Localised impedance monitoring device for the remote clinical assessment of home-based dialysis patients

BioImpedance Spectroscopy (BIS) has been clinically used to determine the hydrational status of patients undergoing haemodialysis (HD). In the present project we are developing a calf-localised, integrated impedimetric device to periodically and conveniently measure and transmit information on the hydrational status of home-based patients to a remote clinic. Surprisingly, we have found that simple postural changes before or during measurement lead to significant fluid shifts in the lower leg that are as important and as long lasting as the effects of haemodialysis. These must be taken into account if potentially hazardous errors are not to be made in assessing a patient's hydrational status.

Physiological and behavioural changes associated to the management of secondary tasks while driving

Sharing attention between two tasks requiring the same mental resources is supposed to increase the resulting strain. Phoning while driving may elicit cognitive interference between driving operations and conversation and consequently, may affect driving efficiency. The road scene cues may thus be perceived late or even omitted, increasing the probability to be involved in a critical situation. The aim of the experiment was to study how the additional strain elicited by a secondary task may change drivers' arousal with potential consequences on driving performance. Electrodermal activity, heart rate and reaction time (RT) were the dependent variables. Listening to the radio, holding an in-vehicle or a cell-phone conversation were the secondary communication tasks, performed by 10 participants during a driving sequence on a private circuit. Within nominal driving, each communication task was requested at random to prevent any habituation or anticipation. The cell-phone conversation made RT increase by about 20%, by comparison to the nominal driving condition. Nevertheless, the in-vehicle conversation impacted RT almost in the same proportion. Physiological data showed that arousal level increased as a function of dual-tasks requirements, the in-vehicle conversation eliciting the same strain as the remote conversation. With caution due to contextual differences between these two communication tasks, conversing with a passenger was thus as detrimental as using a cell-phone.

An integrated platform to assess driver's physiological and functional states

Physiological signals like Heart Rate, Respiration and Skin Resistance are relevant indicators to evaluate driver's mental state. Therefore, most methods based on physiological signals measurements have been improved on driving simulators or in experimental laboratories under carefully controlled conditions and rigorous protocols. To study driver's behavior in actual conditions, we have developed an in-vehicle system which could record contextual driving information, drivers' actions and physiological signals related to them. Recordings from the driver and the vehicle may give valuable information for a close estimation of driver's functional state, its evolution across time and thus a better understanding of driver's behavior. This system provides specific patterns related to the driver's functional state, according to the driving context. This paper is aimed to present the design and implementation of this system, well adapted to ergonomics.