BIS Variability and Change in Quality of Recovery After Surgery

This prospective observational study aims to examine the relationship between fluctuations in anesthesia depth, measured by bispectral index (BIS) monitoring during surgery, and changes in patients' postoperative recovery quality. BIS monitoring is routinely used during general anesthesia to assess the depth of anesthesia, but BIS values often fluctuate over time rather than remaining stable. The clinical significance of this variability is not well understood. In this study, BIS variability during anesthesia induction and maintenance will be evaluated and compared with changes in postoperative recovery quality. Recovery quality will be assessed using the Quality of Recovery-15 (QoR-15) questionnaire, which will be administered before surgery and again on the first postoperative day. The primary outcome of the study will be the change in QoR-15 score from the preoperative baseline to postoperative day one (ΔQoR-15). Delirium screening and routine perioperative clinical data will also be collected. No additional interventions beyond standard anesthesia care will be performed. The results of this study may help improve understanding of how intraoperative anesthesia stability relates to patient recovery after surgery.