Abstract
BACKGROUND: Deficits in cholinergic function are assumed to cause cognitive decline. Studies have demonstrated that changes in serum cholinesterase activities are associated with a higher incidence of delirium in critically ill patients. Additionally, basic research indicates that the cholinergic and circadian systems are interconnected, with each system influencing the functionality of the other. This data analysis of a proof-of-concept pilot study investigates whether modification in ICU design, including dynamic light therapy, may influence the circadian oscillation of serum cholinesterase activities. METHODS: We enrolled adult critically ill patients who were on mechanical ventilation and had an anticipated ICU stay of at least 48 h. The patients were treated in either modified or standard ICU rooms. The modified rooms received extensive architectural modifications, including a new dynamic lighting system. Serum acetylcholinesterase and butyrylcholinesterase activities were measured every four hours for up to three 24-h assessment periods. RESULTS: We included 64 patients in the data analysis (n = 34 patients in modified rooms, n = 30 in standard rooms). The median values of serum acetylcholinesterase and butyrylcholinesterase activities showed different patterns. Acetylcholinesterase activities differed significantly between the groups during the first assessment period (p = 0.04) and the second assessment period (p = 0.045). The intensity of light, as quantified by the effective circadian irradiance, significantly influenced the activities of acetylcholinesterase and butyrylcholinesterase throughout all assessment periods for patients in both groups (p < 0.001). The analysis showed significant interaction (p < 0.001), indicating that the differences in acetylcholinesterase and butyrylcholinesterase activities between the groups were inconsistent over time but apparent during specific periods of the day. CONCLUSION: Implementing a comprehensive set of changes to the design of ICU rooms, including a dynamic lighting system, may influence the course of the activity patterns of acetylcholinesterase and butyrylcholinesterase in critically ill patients. Modifications to environmental factors could potentially offer neuroprotective benefits and facilitate the realignment of circadian rhythms within the cholinergic system. Clinical trial registration ClinicalTrials.gov: NCT02143661. Registered May 21, 2014.