Fresh Gas Research Articles

The carbon footprint of general anaesthesia in adult patients: a multicentre observational comparison of intravenous and inhalation anaesthetic strategies in 35,242 procedures.

The carbon footprint of general anaesthesia in adult patients: a multicentre observational comparison of intravenous and inhalation anaesthetic strategies in 35,242 procedures.

The optimal mode of anaesthesia: are we ready for an evidence-based recommendation?

The optimal mode of anaesthesia: are we ready for an evidence-based recommendation?

Star formation and stellar & AGN feedback in the absence of accretion, not gas stripping, set the quenching timescale in satellite galaxies

Abstract Observational measurements hint at a peak in the quenching timescale of satellite galaxies in groups and clusters as a function of their stellar masses at M⋆ ≈ 109.5M⊙; less and more massive satellite galaxies quench faster. We investigate the origin of these trends using the EAGLE simulation in which they are qualitatively reproduced for satellites with 109 < M⋆/M⊙ < 1011 around hosts of 1013 < M200c/M⊙ < 1014.6. We select gas particles of simulated galaxies at the time that they become satellites and track their evolution. Interpreting these data yields insights into the prevailing mechanism that leads to the depletion of the interstellar medium (ISM) and the cessation of star formation. We find that for satellites across our entire range in stellar mass the quenching timescale is to leading order set by the depletion of the ISM by star formation and stellar & AGN feedback in the absence of sustained accretion of fresh gas. The turnover in the quenching timescale as a function of stellar mass is a direct consequence of the maximum in the star formation efficiency (or equivalently the minimum in the total – stellar plus AGN – feedback efficiency) at the same stellar mass. We can discern the direct stripping of the ISM by ram pressure and/or tides in the simulations; these mechanisms modulate the quenching timescale but do not drive its overall scaling with satellite stellar mass. Our findings argue against a scenario in which the turnover in the quenching timescale is a consequence of the competing influences of gas stripping and ‘starvation’.

A Comparative Study on Minimal Flow Anaesthesia in Geriatric and Middle-aged Patients.

Minimal flow anaesthesia reduces costs and environmental pollution, and has a protective effect on the respiratory tract. This study aimed to compare the ease and tolerability of minimal flow anaesthesia in the geriatric and middle-aged patient populations. In this prospective study, we enrolled 40 patients between 18 and 50 years (Group Y) and 40 patients 65 years or older (Group E), scheduled for abdominal surgery under general anaesthesia. Following a period of high flow with desflurane in O2/air, the fresh gas flow was reduced to 350 mL min-1. Desflurane concentration was adjusted to maintain a bispectral index between 40 and 50. The oxygen concentration in fresh gas flow was titrated by ±10%. Throughout the surgery, gas concentrations, oxygenation parameters, hemodynamic data, and the depth of anaesthesia were monitored. The number of alterations in fresh gas oxygen and desflurane concentrations was recorded. The depth of anaesthesia and oxygenation parameters were adequately sustained within safe limits among all patients, while the number of changes in the fresh gas flow oxygen levels was found to be significantly lower in geriatric patients. The increase in the number of oxygen level was 1.1±0.8 in Group E and 1.8±1.2 in Group Y (P=0.006). Total alteration in oxygen was 1.2±1 in Group E and 1.9±1.3 in Group Y (P=0.01). Oxygenation parameters consistently remained within clinically acceptable ranges in both groups, and the amount of change in desflurane concentration showed no intergroup difference. Administering minimal flow anaesthesia at a rate of 350 mL min-1 in the geriatric population, compared to the younger population, can be performed requiring less manipulation, without inducing hypoxia or inadvertent awareness.

