Farzanegan B, et al. - Given that cerebral oxygen saturation (ScO₂) is important in endoscopic sinus surgery patients and it may be low during controlled hypotension, researchers evaluated ScO₂ in 41 patients who had endoscopic sinus surgery with hypotensive anesthesia and were included in this observational study. ScO₂ was assessed using near-infrared spectroscopy. In the surgical duration, mean arterial blood pressure (MAP) was maintained at 55–60 mmHg. They used t-test, Wilcoxon, and repeated measures analysis of variance (ANOVA). They also assessed the cross-correlation functions of the time series data between end-tidal carbon dioxide (ETCO₂)/MAP and ScO₂. They found that, ScO₂ evaluation and maintained MAP >55 mmHg may offer safe conditions for endoscopic sinus surgery. Findings revealed moderate cross correlation between the MAP and current ScO₂. Within 30 min, recovery was seen in about 92% of the patients. Associations of recovery time with intraoperative MAP, intraoperative ETCO₂, and ScO₂, were also found.