ORI and ETCO₂ Relationship With Arterial Blood Gas During Apnea Test

This observational study aims to evaluate the relationship between the Oxygen Reserve Index (ORI) and End-Tidal Carbon Dioxide (ETCO2) values with arterial blood gas parameters in patients undergoing the apnea test for the diagnosis of brain death. The study will examine the correlation between ORI and PaO2, as well as between ETCO2 and PaCO2. The primary objective is to assess the effectiveness of ORI in evaluating oxygenation and its applicability in the apnea test. The study will also evaluate the routine use of ORI in monitoring PaO2 and its potential benefits compared to traditional methods.