Coagulation Testing

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Coagulation Testing

• What is it?
• Why do we need it POC?

Marcia L. Zucker, Ph.D. Director of Clinical
Research
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Coagulation Testing

• Monitoring hemostasis

Bleeding
Clotting
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Maintaining Hemostasis
Counterbalance thrombosis with anticoagulant
therapy
Thrombosis
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Maintaining Hemostasis
Counterbalance bleeding by correcting defect
(i.e., neutralize heparin, transfuse blood
product)
Bleeding
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Components of Hemostasis
Vessels
Coagulation Proteins
Platelets
Fibrinolysis / Inhibitors
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Vascular System
Basement membrane
Endothelial cells
Red blood cells Platelets
White blood cells
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Components of Hemostasis
Vessels
Coagulation Proteins
Platelets
Fibrinolysis / Inhibitors
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Anatomy of a Platelet
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Resting Platelets
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Platelet Aggregate
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Hemostasis

• Primary hemostasis
• Platelet Adhesion
• Secondary hemostasis
• Coagulation
• Fibrin clot formation

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Platelet Function

• Platelet Adhesion
• shape change
• release

3 sec 10 sec 5 min
ADP release
Platelet Aggregation

• Coagulation
• Fibrin formation

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Platelet Testing

• Peripheral smear
• Platelet count
• Platelet aggregation
• Bleeding time

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Peripheral Blood Smear
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Platelet Aggregation

Aggregate Clumping
Platelet Rich Plasma (PRP)
Aggregating Agent
Baseline Light Transmission
Increased Light Transmission
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Bleeding Time

• Cut 1 mm deep, 5 mm long
• Constant pressure
• Expected Range 2 - 10 minutes

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Components of Hemostasis
Vessels
Coagulation Proteins
Platelets
Fibrinolysis / Inhibitors
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Coagulation
Inactive enzyme
Active enzyme
Inactive enzyme
Active enzyme
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Coagulation is Complex
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Coagulation Testing
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Common(?) Coagulation Tests

• Laboratory
• PT..
• aPTT
• TT..
• Fib.
• Anti Xa
• Anti IIa
• Factor Assays

• Point of Care
• ACT
• Celite
• Kaolin
• Glass beads
• Silica
• thromboplastin

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Differences in test methods

• Point of Care
• Whole Blood
• Usually No Added Anticoagulant
• No Dilution
• No Preanalytical Delay

• Standard Laboratory
• Platelet Poor Plasma
• Sodium Citrate Anticoagulant
• 19 Dilution
• Variable Preanalytical Delay

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POC Coagulation Analyzers

• HEMOCHRON 401 / 801 / Response
• HEMOCHRON Jr. Signature/ Signature
• ProTime
• Medtronic HMS/ HMS / HemoTec ACT II
• CoaguChek/ S / CoaguChek Pro/ Pro DM
• Bayer RapidPoint
• i-STAT
• Helena Actalyke
• Others

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POC Coag Analyzers Differ

• Test methodology
• Sample size and application
• Sample measurement
• Clot detection method
• Enzyme detection method
• Reagent composition
• Results

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Semi - Automation - 1969

• HEMOCHRONOMETER (HEMOCHRON)
• Magnet in tube, detector in instrument
• Upon clot formation, magnet is deflected
• Clotting time displayed

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HEMOCHRON Test Menu

• ACT
• FTCA510, FTKACT, P214
• aPTT and PT
• Fresh or citrated whole blood
• Thrombin time based assays
• TT, HNTT, HiTT
• Fibrinogen
• Dosing Assays
• HRT, PRT, PDAO
• Celite and kaolin

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1980s

• HemoTec (later ACTII)
• Smaller sample volume
• Mechanical detection
• Flag moves up and down
• As clot forms, motion slows
• Instrument displays clotting time
• Medtronics HMS uses same technology

