Systematic review with meta-analysis of relative risk of prolonged times to tracheal extubation with desflurane versus sevoflurane or isoflurane

Doping Strategy of Monolayer MoS2 to Realize the Monitoring of Environmental Concentration of Desflurane: A First-Principles Study

Desflurane is a new volatile inhalation anesthetic that is widely used in medical operation. However, various diseases can be caused by chronic exposure to desflurane, which is also a greenhouse gas. Therefore, it is urgent to find a suitable method for monitoring desflurane. In this paper, the process of doping of Pd, Pt, and Ni on the MoS2 surface is simulated to determine the stability of the doping structure based on first-principles. The adsorption properties and sensing properties of Pd-MoS2, Pt-MoS2, and Ni-MoS2 on desflurane are explored by parameters including independent gradient model based on Hirshfeld partition (IGMH), electron localization function (ELF), and density of states (DOS), sensibility, and recovery time, subsequently. The doping results show that the three doping systems (Pd-MoS2, Pt-MoS2, and Ni-MoS2) are structurally stable, and the chemical bonds are formed with MoS2. The adsorption results show the best chemisorption between Pt-MoS2 and desflurane with the chemical bonds between them. The results of IGMH, ELF, and DOS also confirm it. The sensing characterization results show that the recovery time of Pt-MoS2 ranges between 85.27 and 0.027 s, and the sensitivity ranges from 99.26 to 25.69%, all of which can meet the requirements of the sensor. Considering the adsorption effect and sensing characteristics, Pt-MoS2 can be used as a gas-sensitive material for detecting the concentration of desflurane.

Inhalational Agent Dosing Behaviors of Anesthesia Practitioners Cause Variability in End-Tidal Concentrations at the End of Surgery and Prolonged Times to Tracheal Extubation

INTRODUCTION

Prolonged times to tracheal extubation are intervals from the end of surgery to extubation ≥15 minutes. We examined why there are associations with the end-tidal inhalational agent concentration as a proportion of the age‑adjusted minimum alveolar concentration (MAC fraction) at the end of surgery.

METHODS

The retrospective cohort study used 11.7 years of data from one hospital. All p‑values were adjusted for multiple comparisons.

RESULTS

There was a greater odds of prolonged time to extubation if the anesthesia practitioner was a trainee (odds ratio 1.68) or had finished fewer than five cases with the surgeon during the preceding three years (odds ratio 1.12) (both P<0.0001). There was a greater risk of prolonged time to extubation if the MAC fraction was >0.4 at the end of surgery (odds ratio 2.66, P<0.0001). Anesthesia practitioners who were trainees and all practitioners who had finished fewer than five cases with the surgeon had greater mean MAC fractions at the end of surgery and had greater relative risks of the MAC fraction >0.4 at the end of surgery (all P<0.0001). The source for greater MAC fractions at the end of surgery was not greater MAC fractions throughout the anesthetic because the means during the case did not differ among groups. Rather, there was substantial variability of MAC fractions at the end of surgery among cases of the same anesthesia practitioner, with the mean (standard deviation) among practitioners of each practitioner's standard deviation being 0.35 (0.05) and the coefficient of variation being 71% (13%).

CONCLUSION

More prolonged extubations were associated with greater MAC fractions at the end of surgery. The cause of the large MAC fractions was the substantial variability of MAC fractions among cases of each practitioner at the end of surgery. That variability matches what was expected from earlier studies, both from variability among practitioners in their goals for the MAC fraction given at the start of surgical closure and from inadequate dynamic forecasting of the timing of when surgery would end. Future studies should examine how best to reduce prolonged extubations by using anesthesia machines' display of MAC fraction and feedback control of end-tidal agent concentration.

Generalized Confidence Intervals for Ratios of Standard Deviations Based on Log-Normal Distribution when Times Follow Weibull Distributions

Modern anesthetic drugs ensure the efficacy of general anesthesia. Goals include reducing variability in surgical, tracheal extubation, post-anesthesia care unit, or intraoperative response recovery times. Generalized confidence intervals based on the log-normal distribution compare variability between groups, specifically ratios of standard deviations. The alternative statistical approaches, performing robust variance comparison tests, give P-values, not point estimates nor confidence intervals for the ratios of the standard deviations. We performed Monte-Carlo simulations to learn what happens to confidence intervals for ratios of standard deviations of anesthesia-associated times when analyses are based on the log-normal, but the true distributions are Weibull. We used simulation conditions comparable to meta-analyses of most randomized trials in anesthesia, n ≈ 25 and coefficients of variation ≈ 0.30 . The estimates of the ratios of standard deviations were positively biased, but slightly, the ratios being 0.11% to 0.33% greater than nominal. In contrast, the 95% confidence intervals were very wide (i.e., > 95% of P ≥ 0.05). Although substantive inferentially, the differences in the confidence limits were small from a clinical or managerial perspective, with a maximum absolute difference in ratios of 0.016. Thus, P < 0.05 is reliable, but investigators should plan for Type II errors at greater than nominal rates.