marcia l. zucker, ph.d. zivd llc the beginning….. the lee-white clotting time › add blood to...
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Marcia L. Zucker, Ph.D.ZIVD LLC
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Monitoring hemostasis
Bleeding Clotting2
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PresenterPresentation Notes
Extrinsic Pathway
Common Pathway
CLOT
X Xa
II IIa (thrombin)
WARFARIN
LMWH & DXaI
Hirudin & DTI
Monitor withACT / aPTT
Monitor with PT
Monitor with ???
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Extrinsic Pathway
Common Pathway
CLOT
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In the beginning.. The Lee-White clotting time
Add blood to glass tube, shake No activator required Manual method
Place in heat block Examine for clot every 30 seconds Very slow process Subjective clot detection
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Lee RI, White PD. A clinical study of the coagulation time of blood. Am J Med Sci 1913; 145:495-503
Activated Clotting Time Add blood to glass tube with dirt and shake Diatomaceous earth activator Manual method
Place in heat block Visual clot detection Subjective clot detection
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Hattersley PG. Activated coagulation time of whole blood. JAMA1966 May 2;196(5):436-40.
Initiation of intrinsic coagulation cascade Factor XII (Hageman factor) Pre-kallikrein (Fletcher factor)
Shortens contact activation period Proposed as both screening assay for
coagulation defects and for heparin monitoring
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Glucopolysaccharide MW range: 6,000 - 25,000 daltons Only ~1/3 molecules active
Must contain specific sequence of glucosaccharides to function
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Heparin + AT
Heparin + AT
Heparin + AT
Heparin + AT
Heparin Activity
Prekallikrein .. Kallikrein
D-dimersFDP
Fibrinolysis
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9
8
10
5
2
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FibrinogenCLOT(Fibrin)
Modified from Utley, Vol.1, 1982 Pathophysiology and techniques of cardiopulmonary bypass. Pub: Williams & Wilkins
Thrombin
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PresenterPresentation NotesPlasminogen is normally in circulation and has a high affinity for Fibrin. When a clot is formed, it binds with the clot. Once activated (converted to Plasmin) is is a potent proteolytic enzyme that can dissolve fibrin as well as Fibrinogen and several other proteins.
Secondary Fibrinolysis commences with the activation of Factor 12 which activates prekallikrein activator. It in turn activates several other factors resulting in Kallikrein formation (Kallikrein is not mentioned in Utley at all. This cascade should be verified in another text). The result is that Plasminogen, which had previously bound to the fibrin clot, is activated to Plasmin which dissolves the clot releasing D-dimers.
Primary Fibrinogenolysis is not dependant on activation of the clotting cascade. It results in the activation of circulating Plasminogen to become Plasmin which in the absence of Fibrin is quite happy to dissolve Fibrinogen (fibrinogenolysis) producing
Aprotinin Anticoagulant reference:Factor 9 = Prentice 1970 UI:71043269Contact Phase (PTT) = Dietrich 1990: Anesthesiology73:1119-1126Howard 1993: Blood Coag Fib:4:35-40 Multiple other papers
Potency varies by manufacturer Potency varies by lot
Dose response varies by patient Half life ranges from 60 - 120 minutes Non-specific binding
Functions by accelerating action of antithrombin Antithrombin level critical for appropriate
response
Monitoring hemostasis for heparin anticoagulated patients
Bleeding Clotting12
Point of Care Immediate turn around Rapidly adjust anticoagulant dosing as
needed Heparin half life varies by patient Dose required varies by patient Potency varies by lot
IV Direct thrombin inhibitors very short half life Require immediate intervention No antidote available
Cardiac surgery Percutaneous coronary intervention (PCI) Interventional cardiology ECMO Critical care Interventional radiology Electrophysiology Vascular surgery etc.
