Personal health care services through digital television.

Personal health care has obtained increasing importance in the field of health care as the populations' age in the industrialised countries and resources available for health care remain limited. Personal health care through digital television is an exiting possibility in the realisation of new types of services answering to this demand for increased personal action and responsibility in health care. The possibilities of digital television in health care are studied in the Health Care Television (HCTV) research project of the Digital Media Institute at Tampere University of Technology. In this paper personal health care services are studied mainly from the perspective of the interactive service infrastructure of digital television. Firstly we present the general infrastructure of digital television and the different interactive service types of digital television. The usage of these service types in personal health care applications is also discussed. Finally, a web-based application based on chronic atrial fibrillation and its test use is presented. The application is used as a research platform for personal health care applications in digital television.

Inform: conceptual modelling of intensive care information systems.

Intensive care of a patient requires heavy monitoring and versatile therapeutic actions. These produce a huge amount of patient information. A problem exists in managing this data and other information from all supporting activities creating a need for an automated information management system. To have a sound basis for future automated information systems in intensive care unit (ICU), a conceptual model is created to cover both the clinical and other activities of the ICU. The conceptual model consists of data flow diagrams and entity-relationship diagrams with underlying common data dictionary. A modern CASE tool is utilized to build the model. The work forms a part of AIM-INFORM project, which has a purpose to develop information management and decision support systems for high dependency environment.

Blood pressure and heart rate variability and reactivity as related to daily activities in normotensive men measured with 24-h intra-arterial recording.

The effect of blood pressure and heart rate reactivity on respective variability in everyday life conditions was studied in a group of middle-aged, normotensive men (n = 22, mean age 39.3 years, range 35-45 years). Continuous intra-arterial tape recording was used to measure 24-h blood pressure and heart rate and the subjects completed a 24-h behavioural diary. The variability of blood pressure and heart rate was analysed using 30-s averages and cumulative distribution curves. The overall blood pressure and heart rate variability was calculated as the difference between the 90 and 10% levels of the cumulative distribution curves. Reactivity caused by different daily activities was calculated as the change from baseline level, defined as the 10% level determined from the cumulative distribution curve of waking hours. All regular activities were monitored. Large interindividual differences were found in variability and reactivity. The mean reactivity to different activities varied from 3.3 to 44.7 mmHg for systolic blood pressure, from 1.8 to 16.3 mmHg for diastolic blood pressure and from 2.0 to 46.0 beats/min for heart rate. The mean contribution of reactivity to variability varied between 21 and 74% for systolic blood pressure, from 19 to 58% for diastolic blood pressure and from 20 to 82% for heart rate. As expected, blood pressure and heart rate levels were significantly higher at work than at home. We conclude that the reactivity caused by daily activities has a pronounced influence on blood pressure level and variability during waking hours.

Do beta-adrenergic blockade and sleep state affect cardiorespiratory control in neonatal lambs? Multivariate autoregressive modeling approach.

Beta-Blockers are used in pregnancy-associated hypertension and in postnatal cardiac arrhythmias, and the neonate may get them in breast milk. We therefore studied the effects of beta-adrenergic medication on interrelations between heart rate (HR), respiration, and arterial blood pressure (aBP) in newborn lambs. The influence of sleep state on these cardiorespiratory interrelations was also examined. HR, aBP, and respiration (based on transthoracic electrical impedance) were recorded and the sleep state was visually documented in five healthy chronically instrumented newborn lambs before the age of 30 d. Propranolol was given (1 mg/kg). Two-min stationary segments of the three signals were analyzed using a multivariate autoregressive model, which yields oscillations of the signals and intersignal relationships as source contributions. The variabilities of aBP and HR were greatest at the low frequencies (less than 0.25 Hz) and so were their intersignal relationships (including baroreflex). The respiratory variability was greatest at the frequencies corresponding to the respiratory rate. During quiet sleep, the variabilities in HR, aBP, and respiration were lowest. The impact of respiratory oscillations on other signals increased but the impact of aBP variability decreased during quiet sleep. beta-Blockade and sleep state affected separately the cardiovascular and respiratory variables and their interrelations. beta-Blockade reduced HR and increased pulse pressure. The overall heart rate variability and the respiratory low-frequency contribution to heart rate variability decreased due to the beta-blockade. We postulate that the beta-adrenergic system is an important regulator of HR and HR variability in neonatal lambs and also of the low-frequency components of the respiratory sinus arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

INFORM: integrated support for decisions and activities in intensive care.

