Nurses: New anticoagulants used in ED will revamp treatment of DVT patients

Low molecular weight heparins standard for DVT treatment

New anticoagulants are being used in the ED to treat patients with deep vein thrombosis (DVT), reports Gideon Bosker, MD, assistant clinical professor of emergency services at Yale University School of Medicine.

"For a long time, heparin was the gold standard for treatment," he explains. "But in the past few months, the low molecular weight heparin (LMWH) Lovenox (enoxaparin) was approved. There is a shifting paradigm, and this is quickly becoming the standard of care."

LMWHs represent a major advance in the treatment of DVT. "Studies that compare standard intravenous heparin to subcutaneous LMWH show that LMWH has improved antithrombotic effect and [has] fewer adverse consequences," adds Bosker.

Unlike heparin, LMWHs don’t have to be given intravenously. "With heparin, you have to monitor the bleeding times and PTT (partial thromboplastin time)," says Bosker. "LMWH is sure to revolutionize the treatment for DVT."

This is a radical change, which shifts treatment of DVT from inhospital therapy to outpatient management. "Patients don’t have to be hospitalized as often, and a lot of money can be saved," Bosker explains. "In the past, these patients would have been sent to the ICU or medical floors. Now, treatment can be initiated in the ED and appropriately selected patients can be sent home."

Although heparin has been beneficial for the past century, it is now time to change to LMWH, which has similar and possibly better efficacy, urges Bosker. "The drug is at least as safe, if not safer than heparin," he says. "ED nurses and physicians can lead the way for promoting appropriate use of this safe, cost-effective treatment."

Although LMWHs have been used in Europe for more than 10 years, there are currently three LMWHs approved for use in the United States: ardeparin (Normiflo), dalteparin (Fragmin), and enoxaparin (Lovenox).

Each of these has unique properties based on its molecular weight, says Bosker. "It should be stressed that no two LMWHs are alike."

LMWHs became available for use in the United States as early as 1993, when enoxaparin was approved by the FDA. The following year, dalteparin was approved. Both are indicated for use in the prophylaxis of DVT for patients undergoing surgical procedures, says Bosker.

Only enoxaparin has formal approval for treatment of DVT, and is the LMWH of choice for treatment of DVT, notes Bosker. Currently, enoxaparin is the only drug approved for both treatment and prevention of DVT.

Enoxaparin is the LMWH most commonly used in the ED for DVT management. The drug also carries FDA approval for treatment of eligible patients with unstable angina and non Q-wave myocardial infarction (MI). "Therefore, ED nurses should become familiar with its route of administration, dosage, indications, contraindications, and safety profile," Bosker emphasizes.

Although each of the LMWHs is FDA-approved for prophylaxis of DVT, only enoxaparin is approved for the management of ischemic complications of unstable angina and non Q-wave MI when given with aspirin. It shows superior efficacy when compared to heparin, Bosker says. LMWH is approved for prophylaxis after orthopedic surgery to the lower extremities, and for the treatment of unstable angina, he explains.

Include LMWHs in your protocols

At Providence Hospital in Mobile, AL, the ED’s chest pain protocol now includes enoxaparin because it is cost-efficient and easy for nurses to administer, according to Sandra Sieck, RN, cardiovascular community coordinator at Providence, who developed a protocol for enoxaparin. "It is easy for nurses to use because of the prefilled vials, and it’s safer for patients," she says. (See protocols for Acute Myocardia Infarction and Ischemic Heart Disease, inserted in this issue.)

Shortly after the protocol was developed, inservicing was done to educate nurses about side effects, patient education, dosing regimen, contraindications, and cost.

Here are the benefits of LWMHs:

Less monitoring of patients. Enoxaparin does not require IV infusion, so it is easier for nurses to use, says Bosker.

Heparin requires more monitoring. "You have to maintain an IV site, and it requires daily dose adjustment and daily monitoring," says Sieck. "Enoxaparin has a rapid onset of action. It interrupts the clotting cascade faster than heparin, and has a prolonged half-life, which means it is very stable. Also, it is given in a fixed dose because it adjusts to body weight, and it requires no labs."

Improved patient comfort. "There is a little discomfort because you have to [administer] this drug [in the abdomen]," says Sieck. "But there is much more discomfort with heparin, with starting an IV, getting the labs [which means additional sticks for the patient], having an IV hanging, the probability of the IV infiltrating and having to start another IV, repeated labs, and monitoring. You don’t have to do any of that with this drug."

With the LMWH, it is recommended that you do at least one CBC (complete blood count) and stool culture during the patient’s stay. "That’s nothing compared to monitoring and dose adjustments," says Sieck.

The drug allows patients to be treated as outpatients. The LMWHs allow more cost-effective management in the out-of-hospital setting. "Now, eligible patients with DVT diagnosis and no serious complications can be treated at home," says Bosker.