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Medtronics test menu

• ACT (kaolin)
• Empty cartridge for aPTT
• PT (look up conversion)
• Heparinase ACT
• HMS Dosing Assays
• HDR, HPT

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Newer technologies

• Sample introduction by capillary action

• CoaguChek Pro/ DM
• Time to when capillary flow stops determines
  endpoint

• Bayer RapidPoint
• Sample mixes with magnetic particles
• Pulsating magnetic field
• Motion detected optically

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Test Menu

• CoaguChek ProDM
• ACT
• Tissue factor activated
• PT (FWB)
• aPTT (FWB)
• CoaguChek / S
• Detection as per RapidPoint
• PT only
• CLIA waived

• Bayer RapidPoint
• HMT
• aPTT
• F C WB and plasma
• PT
• F C WB and plasma
• ECT (ecarin time)
• Compassionate use only
• ENOX
• Accent Dosing
• HTT, PRT

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Newer Technologies

• Chemical endpoint detection
• i-STAT Abbott
• Synthetic thrombin substrate
• Electro-active compound formed and detected
  amperometrically
• Coagulation Test Menu
• ACT (Celite)
• PT (cleared but not yet introduced)

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Newer Technologies

• Active pumping system
• Hemochron Jr Signature
• ProTime microcoagulation system

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Test Menu

• ProTime
• PT only
• CLIA waived
• Home use approved
• Integral Controls
• Meet CLIA and CAP requirement for daily QC testing

• HEMOCHRON Jr Signature
• ACT
• ACT, ACT-LR
• PT
• Fresh or citrated WB
• aPTT
• Fresh or citrated WB

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Activated Clotting Time
Extrinsic Pathway
Intrinsic Pathway
ACT
Common Pathway
CLOT
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What do we use an ACT for?

• Maintain Balance
• Bleeding Thrombosis
• Heparin
• Rapid Anticoagulant Effect
• Individual sensitivities vary significantly
• Potency differences
• Source Bovine or Porcine
• Lot to Lot variability
• Rapidly Reversible with Protamine

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Why are there so many different ACTs?
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Monitoring - ACT

• Benefits
• Industry Standard Since 1970s
• Recommended as primary method in AmSECT
  guidelines (perfusion)
• Easy to run

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Monitoring - ACT

• Disadvantages
• Each system yields different numbers
• High sensitivity to hypothermia and hemodilution
  (with exceptions)
• Little or no correlation to heparin level
• especially true for pediatric patients

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Clinical Applications

• Operating Room
• Cardiac Surgery
• Interventional Cardiology and Radiology
• Critical Care
• Satellite Sites
• Dialysis
• ECMO
• Emergency Room

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Heparinized ACT - CPB
Data from Huffman, et.al. 1998 AmSECT meeting
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Monitoring in CPB - ACT

• Data from clinical evaluation, on file, ITC

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Pharmaceutical Intervention

• Amicar or Tranexamic Acid
• No effect on standard celite ACT
• Continued debate on efficacy
• Multiple reports
• Reduction in post-operative blood loss
• Reduced transfusion requirements

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Pharmaceutical Intervention

• Aprotinin
• Significant elevation of celite ACT
• Two dosing regimens
• Full Hammersmith
• 2 x 106 KIU loading dose 2 x 106 KIU pump prime
  0.5 x 106 KIU/hr infusion
• Half Hammersmith
• 1 x 106 KIU loading dose 1 x 106 KIU pump prime
  0.25 x 106 KIU/hr infusion

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ACT Monitoring-Aprotinin Treatment

• Celite ACT
• Not recommended
• Still used with target times of gt750 seconds
• Kaolin ACT
• Unaffected by moderate doses of aprotinin
• Used with target times of gt 480 seconds
• ACT
• Unaffected by ALL doses of aprotinin
• Used with target times of gt 400 seconds

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ACT Monitoring -Aprotinin Treatment
Data from clinical evaluation, on file, ITC
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Non-ACT Monitoring - Aprotinin

