Capillary Lactate and Transfusion Needs

13% of injured normotensive patients arriving in emergency unit need mass blood-transfusion of six or more units of packed Red Blood Cells. It is currently difficult to predict the need for such a mass blood-transfusion. Indeed hemoglobin point of care testing (hemocue) and blood pressure can be normal during the first hours despite intensive bleeding. It's well known that blood or arterial lactate measures correlate with trauma severity but these measures are not available in a pre-hospital setting. The investigators want to test whether capillary lactate measures also correlate with trauma severity and can therefore predicts earlier transfusion needs.