chapter 32 study guide questions (drugs affecting coagulation)

What is the role of the clotting cascade?

The clotting cascade is initiated by the tissue damage and platelet activation, which mobilize the clotting factors circulating in the blood. Once active, these clotting factors work with calcium to form fi brin. At this point, blood coagulation is completed and blood loss stops.

Your patient is receiving alteplase (Activase). The patient reports abdominal pain and vomits 100 cc of dark coffee-ground emesis. The patient's blood pressure has dropped to 80/40. You should anticipate administration of which of the following drugs?

aminocaproic acid (Amicar) - Protamine sulfate is the antidote for heparin; vitamin K is the antidote for warfarin; and pentoxifylline is an antiplatelet drug

Your patient has cirrhosis of the liver and is suspected of having systemic hyperfibrinolysis. What drug do you anticipate will be ordered?

aminocaproic acid (Amicar) -Hyperfi brinolysis causes life-threatening hemorrhage.

Your patient is receiving alteplase (Activase) for an acute MI. In addition to bleeding, you should monitor for

arrhythmias -During the reperfusion process, arrhythmias may occur.

A patient is brought to the emergency room with an evolving MI and started on recombinant alteplase, a thrombolytic agent. To minimize adverse effects during this drug therapy, the nurse should

assess vital signs closely throughout therapy - Vital signs should be assessed frequently throughout therapy with recombinant alteplase because bleeding is possible from therapy. Recombinant alteplase is always administered with an infusion pump, never by gravity fl ow, to prevent overdosage. Avoid IM injections because this may cause internal bleeding. Coffeeground emesis is a sign of internal bleeding and the infusion should be stopped.

Your patient has gone to the cardiac cath lab for a percutaneous transluminal coronary angioplasty with stent placement. Which drug class do you anticipate will be ordered for this patient?

glycoprotein IIb/IIIa inhibitor - Glycoprotein IIb/IIIa inhibitors decrease platelet aggregation, which may occur on the rough endothelium of the stented area of the vessel.

Your patient is to receive heparin 5,000 units SC BID. To appropriately administer this medication, you should

do not aspirate into the syringe, or rub the area after administration - Aspirating and massaging the area increase the risk for bleeding.

Your patient is taking warfarin (Coumadin) for prophylaxis for deep vein thrombosis. The patient should be scheduled for which of the following laboratory tests to monitor the effectiveness of therapy?

either PT or INR - INR is the standard of care; however, some providers still do both tests.

What is a "factor"?

factors are plasma components that are an integral part of the clotting cascade

Your patient is receiving heparin via IV infusion as drug therapy for a deep venous thrombosis (DVT). What is your assessment of an aPTT level of 55 seconds when the control is 30 seconds?

heparin dose is appropriate - Heparin dose is appropriate as it is within the range of 1.5 to 2 times the control

anticoagulants, such as heparin, work by

inactivating factor X -Heparin, along with antithrombin III, rapidly promotes the inactivation of factor X, which, in turn, prevents the conversion of prothrombin to thrombin.

Which of the following patients should not receive alteplase (Activase)?

Louise, 10 days postpartum - Patients with a recent obstetric delivery have an increased risk for bleeding

Your patient is receiving a continuous heparin infusion. You note bruising on the patient's arms, and the aPTT is 150 with a control of 30. You would anticipate administration of which of the following drugs?

protamine sulfate -Protamine sulfate is the antidote for heparin overdose.

A patient with intermittent claudication from peripheral vascular disease in both legs begins taking pentoxifylline, a hemorrheologic drug. A follow-up telephone call is made 1 week after initiation of therapy to see if the patient has any questions or problems with the drug therapy. The patient states, "I don't feel any better. This medicine is not working." Which of the following is the best response of the nurse

"Full therapeutic effect may take 4 to 8 weeks to occur." -Although onset of therapeutic effect begins in 2 to 4 weeks, full effect is delayed. Patients need to realize this and be encouraged to be patient to see results. Drug therapy needs to be continued until full therapeutic effect is achieved. There is always individual variation in response to drug therapy; however, the patient needs to hear reinforcement regarding the delayed onset of action to prevent discouragement and premature cessation of drug therapy.

