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

High-presssure shift freezing. Part 2. Modeling of freezing times for a finite cylindrical model

A comprehensive vision of the heat transfer process involved in high-pressure shift freezing (HPSF) is shown in comparison to the process at atmospheric pressure. In addition, a mathematical model to predict the freezing times is presented. This model takes into consideration the dependence of the thermophysical properties relating to temperature and pressure and the supercooling reached by liquid water at atmospheric pressure after adiabatic expansion in the HPSF process. Experimental and theoretical data appear to agree.Peer Reviewe

Modelling heat transfer in high pressure food processing: A review

The most claimed advantage of high-pressure food processing as compared to thermal processing is that pressure acts instantaneously and uniformly through a mass of food independently of its size, shape or composition. Nevertheless, thermal gradients are established in the products after compression and cause inhomogeneities in the pursued pressure effect. Modelling heat transfer in high-pressure food processes can be a useful tool to homogenise and optimise these treatments. The main difficulty is the lack of appropriate thermophysical properties of the processed materials under pressure. When modelling high-pressure processes at subzero temperatures, pressure/temperature phase transition data and latent heat are also needed. Those for water are known, but there is a total lack for those corresponding to components relevant to foods. Moreover, the precise mechanisms that rule high-pressure shift freezing and induced thawing are not yet clear and so it hinders modellisation. This review collects the difficulties found and the advances made up to date in modelling heat transfer in high-pressure processes, including those performed at subzero temperatures. © 2003 Elsevier Science Ltd. All rights reserved.This paper was carried out with the support of the Spanish ‘Plan Nacional de I+D+I (2000–2003) MCYT through the AGL2000-1440-C02-01 project.Peer Reviewe

High Pressure-Assisted and High Pressure-Induced Thawing: Two Different Processes

High pressure-assisted thawing (HPAT) and high pressure-induced thawing (HPIT) experiments were performed in agar gel samples at different pressures (50 to 210 MPa) and initial temperatures (-5°C to -20°C). Lower pressures and temperatures yielded HPAT processes in which the sample temperature increased during pressurization because no melting took place. The complete phase transition occurred during the holding time. Higher temperature and/or higher pressures yielded HPIT processes in which partial melting occurred during pressure loading, causing the sample temperature to decrease. In practice, whether HPAT or HPIT took place depended on the initial temperature of the sample for a given pressure value. Common situations were nonhomogeneous thawing processes.This research has been carried out with financial support from the Spanish “Plan Nacional de I + D + I (2000-2003) MCYT” through the AGL2000-1440-C02-01 project and the Commission of the European Communities, specific RTD program “Quality of Life and Management of Living Resources,” QLK1- CT- 2002- D2230Peer Reviewe

High-pressure shift freezing. Part 1. Amount of ice instantaneously formed in the process

A mathematical model to calculate the amount of ice formed instantaneously after a rapid expansion in high-pressure shift processes (HPSF) was developed. It considers that when water is expanded it does not extend over its melting curve but reaches a metastable state (supercooled water), which also occurs in practice. Theoretical results appear to agree with experimental data.Peer Reviewe

Influence of temperature and composition on some physical properties of milk and milk concentrates, V. Electrical conductivity

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Volumetric properties of sunflower and olive oils at temperatures between 15 and 55°C under pressures up to 350 MPa

Numeric simulation is used to optimise the high pressure processing of foods. It allows for heat and mass transfer modelling and thus to address process uniformity problems. This modelling involves adiabatic heat, experimentally known to be higher for fats than for water, but hardly calculable due to the lack of data on food properties under pressure. In this work, the volumetric properties of sunflower and olive oils were determined to generate an original data set. A volumetric device working up to 350 MPa was assembled on the plug of high hydrostatic pressure equipment. The specific volume was measured as a function of pressure and temperature. An empirical equation of state was developed to derive the isothermal compressibility and thermal expansivity. Comparison with water properties shows how these results should contribute to improve the predictive skills of models used to simulate high pressure treatments of fat rich foods.Peer Reviewe