Effects of breathing circuit insulation on inspired gas conditioning and water vapour condensation: an in vitro study

PurposeDuring general anesthesia, physiologic conditioning of inspired gases is bypassed. Mechanical ventilation with dry and cold gas from the central gas supply may lead to dehydration of the mucus membranes, cilia dysfunction, retention of secretions, and atelectasis. The use of metabolic fresh gas flow improves the conditioning of inspiratory gases but increases water vapour condensation within the breathing system. We sought to investigate the effects of breathing circuit insulation on the conditioning of inspired gases and the condensation of water vapour.MethodsIn this in vitro study, we used a mechanical nonheated, nonhumidified lung model with carbon dioxide (CO2) insufflation. We tested foam, cotton, and polyester insulation (FOI, COI, and PEI) against control (noninsulated regular tubing). We measured temperature, absolute humidity (AH), and water vapour condensation after 120 min. We performed 8 measurements per group (total N = 32) and adjusted P values and confidence intervals (CIs) for multiple testing using Bonferroni–Holm adjustment.ResultsRegarding mean AH, FOI performed better than control. The mean (standard deviation [SD]) differences in AH between control and insulation were −0.63 (0.52) g·m−3 H2O for PEI (adjusted 95% CI, −1.42 to 0.17; P = 0.26), −0.63 (0.74) g·m−3 H2O for COI (adjusted 95% CI, −1.42 to 0.17; P = 0.26), and −1.13 (0.35) g·m−3 H2O for FOI (adjusted 95% CI, −1.92 to −0.33; P < 0.001). The mean temperature was higher in insulated circuits. The mean (SD) difference compared to control was 0.42 (0.28) °C for PEI (adjusted 95% CI, 0.05 to 0.79; P = 0.002), 0.62 (0.26) °C for COI (adjusted 95% CI, 0.25 to 0.99; P < 0.001), and −1.07 (0.14) °C for FOI (adjusted 95% CI, 0.70 to 1.44; P < 0.001). Condensation of water vapour was lower in insulated breathing circuits compared with control.ConclusionFoam-based insulation was the most effective form of insulation of the breathing circuit to increase temperature and AH of inspired gases and to reduce water vapour condensation. Overall, the results of this in vitro study support the principle of breathing circuit insulation as a method for inspired gas conditioning during the use of metabolic flow anesthesia.

Effects of departmental green anaesthesia interventions on carbon dioxide equivalent emissions: a systematic review.

Effects of departmental green anaesthesia interventions on carbon dioxide equivalent emissions: a systematic review.

Why are thermally and cosmic ray-driven galactic winds fundamentally different?

Galactic outflows influence the evolution of galaxies not only by expelling gas from their disks but also by injecting energy into the circumgalactic medium (CGM). This alters or even prevents the inflow of fresh gas onto the disk and thus reduces the star formation rate. Supernovae (SNe) are the engines of galactic winds as they release thermal and kinetic energy into the interstellar medium (ISM). Cosmic rays (CRs) are accelerated at the shocks of SN remnants and only constitute a small fraction of the overall SN energy budget. However, their long lifetimes allow them to act far away from the original injection site and thereby to participate in the galactic wind launching process. Using high-resolution simulations of an isolated Milky Way-type galaxy with the moving-mesh code Arepo and the new multi-phase ISM model Crisp (Cosmic Rays and InterStellar Physics), we investigate how SNe and CRs launch galactic outflows and how the inclusion of CR-mediated feedback boosts the energy and mass entrained in the galactic wind. We find that the majority of thermal SN energy and momentum is used for stirring turbulence either directly or indirectly by causing fountain flows, thereby self-regulating the ISM and not for efficiently driving outflows to large heights. A simulation without CRs only launches a weak galactic outflow at uniformly high temperatures and low densities by means of the thermal pressure gradient. By contrast, most of the CR energy accelerated at SN remnants (∼80%) escapes the ISM and moves into the CGM. In the inner CGM, CRs dominate the overall pressure and are able to accelerate a large mass fraction in a galactic wind. This wind is turbulent and multi-phase with cold cloudlets embedded in dilute gas at intermediate temperatures (∼10^5 K) and the CGM shows enhanced O vi and C iv absorption in comparison to a simulation without CRs.

'Sealing the deal': An innovative use of the endotracheal cuff manometer.

