Objective:To evaluate the effect of different doses of cisatracurium on the monitoring of motor-evoked potentials (MEPs) in the patients undergoing intracranial aneurysm clipping.Methods:Eighty patients of both sexes, aged 18-64 yr, with body mass index <30 kg/m 2, of American Society of Anesthesiologists physical statusⅠor Ⅱ, with Hunt-Hess grade 0-Ⅱ, undergoing intracranial aneurysm clipping under general anesthesia, were divided into 4 groups ( n=20 each) using a random number table method: conventional group (group R) and different doses of cis-atracurium groups (Cis 1-3 groups). After anesthesia induction, muscle relaxation was monitored, and train-of-four (TOF) stimulation (frequency 2 Hz, wave width 0.2 ms, interval 15 s) was applied to the ulnar nerve of forearm, and the TOF ratio was recorded as the baseline value (T 1). MEPs were assessed with a nerve electrophysiology monitor after induction of anesthesia.In Cis 1-3 groups, cis-atracurium 0.625, 0.833 and 1.000 μg·kg -1·min -1 were intravenously infused, while the equal volume of normal saline was given instead in group R when TOF ratio returned to the baseline value and MEPs could be effectively elicited.At T 1, immediately after dural incision (T 2), immediately after aneurysm occlusion (T 3) and immediately after dural closure (T 4), the TOF ratio, effective elicitation of intraoperative MEPs, and occurrence of intraoperative cardiovascular events, recovery of spontaneous breathing and body movement were recorded. Results:Compared with group R, no significant change was found in TOF ratio at each time point in group Cis 1 ( P>0.05), and TOF ratio was significantly decreased at T 2-4 in group Cis 2 and at T 2-4 in group Cis 3 ( P<0.05). Compared with group Cis 1, TOF ratio was significantly decreased at T 3, 4 in group Cis 2 and at T 2-4 in group Cis 3 ( P<0.05). The effective elicitation rate of MEPs was 100% in the four groups.There was no significant difference in the incidence of intraoperative cardiovascular events, recovery of spontaneous breathing and body movement among the four groups ( P>0.05). Conclusion:Continuous intravenous infusion of cis-atracurium 0.833-1.000 μg·kg -1·min -1 can maintain a certain degree of muscle relaxation without affecting MEP monitoring in the patients undergoing intracranial aneurysm clipping.

Background Air pollution exposure has a significant impact on maternal and child health. However, the research on the association between ambient ozone (O₃) exposure during pregnancy and the risk of premature birth in newborns is limited, and the conclusions are inconsistent. Objective To investigate the association of ambient O₃ exposure during pregnancy with the risk of preterm birth in Guangdong Province. Methods Data of pregnant women in Guangzhou from 2013 to 2019 and Foshan from 2018 to 2023 were collected, and O₃ concentrations during different trimesters were assessed according to maternal residential addresses. Bilinear interpolation was used to evaluate the concentrations of air pollution. A cohort study design was adopted in our study. Restricted cubic spline curves were used to evaluate the exposure-response relationship between O₃ exposure and preterm birth risk and explore potential exposure threshold of O₃. Logistic regression models were used to evaluate the association of O₃ exposure with preterm birth. Results A total of 702 924 pregnant women were included in this study, of whom 43 051 (6.12%) were preterm. The average O₃ exposure concentrations of pregnant women during the first, second, third, and whole trimesters were 95.51, 97.51, 100.60, and 97.87 μg·m⁻³, respectively. We observed J-shaped associations between O₃ exposure and preterm birth risk during the second, third, and whole trimesters of pregnancy using restricted cubic spline curves. This study found that there were threshold concentrations between O₃ exposure and preterm birth risk during different gestational periods, and the threshold concentrations in the first, second, third, and whole trimesters were 112.32, 99.83, 111.74, and 112.46 μg·m⁻³, respectively. During the second, third, and whole trimesters of pregnancy, after adjusting for maternal age, baby sex, pre-pregnancy body mass index, mode of delivery, baby birth weight, gestational diabetes, and gestational hypertension, the odds ratios (OR) of preterm birth were 1.02 (95%CI: 1.01, 1.04), 1.02 (95%CI: 1.00, 1.03), and 1.17 (95%CI: 1.13, 1.21) for each 10 μg·m⁻³ increase in O₃ concentration above the O₃ threshold. No significant association was found between O₃ exposure and the risk of preterm birth during the first trimester. Conclusion There is a nonlinear association between the risk of preterm birth and O₃ exposure during pregnancy, and higher concentrations of O₃ exposure during pregnancy are associated with the risk of preterm birth. Above the O₃ threshold concentration during pregnancy, especially during the second, third, and whole trimesters, the risk of preterm birth elevates with the increase of O₃ exposure concentrations.