Assessment of noise in a medical intensive care unit Kathryn J. Crawford , University of Iowa Follow

[摘要] Exposure to noise in hospital intensive care units (ICUs) can disrupt patients’ sleep and delay their recovery. In this intervention study, noise levels were measured in eight patient rooms of a medical ICU (MICU) every minute with sound level meters for eight weeks before and after an intervention. Implemented over six weeks, the intervention was designed to educate nurses and other staff members to reduce noise levels through behavior modification, including instituting a "quiet time” in the afternoons, encouraging patients to keep televisions off or at lower volumes, and speaking more quietly during conversations. Sound equivalent levels (L eq ) were calculated from one-minute measurements for each hour in each room. These hourly L eq (L eq-H ) values were compared by pod (group of rooms within the MICU), room position (in proximity to a central nurses’ station), occupancy status, and time of day. Days with more than ten hours of one-minute noise levels above 60 dBA were flagged as the loudest time periods and compared to MICU activity logs. The intervention was ineffective with L eq-H values always above World Health Organization guidelines for ICUs (35 dBA in day; 30 dBA at night) before and after the intervention. L eq-H values frequently exceeded more modest project goals during the day regardless of the intervention (50% of L eq-H > 55 dBA both pre- and post-intervention) and at night (68% and 62% of L eq-H > 50 dBA pre- and post-intervention). Statistical analysis of the L eq-H suggests a general source is contributing to the high baseline noise in the MICU, most likely the heating, ventilation, and air-conditioning (HVAC) system. Our analysis of one-minute data indicated that high noise was often associated with high-volume respiratory-support devices. We concluded that our intervention focusing on administrative controls (e.g., education and training) was not enough to reduce noise in the MICU but that an intervention designed with engineering controls (e.g., shielding, substitution) would be more effective.