsic and Common Pathway and Optimal Coagulation time (Reference Range)
A
- Lee and White Coagulation Metho (5-15 mins)
- Howell’s Method (10-30 mins)
- Silicone Tube Method (20-60 min)
9
Q
Explain the process of Howell’s Method
A
- syringe coated with petrolatum
- blood collection
- transfer to tubes
- tilt til coagulation is observed
10
Q
Explain the process of Silicone tube method
A
- Syringe coated with silicone
- blood collection
- blood transferred to 2 tubes coated with silicone
- incubate (water bath) @ 37C
- Tilt til coagulation is observed
11
Q
purpose of silicone in Silicone Tube Method
A
to decrease contact of blood to glass surfaces
12
Q
Result/Outcome of Venous Blood Methods
A
solid clot
13
Q
SOURCES OF ERROR: Coagulation is Hastened
A
- dirty glassware
- tissue fluid in blood [swimming w/ same needle ; squeezing/milking]
- air bubbles [faulty venipuncture ; needle not properly positioned in vein]
- excessive agitation of blood
14
Q
SOURCES OF ERROR: Coagulation is delayed
A
- Temp < 35C (95F)
- Temp > 45C (113F)
15
Q
What is the basis of the test, Plasma Recalcification Time?
A
Except for calcium, normal PRP contains all components necessary for clotting
16
Q
Modification of LWCT
A
Plasma Recalcification Test
17
Q
Plasma Recalcification Test: Samples used
A
citrated plasma, CaCl2 (Calcium Chloride), Glass/ siliconized tubes with PRP or PPP or both
18
Q
Why is the removal of red cells important?
A
Makes the clot easier to see
19
Q
What does the clotting time of Plasma Recalcification test measure?
[Time required to form clot after addition of Calcium]
A
Intrinsic and common pathways
20
Q
What are the reference ranges for PRP and PPP in a Plasma recalcification test?
A
PRP 100-150 sec, PPP 130-240 sec
21
Q
What is the expected clotting time difference between PRP and PPP?
A
PRP should clot 20 sec faster
22
Q
What are the principal disadvantages Plasma Recalcification Test?
A
- Difficulty in standardizing platelet number,
- Lengthy test time,
- Errors in collection technique affect results [amount of glass contact]
23
Q
What should be done with the size of tubes for testing for standardization?
A
Use the same size
24
Q
How to improve the sensitivity of Plasma Retraction Test
A
Dilute plasma
25
Plasma Recalcification Test: What are the three things accomplished by diluting plasma?
1. Adjusts PRP closer to actual in vivo platelet count,
2. increases test sensitivity to factor deficiencies,
3. dilutes natural inhibitors to coagulation present in the sample
26
What should be done with a normal control for each test?
Run normal control with each test
27
What does a prolonged APTT indicate in the absence of heparin use?
Factor deficiency, acquired circulating anticoagulant, antibody to a specific factor
28
What are the sources of error in coagulation tests?
Sample collection, reagent preparation, instrumentation
29
Why should anticoagulant volume be adjusted for individuals with specific hematocrit levels?
To avoid error from incorrect anticoagulant-to-plasma ratio
30
What may cause a falsely shortened APTT?
Hemolysis or platelets in the sample
31
What can spuriously lengthen the APTT?
Unexpected heparin contamination
32
What factors may affect reagents in APTT testing?
Improper storage, water impurities, incorrect dilution
33
Who described PT as one stage PT
Dr. Armand quick
34
Indirect measurement of prothrombin of plasma dependent on presence of fibrinogen
PT
35
factors that can be screened by using PT
1 2 5 7 10
36
Prothrombin factors
2 7 9 10
37
What anticoagulant therapy is PT used for
Vit K antagonist therapy
38
How does Russell's viper venom affect the clotting cascade?
Bypasses Factor VII and activates Factor X
39
viper venom is obtained from
viper russell
40
Tests to determine efficiency of Extrinsic pathway
1. PT
2. Stypven (russell's viper venom test)
3. prothrombin-proconvertin ratio
41
What is the purpose of the prothrombin-proconvertin time (P&P) test?
Detect deficiencies in extrinsic and common pathways
42
What is the significance of an abnormal PT and Russell's viper venom time?
Deficiency or presence of Factor X friuli
43
developed by drs. owren ans aas
p & p test
44
P & P test: Specimen
Plasma diluted @ 1:10 with dilute thromboplastin from bovine brain, CaCl, excess bovine factor 1 and 5
45
What is the difference between the original P&P test and the Thrombotest?
Thrombotest uses a freeze-dried reagent
46
What is Thrombotest commonly used for in the Netherlands and Scandinavia?
Monitoring vit.K antagonist therapy
47
Why was Thrombotest particularly favored in the U.S. at one time?
Sodium oxalate failed to hold factor V stable
48
What has the development of monoclonal antibodies provided for immunologic testing?
Highly specific antisera
49
What have synthetic substrates enabled in the study of coagulation?
Viewing coagulation from an enzymatic perspective
50
What endpoint do methodologies in coagulation testing depend on?
