Abstract
Background
Whether ICU sedation strategies are associated with circadian rhythmicity of vital signs, and whether such disruption mediates delirium, remains unclear.Methods
In a retrospective cohort study of MIMIC-IV (n = 13,592 surgical and mixed medical-surgical ICU patients), with supportive external validation in eICU-CRD (n = 12,004), multivariate dynamic time warping (DTW)-based clustering classified four sedation trajectories over 48 h. Rhythmicity parameters of four vital signs were quantified from available ICU-stay recordings using Lomb-Scargle, wavelet, entropy, and cosinor methods. Marginal structural models estimated associations, and exploratory mediation analysis examined indirect pathways.Results
Sustained high-dose propofol showed the weakest vital-sign rhythmicity. Compared with this group, the early high-dose propofol and propofol-to-dexmedetomidine transition groups had higher spectral power for heart rate (β = 0.033 and 0.015) and temperature (β = 0.055 and 0.020; all P Conclusions
ICU sedation trajectories were associated with vital-sign rhythmicity parameters. Temperature-derived rhythmicity was consistent with an exploratory indirect pathway to delirium, but estimates depended on analytic assumptions. These proxies should not be interpreted as direct measures of central circadian function.