Intraoperative air leakage from the endotracheal tube (ETT) cuff can lead to significant complications, including compromised tidal volume delivery, ineffective ventilation, and an increased risk of pulmonary aspiration. These issues, if unrecognized and unmanaged, contribute to heightened perioperative morbidity and mortality. While structural defects in the ETT cuff or pilot balloon system are common causes of leakage, additional factors such as cuff malposition, excessive airway pressure, and material degradation can also contribute. Early identification of the underlying etiology is critical for implementing appropriate interventions, mitigating airway-related complications, and ensuring surgical continuity. This report presents a case of intraoperative ETT cuff leakage identified after surgical positioning in the prone position. To address this challenge, an innovative approach utilizing an ETT cuff manometer was employed, allowing for continuous monitoring of cuff pressure. This strategy enabled real-time detection of pressure deviations and facilitated prompt reinflation whenever the cuff pressure dropped below 20 cm H₂O or a fresh gas flow leak was observed. This technique effectively maintained adequate cuff inflation, preventing intraoperative airway compromise. ETT cuff leaks can be categorized into two primary mechanisms: (1) those resulting from structural failure of the cuff or inflation system and (2) those occurring due to inadequate sealing despite an intact cuff. Intraoperative air leaks pose risks to the patient-through impaired ventilation and aspiration risk-and to operating room personnel by potentially exposing them to unfiltered anesthetic gases. Various strategies for managing ETT leaks have been described, including conservative approaches such as pharyngeal packing, application of lubricating agents like lidocaine jelly, and continuous inflation via an oxygen flowmeter. In cases where these measures fail, ETT replacement remains the definitive intervention. However, exchanging the ETT presents a significant challenge in prone-positioned patients, necessitating a thorough risk-benefit assessment before attempting tube replacement or repositioning the patient. While previous studies have explored methods for addressing intraoperative ETT leaks, continuous quantitative monitoring of cuff pressure using a manometer has not been widely reported. This technique provides a dynamic assessment of cuff integrity and allows for proactive management of intraoperative air leaks. In this case, the application of an ETT cuff manometer enabled continuous, quantitative assessment of cuff pressure, facilitating early leak detection and effective management. This approach represents a valuable adjunct in the intraoperative setting, enhancing patient safety and reducing the likelihood of airway-related complications. Further research is warranted to explore the broader clinical implications of continuous ETT cuff pressure monitoring in perioperative airway management.

Feasibility and Safety Properties of Metabolic-Flow Anesthesia Driven by Automated Gas Control® in Pediatric Patients: A Prospective Observational Study.

Background and Objectives: Metabolic-flow (<0.35 L/min) anesthesia is practiced more often as manufacturers provide newer technologies, yet the benefits of metabolic-flow anesthesia have not been fully investigated. This study aimed to investigate the feasibility and safety of automated gas control (AGC®) mode, which provides metabolic-flow anesthesia, in a pediatric population. Materials and Methods: Pediatric surgery patients between 1 and 10 years of age were included in this prospective observational trial. After intravenous induction and safe orotracheal intubation, AGC® was initiated, and total sevoflurane consumption (mL) and wash-in speed-based sevoflurane consumption data were collected to measure feasibility. For safety, inspired (FiO2), alveolar (FAO2), and expired (FEO2) oxygen concentration data, and inspired and alveolar sevoflurane (FiSevo and FASevo, respectively) concentration data, were recorded. Changes in fresh gas flow (FGF) throughout the procedure and postoperative recovery data were also compared. Results: A total of 130 patients were eligible for this study, and 121 patients were included in the analyses; 30 patients had a wash-in speed of 4 (WI4) and 91 patients had a wash-in speed of 8 (WI8) at follow-up. The total mean sevoflurane consumption was 9.35 ± 4.93 mL for a median surgery duration of 100 min. WI8 patients consumed more sevoflurane (9.92 ± 5.08 mL vs. 7.79 ± 4.19 mL, p = 0.04). At the 15th and 30th minutes, the FGF dropped under minimal flow and metabolic flow limits, respectively (p < 0.001). The times to extubation and obeying commands were shorter in WI8 patients (8 (5-10) vs. 11 (5-15) p = 0.03, and 9.5 (5-10.5) vs. 13 (9-17) p < 0.01). Conclusions: Maintenance with AGC® may offer up to 40 h of anesthesia, considering that the volume of a sevoflurane bottle is 250 mL, reflecting exceptional savings compared to conventional anesthesia management. Metabolic flow anesthesia driven by AGC® is feasible and safe in pediatric anesthesia practice.

