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

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

Analysis of dynamic crack propagation in elastomers by simultaneous tensile- and pure-shear-mode testing

The present work proposes a new fracture mechanical testing concept for determination of dynamic crack propagation of rubber materials. This concept implements a method of simultaneous tensile- and pure-shear-mode testing. The present approach is based on an upgrade of the Tear Analyzer (Co. Coesfeld GmbH & Co. KG), on the fracture mechanics theory of dynamically loaded test specimens and on the definition of pure-shear states according to the test specimen's geometry ratio. The main focus of this work can be divided into three parts. Firstly, it introduces the development of a method for analysis of dynamic crack propagation in filled rubber by simultaneous tensile- and pure shear mode testing. The servo-hydraulic machine with controlled temperature testing chamber is equipped with simultaneously operating two-mode test equipment that represents a new fracture testing method. This two-mode test allows the measurement of crack propagation on different rubber specimens simultaneously and under identical load. The data analysis allows a comparison between the two parallel running testing modes. Secondly, this work deals with the development of a method for the defined creation of a notch in a rubber specimen. This method serves as a basis for the reproducible and reliable determination of fracture mechanical parameters for elastomers. After insertion of notches in a defined way, fracture tests under different loading conditions were performed. A significant influence on the notch geometry was observed in the test results. The results illustrated the importance of a defined and reproducible notching of elastomeric specimens. Next, the analysis of crack propagation under dynamic loading conditions is practiced with this method. It is shown how the tearing energy and the crack growth rate depend on the test specimen's geometry ratio and crack length. It is also demonstrated that the values for tearing energies and crack growth rates for short crack lengths in SENT, as well as in pure-shear test specimens, are identical. Another important aspect of the results is related to the different values of tearing energies and crack growth rates for cracks with short and large lengths in pureshear test specimens. The results show the dependence of fracture behavior on the manufacture of the test specimens. The new fracture mechanical testing concept offers a comparison between fracture behaviors of rubber materials independent of the test specimen's geometry. © Springer-Verlag Berlin Heidelberg 2013.

Experimental Observation and Modelling of Preconditioning in Soft Biological Tissues

Constitutive models for soft biological tissues and in particular for human organs are required for medical applications such as surgery simulation, surgery planning, diagnosis. In the literature the mechanical properties of biosolids are generally presented in "preconditioned" state, i.e. the stabilized conditions reached after several loading-unloading cycles. We hereby present experiments on soft tissues showing the evolution of the mechanical response in a series of loading and unloading cycles. The experimental procedure applied in this study is based on the so called "aspiration experiment" and is suitable for in-vivo applications under sterile conditions during open surgery. In the present study this technique is applied ex-vivo on bovine liver. A small tube is contacted to the target organ and a weak vacuum is generated inside the tube according to a predefined pressure history. Several identical loading and unloading cycles are applied in order to characterize the evolutive behaviour of the tissue. The experimental data are used to inform the fitting of uniaxial and threedimensional continuum mechanics models. This analysis demonstrates that a quasi-linear viscoelastic model fails in describing the observed evolution from the "virgin" to the preconditioned state. Good agreement between simulation and measurement are obtained by introducing an internal variable changing according to an evolution equation