 In our daily practice, the surgeries for fracture in lower extremities can performed under either general anesthesia or regional anesthesia, such as spinal anesthesia epidural anesthesia, and nerve block. The anesthetic method is determined under each patients condition. EKG, arterial catheter, pulse oximeter are usually basic for intra-operative monitoring. However, these tools are unable to inform us the real-time cardiac output and the exact status of tissue perfusion. Nowadays, there are many non-invasive instruments able to estimate more detailed hemodynamic parameters, which are very crucial during anesthesia.1 But these instruments are not widely used in our daily practices. We need more researches to support the beneficial roles of these non-invasive monitors to high-risk patients during surgery. 