ABSTRACT & COMMENTARY
Can the Physical Layout of an ICU Influence Delirium Rates?
By Linda L. Chlan, PhD, RN, FAAN
SYNOPSIS: Intensive care units that contain multiple beds in one area may increase patient risk for the development of delirium.
SOURCE: Caruso P, et al. ICU architectural design affects the delirium prevalence:
A comparison between single-bed and multibed rooms. Crit Care Med 2014;42:2204-22 10
Delirium, or acute brain dysfunction, is a syndrome that affects many patients in the intensive care unit (ICU). A number of modifiable and non-modifiable risk factors contribute to the development of delirium, such as illness severity, receipt of benzodiazepine medications, and metabolic alterations. Likewise, clinicians can implement a number of evidence-based interventions that to reduce the incidence of delirium, such as reducing sedation medications and early mobility programs. One area that has not received much attention from researchers is the consideration of the physical design and layout of the ICU itself. The study by Caruso and colleagues was intended to begin to address this knowledge gap.
This retrospective study was conducted in two ICUs contained in a 290-bed Brazilian oncological teaching hospital. The investigators posited that environmental risk factors, specifically the physical architecture of the ICU, can influence the development of delirium. The investigators hypothesized that those patients admitted to multibed ICU areas would have a higher prevalence of delirium due to sleep disruption and exposure to more intense noise, stress, poor lighting control, lack of privacy, and exposure to unknown sounds, conversations, and movements. The multibed ICUs consisted of 23 beds in two areas. The single-bed ICU had eight beds. A total of 1253 patients admitted to the ICUs from February to November 2011 over the age of 18 years were included in this study. Unit routines included assessing level of consciousness four times daily with either the Richmond Agitation Scale or Glasgow Coma Scale, and delirium assessments twice daily with the Confusion Assessment Method-ICU. A number of demographic and clinical variables were abstracted from the electronic medical record. Main outcomes of interest were delirium prevalence, coma/delirium-free days, the first day in delirium, and the specific subtype of delirium.
There was no difference among patients on clinical characteristics such as mechanical ventilation, ICU-acquired infections, use of renal replacement therapy, ICU length of stay, or mortality. Overall, 13% of the patients developed delirium. Those patients admitted to single-bed ICU rooms had a 6.8% delirium rate, whereas the rate of delirium in the multibed ICUs was 15.5%, which was statistically significant. Significant risk factors found to contribute to delirium were admission to a multibed ICU, older age, ICU-acquired infection, and higher illness severity. There was no difference in coma/delirium-free days, first day in delirium, or delirium sub-type among patients who developed delirium in either the multibed ICUs or patients in the single-bed ICU.
COMMENTARY
The study findings reported by Caruso and colleagues highlight an important area for further consideration when investigating factors that might reduce the occurrence of delirium, namely the physical layout of the ICU environment. The ICU clinician should keep in mind, however, that there are many interrelated factors that contribute to and increase the risk for the development of delirium. These factors, among others, include receipt of certain sedative medications, sleep disruption, exposure to more intense noise, stress, poor lighting control, lack of privacy, and exposure to unknown sounds such as conversations. None of these contributing factors were measured or considered in the analysis in this study by Caruso et al.
The overall rate for the development of delirium was low (13%). This rate is significantly lower than those rates reported in other studies, with upwards of 60-80% of patients experiencing delirium during their ICU stay. Regardless of the lower delirium rate reported in the Caruso et al study, enhancing the environment for all ICU patients by reducing noise and intense overhead lighting while promoting exposure to natural light and more "normal" sleep-wake cycles is warranted.
The application and generalizability of the study findings to ICUs in the United States are not known. Further, ICUs that have undergone remodeling or reconfiguring of existing spaces to provide for single-bed rooms and exposure to natural light may promote a more therapeutic milieu for patients. Also, most ICUs in the United States now have private patient rooms. However, as in other studies that examined delirium development risk factors, the study reviewed here also identified older age, infections, and higher illness severity as significant risk factors for the development of delirium among ICU patients. ICU clinicians need to redouble their efforts to reduce risk for the development of delirium when patients fall into these high-risk categories. Enhancing the immediate environment may be one easily implemented area to meet this care need.
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