Event-based MPC for propofol administration in anesthesia

Background and Objective : The automatic control of anesthesia is a demanding task mostly due to the presence of nonlinearities, intra- and inter-patient variability and specific clinical requirements to be meet. The traditional approach to achieve the desired depth of hypnosis level is based on knowledge and experience of the anesthesiologist. In contrast to a typical automatic control system, their actions are based on events that are related to the effect of the administrated drug. Thus, it is interesting to build a control system that will be able to mimic the behavior of the human way of actuation, simultaneously keeping the advantages of an automatic system.Methods : In this work, an event-based model predictive control system is proposed and analyzed. The nonlinear patient model is used to form the predictor structure and its linear part is exploited to design the predictive controller, resulting in an individualized approach. In such a scenario, the BIS is the controlled variable and the propofol infusion rate is the control variable. The event generator governs the computation of control action applying a dead-band sampling technique. The proposed control architecture has been tested in simulation considering process noise and unmeasurable disturbances. The evaluation has been made for a set of patients using nonlinear pharmacokinetic/pharmacodynamic models allowing realistic tests scenarios, including inter- and intra-patient variability.Results For the considered patients dataset the number of control signal changes has been reduced of about 55% when compared to the classical control system approach and the drug usage has been reduced of about 2%. At the same time the control performance expressed by the integrated absolute error has been degraded of about 11%.Conclusions : The event-based MPC control system meets all the clinical requirements. The robustness analysis also demonstrates that the event-based architecture is able to satisfy the specifications in the presence of significant process noise and modelling errors related to inter- and intra-patient variability, providing a balanced solution between complexity and performance. (c) 2022 Elsevier B.V. All rights reserved

MPC for Propofol Anesthesia: the Noise Issue

The design of automatic control systems for general anesthesia is a challenging task due to the severe safety requirements and process constraints. This is even more complex when model-based control techniques are used due to the significant variability of the process model. Additionally, issues like noisy measurements and interference also influence the control system overall performance. In this context, adequate filtering and control system sampling period selection should be analyzed to test their influence on the controller. In this paper, an MPC system for the depth of hypnosis, where the BIS signal is used as a controlled variable, is analyzed. The main purpose is to test and evaluate how the process noise affects the performance of the control system. The analysis is performed in a simulation study using a dataset of virtual patients representative of a wide population. Results show that a satisfactory performance is obtained when the noise is explicitly taken into account in the controller tuning procedure for a specific sampling period

Familial fetal-type rhabdomyoma of the tricuspid valve in the neonate: Malignant course for a benign disease

Familial fetal-type rhabdomyoma of the tricuspid valve in the neonate: malignant course for a benign disease

Pseudopapillary tumor in pediatric age: clinical and surgical management

BACKGROUND:Solid pseudopapillary tumors of the pancreas are rare exocrine pancreatic tumors. Through a review of pediatric cases in a single Institution, we present the clinical and surgical management of this neoplasm.METHODS:We retrospectively reviewed the clinical charts of patients treated at our unit between 1995 and 2009 for SPT. Clinical and surgical management were analyzed and reported.RESULTS:During the study period 11 patients underwent surgery for pseudopapillary tumor. Five patients were treated with duodenum-preserving pancreatic head resection and six patients with splenopancreasectomy with a Roux-en-Y pancreatic jejunostomy. Patients did not show recurrence and are currently disease free. Blood tests, Ultrasound, Computed tomography and Magnetic Resonance Imaging were not useful to preoperatively identify the nature of the pancreatic masses.CONCLUSION:Solid pseudopapillary tumor is a rare condition that should be taken into account for the differential diagnosis of pancreatic masses in pediatric age. Due to its favourable prognosis, surgical removal should be planned and done following the intraoperative findings

Electrocardiogram analysis in Anderson-Fabry disease: a valuable tool for progressive phenotypic expression tracking

