Intraoperative Monitoring With Noninvasive Near-infrared Spectroscopy and Noninvasive Cardiac Output Measurement, and Postoperative Outcome in Elderly Patients With Fractures of Lower Extremities

Aging is associated with progressive loss of functional reserve in all organ systems. For most people, physiologic compensation for age-related changes is adequate. However, it is easy to decompensate under stressful circumstances, such as surgery and illness. Under the specific physiologic phenomenon, geriatric anesthesia is acquired for more intensive monitoring. In Taiwan, about 75.92% of the elderlies above 65 years old suffered from chronic diseases or major diseases, especially in circulatory system. Thus, dramatic hemodynamic change is often observed in surgeries in this population. For the elderlies with fracture are more vulnerable to have complications, poor prognosis and decompensated organ functions.

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 patient's 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.

Due to the hemodynamic feature in elderlies, we will use conventional measurements as EKG, arterial blood pressure and pulse oximeter. To measure the perfusion of the lower extremities, we use a relative new tool, the non-invasive transcutaneous near infrared spectroscopy (NIRS).2,3 NIRS was used as the cerebral oximetry to measure the tissue perfusion of the cerebral cortex. It uses reflectance oximetry to measure the oxygen saturation of the tissue underneath the sensor.1 Recently, NIRS has been proved not only to continuously monitor tissue oxygenation saturation (StO2) continuously, but also to predict the patient's poor prognosis.3,4 To measure the cardiac output intra-operatively, we will use the non-invasive cardiac output monitor (NICOM®, Cheetah). Bioreactance technique allows the measurement of hemodynamic changes via four electrodes placed on the thorax. The electrical current crossing the thorax makes "signal phase shift", which is related to changes in the volume of the thoracic aorta. Thus, the volume change in the thoracic aorta is able to estimate stroke volume.1,5 Postoperative prognosis is adjusted with the recovery of ambulation, the duration of ICU stay, the morbidity and mortality, and the questionnaire (SF-36) about quality of life.