Use of anti-Xa factor titration as efficacy marker of enoxaparin in critically ill patients

Introduction

Low molecular weight heparins (LMWH) are frequently used for thrombosis prophylaxis or anticoagulation treatment in critically ill patients without efficacy control in specific patient groups.

Objective

To evaluate the efficacy of sodium enoxaparin in critically ill patients and the acute decompensation of baseline conditions.

Method

We evaluated critically ill patients admitted to a cardiology critical care unit with indications of anticoagulation, either prophylactic or therapeutic. Patients with body weight >110 kg or serum creatinine ≥ 2.5 mg/dl were excluded. Anthropometrics, clinical data and the prognostic index were recorded. Anti-Xa factor was titrated in three different moments: baseline (before enoxaparin administration), and T1 (first or second day) and T2 (fifth to seventh day) after use of enoxaparin, 40 mg/day for prophylaxis and 1 mg/kg every 12 hours for anticoagulation therapy. Lower limb sonography was performed to scan for deep vein thrombosis (DVT) in the prophylactic group of patients.

Results

Thirty-two patients were included (16 patients in the prophylactic group and 16 patients in the therapeutic group). Mean age was 62 ± 16 years (from 20 to 92 years). The main diagnosis included cardiogenic shock (10 patients), decompensated cardiac failure (five patients), arrhythmia (six patients), pulmonary embolism (two patients), lung infection (three infections), prosthetic valve dysfunction (one patient) and others (five patients). The mean APACHE II score was 10.9 ± 5. The T1 mean anti-Xa factor titration for the prophylactic group was 0.35 ± 0.10 IU/ml and for the therapeutic group was 0.57 ± 0.10 IU/ml (Mann–Whitney test, P < 0.001). The T2 mean anti-Xa factor titration for the prophylactic group was 0.46 ± 0.11 IU/ml and for the therapeutic group was 0.69 ± 0.08 IU/ml (Mann-Whitney test, P < 0.001). One patient presented with DVT in spite of proper anti-Xa factor levels for prophylaxis.

Conclusion

Sodium enoxaparin in the used schedules was effective. Anti-Xa factor titration is useful in monitoring critically ill patients, especially those with low cardiac output.