In Vitro Performance of a Charcoal-capturing Device with Desflurane.

The use of capturing devices may become required for the continued use desflurane. This study tested the percentage of desflurane captured by a charcoal filter (CONTRAfluran; Zeosys GmbH, Germany)-workstation (Aisys; GE Healthcare, USA) combination in vitro . Desflurane in oxygen/air was administered via an Aisys workstation into a 2-l test lung that was insufflated with carbon dioxide (160 ml/min). First, to confirm that all vaporized desflurane reached the capturing device, the amount of desflurane collected in a Douglas bag attached to the machine exhaust was compared to the vaporized amount during 15-min runs with the following fresh gas flow and vaporizer setting combinations: 0.3 l/min and 8%, 0.5 l/min and 8%, 1 l/min and 6%, 2 l/min and 6%, 3 l/min and 6%, 4 l/min and 6%, 5 l/min and 6%, and 6 l/min and 6%. Next, to determine the effect of carbon dioxide, the capturing device weight gain was measured with the same fresh gas flow run for longer than 1 h but without desflurane. Finally, the ratio of the capturing device weight gain/vaporizer weight loss (which equals the performance, expressed as a percentage) was determined for the same 15-min runs with the desflurane vaporizer settings described above. All experiments were arbitrarily repeated five times. The amount of vaporized desflurane did not differ from the amount collected in the Douglas bag. When carbon dioxide, oxygen, and air were delivered without desflurane, the capturing device lost a relatively small amount of weight (less than 5 g), especially with fresh gas flow less than or equal to 1 l/min. Finally, performance with 0.3, 0.5 to 2, and 3 to 6 l/min fresh gas flow was 103, 100, and 95 to 93%, respectively. CONTRAfluran charcoal filter in vitro performance for desflurane in oxygen/air combined with the Aisys workstation ranged from 93 to 103% with fresh gas flow of 0.3 to 6 l/min with vaporizer settings that reflect clinical conditions. Defining the place of charcoal filters in clinical practice requires full life-cycle analysis of both the charcoal and inhaled agent.

Optimal fresh gas flow during total intravenous anaesthesia

Optimal fresh gas flow during total intravenous anaesthesia

Investigating the effects of fresh gas on the Active Galactic Nuclei luminosity of early- and late-type galaxies

Abstract The main fuelling processes for Active Galactic Nuclei (AGN) are currently unknown. Previous work showed that galaxies with a large kinematic misalignment between their stellar and gas reservoirs have a higher AGN fraction than galaxies without misalignment. Such misalignment is a strong indication of a past galaxy interaction or an external accretion event. In this work we use integral field spectroscopy data from the SAMI and MaNGA surveys to investigate the AGN luminosity as a function of kinematic misalignment angle. Our sample of AGN exhibit bolometric luminosities in the range 1040 to 1043 erg s−1, indicative of low to moderate luminosity AGN. We find no correlation between AGN luminosity as a function of misalignment for AGN host galaxies from both surveys. We find some differences between the AGN luminosity of early- and late-type AGN host galaxies (ETGs, LTGs). AGN in LTG hosts have a wider luminosity range, with most LTG hosts showing aligned stellar to gas kinematics. AGN in ETG hosts have a luminosity range that does not depend on misalignment angle, suggesting AGN in ETG hosts are consistent with being fuelled by external accretion events, irrespective of their stellar to gas kinematic misalignment. While all the AGN in ETGs in our sample are consistent with being activated and fuelled by external gas, the range of observed AGN luminosities is likely caused by secondary factors such as the amount of fresh gas brought into the galaxy by the external interaction.

Improving the efficiency of sevoflurane delivery during general anaesthesia by educating and motivating anaesthetists to utilise the Volatile Efficiency Ratio.

