Figure 2 Correlation between oxygen reserve index (ORi) and PaO2 in BEG, PP+T, and ZERO time points. The figure shows scatter plots illustrating the correlation between ORi and PaO2 at 3 selected measurement points: BEG – before induction of anesthesia, PP+T – after placing the patient in the Trendelenburg position and establishing pneumoperitoneum, and ZERO – after returning the patient to the initial position. (A) G1 PaO2 – partial pressure of oxygen in arterial blood before induction of anesthesia, (B) G2 PaO2 – partial pressure of oxygen in arterial blood after placing the patient in the Trendelenburg position and establishing pneumoperitoneum, (C) G3 PaO2 – partial pressure of oxygen in arterial blood after returning the patient to the initial position. For each measurement point, individual observations are presented. The relationship between ORi and PaO2 was assessed using Spearman’s rank correlation coefficient. Statistically significant positive correlations between ORi and PaO2 were found at all measurement points analyzed (detailed data are presented in the text).