Thrombelastography Based Dosing of Enoxaparin

Oregon Health & Science University (OHSU)

Status: Completed

Conditions: Thromboembolic Complications

Treatments: Drug: Enoxaparin 30 mg BID; Drug: Enoxaparin dose adjusted Lovenox based on TEG

Study type: Interventional

Funder types: Other

Identifiers

NCT00990236

001-01

Details and patient eligibility

About

The risk of developing a blood clot occurs in up to 60% of all critical care patients. Many times enoxaparin (or Lovenox®) is given to patients who are at a higher risk of developing clots in their legs or lungs. Recent data suggest that a standard dose of Lovenox may not fully prevent the development of these clots especially in critically ill or obese patients. Routine enoxaparin dosing can also result in bleeding complications. Thrombelastography (TEG®) can be used to measure how blood clots. The purposes of this study are:

• to learn if the TEG® can better guide physicians in prescribing an effective dose of Lovenox compared to standard doses recommended by the drug company in preventing blood clots from developing in the legs and lungs, and
• to compare the development of blood clots in patients receiving the standard dose of enoxaparin compared to patients receiving a TEG® guided dose of enoxaparin.
• to determine if TEG guided dosing results in decreased bleeding complications compared to standard dosing.

Full description

Hypothesis:

Enoxaparin dosed to maintain a TEG® ΔR greater than 1.0 minute will decrease the incidence of DVT compared to standard dosing.

Initiation of enoxaparin thromboprophylaxis will be done by the treatment team. Once enrolled, the subject will be randomized to continue receiving standard dose enoxaparin (30 mg twice daily) or variable TEG® guided enoxaparin dosing. The treatment team and the subject will be blinded regarding the arm in which the patient is enrolled. Patient characteristics: age, gender, body mass index (BMI), comorbidities, Acute Physiology and Chronic Health Evaluation II score (APACHE II), injuries, and operations will be collected. As part of standard protocol in the ICU, all patients will undergo weekly ultrasound duplex examination of the lower extremities for presence of deep venous thrombosis.

A baseline TEG® will be completed on each patient when they are enrolled in the study. The blood will be drawn between four and six hours after the morning dose is administered, corresponding to maximum tissue levels of enoxaparin. TEG® assays will be run in duplicate for each patient, with and without heparinase, which negates the effects of enoxaparin in the assay.

Those patients randomized to the control arm of the study will have TEG® performed at baseline and daily for one week, then twice weekly. The twice weekly TEG® assays will be done until the patient is discharged from inpatient care or enoxaparin is discontinued by the treatment team. No adjustments will be made to their enoxaparin dosing.

Patients in the TEG® guided enoxaparin dosing arm will start treatment as ordered by the primary treatment team. After the second TEG®, the dose of enoxaparin will be adjusted in 10 mg increments per dose in order to reach a target ΔR between 1.0 and 1.4 minutes. If the initial ΔR is greater than 1.4 minutes, the dose of enoxaparin will be decreased by 10 mg increments until the target ΔR is achieved. Patients will have TEGs® performed daily and adjustment of dosing until the target ΔR is reached. Once the target ΔR is achieved, TEG® will be done twice weekly until the patient is discharged from inpatient care or enoxaparin is discontinued by the treatment team. All patients will be assessed daily by study personnel for bleeding complications. If bleeding complications occur, subjects will be withdrawn from the study. If interim analysis identifies a significant difference in bleeding complications between groups the study will be terminated.

Enrollment: 185 patients

Sex: All

Ages: 15+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Inpatient initiated on enoxaparin thromboprophylaxis
• Age greater than 15 years

Exclusion criteria

• Unable to obtain consent from patient or ARR
• Presence of: intracranial hemorrhage, brain injury
• Receiving therapeutic dose enoxaparin
• Receiving other forms of anticoagulation
• Receiving non-standard dosing regimen of enoxaparin

Trial design

Primary purpose: Prevention

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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185 participants in 2 patient groups

Enoxaparin 30 mg BID

Active Comparator group

Description:

standard dose enoxaparin thromboprophylaxis (30 mg twice daily)

Treatment:

Drug: Enoxaparin 30 mg BID

Enoxaparin dose adjusted based on TEG

Experimental group

Description:

enoxaparin dose modified based on TEG results

Treatment:

Drug: Enoxaparin dose adjusted Lovenox based on TEG