Il trapianto di pancreas e rene nel trattamento del paziente diabetico e uremico

Il trapianto di pancreas rappresenta un’alternativa terapeutica di interesse nel trattamento dei pazienti con diabete mellito tipo 1. Il delicato rapporto rischi/benefici rende tuttavia necessarie ulteriori approfondimenti circa i risultati a lungo termine associati a tale procedura. Nel nostro centro complessivamente sono stati eseguiti 355 trapianti in 331 pazienti selezionati secondo le indicazioni fornite dalle associazioni mediche nazionali ed internazionali. Di tutti i trapianti eseguiti, 107 trapianti combinati rene-pancreas (SPK) hanno completato il follow-up a 10 anni. Dei pazienti inclusi nello studio sono stati analizzati i risultati metabolici prima del trapianto e ad 1,5 e 10 anni post trapianto, in termini di sopravvivenza del paziente, effetti del trapianto su glicemia a digiuno, emoglobina glicosilata, peptide C, di valutazione della funzione renale mediante misurazioni seriate dei valori di creatinina plasmatica e di valutazione del filtrato glomerulare (stimata con MDRD). Sono stati valutati inoltre gli effetti su altri fattori di rischio cardiovascolare quali pressione arteriosa e profilo lipidico. A 10 anni dal trapianto, la sopravvivenza dei pazienti è risultata pari al 81.2% nei pazienti sottoposti a SPK mentre quella del pancreas death-censored allo 85.2%. Nei soggetti con organo funzionante, il ripristino della secrezione insulinica endogena ha consentito il conseguimento e il mantenimento di normali valori di glicemia a digiuno e di HbA1c. Il colesterolo totale e quello LDL, nonché i valori dei trigliceridi sono risultati anch’essi ridotti significativamente, consentendo in oltre la metà dei pazienti la sospensione della terapia con statine. La funzionalità renale, ha mostrato una riduzione del filtrato glomerulare (GFR) di 1.34±1.8 ml/min/annuo a fronte di una microalbuminuria di 0.29±0.5 g/24h, stabile nel corso degli anni. I risultati del nostro studio confermano l’efficacia e ragionevole sicurezza del trapianto combinato rene-pancreas come trattamento in grado di migliorare la prognosi a lungo termine dei pazienti affetti da diabete mellito tipo 1 ed uremia, contribuendo al miglioramento di diversi fattori di rischio cardiovascolare

Comparison of State and Parameter Estimators for Electric Vehicle Batteries

A Battery Management System (BMS) is needed to ensure a safe and effective operation of a Lithium-ion battery, especially in electric vehicle applications. An important function of a BMS is the reliable estimation of the battery state in a wide range of operating conditions. To this end, a BMS often uses an equivalent electrical model of the battery. Such a model is computationally affordable and can reproduce the battery behaviour in an accurate way, assuming that the model parameters are updated with the actual operating condition of the battery, namely its state-of-charge, temperature and ageing state. This paper compares the performance of two battery state and parameter estimation techniques, i.e., the Extended Kalman Filter and the classic Least Squares method in combination with the Mix algorithm. Compared to previous ones, this work focuses on the concurrent estimation of battery state and parameters using experimental data, measured on a Lithium-ion cell subject to a current profile significant for an electric vehicle application

First World Consensus Conference on pancreas transplantation: Part II - recommendations.

Funder: Fondazione Pisa, Pisa, Italy; Id: http://dx.doi.org/10.13039/100007368Funder: Tuscany Region, Italy; Id: http://dx.doi.org/10.13039/501100009888Funder: Pisa University Hospital, Pisa, ItalyFunder: University of Pisa, Pisa, Italy; Id: http://dx.doi.org/10.13039/501100007514The First World Consensus Conference on Pancreas Transplantation provided 49 jury deliberations regarding the impact of pancreas transplantation on the treatment of diabetic patients, and 110 experts' recommendations for the practice of pancreas transplantation. The main message from this consensus conference is that both simultaneous pancreas-kidney transplantation (SPK) and pancreas transplantation alone can improve long-term patient survival, and all types of pancreas transplantation dramatically improve the quality of life of recipients. Pancreas transplantation may also improve the course of chronic complications of diabetes, depending on their severity. Therefore, the advantages of pancreas transplantation appear to clearly surpass potential disadvantages. Pancreas after kidney transplantation increases the risk of mortality only in the early period after transplantation, but is associated with improved life expectancy thereafter. Additionally, preemptive SPK, when compared to SPK performed in patients undergoing dialysis, appears to be associated with improved outcomes. Time on dialysis has negative prognostic implications in SPK recipients. Increased long-term survival, improvement in the course of diabetic complications, and amelioration of quality of life justify preferential allocation of kidney grafts to SPK recipients. Audience discussions and live voting are available online at the following URL address: http://mediaeventi.unipi.it/category/1st-world-consensus-conference-of-pancreas-transplantation/246

Il trapianto di pancreas isolato nel diabete mellito di tipo 1: effetti a lungo termine.