Detection of a fibrin clot
51
What are the common methods for clot detection?
Manual tilt-tube, electromechanical (fibrin strand), optical density (turbidity)
52
Which clot detection method potentially offers more reproducible results?
Optical density (turbidity) methods
53
What are B immunologic methods gaining importance for?
Hereditary variants of coagulation proteins
54
What is a protein termed when it has normal antigenic properties but lacks functional activity?
Cross reactive material (CRM)
55
What is plasma containing a protein lacking functional activity called?
CRM+
56
What is the reason for the blood clots faster in a test tube with a small diameter?
the amount of foreign surface area (glass) to the amount of a blood is increased
57
The Coagulation Time is mainly used in the diagnosis and treatment of what?
hemorrhagic diseases [Abnormal bleeding]
58
Coagulation time can be used before surgical operations. T or F
TRUE
59
Discuss the relationship of Coagulation (clot formation) and Coagulation time (time it takes for clot to form)
? Coagulation = ? Coagulation Time [Hastened clot formation decreases time for clot to appear]
? Coagulation = ? Coagulation Time [Delayed clot formation increases time for clot to appear]
Therefore, Inversely proportional
60
What temperature does diatomaceous earth require blood to be kept warmed to?
37?C
61
What does diatomite act as in ACT?
Activator for contact factors
62
What are the contact factors
Factor 11, Factor 12, PK, HMWK
63
What temperature is the blood temperature constant?
37?C
64
How much diatomite is needed in each of the 2 evacuated tubes?
12 mg
65
what special incubator is used for warming?
portable heat block
66
When blood begins to flow into the tube, what is started?
the first stopwatch
67
clot is check at what intervals in ACT
tilting it at 5-sec intervals
68
ACTIVATED CLOTTING TIME: Principle
WB contains all components to form clot, when removed from veins and put into a glass tube. By addition of an activator and warming, a reliable and rapid screen for intrinsic and common pathway is obtained
69
ACTIVATED CLOTTING TIME: Reagent
2 Evacuated Tubes with 12 mg diatomite
70
ACTIVATED CLOTTING TIME: Equipment
Portable heat block, thermometer, stopwatch
71
ACTIVATED CLOTTING TIME: Procedure
1. Evacuated tubes are prewarmed @ 37C in heat block
2. 2ml of blood is obtained
3. Tourniquet is removed, and first tube is inserted in needle
4. 1st stopwatch is started at first contact of blood with tube.
5. Tube is filled and placed in the heat block
6. 2nd tube inserted in needle
7. 2nd stopwatch is started at first contact of blood with tube. Tube filled and placed in heat block.
8. After 60s, 1st/2nd tube is tilted @ 5 SEC INTERVALS until clot is formed
9. stopwatch is stopped at first sight of clot.
72
ACTIVATED CLOTTING TIME: Reference Range
Normal: 75 - 120 secs
Heparin Therapy: 140 - 185 secs
73
Duplicates (Difference if T1 and T2) in ACT should agree at how many seconds?
10 secs
74
What is the target range during heparin therapy?
140 to 185 seconds
75
ACTIVATED CLOTTING TIME: Interpretation
Prolonged ACT
1. one or more factor defects in the intrinsic/ common pathway
2. presence of circulating anticoagulant [Heparin (due to heparin therapy)}
76
How was PTT refined
addition of negative charged particles
77
modification of PTT
APTT
78
APTT/ PTT is the Test of choice for (3)?
1. factor deficiencies in the intrinsic and common pathways
2. heparin monitoring
79
APTT reagent consists of two components
1. platelet substitute (Phospholipids)
2. Activators
80
Source of phospholipids
brain/plant phospholipids
81
Activators in APTT/PTT
Kaolin, Celite, Ellagic acid, micronized silica
82
What type of acid is used as the activator?
ellagic acid
83
APTT/PTT: Principle
APTT measure all factors except 7 and 8. Maximum activation of contact factors is achieved by addition of activator. Phospholipids are used to substitute/replace factor 3
84
APTT/PTT: Reagents
Phospholipid + Activator (APTT reagent)
0.025M CaCl2
85
APTT/PTT: Control
Commercial lyophilized control
86
APTT/PTT: Procedure
1. 0.1 ml of PPP to 0.1 ml APTT
2. Incubate @ 37C in heat block for 3-5 mins
3. to warmed soln, add 0.1ml CaCl
4. Record time of clotting
87
APTT/PTT: Reporting
report in seconds to the nearest tenth
88
APTT/PTT: Reference range
20-45 secs
89
APTT/PTT: Interpretation
Prolonged APTT
1. deficient of factors in intrinsic and common
2. presence of circulating anticoagulant (lupus inhibitor)
3. antibody specific factor (factor 8 )
90
What factors does the APTT not measure?
VII and XIII
91
What adds the maximum activation of contact factors?
activator
92
What is supplied to substitute for platelet Factor 3?
Phospholipid
93
What type of plasma should be collected?
Citrated platelet-poor plasma
94
What is the concentration of Ca chloride ?