Your patient has hemophilia and intermittently takes antihemophilic factor (AHF) at home. Patient teaching should include a. "Keep th

"keep the medication refrigerated until you use it." -Although the medication is refrigerated before use, it should be in room temperature when it is infused.

Your 55-year-old patient has just started taking pentoxifylline (Trental) for intermittent claudication. Patient teaching should include

"you may not see immediate results, but keep on taking the medication." -Therapeutic effects occur in 2 to 4 weeks

When assessing the results of heparin anticoagulation, the aPTT should be

1.5 to 2 times the control - The monitoring test for heparin in an aPTT. The therapeutic range is 1.5 to 2 times the control.

When assessing the results of warfarin (Coumadin) anticoagulation, the INR should be

2 to 3 - The monitoring tests for warfarin are the PT and INR. Therapeutic values for the PT are 1.4 to 1.6 times the control; therapeutic value for the calculated INR is 2 to 3.

After dilution, antihemophilic factor (AHF) should be administered within _____ hour(s)

3 - This is necessary to prevent bacterial growth

Maximum effects of warfarin (Coumadin) occur within

3 to 4 days - This is the time required for the drug to reach a steady state in the blood.

How do anticoagulants, antiplatelet agents, hemorrheologics, and thrombolytic agents affect homeostasis?

Anticoagulant drugs "thin" the blood by interrupting the clotting cascade. Antiplatelet drugs decrease the ability of the blood to clot by interfering with platelet membrane function and platelet aggregation. Hemorrheologics reduce blood viscosity, increase fl exibility of the RBC, and decrease platelet aggregation. Thrombolytics have the ability to dissolve existing clots.

Your patient takes clopidogrel (Plavix) after experiencing a stroke. Patient teaching should include the need for periodic laboratory testing of

CBC, bleeding time, platelet function -Bleeding time and platelet function assess its antiplatelet action, and the CBC assesses the neutrophil count.

Which of the following patients should be closely monitored during heparin therapy?

Constance, with a history of peptic ulcer disease -Patients with peptic ulcer disease may have an increased risk for bleeding because of the alteration in the stomach lining.

The most common adverse effects of aminocaproic acid therapy affect the

GI system -Aminocaproic acid induces anorexia and nausea

Your patient has been admitted to the emergency department with a CVA. The computed tomography (CT) scan indicates the stroke is hemorrhagic in nature. Which of the following drugs would be effective for this CVA?

Using a thrombolytic in a patient with a hemorrhagic stroke would increase bleeding. (use a clotting factor of hemostatic)

The most useful test for monitoring the effectiveness of heparin is

aPTT -The monitoring test for heparin is the aPTT. The PT is more helpful for warfarin, the bleeding time for thrombolytics, and a CBC is not helpful for any of the anticoagulant drugs.

clopidogrel, an antiplatelet, inhibits platelet aggregation, thus prolonging the bleeding time. it works by irreversibly modifying the platelet ADP receptor so that the exposed platelet is affected for its life span and it is used to reduce the occurence of atherosclerotic events (MI, stroke, and vascular death) when aspirin is not tolerated or is not effective. clopidogrel must be converted into an

active metabolite to be therapeutic. drugs that inhibit the enzymatic pathway needed for this conversion, such as proton pump inhibitors, will decrease the therapeutic level of clopidogrel, placing patients at risk of clot formation. other drug interactions are possible through other hepatic enzymes. adverse reactions to clopidogrel are similar to those of aspirin. the most common adverse effect is GI distress. serious GI problems can occur including GI bleeding and ulceration (risk of these adverse effects is less than for aspirin, however).

warfarin, an anticoagulant, blocks vitamin K and prevents activation of prothrombin and other factors. warfarin completes treatment of a thrombus or embolism (after heparin) and is used prophylatically for patients with a long-term risk for thrombus formation (after mintral valve replacement or chronic venous stasis). it is also used prohphylactially in patients with

atrial fibrillation. warfarin is given orally. avoid the use of warfarin during pregnancy because fetal warfarin syndrome will occur.