• HiTT - High Dose Thrombin Time

Adapted from Huyzen, et. al. J.CardioThorac.
Vasc. Anesth. 8153, 1994
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Alternative Monitoring - Aprotinin

• Adapted from Huyzen, et. al. J.CardioThorac.Vasc.A
  nesth. 8153, 1994

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Thrombin Time
Extrinsic Pathway
Intrinsic Pathway
Common Pathway
TT
CLOT
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Other POC in the OR

• Heparin Level
• ?Xa Activity
• laboratory only, impractical
• Medtronic Hepcon HMS
• indirect measure of protamine reversible heparin
  activity in whole blood
• correlates with ?Xa and ?IIa activity
• HEMOCHRON PRT
• ACT based protamine titration
• HEMOCHRON HiTT
• unaffected by hemodilution, hypothermia
• insensitive to aprotinin
• correlates with ?Xa and ?IIa activity

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Monitoring - Heparin Level

• Benefits
• Measures concentration, not activity
• Correlates with laboratory standards
• Disadvantages
• Each system yields different numbers
• apples and oranges do not compare
• Correlation to anticoagulation status is still
  disputed
• Target for neonate, pediatric and adult patients
  may differ

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Monitoring - Heparin Level

• Young lt4.5 years
• Shayevitz, JR and OKelly, SW Progress in
  Anesthesiology, vol. IX, chapter 16 1995

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Other POC Coag in the OR

• aPTT / PT
• Pre- and post-procedural screening
• Fibrinogen
• Pre- and post-procedural screening
• Dosing Assays
• Customize heparin and protamine for each patient
• HEMOCHRON HRT / PRT
• Hepcon HMS

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Other POC Coag in the OR

• Heparin neutralization verification
• Ensure complete removal of circulating heparin
• aPTT
• PDA-O - ACT based
• TT / HNTT - Thrombin Time based
• heparinase ACT

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Outcome studies - POC in OR

• Reduced Blood Loss/Transfusion
• Use of HRT and PRT (RxDx System)
• Jobes, D. et. al., 1995. J.Thorac.Cardiovasc.Surg.
  
• Reduced Cost
• Resulting from POC Assays
• RxDx combined with TT / HNTT
• Jobes, D. et. al., 1996. Am Soc Anesth Mtg.

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Outcome studies - POC in OR

• Reduced Complication Rates
• TT /HNTT
• Re-Exploration for Bleeding Reduced from 2.5 to
  1.1
• Re-Exploration for Coagulopathy Reduced from 1.0
  to 0.0
• Jobes, et.al. 1997, NACB Presentation, Phila.

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Clinical Applications

• Operating Room
• Cardiac Surgery
• Interventional Cardiology and Radiology

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Procedures

• Diagnostic
• Catheterization
• locate and map vessel blockage(s)
• determine need for interventional procedures
• Electrophysiology
• Interventional
• Balloon angioplasty
• Atherectomy (roto-rooter)

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Diagnostic Low dose heparin

• Catheterization and Electrophysiology
• 2500 - 5000 unit bolus dose
• frequently not monitored
• if monitored
• ACT
• aPTT

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Interventional Moderate dose

• Angioplasty and Atherectomy
• 10,000 unit bolus dose or
• 2 - 2.5 mg/kg
• target ACT 300 - 350 seconds
• unless platelet inhibitors used
• 200 300 in presence of ReoPro

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Why use platelet inhibitors?
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Angioplasty promotes aggregation
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Platelet Inhibitors

• ReoPro
• elevates ACTs
• target time 250 sec with ReoPro
• determined using FTCA510 tube
• Integrelin
• No clinically significant effects on ACT
• Slight decrease in ACT observed
• Aggrastat
• No reported effects on ACT

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QUESTIONS?
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Coagulation Testing

• What is it?
• Why do we need it POC?

