Intravascular volume and fluid therapy for severe sepsis.

Hypovolemia is one of the principal defects contributing to cardiovascular instability and circulatory failure during septic shock. Fluid infusion is the mainstay of initial resuscitation. Large amounts of fluids may be required and should be titrated to optimal hemodynamic effects while attempting to minimize the development of pulmonary and systemic edema. Hemoglobin and hematocrit should be carefully monitored, with transfusions being used as necessary to maintain adequate levels of systemic oxygen delivery. Crystalloids and colloids are equally effective, although the volume of fluids required with crystalloids is two to four times that of colloids. In older patients, where high filling pressures may be required for optimal hemodynamic effect, colloids may be associated with a lower frequency of pulmonary edema.