Heparin has many potential drug-drug interactions. In general, what is the most common potential adverse effect from these interactions?

bleeding -Whenever you alter coagulation factors, bleeding is a potential adverse effect

anticoagulants prevent blood clots from forming. they do not

break down existing clots. they do not technically "thin" the blood

Pentoxifylline (Trental) is chemically related to theophylline; therefore, adverse effects are primarily _____ in nature

central nervous system (CNS) -Pentoxifylline's (Trental) adverse effects occur primarily in the central nervous, cardiovascular, and GI systems.

Your patient had a nephrectomy 1 hour ago. Systemic hyperfibrinolysis has developed, and the patient is experiencing severe hemorrhaging. Aminocaproic acid, a haemostatic drug, has been ordered. To minimize adverse effects from this therapy, you should

check the incision site for bleeding every 15 to 30 minutes - The fresh incision is a likely source for bleeding. Checking the incision frequently will help to determine that an appropriate amount of aminocaproic acid has been administered to control bleeding. Aminocaproic acid is administered by the IV route. It should not be mixed with other drugs. The patient should be connected to a cardiac monitor throughout therapy to detect any cardiac arrhythmias that may occur

Anticoagulants, such as warfarin (Coumadin), work by

competitively blocking vitamin K at its sites of action -Warfarin (Coumadin) works by competitively blocking vitamin K at its sites of action. Thus, it prevents the activation of factors II (prothrombin), VII, IX, and X.

Your patient is presenting to the ED with signs of a thrombotic stroke. The physician would like to order alteplase as treatment. Which of the following should be the nurse's first action?

confirm that it has not been greater than 3 hours since the start of stroke symptoms -Alteplase should not be started if more than 3 hours have elapsed since the onset of stroke symptoms.

Alteplase (Activase) works by

converting plasminogen to plasmin - Alteplase (Activase), recombinant binds to the fibrin in a clot and converts the trapped plasminogen to plasmin. Fibrinolysis, or breakdown of the clot, then occurs.

pentoxifylline is a hemorrheologic drug used to manage symptoms of intermittent claudication from peripheral vascular disease. using this drug improves the patient's ability to walk for longer distances without pain. it is also used to treat acute and chronic cerebral vascular disease because it improves the psychopathologic symptoms. pentoxifylline reduces blood viscosity and increases flexibility of the RBCs, which

decreases platelet aggregation and promotes vasodilation. full therapeutic effects are not seen until 4 to 8 weeks of therapy. smoking limits the effectiveness of drug therapy. pentoxifylline's adverse effects occur primarily in the central nervous, cardiovascular, and GI systems. the effects on these systems may result from this drug's similarity to caffeine and theophylline

In the treatment of angina, dipyridamole (Persantine) works by

dilating the coronary arteries - Dipyridamole (Persantine) increases functional levels of adenosine, which produces vasodilation.

thrombolytic drugs break down to form blood clots. alteplase (sometimes also referred to as recombinant tissue-type plasminogen activator (rt-PA) recombinant is indicated in the treatment of acute evolving MI and acute ischemic stroke. it works by binding to the fibrin in a clot and converting the plasminogen back to plasmin. fibrinolysis then occurs. this therapy is most effective when

initiated ASAP after the onset of symptoms. bleeding is the most frequently occurring adverse effect. For this reason, intracranial bleeding (hemorrhagic stroke) must be ruled out via computed tomography (CT) scan before this agent is used to treat ischemic stroke. Other conditions that increase risk of bleeding must also be evaluated.

how does clopidogrel (Plavix) work?

it inhibits the binding of adenosine diphosphate (ADP) to its platelet receptor -Inhibiting ADP binding decreases the subsequent ADP-mediated activation of the glycoprotein GPIIb/IIIa complex and thus inhibits platelet aggregation.

Your patient has been on warfarin since last night when they received their first dose. Today's INR is 1.0. What is your assessment of the dose based on this data?

it is too soon to determine the full effect of this dose of warfarin -It takes about 72 hours after starting the drug for all previously activated clotting factors to be used up and the warfarin to take full anticoagulant effect

Pharmacotherapeutics for haemostatic drugs include

life-threatening bleeding disorders - Hemostatics stop blood loss by enhancing blood coagulation.