Studies have examined the safety and utility of home treatment of DVT. In two recent studies, researchers compared adjusted-dose intravenous standard heparin administered in the hospital to fixed-dose subcutaneous low molecular weight heparin administered twice daily at home.1, 2

In both studies, home treatment with LMWH resulted in better outcomes than standard in-hospital therapy. Patients treated at home, or with a short hospitalization with early discharge to home, spent 67% less time in the hospital and had greater physical activity and social functioning than those treated with standard heparin. Some patients had professional (i.e., home health care by RNs or nurse assistants) assistance with their injections, notes Bosker.

Initial treatment of DVT at home should follow a protocol in which all aspects of the treatment are clearly defined, says Bosker. "The protocol should include criteria for patient selection, drug selection, patient and caregiver education, monitoring, and LMWH dose preparation."

At Jefferson, enoxaparin is used primarily on patients who are newly diagnosed with DVT, says Susan Lynch, RN, nurse coordinator for the antithrombotic therapy service at Jefferson University Hospital in Philadelphia. "ED patients who qualify for home treatment, will be discharged with no admission. However, some patients with newly diagnosed DVT are admitted for 24-36 hours," she reports.

After arrangements can be made for home services, these patients are discharged on enoxaparin and warfarin (Coumadin) for outpatient management. (See guidelines for home DVT treatment on p. 118.)

These arrangements would be made in the ED, using a protocol-based approach in which the visiting nurse service at the hospital is informed that a patient with low-risk DVT has been sent home for outpatient-based therapy, says Bosker. Those arrangements would be triggered by the ED nurse and implemented by a pre-existing home visiting home nursing team trained to implement this protocol.

Reduced length of stay. The protocols significantly reduce a patient’s length of stay (LOS), notes Sieck. "These protocols actually reduce LOS for ruling out an MI from 2.66 days at a cost between $5,000 and $6,000, to nine hours or less at about one-third the cost — with better outcomes," she says.

The protocols meet national guidelines published by the American College of Cardiology, the Agency for Health Care Policy and Research, and the American Heart Association. "When you develop a protocol, take the general consensus of all of [the guidelines]; if all three recommend that beta blockers should be included, then there is no controversy."

Reduced cost. The total cost of drug treatment with enoxaprin for 3-5 days of outpatient treatment is $140 to $240 per course of therapy, as opposed to $17 to $20 with heparin. "However, when approached from a cost/benefit perspective, LMWH is promising. Hospital stays can be decreased — if not eliminated — in certain cases, and there is no need to monitor these agents," says Bosker. "Administration of enoxaparin is via the subcutaneous route vs. the intravenous route for unfractionated heparin, which permits self-administration and decreased nursing care."

The mean cost of enoxaparin therapy is $155, as compared to $80 for heparin. However, total medical costs for inpatient hospitalization were $11,857 for enoxaparin, and $12,620 for heparin, with a savings of $763, Bosker notes.

Fewer complications. LMWHs reduce thromboembolic complications, clinically important bleeding, and mortality when compared to unfractionated heparin, says Bosker.

Because LMWH has little effect on thrombin or platelet aggregation, there are fewer possibilities for hemorrhagic complications than with heparin. "LMWH usually does not elevate the PTT. For this reason, LMWH is valued for its antithrombotic effect and its lack of anticoagulant effect," says Bosker.

LMWHs subcutaneously administered in fixed doses adjusted for body weight and without laboratory monitoring are more effective and safer than adjusted-dose standard heparin, says Bosker. "In a major meta-analysis, LMWH reduced symptomatic thromboembolic complications by 53%, clinically important bleeding by 68%, and mortality by 47%, compared to standard heparin," he says.3

A separate study including more than 2000 patients and 16 controlled trials found that LMWH significantly reduced thrombus extension (odds ratio, 0.51) and demonstrated a trend toward decreased pulmonary embolism, fewer major bleeds, and lowered morality.4

Some things to consider when using the new LWMHs:

Reassure patients about the new medication. Patients with DVT come to the ED with extreme pain in the extremity where the thrombus is and often fear death, stresses Sieck. "They may not know what DVT means, but they do know what blood clot means. They are afraid it will go to their heart, lungs, or brain; and this is an accurate assumption."

Nurses should emphasize to patients that they are being treated aggressively with a drug that will stabilize them quickly, she advises.

Recognize life-threatening conditions. Life-threatening conditions usually involve the presence of extensive DVT and risk for pulmonary embolism and respiratory failure, says Bosker. Warning signs of disease progression include increased swelling, shortness of breath, chest pain, bleeding, and headache, he says. "These patients need treatment in the hospital with enoxaparin."

A clot that travels to the lungs is classified as a pulmonary embolus (PE) and is life-threatening. "Fifty percent of PEs occur in patients who are not suspected of having DVT," says Sieck. "The goals of treatment in the ED are to prevent clot propagation, recurrent DVT and/or PE, and minimize bleeding."

