CHAPTER 1 - HEMOSTASIS PART 7 Flashcards
1
Q
must be avoided
A
Hemolysis
2
Q
Rbc contains(platelet activator)
A
ADP
3
Q
May cause premature activation of
platelet if released in the plasma
A
Hemolysis
4
Q
is the anticoagulant of choice (except for glass bead retention test)
A
Citrate
5
Q
pH is very critical and easily affected by recapping method
A
Citrate
6
Q
pH is best controlled by this buffer
A
Citrate
7
Q
glass bead retention test should
contain
A
heparin
8
Q
sample (anticoag) → 60-100 x g → 10 minutes Plasma → plastic/siliconized test tube
A
Platelet Rich Plasma (PRP) preparation
9
Q
stored in RT (not refrigerated nor incubated)
A
Platelet Rich Plasma (PRP) preparation
10
Q
red cell contamination = hemolysis = release of ADP
A
Platelet Rich Plasma (PRP) preparation
11
Q
upper layer that is not touching the red cell
A
Platelet Rich Plasma (PRP) preparation
12
Q
sample (remains) → 2000 x g for 10 minutes Plasma → plastic/siliconized test tube
A
Platelet Poor Plasma (PPP) preparation
13
Q
layer almost in contact w/ the red cell
A
Platelet Poor Plasma (PPP) preparation
14
Q
upper 3⁄4 layer
A
Platelet Poor Plasma (PPP) preparation
15
Q
-samples are centrifuged at 2-4 deg celcius
A
beta-Thromboglobilin (bTG) and PF4 determinations
16
Q
cold (not RT)
A
beta-Thromboglobilin (bTG) and PF4 determinations
17
Q
most stable b/w:
A
30 minutes to 3 hours
18
Q
performed 1st
A
-Ristocetin
19
Q
plt responds to ristocetin will decerase as the pH of the plasma changes
A
-Ristocetin
20
Q
as soon as blood is exposed to air after centri, blood pH will start to decrease, hence aggregation will be affected
A
-Ristocetin
21
Q
performed last
A
Epinephrine
22
Q
response w/ plt increases w/ time
A
Epinephrine
23
Q
tales 60 mins to take effect
A
Epinephrine
24
Q
: more sensitive to aggregating agents than @ 37 deg cel
A
platelets @ room temp
25
sensitive to RT making them more aggregatable than inside the body
platelets @ room temp
26
plts prepared for aggregation studies
due to sensitivity to various
aggregating agents
platelets @ room temp
27
spontaneous aggregation
platelets @ 0-4 deg
28
beta-Thromboglobilin (bTG) and PF4
determinations
platelets @ 0-4 deg
29
Measures the ability of the small blood vessels to control bleeding after injury
. Bleeding time
30
Factors affecting BT
: number of platelets and the ability of platelets to form (?); Thickness and vascularity of the skin and the ability of the blood vessels to (?) may also affect results.
plugs
constrict
31
Prolonged: when platelet count is lower than (?)or when platelets are dysfunctional.
: in Vwd
: after ingestion of aspirin/aspirin-containing compounds, anti-inflammatory, anticoagulants, and some antibiotics
30 - 50, 000/uL
32
Puncture is done on the earlobe. bleeding ceases.
Duke method
33
Reference value: 1 - 3 mins
Duke method
34
Done on the forearm; Standard pressure applied is 40 mmHg
Ivy method
35
• Reference value: 1 - 7 mins.
Ivy method
36
Uses a template containing a standardized slit
Template BT (by Mielke)
37
Platelet adhesiveness/Retention Test
→ Reference values:
26% - 60%
38
3 substances required by platelet to adhere successively:
Ionized Calcium, Fibrinogen, ADP
39
- (?) is not required in vitro/initial adhesion, but required for longer retention and accurate measurement, along w/ ADP
VWF
40
: involves the formation of plt aggregates in the column (long rubber tubing) where platelet adhesion test will take place; measurement of retained platelets
- Retention
41
enhances plt retention
RBC
42
→ Collect 2 whole blood samples, 1 using EDTA and the other using glass bead collecting system.
Glass Bead Method/Salzman Method
43
Perform platelet counts separately. (higher in EDTA
Glass Bead Method/Salzman Method
44
-Collect in 2 tubes (EDTA and glass bead collecting system)
Glass Bead Method/Salzman Method
45
- Counts are higher in EDTA
Glass Bead Method/Salzman Method
46
→ Perform separate platelet count on venous blood and capillary blood samples. % = plate count aust our Vet count callary blood x 100
Borshgervinct Method (in vivo test)
47
→ Clinical Significance of platelet adhesiveness
Borshgervinct Method (in vivo test)
48
⁃ Glanzmann's thrombasthenia; Chediak
Decrease platelet adhesiveness
49
- Higashi syndrome
Decrease platelet adhesiveness
50
⁃ Some myeloproliferative disorders; Uremia
Decrease platelet adhesiveness
51
⁃ Ingestion of aspirin and other drugs
Decrease platelet adhesiveness
52
⁃ Venous thrombosis; Pulmonary embolism; Carcinoma
Increase platelet adhesiveness
53
⁃ During pregnancy; Following splenectomy; Oral contraceptive intake
Increase platelet adhesiveness
54
-Involves platelet count on venous and capillary blood samples.
