The MADE Reference Information Model for Interoperable Pervasive Telemedicine Systems.

OBJECTIVES: The main objective is to develop and validate a reference information model (RIM) to support semantic interoperability of pervasive telemedicine systems. The RIM is one component within a larger, computer-interpretable "MADE language" developed by the authors in the context of the MobiGuide project. To validate our RIM, we applied it to a clinical guideline for patients with gestational diabetes mellitus (GDM). METHODS: The RIM is derived from a generic data flow model of disease management which comprises a network of four types of concurrent processes: Monitoring (M), Analysis (A), Decision (D) and Effectuation (E). This resulting MADE RIM, which was specified using the formal Vienna Development Method (VDM), includes six main, high-level data types representing measurements, observations, abstractions, action plans, action instructions and control instructions. RESULTS: The authors applied the MADE RIM to the complete GDM guideline and derived from it a domain information model (DIM) comprising 61 archetypes, specifically 1 measurement, 8 observation, 10 abstraction, 18 action plan, 3 action instruction and 21 control instruction archetypes. It was observed that there are six generic patterns for transforming different guideline elements into MADE archetypes, although a direct mapping does not exist in some cases. Most notable examples are notifications to the patient and/or clinician as well as decision conditions which pertain to specific stages in the therapy. CONCLUSIONS: The results provide evidence that the MADE RIM is suitable for modelling clinical data in the design of pervasive telemedicine systems. Together with the other components of the MADE language, the MADE RIM supports development of pervasive telemedicine systems that are interoperable and independent of particular clinical applications.

Evaluation of a computer program for non-invasive determination of pulmonary shunt and ventilation-perfusion mismatch.

We describe a three-compartment model (shunt and two perfused compartments) to analyse the relationship between inspired oxygen (FIO2) and arterial oxygen saturation (SaO2) in terms of pulmonary shunt and ventilation-perfusion ratio (VA/Q). The program was tested using 24 exact datasets, each with six pairs of FIO2 and SaO2 data points with known VA/Q and shunt, generated by a complex calculator of gas exchange. Additional datasets were created by adding noise and rounding the exact sets, and by reducing the number of data points per dataset. The importance of the oxyhaemoglobin dissociation curve and the arterio-venous difference in oxygen content (avDO2) were also tested. Analysis using the three compartment model was more accurate than the two compartment model and less affected by data degradation. The absolute error in shunt estimation was never more than 2.2 % for the exact and rounded datasets, but the error in VA/Q estimation was -29 to 19 % of the true value (10th-90th centiles). The characteristics of the well-ventilated compartment were not determined accurately. At extremes of cardiac output, an assumed value of avDO2 resulted in significant errors. It is probably advantageous to correct for foetal haemoglobin in neonatal datasets. Analysis of FIO2 versus SaO2 datasets using a three compartment model provides accurate estimates of shunt and VA/Q when arterio-venous difference in oxygen content is known. The estimates may have value as objective measures of gas exchange, and as a visual guide for oxygen therapy.