Many medical decision support systems that have been developed in the past have failed to enter routine clinical practice. Often this is because the developers have failed to analyse in sufficient detail the precise user requirements, because they have produced a system which takes too narrow a view of the patient, or because the decision support facilities have not been sufficiently well integrated into the routine clinical data handling activities. In this paper we discuss how the AIM-INFORM project is setting out to deal with these issues, in the context of the provision of decision support in the intensive care unit.

A data model for intensive care.

The paper describes a model of clinical management data in a typical general intensive care unit, intended as a generic database specification for advanced intensive care computer systems. The data model was developed as part of the INFORM project. The INFORM project is summarised and the relevance of the data model to the objectives of the project are discussed. An object oriented extension to the entity relationship diagram methodology is presented. The methodology is illustrated with reference to some specific aspects of the data model including: the principle clinical entities; classification of patient state related data and the homogeneous patient group system. It is suggested that such a model will contribute to the better understanding of the data in the system, to the better design of future intensive care computer systems and to the setting of standards for medical data.

INFORM: development of information management and decision support systems for High Dependency Environments.

The long-term aim in the INFORM Project is to develop, evaluate and implement a new generation of Information Systems for hospital High Dependency Environments (HDE-Intensive Care Units, Neonatal Units, Burns Units. Operating and Recovery Rooms, and other specialised areas). The distinguishing feature of the HDE is the very large amount of data that is collected through monitors and paper records about the state of critically ill patients; this has made the role of the staff a technical one in addition to a caring one. The INFORM System will integrate Decision Support with on-line, off-line and observed patient data and, in addition, will incorporate and integrate unit management features. In the Exploratory Phase of the Project, functional requirements have been set out. These are based on four components: conceptual model of the HDE; evaluation of existing HDE Information Systems; development of a novel software architecture using a Knowledge-Based Systems (KBS) methodology, and based on a critical review of KBS applied to the HDE: monitoring of appropriate leading-edge technological developments. The conceptual model has two components: a patient-related information model, and a department-related cost model. The patient-related model is identifying key and difficult areas of decision making. A key aspect of INFORM is integration of clinical Decision Support for these areas into the Information System through a layered software architecture. The lower layers are concerned with monitoring and alarming and the higher levels with patient assessment and therapy planning. The functionality and interconnection of these layers are being determined.

Short-term variability of systolic blood pressure and heart rate in normotensive subjects.

Short-term fluctuations in systolic blood pressure (SBP) and heart rate (HR) and their inter-relationship were analysed in a group of normotensive middle-aged men (n = 16) using a multivariate autoregressive modelling technique. This study is the first to evaluate the beat-to-beat variability of SBP and HR in a group of real normotensive subjects. Direct intra-arterial blood pressure was registered together with ECG using an ambulatory tape recording technique (the Oxford method). Power spectrum density estimated (PSD) were used as a measure of the variability. PSDs were calculated over 3-min periods for four basic physiological conditions: during sleep and in the supine, sitting and standing positions. The inter-relationship between the blood pressure and heart rate variabilities was analysed using a closed-loop model. In agreement with results presented earlier in the literature, the beat-to-beat variation in SBP and HR was concentrated in three typical power spectrum regions: the high-frequency (HF = 0.15-0.35 Hz) region (respiration), the mid-frequency (MF = 0.075-0.15 Hz) region (vasomotor oscillation) and the low-frequency (LF = 0.02-0.075 Hz) region (thermoregulation). The variability changes considerably between different situations, especially that of the MF region. The variability was most prominent in the MF region and in the standing position. The variability was generally smallest in the HF region and in sleep. The results also demonstrate that the beat-to-beat variability in SBP and HR can considerably affect one another.