Borshgervinct Method (in vivo test)
55
-Venous Thrombosis
INCREASE
56
-Pulmonary Embolism
INCREASE
57
-Carcinoma
INCREASE
58
-During pregnancy
INCREASE
59
-Splenectomy
INCREASE
60
-Oral contraception
INCREASE
61
-Glanzmann's Thrombasthenia
DECREASE
62
-Chediak
DECREASE
63
Higashi
DECREASE
64
Myeloproliferative disorders
DECREASE
65
Uremia
DECREASE
66
-Aspirin and other drugs
DECREASE
67
Aggregating agents:
thrombin, arachidonic acid, ADP, collagen,
epinephrine and ristocetin
68
→ Currently, this test is considered the gold standard for evaluation of aspirin resistance
Platelet Aggregation Test
69
Principle of Aggregation
Aggregating agents added to a stirred suspension of (?) induce a shape change and aggregation of platelets. As a result, the PRP changes from a turbid suspension to one that transmits more light (clear) as the aggregates are formed. The aggregometer records changes in (?) in the form of a graph.
PRP
optical density
70
Aggregating agents added to PRP→ induces shape change and aggregation → PRP changes from turbid to clear (transmits more light) as aggregates are
formed → optical density is recorded
by aggregometer.
Principle of Aggregation
71
:light-transmittance aggregometer
Platelet-Rich Plasma Aggregometry
72
: electrical impedance
Whole-Blood Platelet Aggregometry
73
for simultaneous measurement of platelet aggregation and the secretion of ATP
Optical Lumi-Aggregometer.
74
Tests the ability of small capillaries to retain blood when subjected to increased hydrostatic pressure and
anoxia.
Tourniquet test/Capillary Fragility test)
75
Nonspecific screening test
Tourniquet test/Capillary Fragility test)
76
Principle: an inflated blood pressure cuff on the upper arm is used to apply pressure to the capillaries for 5 minutes.
Rumple-Leede Method (Positive pressure)
77
The forearm, hands and fingers are then examined for petechiae
Rumple-Leede Method (Positive pressure)
78
Rumple-Leede Method (Positive pressure) Normal:
0 to occasional petechiae
79
uses positive pressure
Rumple-Leede Method (Positive pressure)
80
A suction cup (diameter) is placed in close contact with the skin at midpoint of upper arm for (?). An area within a circle of (?) diameter is observed for petechiae (?) after removal of suction cup.
Hess/Suction test (Negative pressure)
2-cm
1 min (pressure of 200 - 250 torr)
1 cm
5 minutes
81
Hess/Suction test (Negative pressure)
● Clinical significance: Positive in
thrombocytopenia, hypofibrinogenemia and in vascular purpura.
82
● -uses negative pressure
Hess/Suction test (Negative pressure)
83
-Uses suction cup (2-cm diameter) → midpoint of upper arm → 1 min (200-
250 torr) → 1 cm diameter area is observed after 5 minutes of suction cup removal
Hess/Suction test (Negative pressure)
84
Clot Retraction Principle: When blood coagulation is complete, clot normally undergoes retraction where clot becomes denser and serum is expressed. Normally, clot retraction begins within (?) after the blood has clotted & complete within (?)
30 minutes
24 hours.
85
● Normal clot retraction requires
normal number of functioning platelets, Ca*, ATP, fibrinogen, normal interaction of the platelets with fibrinogen
86
- ratio of the plasma volume and red cell mass; activity of a retraction-promoting principle in serum
& nature of the surface on which CRT
is being measured.
Thrombosthenin
87
Clinical significance: CRT is poor
when platelet count is less than 100,000/uL; in dysfibrinogenemia or hypofibrinogenemia, paraprotinemias
Clot Retraction
88
Qualitative: Test for the presence or
absence of retraction
Hirschboeck Method (Castor oil Method)
89
● Formation of dimpling/droplet like
serum on the surface of blood drop
Hirschboeck Method (Castor oil Method)
90
● Normal Values = 15 - 45 minutes
Hirschboeck Method (Castor oil Method)
91
● Normal: clot retraction begins within 1
hour, complete within 18 to 24 hours
Stefanini Method (Test tube)
92
● Provides quantitative estimate of the degree of retraction
Mac Farlane Method
93
● Normal Values = 44% - 67 %
Mac Farlane Method
94
• Sodium citrate - anticoagulant
Tocantins Method (Rees -Ecker diluting fluid composition)
95
• Formalin - fixative; prevent premature lysis (preserves both red cells and platelets)
Tocantins Method (Rees -Ecker diluting fluid composition)
96
• BCB - stains the platelets
Tocantins Method (Rees -Ecker diluting fluid composition)
97
• Brecker - Cronkite Method (Diluent: 1% NH4 oxalate)
Phase - Contrast Microscopy Method
98
• Counting chamber: Spencer — Briteline # 1475
Phase - Contrast Microscopy Method
99
• Platelets are counted in 5 R squares
Phase - Contrast Microscopy Method
100
• Uses EDTA and ammonium oxalate Diluent
Composition:
Unopette Method
0.44% NHa oxalate; 0.22% K: EDTA; 0.75% Crystal Violet
101
• Uses 14% MgSO4 as diluent
Fonio's Method
