Heat transformation based on reversible chemical reactions has gained significant interest due to the high achievable output temperatures. This specific type of chemical heat pump uses a reversible ...gas–solid reaction, with the back and forward reactions taking place at different temperatures: by running the exothermic discharge reaction at a higher temperature than the endothermic charge reaction, the released heat is thermally upgraded. In this work, we report on the experimental investigation of the hydration reaction of strontium bromide (SrBr2) with regard to its use for heat transformation in the temperature range from 180 °C to 250 °C on a 1 kg scale. The reaction temperature is set by adjusting the pressure of the gaseous reactant. In previous experimental studies, we found the macroscopic and microscopic properties of the solid bulk phase to be subject to considerable changes due to the chemical reaction-. In order to better understand how this affects the thermal discharge performance of a thermochemical reactor, we combine our experimental work with a modelling approach. From the results of the presented studies, we derive design rules and operating parameters for a thermochemical storage module based on SrBr2.
This study investigated the critical care staff's attitude, knowledge and involvement with donation, skills and confidence with donation-related tasks and their association with consent rates at the ...hospital level. In 2015, we conducted a cross-sectional survey among critical care staff of hospitals involved in organ donation using an anonymous online questionnaire with a response rate of 56.4% (n = 2799). The hospital level consent rate was obtained from the Swiss Monitoring of Potential Donors database (2013-2015). For each hospital, we calculated a mean score for each predictor of interest of the Hospital Attitude Survey and investigated the association with hospital consent rates with generalized linear mixed-effect models. In univariable analysis, one score point increase in doctors' confidence resulted in a 66% (95% CI: 45%-80%) reduction in the odds to consent, and one score point increase in nurses' attitudes resulted in a 223% (95% CI: 84%-472%) increase in the odds to consent. After simultaneously adjusting for all major predictors found in the crude models, only levels of education of medical and nursing staff remained as significant predictors for hospital consent rates. In Switzerland, efforts are needed to increase consent rates for organ donation and should concentrate on continuous support as well as specific training of the hospital staff involved in the donation process.
Switzerland has a low post mortem organ donation rate. Here we examine variables that are associated with the consent of the deceased's next of kin (NOK) for organ donation, which is a prerequisite ...for donation in Switzerland.
During one year, we registered information from NOK of all deceased patients in Swiss intensive care units, who were approached for consent to organ donation. We collected data on patient demographics, characteristics of NOK, factors related to the request process and to the clinical setting. We analyzed the association of collected predictors with consent rate using univariable logistic regression models; predictors with p-values <0.2 were selected for a multivariable logistic regression.
Of 266 NOK approached for consent, consent was given in 137 (51.5%) cases. In multivariable analysis, we found associations of consent rates with Swiss nationality (OR 3.09, 95% CI: 1.46-6.54) and German language area (OR 0.31, 95% CI: 0.14-0.73). Consent rates tended to be higher if a parent was present during the request (OR 1.76, 95% CI: 0.93-3.33) and if the request was done before brain death was formally declared (OR 1.87, 95% CI: 0.90-3.87).
Establishing an atmosphere of trust between the medical staff putting forward a request and the NOK, allowing sufficient time for the NOK to consider donation, and respecting personal values and cultural differences, could be of importance for increasing donation rates. Additional measures are needed to address the pronounced differences in consent rates between language regions.
Various actions have been taken during the last decade to increase the number of organs from deceased donors available for transplantation in Switzerland. This study provides an overview on key ...figures of the Swiss deceased organ donation and transplant activity between 2008 and 2017. In addition, it puts the evolution of the Swiss donation program's efficiency in relation to the situation in the neighboring countries.
This study is an analysis of prospective registry data, covering the period from 1 January 2008 to 31 December 2017. It includes all actual deceased organ donors (ADD) in Switzerland. Donor data were extracted from the Swiss Organ Allocation System. The "donor conversion index" (DCI) methodology and data was used for the comparison of donation program efficiency in Switzerland, Germany, Austria, Italy and France.
During the study period there were 1116 ADD in Switzerland. The number of ADD per year increased from 91 in 2008 to 145 in 2017 (+ 59%). The reintroduction of the donation after cardiocirculatory death (DCD) program in 2011 resulted in the growth of annual percentages of DCD donors, reaching a maximum of 27% in 2017. The total number of organs transplanted from ADD was 3763 (3.4 ± 1.5 transplants per donor on average). Of these, 48% were kidneys (n = 1814), 24% livers (n = 903), 12% lungs (n = 445), 9% hearts (n = 352) and 7% pancreata or pancreatic islets (n = 249). The donation program efficiency assessment showed an increase of the Swiss DCI from 1.6% in 2008 to 2.7% in 2017 (+ 69%). The most prominent efficiency growth was observed between 2012 and 2017. Even though Swiss donation efficiency increased during the study period, it remained below the DCI of the French and Austrian donation programs.
Swiss donation activity and efficiency grew during the last decade. The increased donation efficiency suggests that measures implemented so far were effective. The lower efficiency of the Swiss donation program, compared to the French and Austrian programs, may likely be explained by the lower consent rate in Switzerland. This issue should be addressed in order to achieve the goal of more organs available for transplantation.
