Ewart R. Carson

A model-based approach to insulin adjustment

A differential equation model of carbohydrate metabolism was implemented in the form of a causal probabilistic network. This permitted explicit represen-tations of the uncertainties associated with model based predictions of 24-hour blood glucose profiles. In addition, the implementation gave automatic learning and adjustment of model parameters based on measured blood glucose profiles. Insulin therapy was adjusted using a decision theoretical approach. Losses were assigned to blood glucose values that deviated from normal, and the insulin therapy was adjusted to minimize the expected total loss. The system was tested retrospectively on cases from 12 insulin dependent patients and seemed to compare favourably with clinical practice.

Time series analysis and control of blood glucose levels in diabetic patients

This paper describes features of a computer-based decision support system which is being developed to assist in the management of insulin-dependent diabetic patients. The clinical context is the provision of advice on the adjustment of the basic insulin regimen such as occurs at regular visits to the clinician. The integrated system combines data processing and interpretation, generation of qualitative advice and testing the implications of that advice using a glucose/insulin dynamic simulator. The two major features described in this paper are time series analysis of blood glucose data, and their interpretation in relation to the provision of advice for controlling the patients blood glucose level. It is demonstrated that two approaches may be adopted in such time series analysis: an intuitive approach, manipulating symbolic representations of the data, and formal time series methods which decompose the series into clinically related components.

Design, implementation and preliminary evaluation of a telemedicine system for home haemodialysis.

A telemedicine system for home haemodialysis was designed using a systems approach and a feedback model to produce the hardware and software specifications. Preliminary clinical trials at four European locations involved 29 patients and 305 sessions of haemodialysis. The evaluation included an evaluability assessment and formative evaluation. Central to the methodology was the detailed specification of a stakeholder/evaluation criterion matrix. Preliminary results indicated that the telemedicine system was capable of satisfying the requirements of formative evaluation as a precursor to evaluating its overall worth.

A Metabolic Prototype to Assist in the Management of Insulin-Treated Diabetic Patients

A prototype computer system has been developed to provide advice on the day-to-day adjustment of carbohydrate intake and insulin regimen in the diabetic patient. The prototype is intended to be used as a decision support system by clinical personnel in the context of day-to-day management of insulin-treated diabetic patients. It is designed for use during consultations, as a simulator of patient response following changed insulin and dietary regimen and as a system to provide education on planning insulin therapy. Advice is generated by a qualitative knowledge based system (KBS) which suggests what the next step in improving glycaemic control might be for a given patient, e.g. ‘decrease evening medium-acting insulin’. A model of glucose-insulin interaction has been developed to stimulate the effects of these adjustments on the patient’s blood glucose profile.

Modelling and control in biomedical systems

Modelling and Control in Biomedical Systems (including Biological Systems) was held in Reims, France, 20-22 August 2006. This Symposium was organised by the University of Reims Champagne Ardenne and the Societe de l’Electricite, de l’Electronique et des TIC (SEE). The Symposium attracted practitioners in engineering, information technology, mathematics, medicine and biology, and other related disciplines, with authors from 24 countries. Besides the abstracts of the four plenary lectures, this volume contains the 92 papers that were presented by their authors at the Symposium -- publisher

Clinical Assessment of a Computer System for Insulin Dosage Adjustment

A computer system has been developed to provide advice on the day-to-day adjustment of carbohydrate intake and insulin regime in the diabetic patient. The prototype is intended to be used as a decision support system by clinical personnel in the context of day-to-day management of insulin-treated diabetic patients. It is designed for use during consultations, as a simulator of patient response following changed insulin and dietary regime and as a system to provide education on planning insulin therapy. Advice is generated by a qualitative knowledge based system which suggests what the next step in improving glycaemic control might be for a given patient, e.g. ‘decrease evening medium-acting insulin’. A clinical model is being developed to allow predictions of the patient’s blood glucose profile to be generated based on these adjustments. Clinical scenarios taken from postgraduate teaching cases have been used to compare the advice given by the computer with that of four independent diabetologists. The results of seven case studies are presented.

A Validation Methodology for Testing Decision-Support Systems for Insulin Dosage Adjustment

A medical validation protocol has been developed to test three decision-support systems in the management of insulin-dependent diabetic patients. The systems have been chosen as representative of the range of computational strategies recently reported and the protocol is designed to compare their relative merits directly using retrospective data, before planning full, clinical evaluations. In particular, the protocol allows computer advice on insulin therapy adjustments to be compared with that provided by the individual clinician acting in the clinic, or acting independently on recorded data alone, as well as comparing computer advice with a consensus view of a group of clinicians. It is sufficiently flexible to match available clinical resources, incorporating statistical and domain-specific checks to ensure that staff and time are used appropriately. The new validation protocol is considered a fairer and more informative test for decision-support systems in a domain that has as yet few rigid standards for information technology and is characterised. By performing a strictly controlled clinical trial to test the efficacy of a new proposed treatment. It is, therefore, considered appropriate for use in other areas of chronic health care.

Challenges for measurement science and measurement practice: the collection and interpretation of home-monitored blood glucose data

In insulin-dependent diabetes mellitus, home monitoring of blood glucose was a major breakthrough in the empowerment of patients and for the first time provided raw data of sufficient accuracy from which to infer insulin therapy adjustments. Typically recorded on paper, such data are often illegible, lack details of measurement times and insulin doses and omit contextual information on diet, behaviour and general health. Home meter technology is offering improved access to patient data and allowing a more flexible range of variables to be recorded. Psychometric questionnaires give a broader view of individual and patient group perceptions of the disease and its treatment. This paper reports on early studies of home data collection using the Accutrend DM meter and the Diabetes Quality of Life and Treatment Satisfaction Questionnaires. It also describes a prototype computer system for interpreting data collected with such meters and advising on insulin dosage adjustment, based primarily on principles of time series analysis together with mathematical models of insulin profiles and search algorithms.

A Causal Probabilistic Network Model Of Carbohydrate Metabolism For Insulin Therapy Adjustment

A differential equation model of carbohydrate metabolism was implemented in the form of a causal probabilistic network. This permitted explicit representations of the uncertainties associated with model based predictions of 24-hour blood glucose profiles. In addition the implementation gave automatic learning and adjustment of model parameters based on measured blood glucose profiles.Insulin therapy was adjusted using a decision theoretical approach. Penalties were assigned to blood glucose values that deviated from normal, and the insulin therapy was adjusted to minimize the expected Occurrence of penalties.

DEALING WITH BIO- AND ECOLOGICAL COMPLEXITY: CHALLENGES AND OPPORTUNITIES: “Status report prepared by the IFAC Coordinating committee on Bio- and Ecological Systems”

Abstract The complexities of the dynamic processes and their control associated with biological and ecological systems offer many challenges for the control engineer. Over the past decades the application of dynamic modelling and control has aided understanding of their complexities. At the same time using such complex systems as test-beds for new control methods has highlighted their limitations (e.g. in relation to system identification) and has thus acted as a catalyst for methodological advance. This paper continues the theme of exploring opportunities and achievements in applying modelling and control in the bio- and ecological domains.