Aminocaproic acid is a systemic haemostatic drug that stops blood loss by enhancing coagulation. It is used only in

life-threatening situations. Administer with an IV pump. The most common adverse effect is GI distress. Place the patient on cardiac monitoring to detect arrhythmias. Thrombophlebitis and hypotension are also possible adverse effects.

Which of the following statements accurately refl ects the differences between traditional heparin and low molecular weight heparin?

low molecular weight heparin yields a predictable dose response - The predictability of low-molecularweight heparin is one reason some prescribers do not always order aPTT testing.

monitor the active partial thromboplastin time (aPTT) to determine the patient's response to therapy with tradition unfractionated heparin; therapeutic aPTT levels are

one and one half to two times the control level. (the aPTT is not greatly altered by low molecular weight heparin, enoxaparin and therefor may not be monitored.) the most common adverse effect is bleeding. antidote to overdosage is protamine sulfate.

Antihemophilic factor (AHF) is factor VIII and is used to temporarily treat or prevent bleeding in hemophilia. It is made from pooled human sources and carries a very slight risk of hepatitis and human immunodefi ciency virus (HIV) transmission. Dosage is individualized to meet

patient needs. Reconstitute (without shaking) and then administer IV. Teach patient to avoid injury, not to use aspirin or ibuprofen, and carry identification of hemophilia.

In addition to reducing the occurrence of atherosclerotic events, what is another pharmacotherapeutic use for clopidogrel (Plavix)?

patients with acute coronary syndrome, patients undergoing percutaneous coronary intervention, patients undergoing coronary artery bypass graft surgery - In these procedures, the blood is thinned, but not as much as with anticoagulants

which of the following drugs is NOT classified as an antiplatelet?

pentoxifylline (Trental) - Pentoxifylline (Trental) is classified as a hemorrheologic drug. It increases the flexibility of RBCs by increasing cAMP levels. In turn, this decreases platelet aggregation and promotes vasodilation

Which of the following drugs would be effective for intermittent claudication?

pentoxifylline (Trental) -Pentoxifylline (Trental) increases the fl exibility of RBCs by increasing cAMP levels. In turn, this decreases platelet aggregation and promotes vasodilation.

Glycoprotein IIb/IIIa inhibitors are frequently used after a(n)

percutaneous transluminal coronary angioplasty (PTCA) -These drugs may be used alone or in combination with low-molecular-weight heparin

Your patient comes to the clinic for follow-up of medical problems. Current medications include clopidogrel (Plavix), phenytoin (Dilantin), cimetidine (Tagamet), and digoxin (Lanoxin). Because the patient takes clopidogrel, which of these drugs, if any, may increase this patient's risk for hemorrhage?

phenytoin -Drugs metabolized through the P-450 2C9 pathway may increase the potential for bleeding.

What is plasmin?

plasmin is the substance that lyses a blood clot

Drotrecogin alfa, activated (Xigris) is used to

prevent and control excessive bleeding - Patients with sepsis are prone to clot development. Drotrecogin alfa, activated (Xigris) prevents processes that are involved in creating stable clots.

Antihemophilic factor (AHF) is used to

prevent and control excessive bleeding -Factor VIII is required for the conversion of prothrombin to thrombin.

A patient with hemophilia is brought to the emergency room for uncontrolled bleeding. Antihemophilic factor is ordered. Nursing management in this drug therapy should include which of the following

rotate the vial of diluted drug gently to mix, monitor coagulation studies during therapy, administer drug by the IV route -This drug is kept refrigerated but must be allowed to come to room temperature before dilution. Diluted drug is rotated, not shaken, to prevent gel formation in the antihemophilic factor. The drug is administered by the IV route to deliver it directly into the bloodstream where it can act. Intarmuscular routes are avoided to prevent bleeding into the muscle. Coagulation studies are monitored during therapy to assess for therapeutic effect of the drug. Additional antihemophilic factor may be needed if bleeding is not controlled or coagulation studies show subtherapeutic levels of the factor

heparin, an anticoagulant, prevents the conversion of prothrombin to thrombin and prevents the formation of a stable clot. it is used to prevent the extension of a blood clot (particularly DVT or PE) and is used prophylactically in patients with

short-term increased risk for thrombus formation. heparin is administered IV or SC (low molecular weight heparin is different and given only SC). heparin use is safe during pregnancy

Your patient had hip surgery today. The health care provider ordered enoxaparin (Lovenox) daily. With your knowledge of this drug, you would expect the patient's aPTT to

stay within the normal dosage range - Low-molecular-weight heparin does not signifi cantly prolong bleeding.

