Experimentally-guided development of a sensor for pleural cavity pressure sensing.

The precise monitoring of the intrapleural pressures, necessitates the development of a specific instrumental approach to select the correct shape, dimensions and material to implement the sensing balloon which will be inserted into the pleural cavity. We demonstrate that a 10 cm diameter disk, printed with filaments of TPU (Thermoplastic polyurethane) with hardness 92A offers the best compromise in terms of static sensitivity (0.28 mV/cmHg) and dynamic frequency response (48 Hz).

Automatic detection of falling of the elderly subject among his daily activities.

Most elderly patients after falling, being not able to rise up or call for help, are particularly at risk of complication. This urges for the development of autonomous devices for earliest detection of falls. This paper is an overview of the current design approaches to autonomous fall detectors - sensors and algorithms- and a methodology to assess their efficiency. We then propose our fall sensor, which features high sensitivity (95%) and specificity (99%) on simulated falls in lab settings, and lower sensitivity (62.5%) in real settings in a group of 10 patients, with 8 falls detected over a period of 28 days.

Comparison of pleural and esophageal pressure in supine and prone positions in a porcine model of acute respiratory distress syndrome.

Patients with moderate to severe acute respiratory distress syndrome (ARDS) benefit from prone positioning. Although the accuracy of esophageal pressure (Pes) to estimate regional pleural pressure (Ppl) has previously been assessed in the supine position, such data are not available in the prone position in ARDS. In six anesthetized, paralyzed, and mechanically ventilated female pigs, we measured Pes and Ppl into dorsal and ventral parts of the right pleural cavity. Airway pressure (Paw) and flow were measured at the airway opening. Severe ARDS [arterial partial pressure of oxygen ([Formula: see text])/fraction of inspired oxygen ([Formula: see text]) < 100 mmHg at positive end-expiratory pressure (PEEP) of 5 cmH2O] was induced by surfactant depletion. In supine and prone positions assigned in a random order, PEEP was set to 20, 15, 10, and 5 cmH2O and static end-expiratory chest wall pressures were measured from Pes (PEEPtot,es) and dorsal (PEEPtot,PplD) and ventral (PEEPtot,PplV) Ppl. The magnitude of the difference between PEEPtot,es and PEEPtot,PplD was similar in each position [-3.6 cmH2O in supine vs. -3.8 cmH2O in prone at PEEP 20 cmH2O (PEEP 20)]. The difference between PEEPtot,es and PEEPtot,PplV became narrower in the prone position (-8.3 cmH2O supine vs. -3.0 cmH2O prone at PEEP 20). PEEPtot,PplV was overestimated by Pes in the prone position at higher pressures. The median (1st-3rd quartiles) dorsal-to-ventral Ppl gradient was 4.4 (2.4-6.8) cmH2O in the supine position and -1.5 (-3.5 to +1.1) cmH2O in the prone position (P < 0.0001) and marginally influenced by PEEP (P = 0.058). Prone position narrowed end-expiratory dorsal-to-ventral Ppl vertical gradient, likely because of a more even distribution of mechanical forces over the chest wall.NEW & NOTEWORTHY In a porcine model of acute respiratory distress syndrome, we found that static end-expiratory esophageal pressure did not change significantly in prone position compared with supine position at any positive end-expiratory pressure (PEEP) tested between 5 and 20 cmH2O. Prone position was associated with an increased ventral pleural pressure and reduced end-expiratory dorsal-to-ventral pleural pressure (Ppl) vertical gradient, likely due to a more even distribution of mechanical forces over the chest wall.

Comparison of methods for the evaluation of NIBP from pulse transit time.

Non-invasive blood pressure measurement (NIBP) is one of the most discussed topic in cardiovascular medicine. Currently continuous measurement of blood pressure is possible by invasive methods, which makes the measurement impractical for Doctors and uncomfortable for the patients. It is possible to use special devices to measure blood pressure noninvasively continuously but there are still some problems with long time monitoring and comfort for patient. Physiologically there is connection between electrical and mechanical heart functions, propagation of pulse wave and blood pressure value. Our paper investigates various methods for the evaluation of NIPB from pulse transit time. We analyse real signals which we obtained during surgical interventions in Hospital, with invasive measurements of blood pressure waves, and non-invasive measurements of pulse waves and ECG signal.

A portable heat flux sensor.

Nowadays monitoring physiological signals in real situations is essential to get the best diagnosis on patients. In this study we focus on the heat flux generated by the human body. We are developing a portable heat flux sensor using specific thermal materials.

Computer simulation of the activity of the elderly person living independently in a Health Smart Home.

We propose a simulator of human activities collected with presence sensors in our experimental Health Smart Home "Habitat Intelligent pour la Sante (HIS)". We recorded 1492 days of data on several experimental HIS during the French national project "AILISA". On these real data, we built a mathematical model of the behavior of the data series, based on "Hidden Markov Models" (HMM). The model is then played on a computer to produce simulated data series with added flexibility to adjust the parameters in various scenarios. We also tested several methods to measure the similarity between our real and simulated data. Our simulator can produce large data base which can be further used to evaluate the algorithms to raise an alarm in case of loss in autonomy.

