HYPEROXY

Oxygen administration is essential in the perioperative period to prevent hypoxia; however, excessive oxygen may cause hyperoxia and related complications. While pulse oximetry is effective in detecting hypoxemia, it is insufficient for identifying hyperoxia when SpO₂ exceeds 97%, often necessitating invasive arterial blood gas analysis. The Oxygen Reserve Index (ORI) is a noninvasive, real-time monitoring parameter reflecting moderate hyperoxic ranges (PaO₂ 100-200 mmHg) and provides early warning of oxygenation changes before SpO₂ alterations occur. Combined use of ORI and pulse oximetry may enable optimal oxygen titration and prevention of both hypoxemia and hyperoxemia. Laparoscopic nephrectomy is widely performed due to its clinical advantages. In our practice, low and normal fresh gas flow anesthesia are commonly used. Low-flow anesthesia offers benefits such as preservation of heat and humidity, reduced cost, and improved airway physiology. This study aims to determine optimal oxygenation levels during laparoscopic nephrectomy under low and normal fresh gas flow conditions using ORI monitoring.