Volatile anaesthetic agents such as sevoflurane contribute to greenhouse gas emissions, and selecting low fresh gas flows on anaesthetic machines minimises their waste. Facilitating improvements in sevoflurane use requires the education, motivation, and standardised evaluation of anaesthetists. There is currently no standard of practice related to the efficiency of anaesthetic gas delivery per case. We conducted a multi-component study termed 'Low With The Flow' (LWTF) to directly address these requirements by educating and motivating anaesthetists to reduce fresh gas flow and thereby sevoflurane use. We introduced a novel metric, the 'volatile efficiency ratio' (VER), able to be calculated on Draeger Primus™, the Draeger Atlan™ family and Draeger Perseus A500™ machines, to audit sevoflurane use in a case-by-case fashion, and assess whether the intervention could achieve a set VER target. The LWTF intervention significantly improved the efficiency of sevoflurane delivery (VER 0.46 pre-intervention (n = 518) versus VER 0.57 post-intervention (n = 531), 95% confidence interval 0.092 to 0.129, P < 0.0001) resulting in a calculated average of 1.3 kg carbon dioxide equivalent emissions reduction and approximately AUD 3.50 saving per case. Consequently, the financial and environmental outcomes from sevoflurane delivery were considerably reduced. Our LWTF intervention provides a valuable model for other anaesthetic departments to investigate and address the global environmental and financial burdens related to their volatile anaesthetic use. For anaesthetists using anaesthesia machines that do not facilitate calculation of VER, an approach using components of our LWTF intervention may still reduce the environmental and financial impacts associated with administration of volatile anaesthesia.

Optimization of Albuterol Delivery via Anesthesia Bag in Pediatric Critical Care.

Background/Objectives: Aerosolized medications are common practice for mechanically ventilated pediatric patients. Infants often receive nebulized medications via hand ventilation using an anesthesia bag, but evidence on optimal aerosol delivery with this method is limited. For this study, various configurations of the Mapleson breathing circuit were tested to optimize albuterol delivery to a simulated pediatric model. Methods: Using a simulated pediatric lung model (ASL 5000) with the semi-open Mapleson anesthesia circuit, 2.5 mg/3 mL of albuterol sulfate solution was nebulized to a viral/bacterial filter (Respiguard 202). Four models were compared with varying fresh gas flows (FGFs), small-volume nebulizer (SVN) placements, and adjusting dead space. Five Registered Respiratory Therapists (RRTs) bagged the aerosol into a collection filter following defined ventilation parameters. Each model was tested in random order to avoid fatigue bias. Albuterol concentrations eluted from in-line filters were measured by spectrophotometry (absorbance at 276 nm). Results: No inter-user variability was observed among the RRTs. Significant differences in albuterol recovered were noted between models (One Way ANOVA, Tukey's post hoc, n = 5). Model 4, with the nebulizer closest to the collecting filter, recovered 21.77 ± 1.89% of albuterol. The standard clinical model was the least effective, with only 0.10 ± 0.17% albuterol recovery. Conclusions: Modifying the anesthesia breathing circuit significantly improved aerosol drug delivery efficiency. Our findings suggest that current clinical practices for nebulized drug delivery are inefficient and can be markedly improved with simple adjustments in nebulizer positioning and gas flow within the circuit.

Sevoflurane and its metabolic byproduct compound A induce nephrotoxicity: a systematic review and meta-analysis of animal studies.

