Question

Week 5: Case Study: Pharmacology

Scenario

You are the nurse working in an anticoagulation clinic. One of your patients is K.N., who has a long-standing history of an irregular heartbeat, known as atrial fibrillation or A-fib, for which he takes the oral anticoagulant warfarin. Recently K.N. had his mitral heart valve replaced with a mechanical valve.

1. How does atrial fibrillation differ from a normal heart rhythm?

2. What is the purpose of the warfarin in K.N.'s case?

CASE STUDY PROGRESS K.N. calls your anticoagulation clinic to report a nosebleed that is hard to stop. You ask him to come into the office to check his coagulation levels. The laboratory technician draws a PT/INR test.

3. What is a PT/INR test, and what are the expected levels for K.N.? What is the purpose of?

the INR?

4. When you get the results, his international normalized ratio (INR) is critical at 7.2.

What is the danger of this INR level?

The health care provider does a brief focused history and physical examination, orders additional laboratory tests, and determines that there are no signs of bleeding other than the nosebleed, which has stopped. The provider discovers that K.N. recently started to take daily doses of an over-the-counter pro ton pump inhibitor (PPI), omeprazole (Prilosec OTC), for heartburn.

5. What happened when K.N. began taking the PPI?

.

6. What should K.N. have done to prevent this problem?

The provider gives K.N. a low dose of vitamin K orally, asks him to hold his warfarin dose that evening, and asks him to come back tomorrow for another prothrombin time (PT) and INR blood draw. Why is K.N. instructed to take the vitamin K?

You want to make certain K.N. knows what "hold the next dose" means. What should you tell him?

K.N. grumbles about all the laboratory tests but agrees to follow through.

What is potential S/S of bleeding that should be taught to K.N.? (Select all that apply.)

a. Black, tarry stool

b. Stool that is pale in color

c. Paresthesia lower extremities

d. Bruising

CASE STUDY PROGRESS You know that sometimes the only needed action is to stop the warfarin several days before the surgery. Other times, the provider initiates "bridging therapy," or stops the warfarin and provides anti coagulation protection by initiating low-molecular-weight heparin. After reviewing all his anticoagulation information, the provider decides that K.N. will need to stop the warfarin 1 week before the surgery and in its place be started on enoxaparin therapy.

Which nursing interventions are appropriate when administering enoxaparin? Select all that apply.

a. Monitor activated partial thromboplastin time (aPTT) levels.

b. Administer via intramuscular (IM) injection into the deltoid muscle.

c. The preferred site of injection is the lateral abdominal fatty tissue.

d. Massage the area after the injection has been given.

e. Inject two inches from belly button.

Answer 1

Solution 1.

Atrial fibrillation:-

• the atria beats in a disorganized manner
• the atrial rate is 300 to 600 bpm
• no atrial contraction
• the ventricular contraction is irregular
• the ventricles often beat with a rapid rate causing a decrease in ventricular filling and cardiac output.

Normal rhythm:-

• the atria contract together
• blood gets pumped into the ventricles
• the ventricles contract
• blood is pumped into the pulmonary arteries and aorta.

Solution 2.

Indications:-

Prophylaxis and treatment of: Venous thrombosis, Pulmonary embolism, Atrial fibrillation with embolization. Management of myocardial infarction: Decreases risk of death, Decreases risk of subsequent MI, Decreases risk of future thromboembolic events. Prevention of thrombus formation and embolization after prosthetic valve placement.

Action:-

Interferes with hepatic synthesis of vitamin K-dependent clotting factors (II, VII, IX, and X). Therapeutic Effects: Prevention of thromboembolic events

Atrial fibrillation causes blood pooling in the atria this could cause a thrombus. To prevent thrombus formation Warfarin is given.

Solution 3.

International normalized ratio - It is a standardized reporting system established by the World Health Organization (WHO).It is used as the measure of patient's level of anticoagulation when being treated with warfarin.

For atrial fibrillation tha preferred INR is 2.0 to 3.0.

*If INR , below than 2.0 then there is ;

Risk of blood clots like stroke , venous thromboembolism.

*If INR , more than 3.0 then there is;

Risk of bleeding like brain hemorrhage.

Solution 4.

The higher your INR is, the longer it takes your blood to clot. In other words, as the INR increases above a given level, the risk of bleeding and bleeding-related events increases. The provider would have to examine K.N. because his INR level exceeds the target range.

Solution 5.

Sulfonamides, including sulfamethizole, sulfamethoxazole, and sulfisoxazole, potentiate the anticoagulant effect of warfarin. Monitor for bleeding and needed warfarin dosage adjustments based on the INR. Sulfonamides are known to inhibit the hepatic metabolism of the S-warfarin and have, in some cases, doubled the hypoprothrombinemic effect of warfarin. A protein-binding interaction also may be possible, with sulfonamides displacing warfarin from protein binding sites. The combination of sulfamethoxazole and trimethoprim, which may be due to the additive effects of trimethoprim mediated CYP2C8 inhibition of warfarin metabolism. As a result, K.N. has an increased risk of bleeding.

Solution 6.

K.N. should have told the staff at the urgent care center that he was taking warfarin. He should have also alerted his provider of the antibiotic to confirm there were no contraindications to taking sulfamethoxazole-trimethoprim (Septra).