Industry Standard Since 1970s Recommended as 1o method in AmSECT
guidelines ACT improves outcome in CPB, PCI
AACC NACB LMPG for POCT Strongly recommend ACT monitoring of heparin
anticoagulation and neutralization in cardiac surgery. (Class A, Level I)
Insufficient evidence to recommend specific target times for use during cardiovascular surgery. (Class I conflicting evidence across clinical trials).
Easy to run15
Disadvantages Each system yields different numbers Most sensitive to hypothermia and
hemodilution Little or no correlation to heparin level especially true for pediatric patients
Standard target time = 480 seconds Developed with manual ACT Suggested due to high variability
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Diagnostic Catheterization locate and map vessel blockage(s) determine need for interventional procedures
Electrophysiology Interventional
Balloon angioplasty Atherectomy (roto-rooter) Stent placement
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Angioplasty, Atherectomy, Stent placement 10,000 unit bolus dose or 2 - 2.5 mg/kg target ACT 300 - 350 seconds Target time be reduced if ReoPro Used ReoPro is one of 3 GPIIb/IIIa Inhibitors
Catheterization and Electrophysiology Same dosing and targets for vascular surgery 2500 - 5000 unit bolus dose frequently not monitored if monitored Targets ~ 200 seconds OR twice
baseline18
ExtraCorporeal Membrane Oxygenation Very small window of safety NACB Guidelines: Strongly recommend ACT monitoring to control
heparin anticoagulation during ECMO. (Class A Level III)
Target times for ECMO based on the ACT system. (Class B Level III)
Target often 180 200 seconds Based on Hemochron P214/215 tubes
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Determine when to pull the femoral sheath Premature sheath pull can lead to bleeding. Delayed removal can increase time in CCU. Target set at each site. ACT targets range from 150 220 seconds aPTT targets range from 40 70 seconds
Monitor heparin therapy Target times determined by each facility ACT or aPTT
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ACT Activated clotting
time POC Only Low, moderate or
high dose heparin System dependent
aPTT Activated partial
thromboplastin time Laboratory or POC Low dose heparin only
System dependent upper limit
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Why are the results from different systems SO VERY different? Multiple activators Multiple detection mechanisms NO standardization
ACT Differences
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1969 -HEMOCHRONOMETER Hattersley ACT Automated heating Objective fibrin clot
detection two different activators CA510 (later FTCA510) diatomaceous earth P214 glass bead
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0
100
200
300
400
500
600
700
0 1 2 3 4 5
Heparin (units/ml)
Clo
tting
Tim
e (s
ec) C-ACT
P214
ECMO Dialysis
CATHPTCA CPB
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Chart1
00
11
22
33
44
ECMO Dialysis
CATH
PTCA
CPB
C-ACT
P214
Heparin (units/ml)
Clotting Time (sec)
86.53
109
210.63
265.54
334.73
466.905
458.83
593.2575
582.93
Sheet1
HeparinC-ACTK-ACTP214ACT-LRACT+
08790109123103
1211222266243205
2335354467345306
3459487593446408
4583619509
Sheet1
C-ACT
K-ACT
P214
ACT-LR
ACT+
Heparin (units/ml)
Clotting Time (sec)
Sheet2
SUMMARY OUTPUTSUMMARY OUTPUTSUMMARY OUTPUT
Regression StatisticsACT-LRRegression StatisticsRegression Statistics
Multiple R0.9909264658Multiple R0.998744215Multiple R1
R Square0.9819352606R Square0.997490007R Square1
Adjusted R Square0.9774190757ACT-LR = 101.381*heparin +142.1Adjusted R Square0.9971762579Adjusted R Square1
Standard Error14.3810243875Standard Error13.3859912085Standard Error0
Observations6Observations10Observations5
