Coagulation Disorders Flashcards
Three major steps in the process of hemostasis
Prothrombinase converts prothrombin to thrombin
Thrombin converts fibrinogen to fibrin
Fibrin strands trap RBCs forming clot
Role of platlets
Platelets adhere to and aggregate at site of injury in vessel
Role of Platelets
Platelet activation leads to formation of fibrin network that trap RBCs forming clot
Role of Cofactors in Hemostasis
Ca+2 and Vitamin K are critical for synthesis of clotting factors which stop wounds from bleeding
Deep venous thrombosis (DVT)
Venous clots often develop in the legs as a DVT, but can migrate to lungs creating a pulmonary embolism
Fibrinolysis
Plasmin breaks down fibrin network
Clots migrating from left atrium can cause
strokes
Clots migrating from the right atria can cause a
pulmonary embolism
Coronary artery clots cause
MIs
Heparin (Know this)
Enhances antithrombin activity
Decreases thrombin activity
Decreases prothrombinase activity
Low molecular wt Heparin
Similar activity
Fewer adverse effects than heparin
Less risk of thrombocytopenia compared to heparin
When do we use heparin
DVT, post stroke, post MI, prevent PE
Mech of action for Heparin
Activates antithrombin III, which inhibits thrombin and factor Xa (prothrombinase).
Remember prothrombin istransformed into thrombin by a clotting factor known as factor X or prothrombinase and then thrombin acts to transform fibrinogen, also present in plasma, into fibrin, which, in combination with platelets from the blood, forms a clot
-DONT NEED TO KNOW
Prevents clot formation; does not break down existing clots
Antidote for heparin
Protamine Sulfate
Adverse effects of heparin
Osteoperosis
Bleeding
Skin lesions
Heparin Induced thrombocytopenia
Warfarin used for
Prophlaxis of eventls like DVT and PE
prevention of CVA /MI
Does not treat
Low molecular wt heparin advantages
Possess the same degree of anticoagulant activity as heparin but have several advantages which are;
Less likely to cause thrombocytopenia
Duration of action is 2 to 4 times longer.
Produce a more stable response.
Fewer follow up labs are needed.
Client can be trained to give S/C injections at home.
Often the drug of choice now .
Heparin half life
Very brief
Mech of action - Warfarin
Warfarin inhibits/blocks two enzymes that use Vitamin K to produce clotting factors
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Adverse effects of Warfarin
Purple toe syndrom
Microembolism, osteperosis
Bone fractures
Abnormal bleeding
Antidote for warfarin
Vit K
Dietary reccomendations for Warfarin
Avoid Vit K high foods
Nursing considerations for pts recieving anticoagulant therapy
Obtain a complete health history including allergies and drug history
Obtain baseline vital signs, especially heart rate and blood pressure, and clotting times
What to be careful of for someone on anticoag therapy
Any accidental bumps
Aggressive teeth brushing
What to monitor for pts on Heparin
CBC, INR, PT
What pts should be more closely moniored if opn anticoag therapy
Also monitor patients with kidney or liver disease, GI, diabetes with extra care.
At increased risk for bleeding/low platelets (liver)
DM increases risk of blood clotting
PT Test
PT stands for prothrombin time. It is a measure of how quickly blood clots. The traditional method for performing a PT test is to blood drawn and sent to a lab. At the lab, a substance called a reagent is added to the blood. The reagent causes the blood to begin clotting. The PT result is the time in seconds that is required for the blood to clot.
INR Test
INR stands for International Normalized Ratio. As its name suggests, one INR result can be compared to another INR result regardless of how or where the result was obtained. So, the INR is just the standard unit used to report the result of a PT test.
Range: Varies for person to person
Most common is bw 2 and 4
Normal pt would have 1
Higher INR means
Longer time for blood clotting
Lower INR means increased risk for
Clotting
Typical APTT
25-30 seconds
Direct Thrombin and Factor Xa inhibitors
Newer drugs in the prevention and TX of venous thromboembolism and pulmonary emboli.
Originally derived from chemicals found in leeches.
Directly inhibit thrombin preventing the formation of fibrin used for the same types of indications as heparin or LMWH>
Why would someone get an apixiban over warfarin
Apixiban requires NO monitoring
Direct Thrombin and Factor Xa inhibitors use
Shorter half life, work faster
Antiplatlet drugs include
Aspirin
Reduces formation of thromboxanes (promotes activation of platelets)
ADP receptor antagonists
Prevent aggregation by blocking receptor
Prevent activation of platelets
Mech of action of antiplatlet drugs
Blocks ADP receptors on platelets, inhibiting platelet activation and aggregation, thereby extending clotting times
Adverse effects of antiplatlet drugs
Headache, dizziness
Flu-like syndrome
Diarrhea
Bruising
Upper respiratory tract infections
Rash, pruritis
Serious bleeding
Direct Xa inhibitors
Direct Oral Anticoagulants DOAC
Only given PO
Result in prolonged clotting time
Reduce risk of stroke and systemic embolism in clients with nonvalvular a fib.
TX of DVT and Pulmonary embolism
Prophylaxis of DVT in client who have undergone knee or hip surgery. Apixaban and rivaroxaban.
Adverse effect bleeding and there is no antidote.
Abrupt discontinuation increases risk for thromboembolism.
Increased risk of spinal and epidural hematomas in uncoagulated patients
Thrombolysis
Anticoagulants prevent new clot formation
Thrombolytics break down existing clots
Fibrinolysis
breakdown of fibrin fibers leading to disruption of clot
Antiplatlet meds are NOT clot buster > T or F
True
Therapeutic effects and uses
Thrombotic CVA
Off-label use to restore IV catheter patency
Mechanism of action
Converts plasminogen to plasmin which breaks down fibrin in clot
Lowers circulating fibrinogen and plasminogen
Adverse effects of alteplase
Bleeding
Angioedema (Also ace inhibs)
Intercranial bleeding
What to monitor when administering a thrombolytic?
BP, Pulse
Q15 min for and H, then Q30 min
INR, CBC, Monitor for internal bleeding
Antifibrinolytics
Used to prevent and treat excessive bleeding post-surgery
Formation of abnormal clots, possibly pulmonary clots
Inactivates plasminogen precursor for plasmin that digests the fibrin clot.
Very rare
Acute uses of fibrinolytics
Acute hemorrhages
Prevention of post-operative bleeding
aptt used to monitor effectiveness of
Used to monitor the effectiveness of heparin
PT used to monitor effectivness of
Warfarin