BackgroundElectrocardiogram (ECG) has proven to be useful for early detection of cardiac involvement in Anderson-Fabry disease (AFD); however, little evidence is available on the association between ECG alterations and the progression of the disease.Aim and MethodsTo perform a cross sectional comparison of ECG abnormalities throughout different left ventricular hypertrophy (LVH) severity subgroups, providing ECG patterns specific of the progressive AFD stages. 189 AFD patients from a multicenter cohort underwent comprehensive ECG analysis, echocardiography, and clinical evaluation.ResultsThe study cohort (39% males, median age 47 years, 68% classical AFD) was divided into 4 groups according to different degree of left ventricular (LV) thickness: group A & LE; 9 mm (n = 52, 28%); group B 10-14 mm (n = 76, 40%); group C 15-19 mm (n = 46, 24%); group D & GE; 20 mm (n = 15, 8%). The most frequent conduction delay was right bundle branch block (RBBB), incomplete in groups B and C (20%,22%) and complete RBBB in group D (54%, p < 0.001); none of the patients had left bundle branch block (LBBB). Left anterior fascicular block, LVH criteria, negative T waves, ST depression were more common in the advanced stages of the disease (p < 0.001). Summarizing our results, we suggested ECG patterns representative of the different AFD stages as assessed by the increases in LV thickness over time (Central Figure). Patients from group A showed mostly a normal ECG (77%) or minor anomalies like LVH criteria (8%) and delta wave/slurred QR onset + borderline PR (8%). Differently, patients from groups B and C exhibited more heterogeneous ECG patterns: LVH (17%; 7% respectively); LVH + LV strain (9%; 17%); incomplete RBBB + repolarization abnormalities (8%; 9%), more frequently associated with LVH criteria in group C than B (8%; 15%). Finally, patients from group D showed very peculiar ECG patterns, represented by complete RBBB + LVH and repolarization abnormalities (40%), sometimes associated with QRS fragmentation (13%).ConclusionsECG is a sensitive tool for early identification and long-term monitoring of cardiac involvement in patients with AFD, providing "instantaneous pictures" along the natural history of AFD. Whether ECG changes may be associated with clinical events remains to be determined

La Provincia di Sassari: ambiente, storia, civiltà

Essere cittadino di una provincia non significa soltanto abitarvi. Significa anche lavorarvi, esercitarvi una attività che vada a vantaggio del benessere individuale e insieme del benessere della collettività. Per fare questo, per raggiungere meglio questo obiettivo, la realtà in cui si vive e si lavora bisogna conoscerla meno superficialmente di quanto normalmente non succeda. E' una constatazione che si può fare per tutti coloro che abitano in un luogo, ma che si deve fare in modo particolare quando lo strumento di conoscenza che si propone è un libro come questo

Kalman Filter method for state of charge estimation of vanadium redox flow batteries

openL’obbiettivo di questo elaborato è di analizzare la robustezza e l’idoneità dell’algoritmo di filtro di Kalman applicato alla stima dello stato di carica nelle batterie a flusso di Vanadio. Nelle batterie a flusso si usa solitamente il metodo OCV, che necessita di misure dirette per la stima dello stato di carica, l’algoritmo di Kalman permette invece di stimare lo SoC indirettamente a partire dalla tensione ai morsetti e dalla corrente assorbita o erogata, tramite delle equazioni di predizione e aggiornamento implementate da questo osservatore di stato in retroazione, che considera il rumore di misura e di processo. Si considerano due diversi modelli elettrici semplificati individuati in letteratura, ai quali si applica il filtro per ottenere delle stime dello stato di carica, confrontando i risultati con quelli ottenuti sperimentalmente. Questi modelli sono non lineari, perciò il tipo di filtro applicato è quello esteso, che permette di eseguire stime a priori linearizzando le funzioni localmente. Il primo modello è basato sul modello di Thevenin, utilizza una combinazione di un generatore di tensione dipendente dallo stato di carica, resistori, condensatori ed elementi non lineari che rappresentano la dinamica della batteria, ha come obbiettivo quello di catturare i trend elettrochimici della batteria attraverso le sue caratteristiche elettriche. Il secondo modello considerato viene elaborato per una maggior precisione, considera infatti anche gli effetti della temperatura sullo stato di carica, consiste in quattro parti, un generatore di tensione, resistenze interne di carica e scarica, un modello di predizione della temperatura e un unità di sovrapotenziale di concentrazione. Testando questo metodo su i modelli, si è rivelato in entrambi i casi robusto e affidabile, in grado di filtrare significativamente rumori di misura e processo

Phenacetin nephropathy.

This book is based on the idea that Boltzmann-like modelling methods can be developed to design, with special attention to applied sciences, kinetic-type models which are called generalized kinetic models. In particular, these models appear in evolution equations for the statistical distribution over the physical state of each individual of a large population. The evolution is determined both by interactions among individuals and by external actions. Considering that generalized kinetic models can play an important role in dealing with several interesting systems in applied sciences, the book provides a unified presentation of this topic with direct reference to modelling, mathematical statement of problems, qualitative and computational analysis, and applications. Models reported and proposed in the book refer to several fields of natural, applied and technological sciences. In particular, the following classes of models are discussed: population dynamics and socio-economic behaviours, models of aggregation and fragmentation phenomena, models of biology and immunology, traffic flow models, models of mixtures and particles undergoing classic and dissipative interactions