Objective To examine the effects of different doses of midazelam on ED50 of emulsified isoflurane and to determine the type of interaction between them for hypnosis by isobelographic analysis in rats. Methods One hundred and twenty-five adult male SD rats weighing 240-300 g were randomized into 5 groups (n=25 each): group Ⅰmidazolam (M); group Ⅱ emulsified isnflurane (Ⅰ); group Ⅲ ,Ⅳ ,Ⅴ, 1/4, 1/2 and 3/4 ED50 of midazelam for hypnosis + emulsified isoflurane (MI1 , MI2, MI3). Up-and-down sequential experiment was used to determine ED50of midazolam and emulsified isoflurane for loss of righting reflex in group Ⅰ -Ⅴ . The intial dose of midazolm was 17.3 mg/kg in group M. The initial doses of emulsified isoflurane (120 mg/ml) were 0.55 (in group Ⅰ, 0.22 (MI1), 0.19 (MI2) and 0.12 ml/kg (MI3) respectively. In group MI1-3 midazolam was injected over 15 seconds and after an interval of 2.5 min emulsified isoflurane was injected over 10 s. ED50 was calculated using Dixon-Mood method. Isebolographic and algebraic analyses were used to determine the type of interaction between midazolam and emulsified isoflurane. Results The five groups were comparable with respect to M/F sex ratio and body weight. The Edso of midazolam was 26.0 mg/kg in group M. Midazolam 6.5, 13.0 and 19.5 mg/kg were given in group MI1 , MI2 and MI3 respectively. The ED50 of emulsified isoflurane was 0.67 (ingroup Ⅰ), 0.30 (MI1), 0.22 (MI2) and 0.18 ml/kg (MI3) respectively. The isobolographic analysis indicated that with increasing doses of midazolam, the Edw of emulsified isoflurane decreased progressively in a non-linear fashion. The isobolographic and algebraic analyses demonstrated that the interaction between midazolam and emulsified isoflurane was synergistic for hypnosis. Conclusion The hypnosis is synergistic when midazolam 6.5,13 mg/kg are combined with emulsified isoflurane and additive when midazolam 19.5 mg/kg is combined with emulsified isoflurane.

Objective:To develop a predictive model for intrapartum fever related to chorioamnionitis in parturients undergoing epidural labor analgesia.Methods:This was a retrospective study. The parturients with intrapartum fever (axillary temperature ≥38 ℃) who received epidural labor analgesia from January 2020 to December 2022 in Sichuan Maternal and Child Health Hospital were selected as model group, and parturients with intrapartum fever who received epidural labor analgesia from January to October 2023 in Sichuan Maternal and Child Health Hospital were selected as validation group. The parturients in model group were divided into histological chorioamnionitis stage ≥Ⅱ group (HCA≥Ⅱ group) and histological chorioamnionitis stage <Ⅱ group (HCA<Ⅱ group) according to the results of placental histopathological examination. Logistic regression analysis was used to screen the independent risk factors for intrapartum fever related to chorioamnionitis in parturients, and then a nomogram model was established. The discrimination of the model was verified by the area under the the receiver operating characteristic curve. The consistency of the model was verified by the calibration curve, and the clinical effectiveness of the model was determined by the decision curve. The validation dataset was used to further evaluate the model.Results:A total of 308 parturients were finally included in model group and 99 parturients in validation group. Multivariate logistic regression analysis showed that the gestational age, meconium-stained amniotic fluid, c-reactive protein concentration and maximum body temperature were independent risk factors for intrapartum fever related to chorioamnionitis in parturients undergoing epidural labor analgesia ( P<0.05). Based on this, a nomogram risk prediction model was developed. The area under the curve (95% confidence interval) was 0.844 (0.744-0.944) in model group and 0.812 (0.674-0.950) in validation group. The calibration curve showed that the prediction probability of the model had good consistency with the actual probability of diagnosis. The decision curve showed that the threshold probability of the prediction model in model group and validation group was 10%-98% and 10%-78%, respectively. Conclusions:A nomogram prediction model for intrapartum fever related to chorioamnionitis is successfully established based on the gestational age, c-reactive protein concentration, meconium-stained amniotic fluid and maximum body temperature in parturients undergoing epidural labor analgesia. The model has good predictive performance and clinical value.