Evaluation of Cognitive Functions by Cerebral Pulse Oximetry

Cerebral Oximeter is a monitoring application based on the measurement of regional oxygen saturation by transcutaneous route by near infrared spectroscopy technology. With this system that analyzes the intraparenchymal and microcirculation in the frontal cortex, cerebral oxygenation changes caused by possible hypoxemia are followed. Unlike pulse oximeter, it works in non-pulsatile conditions. In other words, continuous, real-time and safe oxygen saturation is continued to be measured even in the case of cardiopulmonary arrest. It is a significant advantage of noninvasive measurement according to jugular venous oxygen saturation measurement. For normal healthy people, the accepted normal range is 58-82%, while 0 to 15% of measurements are important for providing CPR process information.

Oxygen saturation measured by cerebral oximetry is different from that measured by other oxygen saturation measurement techniques. The main reason for this is the technique itself and the region where it is used. The radiation emitted by the cerebral oximetry sensor is aimed at the microvessel structure with venous and arterial mix. Since the contribution of venous and arterial blood volume in this structure is between 70-75% and 30-25%, different results are obtained based on only arterial or just venous bed measurements. In this sense, the measured saturation value is lower than the arterial oxygen and pulse oximetry saturation values; higher than venous values.

The ratio of oxyhemoglobin to the total hemoglobin below the region under evaluation of the system is expressed as, value in% System and reflected to the user as Regional Oxygen Saturation (rSO2). There are publications that can be used not only for cerebral but also for different tissues (ischemic limb, kidney, etc.).

General and Spinal Anesthesia can be used in geriatric patients in orthopedic surgery. Post-op cognitive dysfunction may be seen in orthopedic surgery in this patient group. There are not enough studies showing the correlation of cognitive functions with cerebral pulse oximetry after general and spinal anesthesia. In this study, the investigators aimed to compare cognitive functions between spinal and general anesthesia using cerebral and systemic oxygenation, hemodynamic data and pre-op, post-op cognitive function tests.

Inclusion criteria

• ASA 1-2
• patients with lower extremity surgery
• Cognitive functions sufficient

Exclusion criteria

• Brain functions affected
• Peri-operative MAP <60 ones
• Those with electrolyte dysfunctions
• Those who need more blood and blood transfusion
• Patients with ASA 3 and above