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Roomies Collab Deck 1: Infectious Disease and CV > Parenteral Anticoagulation > Flashcards

Parenteral Anticoagulation Flashcards

1
Q

Why are anticoagulants used? (2)

A
  1. To prevent thrombus formation
  2. To prevent extension of existing thrombus in the slow-moving venous circulation (where clots are mainly composed of fibrin and some platelets and red cells)

(Notably, NOT to break down pre-existing thrombi)

*anticoagulants are of less use in preventing thrombus formation in arteries because in faster-flowing vessels, thrombi are composed mainly of platelets (with little fibrin)

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2
Q

What information should be given to patients taking anticoagulants?

A

Patients should be provided with verbal AND written information about their treatment, including how and when to seek medical attention

Immediate medical attention is required in certain patients (such as in those with bleeding that is severe, does not stop or recurs, or who have other signs or symptoms of concern); in particular, patients who have sustained a heated injury should be referred to the hospital emergency department

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3
Q

What are the main parenteral anticoagulants? (7)

A
  1. Heparin (‘standard’ or unfractionated)
  2. Low molecular weight heparins (dalteparin, enoxaparin, tinzaparin)
  3. Heparinoids (danaparoid)
  4. Argatroban
  5. Hirudins (bivalirudin)
  6. Epoprostenol (prostacyclin)
  7. Fondaparinux
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4
Q

What is the main difference between standard heparin and LMWH?

A

Standard heparin acts rapidly but has a short duration of action whereas LMWH has a longer duration of action

Although a low molecular weight heparin is generally preferred for routine use, heparin (unfractionated) can be used in those at high risk of bleeding because its effect can be terminated rapidly by stopping the infusion

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5
Q

What is the main advantage of LMWH over standard heparin?

A

Lower risk of heparin-induced thrombocytopenia

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6
Q

Is monitoring required when administering LMWH?

A

No

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7
Q

What are the indications of LMWH?

A
  1. Treatment of DVT
  2. Treatment of PE
  3. Prevention of clotting in extracorporeal circuits
  4. Unstable coronary artery disease (other agents are preferred)
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8
Q

What is the mechanism of action of standard heparin?

A

Inactivation of thrombin (II) and activated X (Xa) through an antithrombin-dependent mechanism (AT III)

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9
Q

What is the mechanism of action of LMWH?

A

Activation of antithrombin III to accelerate inactivation of activated factor X (Xa)

*does not act directly on thrombin (II), unlike UFH

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10
Q

What are the indications of danaparoid (a heparinoid)? (2)

A
  1. Prophylaxis of DVT in patients undergoing surgery

2. Treatment of thromboembolic disease in patients with a history of HIT

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11
Q

What is the main indication of argatroban?

A

Anticoagulation in patients with HIT who require parenteral antithrombotic treatment

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12
Q

What is the mechanism of action of argatroban?

A

Inhibition of thrombin

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13
Q

What is the mechanism of action of hirudins?

A

Inhibition of thrombin (only the activated form)

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14
Q

What are the indications of bivalirudin?

A
  1. Unstable angina or NSTEMI in patients scheduled for urgent or early intervention
  2. Anticoagulant for patients undergoing PCI
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15
Q

What is the mechanism of action of epoprostenol (prostacyclin)?

A

Inhibition of platelet aggregation

Also a potent vasodilator with a short half-life (~3 min) so must be administered by continuous IV infusion

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16
Q

What are the indications of epoprostenol (prostacyclin)? (2)

A
  1. Renal dialysis when heparins are unsuitable or contra-indicated
  2. Primary pulmonary HTN resistant to other treatment
17
Q

What is the mechanism of action of Fondaparinux?

A

Inhibition of factor X

18
Q

What are the side effects of all heparins? (3)

A
  1. Hemorrhage
  2. HIT
  3. Skin reactions
19
Q

In cases of hemorrhage due to heparin administration, what is the recommended course of action?

A

Usually sufficient to withdraw unfractionated or LMWH BUT if rapid reversal is required, protamine sulfate is a specific antidote (but only partially reverses the effects of LMWH)

20
Q

Protamine sulfate completely reverses the effect of _______ but only partially reverses the effect of _______.

