NIV Congres

Purpose: LMWH is the first-choice anticoagulant in intensive care (ICU) patients. Dosage is based on admission weight, according to current guidelines of the Dutch Society of Intensive Care Medicine (NVIC). Monitoring anti-factor Xa levels (aFXa) is only advised in ICU patients with renal insufficiency. The target range for aFXa levels in literature, albeit unproven, is 0.2-0.6 IU/ml. The aim of this study was to observe if recommended aFXa levels are being achieved in ICU patients.

Materials and Methods: We conducted an observational, prospective study in a 25-bed general and surgical ICU and an 8-bed medium care unit (MCU) in the Catharina Hospital in Eindhoven. Patients were included between September 15th and December 15th, 2012 and received LMWH subcutaneous. Patients with an ICU stay less than 24 hours were excluded.

Patients received 2500 IU dalteparin (sc.) if admission weight < 80 kg, and 5000 IU dalteparin (sc.) if admission weight ≥ 80 kg. The aFXa levels were measured four hours after administration using the validated chromogenic method (STA® liquid anti-Xa assay).

Results: We collected data from 246 patients of whom 127 < 80 kg and 119 ≥ 80 kg. The median aFXa of the entire population was 0.180 IU/ml (IQR 0.05-1.41). The median aFXa of patients < 80 kg was significantly lower compared to patients ≥ 80 kg (0.165 IU/ml (IQR 0.05-1.41) vs. 0.210 IU/ml (IQR 0.05-0.84) respectively; p = 0.001). In patients < 80 kg 17% (n = 22) did reach the lower limit of the target range (0.2 IU/ml) each day compared to 37% (n = 44) in patients ≥ 80 kg (p = 0.001). In patients < 80 kg 53% (n = 67) never reached the lower limit compared to 29% (n = 35) in patients ≥ 80 kg (p < 0.001).

Conclusion: Dosing of dalteparin (LMWH) based on admission weight, according to current guidelines, leads only in a small minority to therapeutic aFXa activity. Monitoring of the aFXa levels should be considered in all ICU patients.