Effects of skating and diagonal skiing techniques on results and some physiological variables.

In this study, the effects of skating and diagonal techniques on skiing load at various speeds were compared. When skiing at the same speed, subjects' heart rates were significantly lower when using the skating technique than when using the diagonal technique (p less than 0.05). At maximal speed, skating technique gave a significantly higher speed at the same heart rate (p less than 0.001) than diagonal technique. Above the anaerobic threshold (4 mmol.L-1) blood lactic acid levels remained significantly lower (p less than 0.005) when using the skating technique than when using the diagonal technique. The results suggest that at the same speed, skating technique loads aerobic and anaerobic energy production less than diagonal technique, and that the same maximal energy production gives a significantly higher skiing speed when using the skating technique than when the diagonal technique (p less than 0.001).

Multivariate autoregressive modeling of autonomic cardiovascular control in neonatal lamb.

The neonatal cardiovascular control system is a complicated interactive system which is under vigorous development at birth. From the measurement point of view the cardiovascular control is a closed-loop system. However, it can be examined on a beat-by-beat basis by analyzing circulatory-controlled variables with advanced signal analysis techniques. This paper proposes to use a multivariate autoregressive modeling technique in the analysis of several simultaneous physiological signals in order to examine interactions and inherent properties in the system. With the proposed multivariate autoregressive modeling technique, a signal is modeled as a linear combination of its own past and the past values of the other simultaneous signals plus a predictive error term of the model. The interactions in the system after the model identification are analyzed in frequency domain utilizing power spectrum estimates of the signals and signal contributions. The applicability of the proposed method was examined by a three-variable model between heart rate, blood pressure and respiration in the study of autonomic cardiovascular control in a chronic neonatal lamb model, in which the cardiovascular status was changed by using a beta-adrenergic autonomic nervous blockade. The study showed that the multivariate autoregressive modeling technique is a feasible technique in studying complicated interactions within the cardiovascular control system.

Blood pressure level changes caused by posture change and physical exercise: can they be determined accurately using a standard cuff method?

The accuracy of the indirect standard cuff method of measurement was tested against intra-arterial blood pressure readings (Oxford method) in a series of simple clinical tests: in the sitting, supine and standing positions, during bicycle ergometer test and during recovery. The mean discrepancy between methods varied in tests from -2.3 to 12.9 mmHg for systolic blood pressure level and from -4.3 to 18.2 mmHg for diastolic blood pressure level. Blood pressure responses to other tests were analysed using the value measured in the sitting position as the reference. The mean discrepancy between the methods in test responses varied from -6.3 to 8.9 mmHg for systolic responses and from -2.3 to 20.3 mmHg for diastolic responses. The data analysis indicates that the accuracy of the indirect method varies considerably between tests and also between subjects. We conclude that at present the standard cuff method cannot replace the direct method for determining blood pressure responses and reactivity.

Diurnal blood pressure profiles and variability in normotensive ambulant subjects.

The 24-hour variability in blood pressure and heart rate of 14 normotensive subjects was examined under ambulatory conditions with a continuous, invasive method. The results were analysed with 30-second means calculated from beat-to-beat values. The registered time series had three different types of variation: (1) a continuous, fast variation around the mean level; (2) a stepwise, permanent change to a new level; and (3) a slow, continuous rise or fall. Variability in blood pressure and heart rate was determined by the 80 percent range of variation calculated from the cumulative distribution as the difference between the 90th and 10th percentiles. The variability in blood pressure and heart rate was significantly greater during waking hours than during night-time. Variability followed a similar type of diurnal profile as the mean level. However, variability of diastolic pressure changed to a lesser extent than that of systolic pressure. Total 24-hour variability was on average 45 mmHg in systolic blood pressure, 24 mmHg in diastolic pressure and 40 b.p.m. in heart rate. Using night-time to describe the basal state, physical and mental activities in the evening and during daytime were found to raise variability in systolic pressure with 66%, diastolic with 8-16% and heart rate with 130-180%, respectively. The results show that in normotensive subjects the sleep-wake state and activity are the major factors that affect both the diurnal profile and the variability in blood pressure and heart rate.