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Pharmacology · chapter 20 · Anticoagulant, Antiplatelet, and Thrombolytic Drugs

Introduction to Clotting and Coagulation

The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.

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Key points

  1. Clotting: needed, but also causes disease

    The ability of the blood to form clots in response to tissue damage is essential for hemostasis, or the body’s ability to stop bleeding. However, clot formation also underpins many thrombosis -related diseases such as acute myocardial infarction, stroke, and deep vein thrombosis.

  2. Primary hemostasis: the platelet plug

    Primary hemostasis is the process of platelet adhesion to form a platelet plug, or platelets that are aggregated on the injured vessel wall or tissues.

  3. Thrombin turns fibrinogen into fibrin

    Factor Xa facilitates the activation of factor II, which is also known as thrombin. Thrombin facilitates the activation of fibrinogen to fibrin.

  4. Vitamin K and calcium in clotting

    Vitamin K, a vitamin present in foods such as green, leafy vegetables, is a cofactor needed for synthesis of clotting factors II, VII, IX, and X. Calcium is also necessary for activation of several clotting factors.

  5. tPA breaks down clots

    This is accomplished when the enzyme tissue plasminogen activator (tPA) facilitates conversion of plasminogen to plasmin, which degrades fibrin.

  6. Too much clotting or too much fibrinolysis

    Excessive activation of the coagulation cascade can lead to thrombosis, the formation of a clot inside a blood vessel that can block blood flow. Excessive fibrinolysis, mediated by plasmin, can lead to bleeding.

  7. Factor V Leiden: reducing other risks

    Clients with Factor V Leiden cannot change their genetics, but they can work to minimize their other risk factors for thrombosis by maintaining a healthy weight, exercising regularly, and avoiding smoking. These clients should also be vigilant about moving and taking breaks during travel.

  8. Virchow’s Triad

    Thrombus Formation The pathologic formation of thrombi (plural of thrombus) occurs as the result of endothelial injury, hypercoagulability, and stasis of blood flow; this is known as Virchow’s Triad and is depicted in Figure 20.5.

  9. Causes of endothelial injury

    Endothelial injury activates clotting as described above and occurs due to events such as catheter placement, surgery, or trauma (Ashorobi, 2022).

  10. DVT can become a pulmonary embolism

    The clot can break off, travel through the circulatory system, and lodge within the lungs, causing a pulmonary embolism (PE), which can be life-threatening.

  11. Signs of a DVT

    Clients with a DVT may experience swelling, pain, redness, and tenderness at the site of the clot (usually in the leg).

  12. Signs of a pulmonary embolism

    Clients with a PE often describe chest or back pain and have difficulty breathing, tachycardia, hemoptysis (coughing up blood), and if severe, hemodynamic instability (Centers for Disease Control and Prevention [CDC], 2020).

  13. Atrial fibrillation and embolic stroke

    Clients who have atrial fibrillation or certain prosthetic heart valves usually are treated with an anticoagulant to decrease the risk of embolic stroke.

  14. Two antiplatelets after a stent

    These require treatment with two concomitant antiplatelet medications for a period of time after stent placement to prevent clots from forming on the stent.

Terms to know

hemostasis
The ability of the blood to form clots in response to tissue damage is essential for hemostasis, or the body’s ability to stop bleeding.
hypercoagulable
A client with naturally occurring decreased clotting times is described as hypercoagulable.
clotting factors
The coagulation cascade is made up of clotting factors, which are proteins that work to activate different parts of the coagulation cascade.
fibrinolysis
Coagulation is in homeostatic balance with fibrinolysis, or breakdown of fibrin, as shown in Figure 20.4.
thrombosis
Excessive activation of the coagulation cascade can lead to thrombosis, the formation of a clot inside a blood vessel that can block blood flow.
deep vein thrombosis (DVT)
Deep Vein Thrombosis and Pulmonary Embolism A deep vein thrombosis (DVT) is a blood clot that forms within a vein.
coronary artery stent
A coronary artery stent is a wire caging that props open a narrowed coronary artery.