Il trapianto isolato di pancreas (PTA) ripristina la normoglicemia attraverso il reintegro della massa e della funzione β-cellulare in pazienti (pz) con diabete mellito tipo 1 (T1DM). La sicurezza e l'efficacia a lungo termine di tale procedura sono ancora oggetto di discussione. Nel presente studio sono stati studiati 66 pz consecutivi, con le seguenti caratteristiche cliniche al momento del trapianto: età, 38,1 ± 8,2 anni; 30 M e 36 F; BMI: 23,6 ± 2,9 kg/m2; durata del diabete, 23,9 ± 9,1 anni; HbA1c, 77 ± 6 mmol/mol; eGFR, 87.0 ± 22.5 ml/min/1.73m2. Il PTA è stato eseguito con drenaggio enterico - portale o sistemico rispettivamente nel 76 e nel 24% dei casi. La fase di induzione antirigetto includeva basiliximab nel 72,7% dei casi o ATG nel restante 27,3%. Tacrolimus, micofenolato mofetile, sono stati utilizzati nella fase di mantenimento. A 10 anni dal trapianto, la sopravvivenza del pz era del 92,4% e l’insulino-indipendenza era del 60,4%. La funzione del graft a lungo termine è stata associata alla normale glicemia a digiuno (93,5 ± 16,6 mg / dl), HbA1c (5,5 ± 0,5%) e C-peptide (3,0 ± 1,8 ng/ml). Durante il follow-up, 6 pz hanno sviluppato una malattia renale di stadio 4 (2 pazienti) e di stadio 5 (dialisi o trapianto - 4 pazienti). Nei restanti pz con PTA funzionante, il tasso annuale di declino dell' eGFR era di 2,29 ± 2,69 ml/min/1,73 m2, che era simile a quello (2,5 ± 1,8 ml/min/1,73 m2) di 7 pz che avevano avuto la perdita del graft nelle prime settimane dopo il trapianto e successivamente interrotto qualsiasi terapia immunosoppressiva. I risultati a lungo termine di questo studio monocentrico indicano che il trapianto di pancreas isolato possa essere un'opzione efficace e ragionevolmente sicura per curare il diabete in casi selezionati di pz con T1DM

Open circuit voltage of lithium-ion batteries for energy storage in DC microgrids

Rechargeable batteries, particularly Lithium-ion ones, are emerging as a solution for energy storage in DC microgrids. This paper reviews the issues faced in the characterization of the Open Circuit Voltage (OCV) of a Lithium-ion battery, starting from the problem of OCV measurement and ending with the modeling of OCV hysteresis. An accurate OCV modeling is necessary for a reliable estimation of the internal battery states, such as State-of-Charge and State-of-Health. These state variables are useful for a better control and a more efficient utilization of the energy storage system in the microgrid. We also compare with experiments two models that account for the hysteresis in Lithium-Iron-Phosphate batteries

Experimental validation of an efficient charge equalization system for Lithium-ion batteries

The experimental validation of a Battery Management System (BMS) provided with an innovative high-efficiency active balancing circuit is described in this paper. Charge equalization among the series connected battery cells is achieved with a cell to cell balancing topology. The balancing circuit consists of a switch matrix for the individual access of each cell and a bidirectional DC-DC converter to transfer a controlled amount of charge from a cell to a supercapacitor and back to another cell. The balancing algorithm and the experimental setup are also described. The experiments show the functionality of the balancing circuit that restores a fully balanced battery consisting of eleven 40 Ah Lithium-ion cells. For instance, if one of the cells is 17.7 % imbalanced, battery equalization lasts around 25 h and only costs 1 % of the battery energy. It allows the recovery of the full battery charge, otherwise limited to 82.3 %, with an energy saving factor of 6, if compared with passive balancing. The efficiency of the process, calculated by measuring the energy lost during balancing, is higher than 75 %

FPGA Implementation of the Mix Algorithm for State-of-Charge Estimation of Lithium-Ion Batteries

This paper describes the hardware implementation of a model-based State-of-Charge (SoC) estimation algorithm for Lithium-ion batteries. SoC estimation is essential to evaluate the remaining runtime of the battery, as well as to enhance its safety and life expectancy. Model-based SoC estimation is a good solution to the problem, but only offline tests have been presented so far. In this work, the SoC estimation algorithm is implemented on an FPGA device, following an innovative and automatic development flow, which starts from a MATLAB/Simulink model of the algorithm. The SoC estimation hardware block is combined with a soft-core processor to form a System on a Programmable Chip. Experimental results obtained exerting the battery with a current profile that simulates its operation in an electric vehicle are presented and discussed

Comparing Open-Circuit Voltage Hysteresis Models for Lithium-Iron-Phosphate Batteries

The hysteresis in the state-of-charge (SoC) vs. open-circuit voltage characteristic of a lithium-iron-phosphate (LiFeP04, LFP) battery is modelled with two approaches. The first one is based on a first-order charge relaxation equation, the second one is the Preisach model implemented with the Everett function. The advantages and drawbacks of the methods are discussed. Simulation results are compared for a 20 A h LFP cell, stimulated with various SoC evolutions, allowing us to draw minor loops in the SoC-OCV plane. The results are also compared to experimental data

Preisach Modelling of Lithium-Iron-Phosphate Battery Hysteresis

The hysteresis of the open-circuit voltage as a function of the state-of-charge in a 20 Ah lithium-iron-phosphate battery is investigated starting from pulsed current experiments at a fixed temperature and ageing state, in order to derive a model that may reproduce well the battery behaviour. The hysteretic behaviour is modelled with the classical Preisach model used in magnetic materials. The paper shows that the Preisach model can successfully be applied to the lithium-ion battery hysteresis. First, the model is discretised by using the Everett function and identified by means of experiments, in which first-order reversal branches are measured. Then, the model is simulated and compared to some experimental data collected with different current profiles and to a one-state variable model previously used in the literature. The results show that the hysteresis is well reproduced with rms errors around 2 %. The advantages of the Preisach-based method, when compared to other models, are the formal and repeatable identification procedure and the limited computational resources needed for the model simulation that makes it appropriate for the online implementation on low-complexity hardware platforms