Effect of noise isolation with noise-cancelling earmuffs during laparoscopic surgery on acute postoperative pain: a clinical randomised controlled trial.

BACKGROUND: Acute postoperative pain is common in surgical patients, and intraoperative noise isolation has been shown to reduce pain for up to 24 h postoperatively. However, acute postoperative pain primarily occurs during the first three days after surgery, and it remains unclear whether intraoperative noise isolation affects the incidence of moderate-to-severe acute postoperative pain during this period. Therefore, this study aimed to investigate whether the use of noise-cancelling earmuffs during laparoscopic surgery reduces the incidence of moderate-to-severe acute postoperative pain. METHODS: A single-center clinical randomised controlled trial was conducted in Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University. The study included 86 patients aged 18-65 years who underwent elective laparoscopic surgery under general anaesthesia, had an ASA classification I-III, and received patient-controlled intravenous analgesia (PCIA). Participants were randomly assigned to either a noise isolation group or a control group. The noise isolation group wore noise-cancelling earmuffs to attenuate intraoperative noise from induction until the end of surgery, while the control group received conventional anaesthesia management without earmuffs. The primary outcome was the incidence of numeric rating scale (NRS, 0-10) pain scores ≥ 4 at 72 h postoperatively, measured using a 10-point numeric rating scale. Secondary outcomes included the incidence of NRS pain scores ≥ 4 at 24 h and 48 h postoperatively and the proportion of different tiers of NRS pain scores (mild [1-3], moderate [4-6] and severe [7-10]), daily frequency of additional rescue analgesic use over postoperative days 1-3, the maximum resting pain score and the maximum movement-evoked pain score at 24, 48, and 72 h postoperatively and total opioid consumption during the first 72 h postoperatively. RESULTS: The noise isolation group had a significantly lower incidence of moderate-to-severe pain on the third postoperative day (7.1% vs. 25%, P < 0.05) compared with the control group. The incidences of moderate-to-severe pain on the first (33.3% vs. 56.8%, P < 0.05) and second (19.0% vs. 47.7%, P < 0.05) postoperative days were significantly lower in the noise isolation group compared to the control group. Noise isolation reduced the proportion of moderate pain (33.3% (14/42) vs. 56.8% (25/44), P = 0.003; 19% (8/42) vs. 40.9% (18/44), P = 0.027; 4.8% (2/42) vs. 22.7% (10/44), P = 0.016) on postoperative days 1 to 3 compared with the control group. Median additional rescue analgesic use was lower during the three postoperative days in the noise isolation group (0 [0-2] vs. 1.33 [0-2], P = 0.023). The median maximum resting pain scores in the noise isolation group were significantly lower in the postoperative 24 and 72 h periods (1 [0-2] vs. 2 [1-3], P < 0.05; 0 [0-1] vs. 1 [0-2], P < 0.05), as was the median maximum movement-evoked pain scores at 48 and 72 h postoperatively (3 [1.75-3] vs. 3 [2-4], P < 0.05; 2 [1.75-3] vs. 3 [2-3.75], P < 0.05). Opioid dosage (70 [61.6-74] vs. 73.2 [68-76.6], P < 0.05) and the number of PCIA pump button presses (0 [0-0] vs. 1 [0-2.75], P = 0.002) in the noise isolation group were significantly lower in the third postoperative day compared with the control group. Finally, sleep disturbances were less frequent in the noise-isolation group on the third postoperative day (19.0% vs. 40.9%, P < 0.05) compared to the control group. CONCLUSION: Intraoperative noise isolation using noise-cancelling earmuffs reduces the incidence of moderate-to-severe pain and reduces pain severity distribution one to three days after laparoscopic surgery, and it also lowers both total opioid consumption and the need for additional rescue analgesia during the three days after surgery. TRIAL REGISTRATION: Registered in the Chinese Clinical Trial Registry ChiCTR2500097844 (Date: 26/02/2025).