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A physiologically-based approach to model-predictive control of anesthesia and analgesia
No full textThe application of closed-loop control systems in biomedicine unlocks prospects for optimized drug delivery based on the measurement of patients’ physiological variables. However, inter-individual variability and narrow therapeutic indexes are issues that must be carefully considered. We propose an in silico study of a model-based controller of anesthesia and analgesia with propofol and remifentanil, based on bispectral index (BIS) and mean arterial pressure (MAP) measurements. A physiologically-based pharmacokinetic (PBPK) model, combined with a suitable pharmacodynamic model, allows describing and differentiating the dose-effect dependency for the virtual patients. The controller delivers a safe and fast induction of anesthesia, with mean rise times below 3 min and controlled variables within the clinical safe ranges. The PBPK model allows gaining complementary information about the dynamics of the drugs absorption, distribution, metabolism, and elimination in the body. Special attention is devoted to simulate realistic intraoperative surgical stimuli and noise on the controlled variables. The controller successfully rejects disturbances on BIS and MAP related to nociceptive stimuli (e.g., intubation and incision) via a robust control action, and is not diverted by noise
Control strategies in general anesthesia administration
No full textEvery year, 230 million anesthetic procedures take place worldwide. Advances in technology and medicine have not yet been able to eradicate risks of mortality and major complications associated to anesthesia. Medication errors, overdose, and adverse effects often lead to such undesired events. Today, the procedure of anesthesia administration relies greatly on the anesthetists' experience and subjective interpretation of the patient response to drugs and surgical stimuli. Interpatient variability and narrow therapeutic ranges of drugs represent further difficulties to the selection of the optimal drug dose.The introduction of control systems in several fields of human life has resulted in improved performances and safety levels, and lower costs. We believe that these effects can be extended to general anesthesia administration.This chapter compares the state of the art in anesthesia delivery with closed-loop control of intravenous anesthesia and discusses different strategies employed by researchers. Among these, special focus is devoted to the advantages of model-predictive control. Afterwards, model-predictive control application to anesthesia coadministered with propofol and remifentanil is proposed and analyzed. Physiologically based pharmacokinetic modeling allows achieving an increased level of individualization for the response prediction, which is a primary issue because of interindividual variability of patients. Finally, we provide a short discussion on the ethical problem that comes with the application of control systems in this field
Physiologically-based pharmacokinetic simulations in pharmacotherapy: selection of the optimal administration route for exogenous melatonin
Get PDFThe benefits of melatonin on human body are drawing increasing attention from several researchers in different fields. While its role as cure for sleep disturbances (e.g., jet lag, insomnia) is well documented and established, new functions in physiological and pathophysiological processes are emerging. To investigate these effects, there is need for the characterization of melatonin transport processes in the body and resulting pharmacokinetics. Although recent works propose physiologically-based pharmacokinetic modelling of melatonin, no work has yet highlighted the potential of PBPK simulations to shed light on melatonin pharmacokinetic aspects and discrimination among administration routes. This paper presents, validates, and discusses a versatile PBPK model featuring different ways of administration and compares the resulting pharmacokinetic profiles of intravenous, oral, and transdermal administration, with the goal of understanding which is the optimal route to achieve either physiological and/or supraphysiological melatonin levels
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Straining, lavoro e tratti di personalità. Uno studio pilota in una azienda ospedaliera
No full textVariations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Community Mapping for Participatory Decision-Making Processes
No full textCommunity mapping is being increasingly used to support crowdsourcing in participatory decision-making processes but the collection of feed-back is usually carried out in textual form. We describe a proposal for the management of 3D Community Maps which provide a virtual representation of the territory and enable users to contribute to policy making by sharing different types of contributions, such as comments, documents and 3D models. The paper discusses user requirements and personalization aspects in this type of application
An engineering oriented approach to physiologically based pharmacokinetic and pharmacodynamic modeling
No full textPharmaceutical industry and regulatory agencies consider mathematical modeling as a valuable tool to increase the productivity of pharmaceutical research and the efficiency of new drug development processes. This chapter provides an engineering-oriented approach to the definition of pharmacokinetic and pharmacodynamic models with the target of covering and meeting the directives of quantitative systems pharmacology. In particular, we extensively discuss the use of physiologically based pharmacokinetic models and the coupling with alternative versions of pharmacodynamic models. Model designs and the derived equations are critically engaged with a multidisciplinary perspective to acknowledge both anatomical/physiological consistency and mathematical correctness, including model-identifiability issues and parameters-uncertainty assessment. The purpose is to provide a general framework for engineers and pharmaceutical scientists approaching this discipline
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