Impact of Intermediate Care Unit Architecture on Noise, Light, and Delirium Incidence

To evaluate the effect of a newly constructed intermediate care unit (IMCU) on noise levels, lighting conditions, and delirium incidence.

Sound pressure levels, including the equivalent continuous A-weighted sound pressure level (LAeq), background sound pressure level (LA90), peak sound pressure level (LA10), and lighting conditions expressed as melanopic equivalent daylight illuminance (melanopic EDI) were measured continuously for multiple days in an IMCU in Wil, St. Gallen, Switzerland before and after relocation. Delirium incidence was tracked before and after relocation.

Both units constantly exceeded the World Health Organization recommended limits for noise. However, relocation decreased background noise levels (LA90) during day and night ( P   = 0.027, P   =  0.016, respectively). Lower sound pressure levels (LAeq) were also measured at the new nursing station. Lighting conditions were adequate before relocation but failed to meet international standards throughout the day. In the newly constructed IMCU, lighting conditions worsened (lower melanopic EDI compared to the old IMCU; P   < 0.001), and recommended daytime illuminance levels were never achieved. No differences in delirium incidence were observed after relocation ( P   > 0.05).

The observations in this first-ever study suggest unexpected noise and lighting conditions in an IMCU and a central role of architectural factors. Further studies are needed to determine the impact of noise, light, and architectural characteristics in IMCUs on delirium and other significant clinical outcomes. In hospitals, architectural characteristics such as large south-facing windows and other factors influencing light and noise, such as spatial organization and staff awareness, should be considered to promote sleep-wake circadian functions and thus enhance patient comfort and recovery.