A

Standard (unfractionated) heparin /

LMWH

21
Q

What are the signs of HIT? (3)

A
  1. 30% reduction of platelet count
  2. Thrombosis
  3. Skin allergy
22
Q

What is the management of HIT? (3)

A

If heparin-induced thrombocytopenia is strongly suspected or confirmed:

  • heparin should be stopped
  • alternative anticoagulant, such as danaparoid, should be given
  • ensure platelet counts return to normal range in those who require warfarin
23
Q

What electrolyte imbalance is associated with heparin?

A

Hyperkalemia

Inhibition of aldosterone by unfractionated heparin or LMWH can result in hyperkalemia

patients with diabetes mellitus, chronic renal failure, acidosis, raised plasma potassium or those taking potassium-sparing drugs seem to be more susceptible; the risk appears to increase with duration of therapy

24
Q

What are the contraindications of heparins? (10)

A
  1. Major trauma
  2. Epidural anesthesia
  3. Hemophilia or other hemorrhagic disorders
  4. Peptic ulcer
  5. Recent cerebral hemorrhage
  6. Recent eye surgery
  7. Recent nervous system surgery
  8. Spinal anesthesia
  9. Thrombocytopenia (including history of HIT)
  10. Acute bacterial endocarditis
25
Q

What are the major cautions for heparin use? (4)

A
  1. Elderly
  2. Risk of bleeding
  3. Severe HTN
  4. Renal impairment (LMWH may accumulate and should be used at a lower dose OR unfractionated heparin used instead)
26
Q

Are heparins safe to use in pregnancy?

A

Yes, not known to cross the placenta (preferred to warfarin which is teratogenic)

Safe in breastfeeding

27
Q

Are heparins safe to prescribe in hepatic impairment?

A

Manufacturer advises caution in severe impairment due to increased risk of bleeding; consider dose reduction

28
Q

Are heparins safe to prescribe in renal impairment?

A

Risk of bleeding may be increased so dose reduction may be required

Unfractionated heparin preferred to LMWH in renal impairment

29
Q

Is monitoring required during heparin administration?

A

Platelet counts should be measured just before treatment with UFH or LMWH and regular monitoring of PLT counts may be required if given for >4 days

Plasma potassium concentration should be measured in patients at high risk of hyperkalemia before starting heparin and monitored regularly thereafter, particularly if treatment is to be continued for longer than 7 days

30
Q

What are the indications of unfractionated heparin? (9)

A
  1. Treatment of PE (mild-severe)
  2. Treatment of unstable angina
  3. Treatment of acute peripheral arterial occlusion
  4. Treatment of DVT
  5. Thromboprophylaxis in medical or surgical patients
  6. Thromboprophylaxis during pregnancy
  7. Hemodialysis
  8. Prevention of clotting in extracorporeal circuits
  9. To maintain patency of catheters, cannula s, other indwelling IV infusion devices
31
Q

What are the indications of enoxaparin? (8)

A
  1. Treatment of VTE in pregnancy
  2. Prophylaxis of DVT, especially in surgical patients (moderate to high risk)
  3. Prophylaxis of DVT in medical patients
  4. Treatment of DVT and PE in uncomplicated patients
  5. Treatment of DVT and PE in patients with risk factors such as obesity, cancer, recurrent VTE, embolism, or proximal thrombosis
  6. Treatment of acute STEMI (patients not undergoing PCI AND patients undergoing PCI)
  7. Unstable angina and NSTEMI
  8. Prevention of clotting in extracorporeal circuits
32
Q

What are the monitoring requirements for argatroban?

A

Determine aPTT 2 hours after start of treatment, then 2 or 4 hours after infusion rate altered, and at least once daily thereafter

33
Q

What monitoring is required with danaparoid administration?

A

Monitor anti factor Xa activity in patients with body weight over 90 kg and those with renal impairment

Roomies Collab Deck 1: Infectious Disease and CV (84 decks)

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