Chapter 19
Agents affecting Blood Clotting
Blood Clotting p461
• Clotting is necessary to prevent fatal loss of
blood from a minor injury
• Thromboemboli
• Anticoagulants
Drugs that induce bleeding or delay
coagulation time p464
• ASA: increases bleeding
• Delay coagulation times
– ASA
– NSAIDS
– Anticoagulants
.
Anticoagulant Agents p462
• Interrupt the clotting process
– Heparin
– Used to treat: coronary occlusion, cerebral
thrombosis, CVAs, thromboembolism
– Treatment of choice to prevent further DVTs
once a pt has been diagnosed with a DVT
Heparin p462
• Heparin action
– Indirectly interferes with the conversion of
prothrombin to thrombin
– The deficiency of thrombin prevents the
conversion of fibrinogen to fibrin
Heparin p462
• Potency is expressed in units
• Inactivated by stomach acid if given orally
• Administered via IV infusion or subq injection
– No intramuscular injections (risk hematoma formation)
– Subq = longer acting administration route
– Rotate injections sites
– Do not aspirate
– Do not massage injection site
Heparin: Side Effects p462-463
• Prolonged bleeding
• Antidote for heparin toxicity
– Protamine sulfate
• Contraindication
– Do not administer to clients with coagulation
disorders
• Lab test to determine clotting times for
patients on heparin: PTT (partial
thromboplastin time)
Drugs that decrease effect of heparin
p464
•
•
•
•
•
•
Nicotine
Nitroglycerin
Antihistamines
Digitalis
Tetracyclines
Ginkgo biloba and goldenrod (herbals)
Enoxaparin (Lovenox)
Low Molecular Weight heparin p464
• Chemically related to heparin
• Given by subcutaneous injection
• Used:
– Prophylaxis of DVT in pt undergoing hip or knee
replacement
– Treatment of DVT for inpatient and outpatient
Vitamin K and blood clotting p465
• Vitamin K is necessary synthesis of clotting factors
• Decreased vitamin K = decreased clotting factors
• Therefore, decreased vitamin K leads to increased
bleeding tendencies
Oral Anticoagulants p465
• Warfarin (Coumadin)
– Inhibits blood clotting by interfering with the
synthesis of vitamin K-dependent clotting factors
• Close client monitoring
– Dosage is individualized based on labs
– Lab test for pt on warfarin: PT INR
• Expected range is often individualized by
doctor, however, 2-3 INR is often the goal.
Oral anticoagulants cont p466
• As a group, oral anticoagulants have a greater
potential for clinically significant drug
interactions than any other class of drugs.
• Box 19-3 page 466
• Box 19-4 page 467
– Antidote for oral anticoagulants: Vitamin K
Nursing assessment for pt on
anticoagulants p470
• Monitor for development of:
– Hematuria
– Tarry stools
– Excessive vaginal bleeding
– Abdominal, flank, or joint pain
– Headaches
– Changes in neuro status
– Hematomas or ecchymotic areas
– Vomiting blood (coffee grounds
emesis)
– Bleeding from nose or gums
Patient teaching p473
• Oral anticoagulants:
–
–
–
–
–
–
For shaving, use electric razors
Use soft bristle toothbrush
Avoid falls and injury
Avoid ASA or ASA containing products
Necessary compliance with clotting time labs
Avoid too few or too many green leafy vegetables that may
result in more or less Vitamin K
– Do not add or subtract any meds while on warfarin
Antiplatelet Agents p467
• Action: inhibit the aggregation (clumping) of platelets
• Examples
– Aspirin (ASA)
– Clopidogrel bisulfate (Plavix)
Thrombolytic Agents p468
• Action
– Dissolves clots
– Frequently used to unclog central
lines
• Example
– Streptokinase (IV)
• Caution
– Hemorrhage