ANOVAANOVAANOVA
dfSSMSFSignificance FdfSSMSFSignificance FdfSSMSFSignificance F
Regression144966.676587301644966.6765873016217.42583431360.00012312Regression1569674.921914927569674.9219149273179.25988738660Regression1214329.6214329.6
Residual4827.2554497355206.8138624339Residual81433.4780850727179.1847606341Residual300
Total545793.932037037Total9571108.4Total4214329.6
CoefficientsStandard Errort StatP-valueLower 95%Upper 95%Lower 95.0%Upper 95.0%CoefficientsStandard Errort StatP-valueLower 95%Upper 95%Lower 95.0%Upper 95.0%CoefficientsStandard Errort StatP-valueLower 95%Upper 95%Lower 95.0%Upper 95.0%
Intercept142.101587301610.408221308113.65282146630.0001666811113.2036723424170.9995022608113.2036723424170.9995022608Intercept103.39622351377.779166256813.29142739730.000000980385.4574223564121.33502467185.4574223564121.335024671Intercept101.8065535101.8101.8101.8101.8
Heparin101.3809523816.875444711814.74536653710.0001231282.2916180263120.470286735682.2916180263120.4702867356Heparin101.51828316861.800450763256.3849260653097.3664335785105.670132758897.3664335785105.6701327588Heparin146.4065535146.4146.4146.4146.4
Sheet3
Sheet3
00000
11111
22222
33333
44444
CCUDialysis
CATH
PTCA
CPB
C-ACT
K-ACT
ACT+
P214
ACT-LR
Heparin (units/ml)
Clotting Time (sec)
86.53
90.1
103.4
109
123
210.63
222.275
204.92
265.54
243.481
334.73
354.45
306.44
466.905
344.862
458.83
486.625
407.96
593.2575
446.243
582.93
618.8
509.48
Sheet4
HemoTec ACT(later Medtronics ACTPlus) Add blood to dual cartridge Liquid kaolin activator Flag moves up and down As fibrin forms, motion slows Instrument displays clotting
time
25
475
500
525
550
575
600
625
650
675
700
PreCPB
15min
30min
45min
60min
75min
90min
105min
Seco
nds
HemochronHemotec
differences ignored by clinicians26
Collection
Sales 1ActalykeHemochronHemotecTASHMS ACTHMS HPTHeparin
Baseline18616417119517536000
Pre-CPB100010007011000
15 min7036717627276892.5
30 min534681748649634
45 min6236316996216142
60 min590614640641597
75 min5255455875945562
90 min4424445335865435000
105 min5214555295955542
Post CPB152138148201136
Heparin Resp814836506825
% change0.1860.1640.27817403710.175
Matney 2ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin
Baseline12712714213614640000
Pre-CPB402490380486447
15 min4525624945925673.54000
30 min41370050857158810000
45 min672964559624632aborted
Post CPB12311695114
Heparin Resp275363238350301
% change0.3159203980.25918367350.37368421050.27983539090.3266219239
Clark 3ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin
Baseline1231251297913825000
Pre-CPB419510426517503
15 min4024564035144692.510000
30 min6177286046666285000
45 min5285875595886342.5
60 min4865754705216062
Post CPB132122125116118
Heparin Resp296385297438365
% change0.29355608590.24509803920.30281690140.15280464220.2743538767
Stillmock 4ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline15415617515318144000
Pre-CPB412439480512526
15 min3844265385975913.510000
30 min4354485596436286000
45 min4524936296235743.56000
60 min4304906726875506000
75 min4385346476835403.56000
90 min441503659598507
Post CPB177175189204194
Heparin Resp258283305359345
% change0.37378640780.35535307520.36458333330.2988281250.3441064639
Witicop 5ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline12512514514815833600
Pre-CPB618648628673694
15 min5867247205866803.5
30 min624612aborted629630
45 min46063460560758535000
60 min4387976466716435000
75 min5738347267457083
90 min724852706680673
105 min6237516996416032.5
Post CPB147130111139109
Heparin Resp493523483525536
% change0.20226537220.19290123460.23089171970.2199108470.2276657061
Todd 6ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline16116716316116923000
Pre-CPB478565523537674
15 min5427286345946343.5
30 min505646616583641
45 min5687536346126603
