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

Minimising the usage of desflurane only by education and removal of the vaporisers - a before-and-after-trial

BACKGROUND

By exceeding planetary environmental boundaries, multiple global crises have become imminent in the 21st century. The healthcare system is a contributor to the climate crisis, accounting for approximately 5% of greenhouse gas emissions in Western countries. In anaesthetic clinics, desflurane, a highly potent greenhouse gas and volatile anaesthetic with no compelling indications, accounts for up to two thirds of total emissions. Its use can be drastically reduced using simple measures. In the present study, we investigated whether a relevant and timely reduction in use could be achieved by dismounting desflurane vaporisers and providing information to the team without restricting its use.

METHODS

The study was conducted in a German university hospital with approximately 1250 beds, over a 12-month period between 2021 and 2022, with a comparison to the corresponding periods of the previous years up to 2017. The interventions were, first, the removal of desflurane vaporisers, and second, staff education on the climate impact of volatile anaesthetics. The primary outcome variable was the reduction of hypnotic-related emissions in CO2 equivalents per anaesthetic procedure.

RESULTS

Prospective data collection and interventions were conducted from 28 March 2021 to 27 March 2022. The amount of CO2 equivalent emissions per procedure in the form of volatile anaesthetics was reduced by 86% compared with the year before the interventions (p < 0.001). Interestingly, there was already a 52.1% reduction in the year before the procedure (p < 0.001). There were no significant changes in the use of sevoflurane or propofol. Hypnotic-related costs decreased by €14,549, whereas extubation time did not change significantly.

CONCLUSIONS

Removal of desflurane vaporisers and staff training can quickly and significantly reduce the emissions of an anaesthesia department in a large German teaching hospital. This may also reduce the costs.

TRIAL REGISTRATION

The trial was registered with the German Clinical Trials Register, identifier DRKS00024973 on 12/04/2021.

Economic impact of prolonged tracheal extubation times on operating room time overall and for subgroups of surgeons: a historical cohort study

BACKGROUND

Prolonged tracheal extubation time is defined as an interval ≥ 15 min from the end of surgery to extubation. An earlier study showed that prolonged extubations had a mean 12.4 min longer time from the end of surgery to operating room (OR) exit. Prolonged extubations usually (57%) were observed during OR days with > 8 h of cases and turnovers, such that longer OR times from prolonged extubation can be treated as a variable cost (i.e., each added minute incurs an expense). The current study addressed limitations of the generalizability of these earlier investigations.

METHODS

The retrospective cohort study included cases performed at a university hospital October 2011 through June 2023 with general anesthesia, tracheal intubation and extubation in the OR where the anesthetic was performed, and non-prone positioning. The primary endpoint was the interval from end of surgery to OR exit. Mean OR time differences with/without prolonged extubation were analyzed pairwise by surgeon. The variance among surgeons was estimated using the DerSimonian-Laird method with Knapp-Hartung adjustment for the sample sizes of surgeons. Proportions were analyzed after arcsine transformation, and the inverse taken to report results.

RESULTS

There were prolonged extubations for 23% (41,768/182,374) of cases. Prolonged extubations had a mean 13.3 min longer time from the end of surgery to OR exit (95% confidence interval 12.8-13.7 min, P < 0.0001). That result was among the 71 surgeons each with ≥ 9 cases having prolonged extubation times and ≥ 9 cases with typical extubation times. Results were similar using a threshold of ≥ 3 cases, comprising 257 surgeons (13.2 min, P < 0.0001). Among the 71 surgeons with at least nine prolonged extubations, on most days with a prolonged extubation during at least one of their cases, there were > 8 h of cases and turnover times in the OR (77%, 73%-81%, P < 0.0001). Results were similar when analyzed for the 249 surgeons each with ≥ 3 cases with prolonged extubation (76%, P < 0.0001).

CONCLUSIONS

Matching earlier findings, prolonged tracheal extubation times are important economically, increasing OR time by 13 min and usually performed in ORs with lists of cases of sufficient duration to treat the extra time as a variable cost.

Taylor Series Approximation for Accurate Generalized Confidence Intervals of Ratios of Log-Normal Standard Deviations for Meta-Analysis Using Means and Standard Deviations in Time Scale

With contemporary anesthetic drugs, the efficacy of general anesthesia is assured. Health-economic and clinical objectives are related to reductions in the variability in dosing, variability in recovery, etc. Consequently, meta-analyses for anesthesiology research would benefit from quantification of ratios of standard deviations of log-normally distributed variables (e.g., surgical duration). Generalized confidence intervals can be used, once sample means and standard deviations in the raw, time, scale, for each study and group have been used to estimate the mean and standard deviation of the logarithms of the times (i.e., "log-scale"). We examine the matching of the first two moments versus also using higher-order terms, following Higgins et al. 2008 and Friedrich et al. 2012. Monte Carlo simulations revealed that using the first two moments 95% confidence intervals had coverage 92%-95%, with small bias. Use of higher-order moments worsened confidence interval coverage for the log ratios, especially for coefficients of variation in the time scale of 50% and for largern = 50 $$ \left(n=50\right) $$ sample sizes per group, resulting in 88% coverage. We recommend that for calculating confidence intervals for ratios of standard deviations based on generalized pivotal quantities and log-normal distributions, when relying on transformation of sample statistics from time to log scale, use the first two moments, not the higher order terms.

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.