Animal models investigating sevoflurane or compound A and renal function serve as the initial basis for concerns regarding renal injury following sevoflurane anesthesia and subsequent recommendations of minimum fresh gas flow, but this evidence basis has not been critically appraised. Primary literature searches were performed in MEDLINE OVID, PubMed, EMBASE, the Cochrane Library), the Cochrane Central Register of Controlled Trials, the International HTA Database, CINAHL, and Web of Science to identify randomized controlled trials and quasi-experimental studies in animals utilizing sevoflurane or compound A. The primary outcomes included renal function as determined by blood urea nitrogen, serum creatinine, creatinine clearance, and urine volume. The secondary outcomes included the serum fluoride concentration and histopathological findings. A total of 2537 records were screened, and 21 randomized controlled trials and 9 quasi-experimental animal studies were identified. No associations between sevoflurane exposure and subsequent changes in renal function (blood urea nitrogen, serum creatinine or changes in urine volume) were noted. A similar effect on renal function was observed following compound A exposure, but urine volume was elevated following compound A exposure. In addition, the histopathological damage following compound A exposure was observed only at concentrations that are unachievable in clinical practice. Our review of evidence from animal models revealed that sevoflurane usage was not associated with changes in renal function tests or urine volume. Histopathologic changes after sevoflurane exposure were either nonexistent or minor. Studies on compound A did not reveal an alteration in renal function, although histopathological evidence of injury was present when compound A was administered at very high, unphysiologic concentrations. In light of the existing evidence, the initial concerns of sevoflurane-related nephrotoxicity based on animal studies that leads to minimum fresh gas flow recommendations are called into question.

Influence of Practitioner Dashboard Feedback on Anesthetic Greenhouse Gas Emissions: A Prospective Performance Improvement Investigation.

Anesthetic gases contribute to global warming. We described a two-year performance improvement project to examine the association of individualized provider dashboard feedback of anesthetic gas carbon dioxide equivalent (CDE20) production and median perioperative fresh gas flows (FGF) during general anesthetics during perioperative management. Using a custom structured query language (SQL) query, hourly CDE20 for each anesthetic gas and median FGF were determined. During the first year, practitioners were not given any feedback on their use of anesthetic gases. During the second year of the study protocol, a commercially available business intelligence platform was used to deliver individualized monthly dashboard of these parameters to each practitioner. Continuous values are expressed as median [first quartile, third quartile]. During the study period, 53,294 patients managed by 79 anesthesiologists were available for analysis. Bivariate analysis revealed an overall decrease in median FGF from 2.0 [1.9, 3.0] liters/minute (l/min) to 1.9 [1.7, 2.0] l/min (p < 0.001). There was a significant decrease in the overall total CDE20 from 5.10 [0,12.3] to 3.59 [0,8.78] kg/hr (p < 0.001). Multivariate analysis demonstrated an initial decrease in monthly practitioner total CDE20 production with the intervention (odds ratio (OR) 0.875 95% confidence interval (CI) 0.809-0.996, p < 0.001) and a faster decrease rate in monthly total CDE20 (OR 0.986, 95% CI 0.976-0,996, p < 0.001). Dashboard distribution initially decreased isoflurane (intervention OR 0.97 95% CI 0.96-0.99, p = 0.001) and N2O (OR 0.82 95% CI 0.73-0.94, p = 0.003) CDE20 production and was associated with a steeper declining rate of isoflurane (OR 0.87, CI 0.79-0.94, p < 0.001) and desflurane (OR 0.9, 0.84-0.97, p = 0.005) CDE20 production. The intervention did not have a significant effect on the monthly rate of decline of sevoflurane or N2O CDE20. The average practitioner FGF decreased by 0.3l/m (95% confidence interval (CI): -0,011, -0.5, p = 0.002) with dashboard distributions. Dashboard distribution may be an effective tool to decrease FGF as well as components of anesthetic greenhouse gas emissions.

The place of natural resources in the model of transition to a green economy in Azerbaijan

The article explores the role of natural resources in the model of transition to a green economy in Azerbaijan, emphasizing the importance of rational resource use and the implementation of new technologies. A key component of the green economy index is the “natural resources group” sub-index, which includes 10 sub-indicators: volumes of fresh water, water consumption, oil and gas production, land fund structure, fishing, and forest areas. The author also highlights methodological issues that arise in comparative studies, including the dependence of some indicators' absolute values on the size of the country and geographical location. To provide a more accurate assessment of the state of natural resources, the article uses the volume of renewable freshwater per capita, which better reflects the potential for transitioning to a green economy. In conclusion, the article proposes refined indicators for assessing the “natural resources group” based on more reliable data, such as the share of hydrocarbon revenues in GDP, allowing for a deeper understanding of the impact of natural resources on sustainable development in Azerbaijan.

