OBJECTIVE: This study aimed to investigate the impact of different levels of intraoperative noise exposure on postoperative pain intensity and total electroencephalogram (EEG) power in patients undergoing abdominal surgery under general anesthesia.
METHODS: This retrospective cohort study included 154 patients undergoing elective lower abdominal surgery under general anesthesia (March 2024-March 2025). The proportion of operative time with noise ≥70dB was derived from intraoperative monitoring and anesthesia system records and served as the grouping criterion. Patients with ≥40% exposure (n = 51) formed the high-noise group, and those with <40% (n = 103) formed the low-noise group. Postoperative pain numerical rating scale (NRS) was compared between groups for three cohorts: patient-controlled intravenous analgesia (PCIA) users, non‑PCIA patients, and all patients. Analgesic consumption in PCIA users within 0 to 24h was recorded, and intraoperative total EEG power (α, β, δ, and θ waves) was compared. Independent samples t-test and χ2 test were used for intergroup comparisons, with P < 0.05 considered statistically significant.
RESULTS: PCIA users in the high-noise group showed higher maximum NRS scores at 0 to 12 and 12 to 24hours, higher average scores over 0 to 24hours, and greater analgesic consumption compared with those in the low-noise group (P < 0.05). Similar trends were observed in non‑PCIA patients and the entire cohort, with significantly elevated NRS scores across the same intervals (P < 0.05). Moreover, total EEG power (α, β, δ, and θ waves) during surgery was significantly lower in the high-noise group (P < 0.05).
CONCLUSION: High-level intraoperative noise exposure during lower abdominal surgery under general anesthesia is linked to increased postoperative pain within 0 to 24 hours, elevated analgesic use, and decreased total EEG power (α, β, δ, and θ bands). This finding implies a potential connection among noise levels, EEG alterations, and postoperative pain. However, this work cannot confirm causality because of its retrospective nature; prospective research is needed for verification.