PART 2
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Why Bother with POC Coag?

• Improved TAT - Turn Around Time
• Defined from the Clinician, not Lab view
• When is Turn Around Important
• Emergency Room
• ICU/CCU Dose Adjustments
• Operating Room / Cath Lab
• STAT Testing Turn Around

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STAT Testing TAT

• Fitch, et.al, J. Clin Monit Comput. 1999.
  15197-204

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Clinical Applications

• Operating Room
• Cardiac Surgery
• Interventional Cardiology and Radiology
• Critical Care
• Satellite Sites
• Dialysis
• ECMO
• Emergency Room
• Anticoagulation Clinic

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ACT or aPTT

• 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

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ACT or aPTT

• Monitor heparin therapy
• Target times determined by each facility
• APTT outcome study
• Reduce time to result (112 vs lt5 minute)
• Reduce time to stabilization
• Reduce dose adjustments
• Reduce length of stay
• By using POC aPTT instead of lab
• Poster at AACC 2000 Staikos, et.al.

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What did it say?

• Mean time to lab result 112 min
• Mean time to POC result lt5 min
• Fewer dose adjustments needed in POC group to
  reach therapeutic level
• Shorter time required to reach therapeutic level
  in POC group
• Fewer dose changes in POC group

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Activated Partial Thromboplastin Time
Extrinsic Pathway
Intrinsic Pathway
APTT
Common Pathway
CLOT
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Activated Partial Thromboplastin Time

• NOT a PTT
• PTT is the predecessor of the aPTT
• Not used anymore
• Laboratory or Point of Care
• High APTT values
• the presence of heparin
• underlying coagulopathy
• Monitor heparin / coumadin cross-over

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Heparin versus Warfarin
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Prothrombin Time
Extrinsic Pathway
Intrinsic Pathway
PT
Common Pathway
CLOT
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Prothrombin Time

• Monitor warfarin therapy
• Monitor heparin/warfarin crossover
• Target times are set by
• International Normalized Ratio (INR)
• ISI international Sensitivity Index
• INR target ranges are specified by patient
  populations
• prophylactic therapy for DVT INR 2.0 - 3.0
• artificial heart valve INR2.5 3.5

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Will POC Results Match the Lab?
NO!

• (Probably Not)
• but it WILL Correlate

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Correlate Does Not Mean Match
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Coag is NOT Chemistry
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Compare for your site. Same System / Multiple
Sites
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Are differences important?

• Sometimes no - aPTT C

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• Sometimes VERY - aPTT SP

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Lot to Lot Reproducibility
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Clinical Applications

• Operating Room
• Cardiac Surgery
• Interventional Cardiology and Radiology
• Critical Care
• Satellite Sites
• Dialysis
• ECMO
• Emergency Room
• Anticoagulation Clinic

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Dialysis / ECMO

• ACT (or nothing in dialysis)
• Majority use P214 glass activated ACT
• Some use ACT-LR HemoTec
• Better Control of Anticoagulation Leads to
  Increased Dialyzer Reuse
• Potential for Long Term Cost Savings
• No Compromise in Dialysis Efficacy (Kt/V)
• Ouseph, R. et.al. Am J Kidney Dis 3589-94 2000

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Emergency Room

• ACT aPTT PT Fibrinogen
• Immediate Identification of Coagulopathies
• Optimization of Critical Decision Pathways
• ACT Allows Early Detection of Traumatic
  Coagulopathy
• Allows Early Treatment Decisions
• Aids Damage Control Decisions
• Aucar, J. et.al. 1998 SW Surgeons Congress
• Optimize Staffing During Off Hours

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Anticoagulation Clinics

• Results Available While Patient is Present
• Improved Anticoagulation Management
• Improved Standard of Care
• Staff Efficiency
• Immediate Retesting (if needed)
• Fingerstick Sampling
• Same System for Clinic and Home Bound Patients
• Standardized ISI / PT normal
• Test System Specific

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Anticoagulation Clinics

• Potential for Self-Testing
• High Risk Patients
• Patients Who Travel Frequently
• Home-Bound
• Patients in Rural Areas Far from Clinic
• Improved Outcomes Through More Frequent Testing

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How to compare INR differences

• Has the Hemostatic Balance been Upset?
• Is the Clinical Response Different?

