Anesthetic Gas Scavenging System for Gas Evacuation in the ICU

Background: Inhaled sedation is increasing in ICUs, with active carbon filters (ACFs) commonly used for evacuating halogenated gases. However, the potential benefits of a waste anesthetic gas system (WAGS) similar to the ones used in operating rooms should be explored. To limit the suction over the flow sensor where the WAGS is connected on ICU ventilators, an anesthetic gas receiving system (AGRS) is required, constituting with the WAGS an active gas receiving and scavenging system (AGRSS). Ensuring that this whole device does not compromise the flow sensor reliability is crucial. The aim of this study was to compare various gas evacuation devices and assess the reliability of AGRSS on ICU ventilators. Methods: In this experimental study, pressures and flows were recorded during the ventilation of a test lung using various ventilator settings and gas evacuation methods: no device (reference condition), ACF, the WAGS alone, AGRSS (WAGS and AGRS together), and the expiratory valve connected to the medical vacuum system with the AGRS in between. Visual comparisons of the pressure and flow curves followed by a statistical analysis comparing median pressures and flows of each device to the reference were performed. Results: The test lung model demonstrated consistent comparability in pressures and flows among all devices, except for the WAGS alone, which exhibited discordance through significant overestimation or underestimation. Conclusions: These findings indicate that using a WAGS with the AGRS system appeared to be reliable for managing gas evacuation in ICUs without compromising pressure or flow delivery. The data from this experimental trial should be confirmed with clinical studies involving human subjects. Given the increasing use of inhaled sedation in ICUs, these results support the daily application of the WAGS with the AGRS for gas evacuation, similar to its established use in anesthesiology.

In Situ Observations of Halogenated Gases at the Shangdianzi Background Station and Emission Estimates for Northern China

Halogenated gases include ozone-depleting substances and greenhouse gases, such as chlorofluorocarbons, halons, hydrochlorofluorocarbons, hydrofluorocarbons, and perfluorinated gases. In situ atmospheric observations of major halogenated gases were conducted at the Shangdianzi (SDZ) background station, China, from October 2020 to September 2021 using ODS5-pro, a newly developed measurement system. The measurement time series of 36 halogenated gases showed occasional pollution events, where background conditions represented 25% (CH₂Cl₂) to 81% (CF₃Cl, CFC-13) of the measurements. The annual mean background mole fractions of most species at SDZ were consistent with those obtained at the Mace Head station in Ireland. The background conditions were distinguished from pollution events, and the enhanced mole fractions were used to estimate the emissions of four categories of fluorinated gases (F-gases) from northern China using a tracer ratio method. The CO₂-equivalent (CO₂-equiv) emission of F-gases from northern China reached 181 ± 18 Tg year^-1 during 2020-2021. Among the four categories of F-gases estimated, SF₆ accounted for the highest proportion of CO₂-equiv emissions (24%), followed by HFC-23 (22%), HFC-125 (17%), HFC-134a (13%), NF₃ (10%), CF₄ (5.9%), HFC-143a (3.9%), HFC-32 (3.4%), and HFC-152a (0.2%).