Early Warning for Desaturation by Oxygen Reserve Index

During the induction of general anesthesia, the anesthesiologist needs to provide the oxygen supply to meet the patient's needs continuously. In the clinical scenario, the pulse oximeter is used as a standard to monitor hemoglobin oxygen saturation (SpO2) but is limited to assess the oxygenation status beyond the measurement of 100%. The Oxygen Reserve Index (ORi) is a dimensionless parameter between 0 and 1 that is related to real-time oxygenation reserve status. This study was designed to evaluate the duration of warning time for desaturation provided by different ORi alarm triggers during prolonged apnea in surgical patients. The primary endpoint was the duration of additional warning time provided by the ORi trigger. The secondary endpoint was the correlation of ORi and PaO2.