Evaluation of propofol for repeated prolonged deep sedation in children undergoing proton radiation therapy

Background The aim of this study is to evaluate the safety and sufficiency of a fixed dose rate propofol infusion for repeated prolonged deep sedation in children for proton radiation therapy (PRT). Methods With ERB approval, we recorded anaesthesia monitoring data in children undergoing repeated prolonged propofol sedation for PRT. Sedation was introduced with a single bolus of i.v. midazolam 0.1 mg kg−1 followed by repeated small boluses of propofol until sufficient depth of sedation was obtained. Sedation was maintained with fixed dose rate propofol infusion of 10 mg kg−1 h−1 in all patients up to the end of the radiation procedure. Patient characteristics, number and duration of sedation, propofol induction dose, necessity to alter propofol infusion rate, and heart rate, mean arterial pressure, respiratory rate were noted at the end of the radiation procedure before cessation of the propofol infusion. Data are mean (sd) or range (median) as appropriate. Results Eighteen children aged from 1.4 to 4.2 yr (2.6 yr) had 27.6 (sd 2.0) (497 in total) radiation procedures within 44.1 (4.0) days lasting 55.7 (8.8) min. Propofol bolus dose for induction, monitoring, and positioning was 3.7 (1.0) mg kg−1. Propofol bolus requirements were quite stable over the successive weeks of treatment and variability was larger between individuals than over time. In none of the children did propofol infusion rate need to be changed from the pre-set 10 mg kg−1 h−1 flow rate because of haemodynamic state, respiratory conditions or inadequate anaesthesia. Conclusions Repeated prolonged deep sedation over several weeks in very young children using a fixed rate propofol infusion was safe and adequate for all patient

RIS-Aided Localization under Position and Orientation Offsets in the Near and Far Field

This paper presents a rigorous Bayesian analysis of the information in the signal (consisting of both the line-of-sight (LOS) path and reflections from multiple RISs) that originate from a single base station (BS) and is received by a user equipment (UE). For a comprehensive Bayesian analysis, both near and far field regimes are considered. The Bayesian analysis views both the location of the RISs and previous information about the UE as {\em a priori} information for UE localization. With outdated {\em a priori} information, the position and orientation offsets of the RISs become parameters that need to be estimated and fed back to the BS for correction. We first show that when the RIS elements have a half wavelength spacing, this RIS orientation offset is a factor in the pathloss of the RIS paths. Subsequently, we show through the Bayesian equivalent FIM (EFIM) for the channel parameters that the RIS orientation offset cannot be corrected when there is an unknown phase offset in the received signal in the far-field regime. However, the corresponding EFIM for the channel parameters in the received signal observed in the near-field shows that this unknown phase offset does not hinder the estimation of the RIS orientation offset when the UE has more than one receive antenna. Furthermore, we use the EFIM for the UE location parameters to present bounds for UE localization in the presence of RIS uncertainty. We rigorously show that regardless of size and propagation regime, the RISs are only helpful for localization when there is {\em a priori} information about the location of the RISs. Finally, through numerical analysis of the EFIM and its smallest eigenvalue, we demonstrate the loss in information when the far-field model is {\em incorrectly} applied to the signals received at a UE experiencing near-field propagation