Neurology
APTT, PTT, PT, INR
The Tests We All Must Pass
• Chronological Order of the
Presentation
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Introduction
APTT & PTT
PT & INR
Nursing Interventions
Differences
Current Research
Summary
Questions
The Cold Hard Facts
• We all die, but first we must live
• We control our bodies via a large
neurological system
• Depriving this neurological system
of blood flow = death
• Thromboli can impede blood flow
• Therefore thromboli = death
The Selfish Gene
• We all want to live
• Keeping blood flowing to
neurological system prolongs life
• Thromboli impedes blood flow
• Antithrombolitic therapy prevents
thromboli formation
• Therefore antithrombolitic
therapy prolongs life
Too Much of a Good Thing...
• Too much antithrombolitic therapy =
prolonged bleeding
• Prolonged bleeding decreases blood
flow to neurological system
• Decreased blood flow to neurological
system can cause death
• Therefore too much antithrombolitic
therapy can cause death
How to Walk the Line
• Develop tests to measure clotting factor
• APTT & PTT
• PT & INR
APTT & PTT
• APTT – Activated Partial Thromboplastin Time
• PTT - Partial Thromboplastin Time
• Use intrinsic factors to initiate coagulation pathways
• Coagulation is timed and compared to a standard
• Test used to diagnosis and monitor
• 70 seconds…
PT & INR
• PT – Prothrombolin time
• INR – International Normalization Ratio
• Firm fibrin clot formation initiated by
tissue thromboplastin (factor III) and
calcium
• Timed test
PT & INR
• Uses the equation: INR = (PT )x ISI
PT
client
avg
* ISI - International Sensitivity Index *
• INR = 1
• INR = 2-3
• INR = 2.5-3.5
Nursing Interventions
• Both are blood tests = similar
interventions
• Require interventions at all stages
of the test:
– Pre-test
– Intra-test
– Post-test
Pre-Test
• Education
• Client Health History
– Bleeding disorders
– Surgeries, lab tests, diagnostic tests
• Current and recent medications
– Anticoagulants, acetylsalicylic acid,
herbs, nutritional suppliments, and
nutraceuticals
Intra-Test
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Follow directions
Breath normally
Avoid unnecessary movement
Identify client
Label vials accordingly
Fill tube completely
Have sample analyzed within 4 hours
Post-Test
• Observe venipuncture site
• Provide instructions regarding
excessive bleeding and bruising
• Educate regarding prolonged APTT or
high INR
• Reinforce health care provider
information or instructions
• Notify client’s health care provider if
INR < 2 or APTT < 53 seconds
Where are the Differences
• INR internationally recognized and understood
• APTT uses kaolin, celite or elegia acid to speed
up reaction time, therefore increasing the speed
of the test
• APTT not recommended for prophylactic lowdose heparin therapy
• INR affected by more drugs
• INR may be performed on samples older than 4
hours*
* A topic of current research
Current Research
• Certified Diagnostic Plasmas for
INR
• Are 2.0-3.0 INR values optimal?
• Obtaining INR and APTT values
using different analyzers
• INR self testing by clients
Summary
• APTT value < 70 seconds
• INR value 2.0-3.0
• APTT and INR instrumental in
anticoagulation therapies, should
be monitored closely to ensure
adequate dosing
References
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Cha, C.H., Park, C.J., Kim, D.H., Kim, M.J., Cho, Y.U., Jang, S. & Chi, H.S. (2010)
Direct international normalized ratio determination using multicalibrators is
more responsive than the conventional method for measuring prothrombin
time. International Journal of Laboratory Hematology, 32(4), pp. 392–397.
doi: 10.1111/j.1751-553X.2009.01195.x
Christensen, T.D., Jensen, C., Larsen T.B., Maegaard, M., Christiansen, K. &
Sørensen, B. (2010) International normalized ratio (INR), coagulation factor
activities and calibrated automated thrombin generation -- Influence of 24 h
storage at ambient temperature. International Journal of Laboratory
Hematology, 32(2), pp. 206-214. doi: 10.1111/j.1751-553X.2009.01170.x
Peng, L., Yan, C., Wu, X. & Nie, L. (2009) Comparability of the results of PT–INR
with local MNPT and APTTR with MNAPTT on different coagulation analyzers
in China. International Journal of Laboratory Hematology, 31(3), pp. 352-358.
doi: 10.1111/j.1751-553X.2008.01071.x
Plesch, W. & van den Besselaar, A. M. H. P. (2009) Validation of the
international normalized ratio (INR) in a new point-of-care system designed
for home monitoring of oral anticoagulation therapy. International Journal of
Laboratory Hematology, 31(1), pp. 20-25. doi: 10.1111/j.1751553X.2007.00998.x
References
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You, J. H. S., Chan, F. W. H., Wong, R. S. M. & Cheng, G. (2005) Is INR between
2.0 and 3.0 the optimal level for Chinese patients on warfarin therapy for
moderate-intensity anticoagulation? British Journal of Clinical Pharmacology,
59(5), pp.582-587. doi: 10.1111/j.1365-2125.2005.02361.x
Questions?
• A wise person once observed:
“Nurses are like the blood of the
health care system...without
them it would die.”