Noise in cesarean deliveries: a comprehensive analysis of noise environments in the Labor and Delivery operating room and evaluation of a visual alarm noise abatement program

The Effect of Nonstress Device Noise Level on Stress Parameters in Primigravid Women: A Randomized Controlled Trial

INTRODUCTION

This study evaluated the effect of the noise level of the nonstress test (NST) device on stress parameters in primigravid women.

METHODS

A total of 44 pregnant women participated in a randomized clinical trial between February and October, 2021. The participants were divided randomly into 4 equal groups using an automated web-based randomization system and ensuring allocation concealment: the control group (NST device volume turned off), intervention group I (1-35 dB(A)), intervention group II (36-60 dB(A)), and intervention group III (61 dB(A) and above). A data collection form was used to record personal information and stress parameters. Stress parameters (blood pressure, heart rate, oxygen saturation [SpO2], blood glucose, salivary cortisol, and salivary adrenocorticotropic hormone [ACTH]) levels were measured pretest (0-2 minutes before NST starts), midtest (at 10 minutes of the NST), and posttest (within 0-2 minutes after NST was finished). The study was registered at ClinicalTrials.gov (identifier: NCT05488704).

RESULTS

NST sound levels above 35 dB(A) increased the average cortisol and ACTH levels in the posttest. NST sound levels were positively correlated with posttest cortisol (r = .448) and posttest glucose (r = .302). There was interaction effect on heart rate, glucose, and cortisol level by time, indicating that the intervention groups experienced a significant acceleration in heart rate, glucose, and cortisol level after a noise intervention compared with the control group.

DISCUSSION

Midwives should continue applying NST below 36 dB(A), considering the factors that may induce stress during the NST process.

Effect of intraoperative noise on postoperative pain in surgery patients under general anesthesia: evidence from a prospective study and mouse model

BACKGROUND

Most patients are in a noisy environment during abdominal surgery under general anesthesia. This study included patients who underwent abdominal surgery under general anesthesia and established an animal model to determine whether intraoperative noise affects postoperative pain.

MATERIALS AND METHODS

This prospective study included 200 patients who underwent abdominal surgery under general anesthesia. Intraoperative noise and electroencephalograms were continuously recorded, and the mean level and time proportion of noise intensity of greater than 70 dB were calculated. Maximum postoperative pain was assessed using a numerical rating scale at 0-12 h and 12-24 h after surgery, and postoperative analgesia consumption in patients receiving patient-controlled intravenous analgesia was recorded. Postoperative pain intensity and electroencephalogram amplitude were compared between patients with high-noise exposure (time proportion of noise intensity greater than 70 dB ≥40%) and low-noise exposure (<40%). Mechanical pain sensitivity was tested in two groups of mice with plantar incisions exposed to 40 dB or 70-100 dB.

RESULTS

The time proportion of noise intensity greater than 70 dB was identified as an independent risk factor for postoperative pain intensity ( P <0.001). P ain numerical rating scale 0-12 h (4.5±1.5 vs. 3.7±1.3, P =0.001) and 12-24 h (3.9±1.5 vs. 3.2±1.1, P =0.004) after surgery in patients with high-noise exposure was significantly higher than in patients with low-noise exposure. The electroencephalogram amplitude of patients with high-noise exposure was significantly lower than that of patients with low-noise exposure ( P <0.05). In the mouse model, mechanical hyperalgesia in the 70-100 dB group was significantly greater than that in the 40 dB group ( P <0.001).

CONCLUSION

High-level intraoperative noise exposure aggravates the degree of postoperative pain and analgesic needs of patients undergoing abdominal surgery, which may be related to the impact of noise on the neurophysiological activity of the brain and postoperative hyperalgesia.