Coagulation 4 Flashcards
Match each phase of the contemporary model of coagulation to its key event
initiation, propagation, amplification
platelets are activated
a large quantity of thrombin is produced
The TF/7a reaction activates the final common pathway
Initiation: The TF/7a reaction activates the final common pathway
Amplification: Platelets are activated
Propagation: a large quantity of thrombin is produced
What are the three phases of the contemporary cell-based cascade?
initiation
amplification
propagation
Initiation is when
tissue factor is expressed
Amplification is when
platelets and cofactors lay the groundwork for large-scale thrombin production
Propagation is when
large quantities of thrombin are produced on the surfaces of platelets
The propagation phase begins when factor _ is activated by factors
10; activated by factors 4 (Ca2+), 8 & 9 on the surface of the platelet
What is the end result of the initiation phase?
a small amount of thrombin (2a) is produced but not enough to activate fibrin
Why do thrombin levels remain low in the 1st phase of the contemporary coagulation model?
b/c tissue factor pathway inhibitor limits the amount of tissue factor released
Identify the BEST predictor of bleeding during surgery
a. PT/INR
b. history & physical
c. thromboelastogram
d. bleeding time
b. History & physical
____________ assesses the intrinsic and final common pathways
Activated partial thromboplastin time (aPTT)
Normal aPTT is
25-32 seconds
__________ assesses the extrinsic and final common pathways
Prothrombin time (PT)
Normal PT is
12-14 seconds
________________ standardizes PT results
International normalized ratio
The target INR for a patient on warfarin is
2-3 x control
Platelet count monitors __________ but not ___________
the number of platelets but not how well the platelets function
______________ monitors platelet function, but it’s seldom used in clinical practice
Bleeding time
__________ guides heparin dosing
Activated clotting time (ACT)
Normal ACT is
90-120 seconds
The ACT should exceed _______ before going on CPB
400 seconds
_____________ monitors the therapeutic response to unfractionated heparin but not LMWH
PTT
Normal INR value in healthy patients is
about 1
__________ evaluates the ability to form a platelet plug
Bleeding time
Normal value of bleeding time is
2-10 minutes
_______ monitors for fibrinolysis
D-dimer
If fibrinolysis is increased, there’s likely
a thrombus present
Normal value of D-dimer is
<500 mg/mL
Differential in the setting of elevated d-dimer includes
DVT, PE, & DIC
A platelet count less than 20,000 increases the risk of
spontaneous bleeding
The TEG provides a “real-time” visual representation of disorders of
coagulation and fibrinolysis
The basic components of the TEG include
R time
K time
alpha angle
maximum amplitude
amplitude at minutes after maximum amplitude
R time is the time to
begin forming the clot
K time is the time
until the clot has achieved fixed strength
Alpha angle is the
speed of fibrin accumulation
maximum amplitutude is the
measurement of clot strength
Amplitude at minutes after maximum amplitude is the
height of vertical amplitude 60 minutes after the maximum amplitude
Normal r time is
6-8 minutes
If R time is abnormal, the problem area is
coagulation factors
The treatment for abnormal R time is
FFP
The normal value for K time is
3-7 minutes
The problem area for abnormal K values is
fibrinogen
The treatment for abnormal K value is
Cryo
The normal value of the alpha angle is
50-60 degrees
The problem area for abnormal alpha angle is
fibrinogen
The treatment for abnormal alpha angle is
cryo
The normal value of maximum amplitude is
50-60 mm
The problem area for abnormal maximum amplitude is
platelets
The treatment for abnormal maximum amplitude is
Plts +/- DDAVP
The normal value for amplitude at minutes after maximum amplitude is
MA-5
The problem area for abnormal amplitude at minutes after maximum amplitude is
excessive fibrinolysis
The treatment for abnormal amplitude at minutes after maximum amplitude is
tranexamic acid
aminocaproic acid
