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ImportancePostoperative ileus is common after abdominal surgery, and small clinical studies have reported that intraoperative administration of dexmedetomidine may be associated with improvements in postoperative gastrointestinal function. However, findings have been inconsistent and study samples have been small. Further examination of the effects of intraoperative dexmedetomidine on postoperative gastrointestinal function is needed.ObjectiveTo evaluate the effects of intraoperative intravenous dexmedetomidine vs placebo on postoperative gastrointestinal function among older patients undergoing abdominal surgery.Design, setting, and participantsThis multicenter, double-blind, placebo-controlled randomized clinical trial was conducted at the First Affiliated Hospital of Anhui Medical University in Hefei, China (lead site), and 12 other tertiary hospitals in Anhui Province, China. A total of 808 participants aged 60 years or older who were scheduled to receive abdominal surgery with an expected surgical duration of 1 to 6 hours were enrolled. The study was conducted from August 21, 2018, to December 9, 2019.InterventionsDexmedetomidine infusion (a loading dose of 0.5 μg/kg over 15 minutes followed by a maintenance dose of 0.2 μg/kg per hour) or placebo infusion (normal saline) during surgery.Main outcomes and measuresThe primary outcome was time to first flatus. Secondary outcomes were postoperative gastrointestinal function measured by the I-FEED (intake, feeling nauseated, emesis, physical examination, and duration of symptoms) scoring system, time to first feces, time to first oral feeding, incidence of delirium, pain scores, sleep quality, postoperative nausea and vomiting, hospital costs, and hospital length of stay.ResultsAmong 808 patients enrolled, 404 were randomized to receive intraoperative dexmedetomidine, and 404 were randomized to receive placebo. In total, 133 patients (60 in the dexmedetomidine group and 73 in the placebo group) were excluded because of protocol deviations, and 675 patients (344 in the dexmedetomidine group and 331 in the placebo group; mean [SD] age, 70.2 [6.1] years; 445 men [65.9%]) were included in the per-protocol analysis. The dexmedetomidine group had a significantly shorter time to first flatus (median, 65 hours [IQR, 48-78 hours] vs 78 hours [62-93 hours], respectively; P

The interaction of super-large section chamber group in deep and close-distance condition will lead to stress concentration and wide failure range of surrounding rock, especially under dynamic disturbances. In this paper, numerical simulation software FLAC3D is used to establish the calculation model based on the field condition of coal gangue separation system in Longgu Coal Mine. The deformation and failure evolution of chamber group under different chamber spacing and dynamic loads are studied by using built-in dynamic module. The simulation results show that: With the decrease of chamber spacing, the deformation and failure degree of surrounding rock gradually increases, and the overall failure and instability occur eventually. Compared with the static load, the range of critical spacing under dynamic disturbance is enlarged by 33.3%-50%. Meanwhile, the response of anchored surrounding rock is gradually intensified with the dynamic load strength increase, and the critical strength of failure and instability is about 4.0-4.5 MPa. Based on the elastic-plastic mechanics and elastic wave theories, the mechanical model of anchored surrounding rock under dynamic and static loads is established. The failure and instability criterion are obtained. The anchored surrounding rock can be divided into three states: overall stability, static failure and dynamic failure. On this basis, the analytical expression of critical distance between failure and instability is presented. Finally, in-site calculation and field monitoring verify the rationality and feasibility of the theoretical analysis. This study provides a reference for layout design and stability control of super-large section chamber group.

General anesthesia is widely applied in clinical practice. However, the precise mechanism of loss of consciousness induced by general anesthetics remains unknown. Here, we measured the dynamics of five neurotransmitters, including γ-aminobutyric acid, glutamate, norepinephrine, acetylcholine, and dopamine, in the medial prefrontal cortex and primary visual cortex of C57BL/6 mice through in vivo fiber photometry and genetically encoded neurotransmitter sensors under anesthesia to reveal the mechanism of general anesthesia from a neurotransmitter perspective. Results revealed that the concentrations of γ-aminobutyric acid, glutamate, norepinephrine, and acetylcholine increased in the cortex during propofol-induced loss of consciousness. Dopamine levels did not change following the hypnotic dose of propofol but increased significantly following surgical doses of propofol anesthesia. Notably, the concentrations of the five neurotransmitters generally decreased during sevoflurane-induced loss of consciousness. Furthermore, the neurotransmitter dynamic networks were not synchronized in the non-anesthesia groups but were highly synchronized in the anesthetic groups. These findings suggest that neurotransmitter dynamic network synchronization may cause anesthetic-induced loss of consciousness.