ABSTRACT

This study aimed to determine the effects of using a standard dose of fresh frozen plasma (FFP) on the international normalized ratio (INR) of patients with various elevations in INR from using warfarin.

This prospective study was conducted in the emergency department (ED) of a training and research hospital from February 2015 to January 2016 with patients who presented with elevated INRs from using warfarin. Their demographic data, clinical features, and laboratory findings, including pre- and post-transfusion INRs, were recorded. The standard dose of FFP used was 3 units of FFP (900 mL). Delta INR (ΔINR) was defined as the pre-transfusion INR minus the post-transfusion INR. Two hours after the end of the FFP transfusion, each patient’s INR was measured again.

Thirty-two patients who received FFP and whose pre- and post-transfusion INRs were measured were included. Of these 32 patients, 23 (71%) were women, and the patients’ mean age was 72.8±11.1. The mean pre- and post-transfusion levels and ΔINR were 10.6±5.3, 4.3±2.3, and 6.2±4.3, respectively. There was a strong positive correlation between high pre-transfusion INR and ΔINR (p<0.001, r=0.85). Regression analysis performed to estimate ΔINR after the transfusion of a standard dose of FFP found that ΔINR=0.69×(pre-transfusion INR) -1.111 (p<0.001).

The present study found that using a standard dose of FFP caused varying reductions in ΔINRs that correlated with the pre-transfusion INR.

Keywords: Warfarin, fresh frozen plasma, international normalized ratio, emergency department