EVALUATION OF OXYGEN RESERVE INDEX IN LOW AND NORMAL FLOW ANESTHESIA APPLICATIONS IN LAPAROSCOPIC NEPHRECTOMY CASES IN LATERAL DECUBIT POSITION

Oxygen is routinely administered to patients in the perioperative setting to prevent the harmful effects of hypoxia. However, high oxygen concentrations may lead to hyperoxia, which can result in significant complications. Therefore, early detection of both hypoxemia and hyperoxemia during the perioperative period is crucial. Pulse oximetry is highly effective in detecting hypoxemia; however, it is insufficient for evaluating oxygenation when SpO₂ exceeds 97%, limiting its usefulness in identifying hyperoxia. In such cases, arterial blood gas analysis, an invasive method, is typically required.

The Oxygen Reserve Index (ORI) is a noninvasive, real-time, and continuous monitoring parameter used to assess oxygenation status. ORI values range from 0 to 1 and reflect arterial partial oxygen pressure levels between approximately 100 and 200 mmHg. Importantly, ORI provides an early warning of deteriorating oxygenation before any detectable changes occur in SpO₂. The combined use of ORI and pulse oximetry may facilitate more precise titration of inspired oxygen concentration and help prevent both hypoxemia and hyperoxemia.

Laparoscopic surgery offers several advantages, including reduced blood loss, improved wound healing, decreased postoperative pain, and shorter hospital stays. Accordingly, laparoscopic techniques are frequently employed for nephrectomy procedures in our clinic.

Depending on clinician preference, low, normal, and high fresh gas flow rates are commonly and safely used in our practice. Low-flow anesthesia provides benefits such as preservation of heat and humidity within the respiratory system, reduced costs, and decreased environmental pollution. Additionally, improved preservation of mucociliary clearance contributes to better maintenance of airway physiology.

In high-risk and major surgeries such as laparoscopic nephrectomy, ORI monitoring is routinely utilized in our clinic to minimize the risks of hypoxemia and hyperoxemia. In this study, we aim to determine optimal oxygenation levels during laparoscopic nephrectomy procedures performed under low and normal fresh gas flow conditions.