Anticoagulants - Heparin

Anticoagulants are medications that work by interfering with the functional clotting factors in the coagulation cascade, and are used to prevent the formation of thrombi, or blood clots, and are used to prevent or treat thromboembolic events, such as deep vein thrombosis, pulmonary embolism, ischemic stroke, transient ischemic attack, coronary artery disease or myocardial infarction.

They're also used in clients with coagulation disorders, including antiphospholipid syndrome and disseminated intravascular coagulation; as well as in clients who underwent cardiac valve replacement or coronary angioplasty; and during surgical procedures like cardiopulmonary bypass, percutaneous coronary intervention, extracorporeal membrane oxygenation, and in clients undergoing dialysis.

Among the most important anticoagulants are heparins. These include unfractionated heparin, which is derived from porcine sources, and can be administered intravenously or subcutaneously; as well as low molecular weight heparins or LMWHs, which are synthetic analogs of certain portions of the heparin molecule. These include enoxaparin, dalteparin, and tinzaparin, and are given subcutaneously.

Once administered, heparins work by binding to and enhancing the activity of antithrombin III, which is an anticoagulant protein synthesized by the liver. Antithrombin III normally binds to and inhibits Factor Xa and Factor IIa, also known as thrombin, thus making them unavailable to participate in the coagulation cascade. Antithrombin III also inhibits factors VII, IX, XI, and XII, although with much less affinity. Ultimately, heparins stop the formation of the primary clot.

Now, unfractionated heparin is usually used in immediate and short-term anticoagulation because it has a rapid onset of action, usually within seconds, and a short half-life. Additionally, unfractionated heparin doesn't cross the placental barrier, making it the anticoagulant of choice during pregnancy.

On the other hand, LMWHs have better bioavailability and have a much longer half-life compared to unfractionated heparin.

Now, the main side effect of heparins is undue bleeding, which can present as petechiae, ecchymosis, epistaxis, as well as bleeding gums, blood in stools, hematemesis, and uncontrollable internal bleeding from falls or even minor trauma. Thankfully, antidotes are available to reverse the action of most anticoagulants if the bleeding gets severe. These include protamine sulfate for unfractionated heparin, which is also effective to a lesser extent on LMWH.

With respect to specific side effects, heparins can cause burning at the injection site, as well as chills, and hyperkalemia due to suppression of aldosterone production.

A unique and serious side effect is heparin-induced thrombocytopenia, or HIT for short. HIT is an immune response in which clients taking heparin produce antibodies that form complexes with heparin and platelets. As a result, these complexes get activated, causing widespread clot formation, using up the circulating platelet population in the process.

The activated platelets and the antibody bound heparin-platelet complexes subsequently get destroyed within the spleen. The paradoxical end result is a low platelet count, or thrombocytopenia, and risk for venous or arterial thromboembolism.

Finally, prolonged use of heparin can cause an increased risk of osteoporosis. Now, due to the risk of bleeding, heparins are contraindicated in clients with active internal bleeding, recent trauma in the past three months, as well as those with a history of intracranial hemorrhage or ischemic stroke, gastrointestinal ulcers and coagulopathies or bleeding disorders.

In addition, heparins are contraindicated in clients with thrombocytopenia or with a history of HIT, and should be used with caution in clients taking antiplatelet medications like aspirin and clopidogrel; or thrombolytic medications like alteplase, reteplase, and tenecteplase; which can increase the risk of bleeding. Precaution should also be taken in clients who are allergic to porcine products, as well as in clients with hepatic or renal disease, or alcohol use disorder. Also, be sure to obtain informed consent from your client when using animal or human derived products, since these products may be contraindicated in clients of certain religious faiths; such as Hindus, Sikhs and Muslims. Finally, it's important to note that heparins are the only anticoagulants that are safe for use during pregnancy and breastfeeding.

