ZTBus: A Large Dataset of Time-Resolved City Bus Driving Missions.

This paper presents the Zurich Transit Bus (ZTBus) dataset, which consists of data recorded during driving missions of electric city buses in Zurich, Switzerland. The data was collected over several years on two trolley buses as part of multiple research projects. It involves more than a thousand missions across all seasons, each mission usually covering a full day of operation. The ZTBus dataset contains detailed information on the vehicle's power demand, propulsion system, odometry, global position, ambient temperature, door openings, number of passengers, dispatch patterns within the public transportation network, etc. All signals are synchronized in time and include an absolute timestamp in tabular form. The dataset can be used as a foundation for a variety of studies and analyses. For example, the data can serve as a basis for simulations to estimate the performance of different public transit vehicle types, or to evaluate and optimize control strategies of hybrid electric vehicles. Furthermore, numerous influencing factors on vehicle operation, such as traffic, passenger volume, etc., can be analyzed in detail.

Automated Insulin Delivery - Continuous Blood Glucose Control During Ex Situ Liver Perfusion.

OBJECTIVE: With the growing demand for livers in the field of transplantation, interest in normothermic ex situ machine perfusion (NMP) has increased in recent years. This may open the door for novel therapeutic interventions such as repair of suboptimal grafts. For successful long-term NMP of livers, blood glucose (BG) levels need to be maintained in a close to physiological range. METHODS: We present an "automated insulin delivery" (AID) system integrated into an NMP system, which automatically adjusts insulin infusion rates based on continuous BG measurements in a closed loop manner during ex situ pig and human liver perfusion. An online glucose sensor for continuous glucose monitoring was integrated and evaluated in blood. A model based and a proportional controller were implemented and compared in their ability to maintain BG within the physiological range. RESULTS: The continuous glucose sensor is capable of measuring BG directly in human and pig blood for multiple days with an average error of 0.6 mmol/L. There was no significant difference in the performance of the two controllers in terms of their ability to keep BG in the physiological range. With the integrated AID, BG was controlled within the physiological range on average in 80% and 76% of the perfusion time for human and pig livers, respectively. CONCLUSION: The presented work offers a method and shows the feasibility to maintain BG in the physiological range for multiple (up to ten) days during ex situ liver perfusion with the help of an automated AID. SIGNIFICANCE: Maintaining BG within the physiological range is required to enable long-term ex situ liver perfusion.

An integrated perfusion machine preserves injured human livers for 1 week.

The ability to preserve metabolically active livers ex vivo for 1 week or more could allow repair of poor-quality livers that would otherwise be declined for transplantation. Current approaches for normothermic perfusion can preserve human livers for only 24 h. Here we report a liver perfusion machine that integrates multiple core physiological functions, including automated management of glucose levels and oxygenation, waste-product removal and hematocrit control. We developed the machine in a stepwise fashion using pig livers. Study of multiple ex vivo parameters and early phase reperfusion in vivo demonstrated the viability of pig livers perfused for 1 week without the need for additional blood products or perfusate exchange. We tested the approach on ten injured human livers that had been declined for transplantation by all European centers. After a 7-d perfusion, six of the human livers showed preserved function as indicated by bile production, synthesis of coagulation factors, maintained cellular energy (ATP) and intact liver structure.

Model Assisted Analysis of the Hepatic Arterial Buffer Response During Ex Vivo Porcine Liver Perfusion.

OBJECTIVE: The hepatic arterial buffer response is a well-known phenomenon in hepatic circulation, describing the response of hepatic arterial resistance to changes in portal vein flow. Several vasoactive metabolites underlying its mechanism have been proposed, however, there is currently no clear consensus. The aim of this study is to investigate the hepatic arterial buffer response of porcine livers preserved in a controlled ex vivo perfusion machine. METHODS: Porcine livers are perfused on an ex vivo perfusion machine and hemodynamic experiments investigating the hepatic arterial resistance response to portal vein flow and vena cava pressure variations are conducted. A simple hemodynamic model is developed to support the interpretation of the received measurements. Further, a mechanism is proposed that explains hepatic arterial resistance changes in response to vena cava pressure as myogenic and in response to portal vein flow as a combined washout and myogenic effect. RESULTS: A clear correlation between hepatic sinusoidal pressure levels and hepatic arterial resistance is observed where an increase of approximately 4 mmHg of hepatic sinusoidal pressure level results in doubling of the hepatic arterial resistance. This relation is considered during the analysis of the portal vein flow variations resulting in a reduced isolated effect of adenosine washout on hepatic arterial resistance. With an average buffer capacity of 27% during our experiments, the hepatic arterial buffer response shows to be unimpaired in the ex vivo scenario. CONCLUSION: First, washout and myogenic effects both influence the hepatic arterial buffer response; and second, hepatic sinusoidal pressure levels strongly influence the hepatic arterial resistance. SIGNIFICANCE: These results present new findings in hemodynamics of the liver, which are fundamental for successful ex vivo liver perfusion.

Perfusion settings and additives in liver normothermic machine perfusion with red blood cells as oxygen carrier. A systematic review of human and porcine perfusion protocols.

Liver machine perfusion (MP) at normothermic temperature (NMP) is a promising way to preserve and evaluate extended criteria donor livers. Currently, no consensus exists in methodology and perfusion protocols. Here, the authors performed a systematic literature search to identify human and porcine studies reporting on liver NMP with red blood cells. A qualitative synthesis was performed concerning technical aspects of MP, fluid composition, gas supply, and liver positioning. Thirty-seven publications including 11 human and 26 porcine studies were considered for qualitative synthesis. Control mode, pressure, flow, perfusate additives, and targeted blood gas parameters varied across human as well as porcine studies. For future analyses, it is advisable to report flow adjusted to liver weight and exact pressure parameters including mean, systolic, and diastolic pressure. Parenteral nutrition and insulin addition was common. Parenteral nutrition included amino acids and/or glucose without lipids. Taurocholic acid derivatives were used as bile flow promoters. However, short-term human NMP without taurocholic acid derivatives seems to be possible. This finding is relevant due to the lack of clinical grade bile salts. Near physiological oxygen tension in the perfusate is doable by adjusting gas flows, while blood gas parameters regulation needs more detailed description.