60 min558584548559523
75 min4685515385425452.5
90 min403545509526538
Post CPB134127127123143
Heparin Resp317398360376505
% change0.33682008370.29557522120.31166347990.29981378030.2507418398
Vanslooten 7ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline16318918818318146000
Pre-CPB448506592652549
15 min5836866857416473.5
30 min547584611730562
45 min5035476237255613
60 min432570571687487
75 min43147851864346836000
90 min454525538626556
105 min424558abort5585033
Post CPB143129117158136
Heparin Resp285317404469368
% change0.36383928570.37351778660.31756756760.28067484660.3296903461
Raymond 8ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline15815215617015729000
Pre-CPB428485479527498
15 min4745505275295343
30 min4144944985165183500
45 min4425125185565523.56500
60 min476580543569560
75 min5315525335755343.5
90 min4674665125475394000
105 min5025695435725453
Post CPB129119118128125
Heparin Resp270333323357341
% change0.36915887850.31340206190.32567849690.32258064520.3152610442
Verdoorn 9ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline1171241277613647000
Pre-CPB443577587629633
15 min6317976476817293
30 min585aborted611651708
45 min5145416475747453.5
60 min4776095335906036000
75 min5587076056806933
90 min484621533592585
105 min4275634935835343
Post CPB11911010310199
Heparin Resp326453460553497
% change0.26410835210.21490467940.21635434410.12082670910.214849921
Burright 10ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline11911913818813636500
Pre-CPB402565647677722
15 min4646398916768933.55000
30 min491714873568929
45 min4749169626049743.55000
60 min538649831661874
75 min5816878404068663.5
90 min5026197776528563.5
105 min4765347056397673.5
Post CPB143130114175124
Heparin Resp283446509489586
% change0.29601990050.2106194690.21329211750.27769571640.188365651
Anderson 11ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline13413112113512927000
Pre-CPB390631598612757
15 min6478648557219942.5
30 min540650748667894
45 min5486627196708002.54000
60 min718845857632919
75 min403639733687aborted
Post CPB13512010794106
Heparin Resp256500477477628
% change0.34358974360.20760697310.20234113710.22058823530.1704095112
Bennett 12ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline15418716916617335000
Pre-CPB393460461435505
15 min39053447550154435000
30 min4235305275265725000
45 min6156065605316393.5
60 min4585665715415785000
75 min4426325715316213.55000
90 min506571560526583
105 min5247095335466003
Post CPB1271159476104
Heparin Resp239273292269332
% change0.39185750640.40652173910.36659436010.38160919540.3425742574
Jerkovich 13ActalykeHemochronHemotec ACTTASHMS ACTHMS HPTHeparin Admin
Baseline15012914518214128800
Pre-CPB39144040344941510000
15 min5856184936535023.5
30 min564600456596492
45 min4755644475754833
60 min4345223845514224000
75 min4295204225434383.58000
90 min434530444599455
Post CPB9310279
Reported in literature >20 years Clinical evaluations of Hemochron - mid 1970s By 1981 poor correlation between ACT and heparin level
By 1988 Hemochron and HemoTec clinically different
Early 80s to Present Improved clinical outcome with ACT use NACB Laboratory medicine practice guideline for
point of care coagulation testing 2007 http://www.aacc.org/SiteCollectionDocuments/NACB/LMP
G/POCT/Chapter%204.pdf
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http://www.aacc.org/SiteCollectionDocuments/NACB/LMPG/POCT/Chapter%204.pdf
Diatomaceous earth (Celite) Used in original Hatterley and Hemochron tube ACT
Kaolin (clay) Used in suspension in original HemoTec ACT Used as powder in Hemochron tube ACT Unaffected by the use of aprotinin
CVOR to reduce blood loss; no longer marketed
Glass beads Used in Hemochron low dose tube ACT
Phospholipids Used in Roche ACT, HMS HDR and Hemochron Jr ACT+
