Noise Levels in Surgical ICUs Are Consistently Above Recommended Standards

The equipment, monitor alarms, and acuity of patients in ICUs make it one of the loudest patient care areas in a hospital. Increased sound levels may contribute to worsened outcomes in these particularly vulnerable patients. Our objective was to determine whether ambient sound levels in surgical ICUs comply with recommendations established by the World Health Organization and Environmental Protection Agency, and whether implementation of an overnight "quiet time" intervention is associated with lower ambient sound levels.

Prospective, observational cohort study.

Two comparable 18-bed, surgical ICUs in a large, teaching hospital. Only one ICU had a formal overnight quiet time policy at the start of the study period.

Sound levels were measured in 30-second blocks at preselected locations during the day and night over a period of 6 weeks using a simple, hand-held sound meter. All sound measurements in both units at all times exceeded recommended standards. Median minimum sound levels were lower at night in both units (50.8 and 50.3 vs 53.1 and 51.0 dB, p = 0.0003 and p = 0.009) and were similar between the two units (p = 0.52). The maximum overnight sound levels were statistically lower in the unit with the quiet time intervention implemented (62.5 vs 59.6 dB; p = 0.0040) and decreased overnight immediately after implementation of quiet time in the other unit (62.5 vs 56.1 dB; p < 0.0001). Maximum sound levels were lower inside patient rooms (52.2 vs 55.3 dB; p = 0.004), but minimum sound levels were similar (49.1 vs 49.2 dB; p = 0.23). Linear regression analysis showed that ICU census did not significantly influence sound levels.

Ambient sound levels in the surgical ICUs were consistently above levels recommended by the World Health Organization and Environmental Protection Agency at all times. The use of a formal quiet time intervention was associated with a significant, but clinically irrelevant reduction in the median maximum sound level at night. Our results suggest that excessive ambient noise in the ICU is largely attributable to environmental factors, and behavior modifications are unlikely to have a meaningful impact. Future investigations, as well as hospital designs, should target interventions toward ubiquitous noise sources such as ventilation systems, which may not traditionally be associated with patient care.