Searching for HI around MHONGOOSE galaxies via spectral stacking

The observed star formation rates of galaxies in the Local Universe suggests that they are replenishing their gas reservoir across cosmic time. Cosmological simulations predict that this accretion of fresh gas can occur in a hot or a cold mode, yet the existence of low column density (∼1017 cm−2) neutral atomic hydrogen (HI) tracing the cold mode has not been unambiguously confirmed by observations. We present the application of unconstrained spectral stacking to attempt to detect the emission from this HI in the circumgalactic medium (CGM) and intergalactic medium (IGM) of six nearby star-forming galaxies from the MHONGOOSE sample for which full-depth observations are available. Our stacking procedure consists of a standard spectral stacking algorithm coupled with a one-dimensional spectral line finder designed to extract a reliable signal close to the noise level. In agreement with previous studies, we find that the amount of signal detected outside the HI disk is much smaller than implied by simulations. Furthermore, the column density limit that we achieve via stacking (∼1017 cm−2) suggests that direct detection of the neutral CGM and IGM component might be challenging in the future, even with the next generation of radio telescopes.

Comparing the priming methods of anesthesia circuits using passive and ventilator-assisted techniques-An exploratory study.

Priming the breathing circuit with a volatile agent plays a major role in inhalational induction. It depends on the fresh gas flow rate (FGF), concentration setting of the volatile agent, and time taken to attain the desired end-tidal concentration. The aim of the study is to compare ventilator-assisted priming (VAP) and a passive priming technique using different fresh gas flows (FGFs) in neonatal, pediatric, and adult anesthetic circuits with sevoflurane vaporizer. An exploratory study was conducted on a single Datex ohmeda GE Inc. workstation using three different circuits. In both techniques, FGF with 100% oxygen and 8% sevoflurane vaporizer concentration was set at 2 L/min, 4 L/min, and 8 L/min corresponding to their three groups FGF-2, FGF-4, and FGF-8, respectively. The time taken to achieve 6% sevoflurane concentration at the patient end of the circuit was measured. In this study, we have explored various combinations of tidal volumes, respiratory rates with three different fresh gas flows, and their priming time with sevoflurane consumption. The minimum time required to prime neonate, pediatric, and adult circuits using the ventilator-assisted technique to attain end-tidal sevoflurane 6% is 29 seconds, 39 seconds, and 61 seconds with 2 L/min FGF. Their corresponding sevoflurane consumptions are 0.25 ml for the neonate circuit, 0.78 ml for the pediatric circuit, and 2 ml for the adult circuit. The ventilator-assisted priming technique is an effective and quick method to attain end-tidal sevoflurane 6% with low FGF (2 L/min), low tidal volume (100 ml), maximum respiratory rate (20), and minimal sevoflurane consumption when compared to the passive priming technique.

Implementing a Clinical Decision Support Tool to Reduce Operating Room Anesthetic Fresh Gas Flow: A Resident-Led, Sustainability-Focused Quality Improvement Initiative.

Background Lowering fresh gas flow (FGF) can help decrease the carbon footprint of the operating room as FGF levels act as an indirect measure of anesthetic gas waste. Objective The aim of this quality improvement project was to reduce clinician FGF during general anesthesia with clinical decision support (CDS) tools within the electronic health record (EHR) at a single institution. Methods A non-interruptive alert to reduce FGF was coded into the anesthesia intraoperative EHR workspace to alert whenever the 10-minute average FGF exceeded 1 L/min. It was targeted at anesthesia residents, attendings, and certified registered nurse anesthetists at a single US large academic level 1 trauma center. The number of general anesthesia cases with a target FGF of ≤2 L/min and the amount of sevoflurane (L/hr) was tracked on an individual and institutional basis. Results Following CDS implementation from July 2023 through July 2024, 2677 of 4573 (58.5%) had a mean FGF ≤2 L/min, demonstrating a 116.7% increase from our institution's baseline of 27.0% (1200 of 4446 cases) from July 2022 to June 2023, corresponding to a sevoflurane usage reduction of 36.7%. Conclusions Implementing a non-interruptive alert in the EHR altered institution-level behaviors to reduce environmentally harmful anesthetic gas emissions.