Reduction of sound levels in the intermediate care unit; a quasi-experimental time-series design study

Objectives: This study aimed to assess the effectiveness of an architectural redesign and a multicomponent intervention bundle on noise reduction to enhance workplace safety.

Methods/design: Quasi-experimental study with a time-series and intensified intervention design conducted in an intermediate care unit. Two interventions were sequential introduced: the installation of a partition wall in the medication preparation room (architectural redesign) and the implementation of an a bundle. Effects on outcomes were evaluated comparing baseline, after architectural redesign (period-1) and after implementation of the bundle (period-2).

Setting: Intermediate care unit.

Main outcome measures: A-weighted sound levels (LAeq), alarms/day/bed, annoyance ratings (numeric rating scale 0-10) and number of distractions of nurses during the medication preparation process.

Results: LAeq baseline vs period-1, decreased in the medication preparation area from 56.8 (±5.0) to 53.7 (±7.2) dBA (p < 0.001) and in the nursing station from 56.8 (±5.0) to 54.3 (±4.0) dBA (p < 0.001). During period-2, further noise reduction was minimal to absent. Distractions decreased from 58 % during baseline to 45 % (p < 0.001) during period-1, with no further reduction during period-2. The median [IQR] number of alarms/day/bed increased from 263 [IQR 193-320] during baseline to 394 [IQR 258-474] during period-1 (p < 0.001), then decreased to 303 [IQR 264-370] (p < 0.05) during period-2. Median annoyance ratings decreased from baseline 3.0 [IQR 2.0-6.0] to 2.0 [IQR 1.0-3.0] (p < 0.001) during period-2.

Conclusion: An architectural redesign resulted in a significant, clinically relevant decrease in sound levels along with a notable reduction in distractions. The multicomponent bundle lowered alarms and annoyance ratings; however, its effectiveness on other outcomes seems less persuasive.

Implications for clinical practice: Architectural redesign seems to be effective in controlling environmental noise. Architectural redesign results in a decrease in nurses' distractions during the medication preparation process. The effect of an intervention bundle is, despite a positive effect on alarms and perceived annoyance, still insufficiently clear.