Organs donated for transplantation remain a scarce resource in Switzerland. One of the reasons for this situation is the high percentage of patients or families who refuse to consent to donation. ...This study aimed to provide an overview of attitudes towards organ donation among Swiss residents, including any intention to donate organs after death, and whether they had already declared their wish and/or communicated it to anyone.
A representative poll investigating the attitude of the Swiss population towards deceased organ donation was conducted between 16 and 28 March 2015. Survey data were collected in 1000 structured telephone interviews. Participants consisted of residents aged 15 years and over from all Swiss regions, and covering the German, French and Italian language areas.
Of the 1000 survey participants, 92% stated that they have a very positive (58%) or quite positive (33%) attitude towards organ donation, while 6% have a very negative (2%) or quite negative (4%) view. Some 81% of respondents said that they would be willing to donate their organs after death, and 9% expressed a wish not to become a donor. A total of 53% of participants said that they had already communicated or documented whether they wish to donate.
Our study highlights the importance of continuing to raise awareness about the importance of communicating wishes, both in written form and to family members, and suggests that more work is needed to reap the benefits of the substantial support for organ donation among the Swiss population.
The Swiss Monitoring of Potential Organ Donors (SwissPOD) was initiated to investigate the causes of the overall low organ donation rate in Switzerland. The objective of our study was an assessment ...of the donation after brain death (DBD) process in Swiss adult intensive care units (ICUs), and to provide an overview of the donation efficiency as well as of the reasons for non-donation.
SwissPOD is a prospective cohort study of all deaths in Swiss ICUs and accident and emergency departments. This study is an analysis of SwissPOD data of all patients who deceased in an adult ICU between 1 September 2011 and 31 August 2012.
Out of 3,667 patients who died in one of the 79 adult ICUs participating in SwissPOD, 1,204 were possible, 198 potential, 133 eligible, and 94 utilised DBD donors. The consent rate was 48.0% and the conversion rate 47.5%. In 80.0% of cases, the requests for donation took place before brain death was diagnosed, resulting in a similar proportion of consents and objections as when requests were made after brain death diagnosis.
Despite the low donation rate, Swiss adult ICUs are performing well in terms of the conversion rate, similar to major European countries. The refusal rate is among the highest in Europe, which clearly has a negative impact on the donation rate. Optimising the request process seems to be the most effective means of increasing the donation rate.
To provide an overview of heart allocation and transplantation in Switzerland since the introduction of the Swiss Organ Allocation System (SOAS).
This study is a retrospective analysis of SOAS data ...related to heart transplantation between 1 July 2007 and 30 June 30 2013.
During the study period, 300 patients were newly waitlisted for a heart transplant in Switzerland, 199 were transplanted and 52 deceased while on the waiting list. Of the 723 hearts offered by Swisstransplant to the three university hospitals with a heart transplantation programme (Bern, Lausanne and Zurich), 199 (27.5%) were transplanted. Of these, 183 (92.0%) were procured in Switzerland and 16 (8.0%) were offered by a foreign organ procurement organisation. Fifty-two hearts were transplanted to patients who were listed in urgent status, equalling an urgent transplant rate of 26.1%. Whereas the overall waiting list mortality was 19.0%, it was as high as 31.8% in patients older than 60 years.
Our study showed a growing Swiss heart transplant waiting list, as significantly more patients were newly waitlisted than transplanted. Compared with the international data, the acceptance rate of heart offers and the rate of urgent transplantations were relatively low, while the waiting list mortality was higher. The fact that the mortality was highest in candidates aged 60 and above suggests that the new generation of ventricular assist devices as destination therapy should be considered as an alternative to transplantation in selected patients.
•Minimization of thermocline thickness in single tank thermal energy storage tanks.•Misestimation of temperature stratification by assuming perfect flow distribution.•Efficiency gains in thermocline ...thickness due to optimized fluid distributor design.•Sensitivity analysis of fluid distributor geometry in thermocline thermal energy storage tanks.
Single tank thermal energy storage systems based on the thermocline concept have attracted large interest in the last years at both, scientific and industrial levels, as cost-effective alternative to the commercially available and proven molten salt double tank storage system. Recently, many experimental and modeling results of these systems validating the technology and addressing guidelines to optimize its thermal performance have been reported. However, high cyclic efficiencies predicted in simulation have not been reported to be achieved experimentally. This paper addresses one of the reasons for this discrepancy, i.e., the fact that the additional temperature stratification volume generated by the fluid distribution at the tank's inlet is typically not considered in theoretical models. This paper demonstrates that assuming idealized flow distribution in the tank's cross-section will not represent reality adequately. Using this approach, the thermocline thickness at the beginning of the charge operation can be misestimated by more than 50%. Furthermore, a sensitivity analysis of the geometric characteristics of a specific radial fluid distributor type is included in this work. A theoretical model is developed for this purpose and validated with experimental data. The results of the analysis show that the fluid distributor should always be located in the upper-most part of the tank to minimize the initial thermocline thickness. Besides, the analysis of the cross-sectional area occupied by the distributor has been analyzed. It is shown that an optimal value exists for this parameter in order not to inhibit thermal stratification and to create further temperature gradients by subdividing the tank and thereby creating fluid-dead volumes.
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