0.025M
95
What is recommended to be used?
a normal control and at least one abnormal control
96
At what temperature is APTT reagent incubated?
37?C
97
How much warmed Ca chloride is added after incubation?
0.1ml
98
What happens after incubation?
clotting
99
What is the lower limit of reference ranges?
20 sec
100
How long can the reference ranges extend from a lower limit of 20 sec. to an upper limit of what?
45 sec
101
What does calcium react with to convert Factor X to Xa?
factor VIIa and IIIa
102
What does Xa with Va +phospholipid & Ca2+ convert to?
thrombin (Factor IIa)
103
Besides Factor Xa, phospholipid & Ca2+ what else can convert prothrombin to thrombin?
Factor Va
104
PT: Principle
3a + 7a + Ca
10 = 10a
10a + 5a + Ca+ phospholipids
2 = 2a
2a
1 = 1a
1a + 8a
stable fibrin clot
105
PT: Specimen
Citrated PPP
106
What is the reagent added to record the time from the addition of to the formation of a clot?
thromboplastin/CaCl2
107
What is the PT reagent?
Thromboplastin/CaCl2
108
How cool is the PT thromboplastin reagent?
37?C
109
PT: Procedure
1. warmed control and patient plasma
2. PT reagent in water bath @ 37C (3-5mins)
3. plasma in water bath @ 37C for 3-5 mins
4. 0.2ml PT reagent + 0.1ml plasma [while still in water]
5. record clotting time
110
How long does it take to warm the PT thromboplastin reagent?
3 to 5 minutes
111
How much plasma does PT reagent contain?
0.1ml plasma
112
What amount of PT reagent is added to plasma?
0.2ml
113
What are the normal values of REFERENCE RANGE?
10-12 secs/ 12-14 secs
114
In some photo-optical systems, what are the values of manual methods?
12-14 sec
115
PT: Reporting
1. px time (in secs) with reference range
2. px time (in secs) with control
3. Prothrombin Ratio
4. % Activity
5. International Normalized Ratio (INR)
116
What is the name of the standardized prothrombin times?
INR
117
What is the ISI of a standard reagent?
1
118
What is the INR most applicable in?
standardizing anticoagulant intensity
119
PT: Reporting Equations
PT Ratio = (PT of px / mean of reference range)(100)
% Activity = (control/ px PT) (100)
INR = (px PT/control) (ISI)
120
Conditions with recommended INR of 2.0-3.0
1. prevention and treatment of venous thrombosis
2. Acute MI
3. stroke
4. pulmonary embolism
121
Conditions associated with prolonged PT
1. Vit k deficiency
2. Coagulopathy with liver disease
3. warfarin therapy
4. lupus anticoagulants
5. hyperfibrinogenemia/ Dysfibrinogenemia
5. deficiency in individual clotting factors
6. Abs to bovine factor 5
122
The P and p test has little value to the extrinsic systemas an overall screen because of its insensitivity to what?
factor V & fibrinogen
123
What is the anticoagulant of choice?
sodium citrate
124
What does the substrate have?
specificity
125
What allows coagulation testing to be approached as a series of enzymatic reactions in an accurate and sensitive manner?
Synthetic substrate assays
126
What is necessary for optimal use of synthetic substrate assays?
Knowledge of enzyme kinetics
127
Many assays have been adapted for use on what?
automated instrumentation
128
What can be performed?
Endpoint or initial rate analysis
129
What is the first method to measure the prothrombin concentration in?
plasma
130
What is used to defibrinate test plasma?
thrombin
131
What is the result of the addition of thrombin?
defibrinated
132
What are the sources of factors V,VII, and X that convert all prothrombin to thrombin?
thromboplastin, calcium, and a source of factors V,VII, and X
133
How is the thrombin formed measured?
aliquots
134
What are the results expressed in?
prothrombin units/ml of plasma
135
What type of plasma are the results expressed in?
prothrombin units/ml
136
How long has a prothrombin time study been allowed to clot?
60 min
137
What can slow the rate of prothrombin conversion?
platelet deficiencies or abnormalities
138
How long will the prothrombin consumption time be?
short
139
What will have a long time?
a normal serum
140
How long will a normal serum have?
20-25 secs
141
What will adsorb to certain coagulation factors?
barium sulfate or aluminum hydroxide
142
What do barium sulfate and aluminum hydroxide adsorb to?
coagulation factors
143
What can be done to remove factors II, VII, IX, and X?
centrifugation
144
If blood is allowed to clot, the remaining serum will not contain fibrinogen, factor II, the labile factors V & VIII
XIII
145
If blood is allowed to clot, the remaining serum will not contain what?
fibrinogen
146
What is the name of the clot that cannot form a clot?
prothrombin
147
What are the TGT reagents sometimes referred to as?
mixing studies or substitution studies
148
What are assumed to be normal if the patient has a PT & prolonged APTT?
Factors I, II, V, VII & X
149
What is corrected by addition of normal adsorbed plasma?
APTT
150
What is corrected by normal serum with factors IV, VII, IX, X, XI, & XII?
APTT
