Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Model based investigations of the low temperature behaviour of Lithium-ion batteries

Due to their high energy density, Li-ion batteries represent nowadays the most promising electrochemical storage devices for portable electronics, electric vehicles and stationary energy storage application. However, some challenges need to be overcome, especially for automotive applications. These include: the increase of the energy and power densities, decrease the cost, fast charging, safety, aging and recycling of the components, among others. A particular problem regards the sudden degradation due to the many undesired reactions which take place during battery operation. Batteries are complex systems and the effects contributing to capacity fade are still not well understood. One of these undesired reactions is the deposition of metallic lithium on the anode surface during the charging process. This phenomenon, called lithium plating, is not only the main cause for battery degradation when charging at low temperatures, but it may lead to a short circuit, when lithium dendrites deposits in a needle-like form, piercing the battery separator. In large format cells, where temperature and current distributions are not uniform, the lithium deposition process starts locally and it is difficult to detect. A few techniques have been employed to detect and quantify lithium plating, but these are not spatially resolved, and there is still no method that directly detects the deposition of metallic lithium during battery operation. Electrochemical models allow the evaluation of the lithium ions concentration, temperature and potential distribution within the cell, parameters that can be used to identify the plating onset conditions. Experimental parameterization is needed as different parameter combinations lead to the same cell potential curve. Each cell has a specific geometry and the transport parameters depend on the chemistry of the component and on the geometry of the cell. Furthermore, tabulated values for such parameters are scattered and often do not provide information on the electrode geometry. In-operando characterization techniques like optical microscopy and micro-Raman spectroscopy are employed to detect the lithium plating onset in the micro-scale. Intercalation of the plated lithium on the graphite surface was observed during the resting periods after charge and during the constant voltage step. However, at C-Rates higher than C/2 and temperatures below zero degrees, fast capacity decay due to irreversible lithium plating was observed in most commercial cells except in one type. A non-isothermal electrochemical model is used to investigate the lithium plating onset conditions of the commercial Li-ion cell where no plating was found even at very adverse conditions (1C and -10 degrees or 4C and 0 degrees). This model is parameterized experimentally and validated against the individual potentials. Geometry and transport parameters are determined at different temperatures and states of charge. New approaches for a fast parameterization process are introduced and the results are in good agreement with the ones obtained by other techniques. The model can predict well the temperature, potential and current distribution within the cell during charging at high C-rates and low temperatures. This promising model can be used to design new fast charging strategies for Li-ion batteries at low temperature without a detrimental effect on the battery life

Are Polymer‐Based Electrolytes Ready for High‐Voltage Lithium Battery Applications? An Overview of Degradation Mechanisms and Battery Performance

High-voltage lithium polymer cells are considered an attractive technology that could out-perform commercial lithium-ion batteries in terms of safety, processability, and energy density. Although significant progress has been achieved in the development of polymer electrolytes for high-voltage applications (> 4 V), the cell performance containing these materials still encounters certain challenges. One of the major limitations is posed by poor cyclability, which is affected by the low oxidative stability of standard polyether-based polymer electrolytes. In addition, the high reactivity and structural instability of certain common high-voltage cathode chemistries further aggravate the challenges. In this review, the oxidative stability of polymer electrolytes is comprehensively discussed, along with the key sources of cell degradation, and provides an overview of the fundamental strategies adopted for enhancing their cyclability. In this regard, a statistical analysis of the cell performance is provided by analyzing 186 publications reported in the last 17 years, to demonstrate the gap between the state-of-the-art and the requirements for high-energy density cells. Furthermore, the essential characterization techniques employed in prior research investigating the degradation of these systems are discussed to highlight their prospects and limitations. Based on the derived conclusions, new targets and guidelines are proposed for further research

Effects of pre-operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study an international prospective cohort study

We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care. We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care