Your patient has started taking clopidogrel to prevent a stroke after several mild transient ischemic attacks (TIAs). Patient education regarding clopidogrel should include which of the following?

take this drug with food, blood work will be needed periodically throughout therapy, remove throw rugs and fasten loose carpet edges in the home, notify all health care providers that this drug has been started - Clopidogrel may cause GI distress; taking the drug with food will minimize this effect. Lab tests to evaluate bleeding time and white blood cell count (neutropenia is possible) need to be done throughout therapy. The home environment needs to be modified if necessary to minimize the risk of falls in the home. Scatter rugs and loose carpeting are primary causes of falls in the home. This drug lengthens the bleeding time, not shortens it. Patients need to apply extra pressure if they bleed from a minor cut. All providers should be advised of the patient's use of clopidrogrel.

the maximum anticoagulant effect of warfarin takes 3 to 4 days after dosing begins, so therapy usually is begun while the patient is still receiving IV heparin. monitor the prothrombin time (PT) or the international normalized ratio (INR) to determine

the patient's response to therapy; PT should be about one and one-half times the control; INR should be between 2 and 3. vitamin K is the antidote. teach patients not to greatly increase dietary vitamin K intake while taking warfarin.

The patient takes pentoxifylline (Trental) for peripheral vascular disease. While you are assessing the patient's lifestyle, diet, and habits, the patient states, "I guess I should fess up-I smoke 11/2 packs of cigarettes a day." You would expect that this patient's symptoms may be

the same -Smoking is a potent vasoconstrictor that counters the vasodilation effects of pentoxifylline.

The difference between anticoagulants and thrombolytics is that

thrombolytics dissolve clots, whereas anticoagulants prevent additional clot formation -Anticoagulants do not have the ability to dissolve clots.

To prevent hematoma formation when administering subcutaneous heparin, the nurse should

use a 3-cc syringe -Research has shown that a 3-cc syringe produces less hematoma formation than a 1-cc syringe. To further prevent hematomas, do not aspirate before injection and do not massage the insertion site after injection. The scapula is not a recommended site for heparin administration.

Your patient is receiving heparin via continuous IV infusion into a peripheral vein to treat a left DVT. The patient has pneumonia and requires IV antibiotics given every 6 hours. Each antibiotic infusion requires 30 minutes. To accomplish administration of these two drug therapies, you should

use a separate IV insertion site to administer the antibiotic -Intravenous heparin infusions should not be stopped to run other drugs through the IV site because this lowers the blood level of heparin and alters the therapeutic response. Many other drugs are incompatible with heparin, and they should not be piggybacked or added to heparin infusions. Use of a separate IV site for the antibiotics allows continuous infusion of heparin and appropriate dosing of the antibiotics

You are caring for a 26-year-old woman who is to be discharged on warfarin, an oral anticoagulant, after a mitral valve replacement. Patient teaching regarding warfarin should include to

use birth control while taking warfarin -Warfarin causes a known pattern of fetal changes, known as fetal warfarin syndrome. Precautions should be taken to prevent pregnancy during warfarin therapy. Vitamin K is the antidote to warfarin, and increases in dietary sources, such as green leafy vegetables, should be avoided. Potassium does not have an effect on warfarin. The symbol for potassium is "K," but it is not the same thing as vitamin K. Doses should be taken regularly; however, a double dose should not be taken because it may produce bleeding.

During alteplase (Activase) infusion, the nurse should monitor which of the following?

vital signs, abdominal pain, changes in LOC, hunger -These are all symptoms of active bleeding that may occur with therapy

Your patient has mitral valve prolapse and a history of pulmonary emboli, and states, "I took some kind of blood thinner, but I have not been seen for several months." Which of the following drugs do you anticipate this patient will be prescribed?

warfarin (Coumadin) - This patient should be on long-term anticoagulation therapy because of a prosthetic heart valve.