Practice questions

Stuck on select-all-that-apply? How to take them one option at a time.

The graded version needs JavaScript. Every question is below anyway, with the answer and why.

Every question here, with the answer

  1. A client on day 3 after hip surgery reports that the left calf is swollen, red, painful and tender. What does the nurse suspect?

    1. Ischemic stroke
    2. Pulmonary embolism
    3. Normal postoperative swelling that needs no follow-up
    4. Deep vein thrombosis

    Answer: Deep vein thrombosis

    Swelling, pain, redness and tenderness at the site of the clot, usually in the leg, are signs of a DVT, and surgery and limited movement are risk factors. A pulmonary embolism presents with chest or back pain and difficulty breathing, and stroke involves the brain.

  2. A client with a known DVT suddenly becomes anxious. Which findings would make the nurse suspect a pulmonary embolism? Select all that apply.

    1. Chest pain
    2. Tachycardia
    3. Difficulty breathing
    4. Bradycardia with no other symptoms
    5. Coughing up blood

    Answer: Chest pain, Tachycardia, Difficulty breathing, Coughing up blood

    A DVT clot can break off and lodge in the lungs, and clients with a PE describe chest or back pain, difficulty breathing, tachycardia and hemoptysis. Isolated bradycardia is not listed as a sign of PE.

  3. The nurse is identifying clients at risk for DVT. Which clients have a risk factor named in the section? Select all that apply.

    1. A client taking oral contraceptives
    2. A client with obesity
    3. A client who walks in the hallway every hour
    4. A client confined to bed after a stroke
    5. A client with a personal history of DVT

    Answer: A client taking oral contraceptives, A client with obesity, A client confined to bed after a stroke, A client with a personal history of DVT

    Stasis from confinement to bed, increased estrogen from oral contraception, obesity, and a personal history of DVT are all listed risk factors. Regular walking reduces stasis rather than causing it.

  4. A client has Factor V Leiden and is planning a long flight. Which teaching is most appropriate?

    1. "Stay seated for the whole flight to avoid injury."
    2. "Smoking does not affect your clot risk."
    3. "Your genetics mean nothing can lower your risk."
    4. "Get up and move and take breaks during travel."

    Answer: "Get up and move and take breaks during travel."

    Clients with Factor V Leiden can lower other risk factors and should be vigilant about moving and taking breaks during travel. Staying seated increases stasis, and weight, exercise and avoiding smoking do reduce their other risks.

  5. A client asks why his mother, who has atrial fibrillation, takes an anticoagulant. Which explanation is accurate?

    1. The anticoagulant dissolves cholesterol in the arteries.
    2. In atrial fibrillation, blood can pool and clot in the heart and travel to the brain, causing an embolic stroke.
    3. Atrial fibrillation causes the blood to become too thin.
    4. The anticoagulant is used to slow the heart rate.

    Answer: In atrial fibrillation, blood can pool and clot in the heart and travel to the brain, causing an embolic stroke.

    In atrial fibrillation, abnormal blood flow in the left side of the heart can form clots that travel to the brain, so these clients usually receive an anticoagulant to decrease the risk of embolic stroke. The other options describe effects not in the section.

  6. A client just had a coronary artery stent placed. The client asks why two antiplatelet drugs were prescribed. What is the nurse's best response?

    1. "Two drugs are always given together for life after any heart problem."
    2. "They are given for a period of time to prevent clots from forming on the stent."
    3. "One drug protects the heart and the other lowers cholesterol."
    4. "Two drugs are needed to dissolve the clot that caused your heart attack."

    Answer: "They are given for a period of time to prevent clots from forming on the stent."

    After stent placement, two concomitant antiplatelet medications are given for a period of time to prevent clots from forming on the stent. The other statements describe purposes or durations not supported by the section.

Where every quote comes from

Section 20.1 Introduction to Clotting and Coagulation of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.

The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.