Mixtures used in lots of different ACTs
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Microsample ACTs - Hemochron Jr Add blood to sample well, press start Silica, kaolin and phospholipid (ACT+) Diatomaceous earth (ACT-LR) Sample pumped across restriction Flow slows with clot formation Optics measure motion Clotting time displayed
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50
150
250
350
450
550
50 100 150 200 250 300 350 400 450 500FTCA510 ACT
Jr. A
CT
ACT+ACT-LRFTCA510
Chart1
100100100
150150150
200200200
300300300
380380380
500500500
ACT+
ACT-LR
FTCA510
FTCA510 ACT
Jr. ACT
82
127.1
100
124.5
175.1
150
167
223.1
200
252
319.1
300
320
395.9
380
422
500
Sheet1
801ACT+ACT-LRFTCA510
10082127100
150125175150
200167223200
300252319300
380320396380
500422500
Sheet1
ACT+
ACT-LR
FTCA510 ACT
Jr. ACT
Predicted Values
Sheet2
Sheet3
Abbott - i-STAT Add blood to cartridge, press
start Diatomaceous earth or kaolin
Insert into instrument No clot detection Synthetic thrombin substrate Electro-active compound
formed and detected amperometrically
Clotting time reported
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0
100
200
300
400
500
600
700
800
900
1000
0 200 400 600 800 1000 1200
Com
para
tor A
CT
HEMOCHRON 1 ACT
Hemochron 2 i-STAT Celite i-STAT Kaolin
Evaluate by clinical agreement Standard split sample correlation Samples across entire range Correlation coefficient R > 0.88
Two by Two table of agreement
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y = 1.09x - 7.53R = 0.915
0
100
200
300
400
500
600
700
800
900
0 200 400 600 800
New
AC
T
Current ACT
CVOR example
Current New N %> 480 > 520 72 34%> 480 < 520 19 9%< 480 > 520 7 3%
Data used to predict new target time Clinical agreement determined from
predicted target time Only method of value in ECMO, sheath
pull Range of values too small for correlation
analysis
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Parenteral Direct thrombin inhibitors (DTIs) Used if patient at risk for HIT Heparin induced thrombocytopenia Heparin allergy
Argatroban Angiomax
No ACT FDA cleared for monitoring DTIs
Extrinsic Pathway
Common Pathway
CLOT
X Xa
II IIa (thrombin)
WARFARIN
LMWH & DXaI
Hirudin & DTI
Monitor withACT / aPTT
Monitor with PT
Monitor with ???
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Argatroban Synthetic analog of L-arginine Reversible binding to thrombin
PCI monitoring: ACT 300 450 Papers state standard ACT targets for CPB
Angiomax Synthetic analog hirudin (bivalirudin) Reversible binding to thrombin
Labeling requires ACT after initial bolus Original studies with Hemochron ACT-LR Any ACT >250 sec
ACTs are Global Assays Used to monitor heparin Heparin is non-homogenous Difference by manufacturer & Lot
ACTs differ: By manufacturer By activator By detection mechanism
Must establish clinical equivalence New target times that reflect clinical practice
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Marcia L. Zucker, Ph.D.ZIVD [email protected]
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The 123s of ACTCoagulation TestingCoagulation is ComplexCoagulation TestingActivated Clotting TimeWhat is an ACT?1966 - HattersleyParticulate Contact ActivationWhat is Heparin?Heparin Effects on CoagulationWhy Monitor Heparin?Why Use an ACT?Why do we use an ACT?Where is an ACT Used?Cardiac SurgeryCardiac SurgeryCatheterization LaboratoryDosing & Target TimesECMOCritical CareACT versus aPTTACT and aPTTA Little HistoryTwo assays for separate uses1980s Lower values than CA510 1980s - ACT DifferencesMultiple Activators1990sClotting Times Different 2000Number dont Match- Surprise!How can a new ACT be used?Clinical CorrelationClinical ComparisonDirect Thrombin InhibitorsCoagulation TestingACT Monitoring - DTIsSummaryQUESTIONS?