Know other indications for LMWHs. LMWHs such as enoxaparin are also indicated for treatment of unstable angina, so nurses have to become familiar with this agent for indications other than DVT, says Bosker.

Educate patients on home management. Because LMWH can be subcutaneously given once a day without need for coagulation tests, home treatment for DVT is possible.

You will need to give patients instructions on how to use this injectable coagulant. ED nurses show patients how to give the injection in the ED, and the patients are followed up by the pre-existing home nursing team, Bosker says "[The ED nurse has] to take a history to be sure that patients know how to use the syringe, the dosing, what kind of things to look out for in terms of bleeding, and what the indications are for follow-up," she says.

You may be asked to develop protocols for home management programs, says Bosker. "It’s a very critical area, because you are sending patients home with an injectable drug, so the instructions, follow-up, and patient education have to be absolutely meticulous on the part of ED nurses," he says.

Detailed instructions must be provided by the emergency medicine team, stresses Bosker. "The patient or caregiver must be taught to administer the medication, monitor for adverse reactions and efficacy, and perform any other self-care deemed necessary, such as bed rest, leg elevation, and use of compression stockings," he says. "The patient or caregiver must know what steps to take in the event of a complication. (See list of possible side effects, p. 117.)

Instruction should immediately begin after diagnosis, Bosker recommends. "Written instructions should also be provided," he says. "Each ED choosing to begin treating patients with DVT at home will need to develop a protocol that fits its own practice patterns."

Know which patients can be treated with LMWHs. Not every patient is suitable for this management. "Certain criteria have to be fulfilled," says Bosker. (See chart for exclusionary criteria, p. 118.)

Determining which patients are good candidates for outpatient treatment with enoxaparin is difficult, says Bosker. "Sorting patients who have isolated DVT of the lower extremities — without pulmonary embolism and with no high-risk underlying diseases for outpatient treatment with enoxaparin — from those who are sicker and require treatment with LMWHs (enoxaparin) in the hospital requires careful history and physical exam."

Know dosage schedules. Recommended doses for enoxaparin, based on the package insert, are as follows: DVT prophylaxis for a patient receiving surgery — 30 mg SQ every 12 hours or 40 mg SQ once a day depending on the type of surgery; unstable angina and non Q-wave myocardial infarction — 1 mg/kg actual body weight SQ every 12 hours given concurrently with aspirin 100 mg to 325 mg. For inpatient treatment of DVT, with or without PE: 1mg/kg subQ every 12 hours; or 1.5 mg/kg subQ once a day. And, for outpatient treatment of DVT without PE: 1mg/kg every 12 hours. It should be stressed that each LMWH has its own dosing profile, and that one drug cannot be substituted for another, notes Bosker.

"No labs are required with enoxaparin, but it is schedule intensive. When you transfer the patient from the ED to a unit in the hospital, you have to make sure you know when the next dose is given," says Sieck.

Know possible side effects. Possible side effects of the LMWHs include:

Nose bleeds, vomiting, coughing up blood, bleeding gums, bleeding at the injection site, and spontaneous bruising, says Sieck. "However, if you know the proper way to administer the drug, there is less chance of any of these side effects," she notes. "Since the protocol was put in place in July 1998, we have not seen any of these side effects."

Know effects of LMWHs. Each LMWHs is administered by the subcutaneous route only, says Bosker. "Therapeutic levels are obtained within 30 minutes of administration and last for about 24 hours," he notes. "LMWH produces consistent and accurate anticoagulation when given according to a weight-based regimen. However, care should be used in renal failure patients because the effect of the drug may be prolonged."

Know contraindications. LMWHs should not be used in patients with a known bleeding disorder, thrombocytopenia, or known hypersensitivity to heparin. LMWH can cause thrombocytopenia but this does not occur as often as it does with standard heparin.

References

    1. Levine M, Gent M, Hirsh J, et al. A comparison of low-molecular-weight heparin administered primarily at home with unfractionated heparin administered in the hospital for proximal deep-vein thrombosis. N Engl J Med 1996;334:677-681.

    2. Koopman MM, Prandoni P, Piovella F, et al. Treatment of venous thrombosis with intravenous unfractionated heparin administered in the hospital as compared with subcutaneous low-molecular-weight heparin administered at home. The Tasman Study Group. N Engl J Med 1996;334:682-687.

    3. Lensing AW, Prins MH, Davidson BL, et al. Treatment of deep venous thrombosis with low-molecular-weight heparins. A meta-analysis. Arch Int Med 1995;155:601-607.

    4. Leizorovicz A, Simonneau G, Decousus H, et al. Comparison of efficacy and safety of low molecular weight heparins and unfractionated heparin in initial treatment of deep venous thrombosis: A meta-analysis. BMJ 1994;309:299-304.