Alright, when caring for a client prescribed either unfractionated heparin or a LMWH to prevent venous thromboembolism, start by performing a focused baseline assessment of your client's weight and vital signs. Then, review their most recent laboratory test results, including CBC, PTT, aPTT, and renal function tests.

Before administering unfractionated heparin, explain to your client how the medication prevents clot formation, and that you will be monitoring them closely for the formation of clots as well as for bleeding. Prompt them to let you know immediately if they notice signs of bleeding, such as oozing from the IV insertion site, a nose bleed, or a sudden headache; as well as signs of clot formation, such as new pain, swelling, or warmth in their leg, as well as shortness of breath, a sudden onset of confusion, vision changes, trouble speaking, or one-sided weakness.

Then, double check the prescribed dose with another nurse, and be sure protamine sulfate is readily available in case it's needed to reverse the action of unfractionated heparin.

When giving unfractionated heparin by the subcutaneous route, be sure to inject it 2 inches or 5 centimeters away from your client's navel. Pinch the skin slightly, insert the needle at a 90 degree angle, and inject the heparin slowly. After withdrawing the needle, lightly press the site with a dry gauze or an alcohol swab, but do not massage the injection site.

When giving unfractionated heparin by intravenous infusion, ensure a patent IV catheter is in place. Then, follow your facility's protocol to calculate the units of heparin to infuse per kilogram per hour. During the infusion, monitor your client's PTT and hold or increase the infusion, or administer a heparin bolus per protocol. Continue to monitor them for clot formation, bleeding, and thrombocytopenia.

Now, if your client is prescribed a LMWH like enoxaparin and will be self-administering the medication at home, first, be sure to confirm the prescribed dose per the client's weight in kilograms is correct. Then, review the appropriate technique for subcutaneous injections using the prefilled syringe. Instruct your client to inject the medication once per day, at the same time each day. Let them know they may feel some minor discomfort, and slight bruising can occur at the injection site.

Then, review routine bleeding precautions they should take while taking the medication, such as using a soft bristled toothbrush or an electric razor; avoiding medications that affect platelets, like aspirin; and avoiding activities that can cause injuries, such as contact sports. If they fall or are injured, advise them to seek emergency medical care immediately.

Also, advise your client to contact their healthcare provider right away if they notice signs of minor bleeding, such as bleeding gums, nosebleeds, or heavier menstrual periods; and stress the importance of seeking emergency medical care right away if they notice signs of significant bleeding, such as dark urine or stools, coughing up blood, heavy bleeding from a minor cut, or sudden headache or back pain.

Now, if the medication is not working effectively, your client can also be at risk for clot formation, so remind them to also self-monitor for signs of clot formation, including new pain, swelling, or warmth in their leg or foot; shortness of breath, sudden onset of confusion, vision changes, trouble speaking, or one-sided weakness, and instruct them to seek emergency care immediately should any of these symptoms occur. Lastly, remind your client to report their use of an anticoagulant medication to all of their healthcare providers, including dentists, and to consult with their healthcare primary care provider if they require an invasive procedure.

Finally, during treatment with heparins, continue to assess your client for signs and symptoms of bleeding or clot formation, and evaluate for the therapeutic response, including an aPTT value within the therapeutic range and an absence of bleeding or clot formation.

Alright, as a quick recap… Unfractionated heparin and LMWH are medications that work by interfering with the clotting factors in the coagulation cascade to prevent formation of thrombi.

Major side effects include undue bleeding, which can be counteracted with the antidote, protamine sulfate.

An uncommon but serious side effect of unfractionated heparin is heparin-induced thrombocytopenia, or HIT for short, which is an immune response to heparin that results in widespread clotting, that uses up platelets that eventually increases the risk of arterial or venous thromboembolism.

Nursing considerations for clients taking heparins include performing a focused baseline assessment, monitoring aPTT or PTT, and safely administering heparin subcutaneously or intravenously.

Client teaching is focused on safe self-administration techniques, incorporating routine bleeding precautions into their lifestyle, as well as recognizing and reporting serious side effects of bleeding or clot formation.