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Whats the catch?

1. Regulatory compliance
2. Connectivity

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Regulatory compliance

• Who sets the rules?
• JCAHO
• Joint Commission on Accreditation of Health Care
  Organizations
• CAP
• College of American Pathologists
• FDA
• Food and Drug Administration
• CMS (formerly HCFA)
• Centers for Medicare Medicaid Services
• CDC
• Centers for Disease Control

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CLIAC

• CLIA Committee
• Define and interpret CLIA regulations
• CLIA - Clinical Laboratory Improvement Act
• Designed to ensure accuracy of results from
  clinical laboratories
• Compliance required to pass
• JCAHO and / or CAP inspections
• CLIA defines regulations for each test
• CDC / FDA / CMS / CDC complexity categories

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CLIA Applies to ALL Testing Areas

• Central Laboratory
• Satellite Labs
• Critical Care
• Surgical Suite
• Clinics
• Bedside testing
• Doctors office
• Home Testing

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CLIA Regulations for Coagulation

• Central Laboratory can hold the CLIA license
• Satellites can have independent licensure
• Moderately Complex tests
• Except - ProTime and Coaguchek / S are waived
• Requires
• Certified Laboratory Director
• Record Keeping
• Training
• Quality Policy

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Implementing POC coag requires

• RECORD KEEPING
• Method Validation - accuracy
• comparison to current standard
• Performance Range Assessment
• Linearity often used
• Calibration/ verification NOT required for coag
• Is assay performance appropriate to clinical
  needs?
• Does dose responsiveness span clinical range?
• Training
• competency evaluations at predetermined intervals

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• Routine Quality Control
• Instrument Performance Verification
• Electronic Quality Control with Numeric Output
• In GA, make sure state approves specific EQC
• Two levels per 8 hour shift
• Assay Performance Verification
• Wet QC as per Manufacturers Recommendation
• Two levels for each box of reagent when opened

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Connectivity

• Everyone wants it
• Almost no one is ready to implement
• Multiple definitions
• Download to computer
• To LIS or to HIS or to both or to data management
  software
• Real time or batch
• QC data, patient data, or both

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Short term solutions

• Interim programs for configuration, data capture,
  QC compliance tracking
• transfer to file format easily adaptable
• Requires independent transfer protocol
• e.g., ITC Configuration Manager, ReportMaker,
  HRDM
• Dedicated interface specific to one
  manufacturers instrumentation
• e.g., Abbott Lifescan
• Manufacturer ensures system compatibility

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• Instrument manufacturer neutral interface
• RALS-plus
• Telcor
• Manufacturer works with interface supplier to
  ensure compatibility
• Interface supplier works with LIS / HIS supplier
  to ensure compatibility

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Long term Solutions

• POC Connectivity Industry Consortium
• Accepted as NCCLS document POCT1-A
• sections of the CIC specification approved by
• IEEE
• HL7
• Standardization of POC connectivity
• Messages
• Protocols
• Technologies

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Why Bother with POC Coag?

• Improved TAT - Turn Around Time
• Standardized Clinical Interpretation
• Defined Assay Sensitivity
• Requires Lot to Lot Reproducibility
• Defined Reagent Variability
• Identical Instrumentation /Reagents at All
  Testing Sites
• Defined Critical Clinical Decision Points
• No Change of Normal Ranges or Target Times
  Between Lots of Test Reagents or Testing Locations

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Why Bother with POC Coag?

• Improved Clinical Outcome
• Reduced LOS Length of Stay
• Improved, timely patient care