Anisakis simplex larva killed by high-hydrostatic-pressure processing

Anisakis simplex is a common nematode parasite present in many marine fish, including finfish and squid. It can pose a public health problem if it is not destroyed during food processing. Anisakis larvae were isolated from fish tissue, and their survival of high-pressure treatments in distilled water and physiological isotonic solution was assayed. Treatment at a pressure of 200 MPa for 10 min at a temperature between 0 and 15°C kills all Anisakis larvae, with a lack of motility being used as an indicator of larval death. Lower pressures can be successfully employed down to 140 MPa, but with lower pressures, the treatment time must be increased by up to 1 h to kill all larvae. Meanwhile, most larvae treated for > 10 min at pressures of >120 MPa were dead, with the autofluorescence method being used to determine death. Cycles of compression and decompression increase the destruction of larvae compared with a single pressure treatment for a similar treatment time. Our results indicate that high-pressure treatment is an alternative nonthermal method for killing this nematode. The possible mechanism of death and damage by pressure is discussed, and uses for this treatment in food processing are suggested.Peer Reviewe

Effect of high pressure on the reduction of microbial populations in vegetables

Resistance of micro-organisms to high pressure is variable and directly related to extrinsic and intrinsic factors. Pressures of 100, 200, 300, 350 and 400 MPa were applied at 20°C for 10 min and at 10°C for 20 rain using strains of Gram-positive and Gram-negative bacteria, moulds and yeasts, as well as spores of Gram-positive bacteria. The results showed that at pressures of 100 and 200 MPa, decreases in microbial populations were not significant, whereas the populations of all the micro-organisms tested decreased considerably at a pressure of 300 MPa. A pressure of 300 MPa at 10°C for 20 min was required to completely reduce the population of Saccharomyces cerevisiae, and a pressure of 350 MPa was needed to reduce most of the Gram-negative bacteria and moulds. The Gram-positive bacteria were more resistant, and pressures of 400 MPa were unable to completely reduce their populations. The different pressures employed had little effect on the initial numbers of spores. The initial populations of viable aerobic mesophiles and moulds and yeasts in vegetables (lettuce and tomatoes) decreased I log unit at pressures of 300 MPa and above under both sets of experimental treatment conditions. However, treatment at that pressure also resulted in alterations in the organoleptic properties of the samples. In the tomatoes, the skin loosened and peeled away, though the flesh remained firm, and colour and flavour were unchanged. The lettuce remained firm but underwent browning; flavour was unaffected. In vegetables use of moderate pressures in combination with other treatment conditions would appear to be required to reduce the populations of contaminating micro-organisms while avoiding the undesirable alterations in organoleptic properties that take place at 300 MPa.Peer Reviewe

Response to high-pressure, low-temperature treatment in vegetables: Determination of survival rates of microbial populations using flow cytometry and detection of peroxidase activity using confocal microscopy

Application of high hydrostatic pressure (200, 300, 350 and 400 MPa) at 5 °C for 30 min to different micro-organisms, including Gram-positive and Gram-negative bacteria, moulds and yeasts, proved to be more effective in inactivating these organisms than treatments at 20 °C for 10 min and at 10 °C for 20 min. Moulds, yeasts, Gram-negative bacteria and Listeria monocytogenes were most sensitive, and their populations were completely inactivated at pressures between 300 and 350 MPa. The same conditions of pressure, temperature, and time were applied to different vegetables (lettuce, tomato, asparagus, spinach, cauliflower and onion), achieving reductions of from 2-4 log units in both viable mesophiles and moulds and yeasts at pressures of between 300 and 400 MPa. Sensory characteristics were unaltered, especially in asparagus, onion, tomato and cauliflower, though slight browning was observed in cauliflower at 350 MPa. Flow cytometry was applied to certain of the microbial populations used in the above experiment before and after the pressurization treatment. The results were indicative of differing percentage survival rates depending on micro-organism type, with higher survival rates for Gram-positive bacteria, except L. monocytogenes, than in the other test micro-organisms. Growth of survivors was undetectable using the plate count method, suggesting that microorganisms suffering from pressure stress were metabolically inactive though alive. The pressurization treatments did not inactivate the peroxidase responsible for browning in vegetables. Confocal microscopic examination of epidermal tissue from onion showed that the enzyme had been displaced to the cell interior. Use of low temperatures and moderately long pressurization times yielded improved inactivation of micro-organisms and better sensorial characteristics of the vegetables, and should lower industrial costs.Peer Reviewe