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 p 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