Three risk factors chosen by the nurse experts present a strong physiological relationship: blood loss, plasma loss and deficient fluid volume. The literature indicates that a reduction in blood volume may occur because of loss of blood or plasma or isolated loss of water (Maier, 2008). Blood loss is one of the factors that determines reduction in venous return and, consequently,in cardiac output.When it is mild(40%), it is responsible for DCO (Guyton and Hall, 2006; Maier, 2008). Patients with a significant plasma loss may experience a decreased total blood volume and exhibit signs that are similar to those indicating blood loss in addition to increased blood viscosity. Plasma loss may be caused by intestinal obstruction, which leads to increased capillary pressure and extravasations of total plasma proteins and plasma as well as severe burns and other skin conditions (Guyton and Hall, 2006).