Evaluation under real-life conditions of a stand-alone fall detector for the elderly subjects.

BACKGROUND AND OBJECTIVES: Elderly patients unable to get up after a fall or to activate an alarm mechanism are particularly at risk of complications and need to be monitored with extreme care. The different risk factors have fostered the development of stand-alone devices facilitating early detection of falls. We aimed at assessing performance of the Vigi'Fall(®) system, a cutting edge fall detector associating a "passive release" mechanism attached to the patient and including external sensors; in the event of a fall, the system automatically triggers an alarm, and it also incorporates embedded confirmation software. We have put it to the test under real-life conditions so as to evaluate not only its efficacy, but also and more particularly its acceptability and tolerability in elderly subjects. METHOD: The study ran from March 2007 through December 2008 in a geriatric ward with 10 subjects over 75 years of age, all of whom presented with a risk of falling. RESULTS: For eight patients wearing an accelerometric sensor, eight "falling" events and 30 "alarm release" events were recorded. Sensitivity and specificity of the device came to 62.5 and 99.5% respectively. For the two patients wearing the complete device, no events were detected. Not a single adverse occurrence was noted. Local tolerance was excellent in all but one of the subjects. CONCLUSION: Our results clearly show that the device may be worn by patients without discomfort over prolonged periods of time, and also demonstrate that the verification component will help to increase sensitivity in real-life conditions to a level comparable to the level attained in our laboratory studies.

Use of electrical devices reveals our well being.

We want to objectivize the level of activity of elderly persons living independently at home. Most existing monitoring systems are intrusive and/or require a large number of sensors. We hope the "ubiquitous computing" concept could find an application in this context. We proposed to monitor the use of electrical appliances. We built a unique "activity indicator" which integrates all the activities of the person. This was assessed during 6 months within 12 flats occupied by single elderly persons.

Sound and speech detection and classification in a Health Smart Home.

Improvements in medicine increase life expectancy in the world and create a new bottleneck at the entrance of specialized and equipped institutions. To allow elderly people to stay at home, researchers work on ways to monitor them in their own environment, with non-invasive sensors. To meet this goal, smart homes, equipped with lots of sensors, deliver information on the activities of the person and can help detect distress situations. In this paper, we present a global speech and sound recognition system that can be set-up in a flat. We placed eight microphones in the Health Smart Home of Grenoble (a real living flat of 47m(2)) and we automatically analyze and sort out the different sounds recorded in the flat and the speech uttered (to detect normal or distress french sentences). We introduce the methods for the sound and speech recognition, the post-processing of the data and finally the experimental results obtained in real conditions in the flat.

Identification of inactivity behavior in smart home.

To help elderly people live independently at home, the TIMC-IMAG laboratory developed Health Smart Homes called 'HIS'. These smart Homes are composed of several sensors to monitor the activities of daily living of the patients. Volunteers have accepted to be monitored during 2 years in their own flats. During one year, we carried out our survey on one elderly patient. Thanks to this experimentation, we will access to relevant information like physiological, environmental and activity. This paper focuses on daily living activity. We will introduce an original data splitting method based on the relationship between the frame of time and the location in the flat. Moreover we will present two different methods to determine a threshold of critical inactivity and eventually we will discuss their possible utilities.

Preliminary investigation into the use of Autonomous Fall Detectors.

A study was realized in France to meet the requirements of an autonomous fall sensor worn on the body. It consisted of a written questionnaire of which 149 were returned completed, which reveals that users are favorable to the use of a portable fall detector, worn like a watch, all through their daily activities, with a special wish for an audio feed back of the correct activity and, moreover, are ready to pay for the service on a monthly rate basis.

Level of activity, night and day alternation, and well being measured in a smart hospital suite.

The present paper reports a study on the daily activity of elderly people in a hospital suite, with presence infrared sensors. It is an attempt to produce parameters and indicators for the predictive analysis of the daily activity of fragile persons. A relationship is proposed between well being of the patient and the night and day activities alternation.

Fall detection--principles and methods.

Fall detection of the elderly is a major public health problem. Thus it has generated a wide range of applied research and prompted the development of telemonitoring systems to enable the early diagnosis of fall conditions. This article is a survey of systems, algorithms and sensors, for the automatic early detection of the fall of elderly persons. It points out the difficulty to compare the performances of the different systems due to the lack of a common framework. It then proposes a procedure for this evaluation.

A fast algorithm to track changes of direction of a person using magnetometers.

Technological advances in signal processing and in circuits integration offer numerous perspectives in telemedicine and telemonitoring. Considering the increase of life expectancy, accurate and reliable assessement of modification and/or deterioration in the health status of a person is needed. One possible indicator is the "activity index" of a person. To compute such an index, previous studies have used accelerometers. Although these sensors are appropriate for the detection of postural transitions (e.g. Sit To Stand and Stand To Sit), they do not allow to detect changes of direction of a walking individual insofar as such activity occurs in a constant gravitation field. Within this context, the purpose of the present work is to investigate whether magnetometers can be used to monitor the changes of direction of a person.

Ambient multi-perceptive system with electronic mail for a residential health monitoring system.

Based on several years of experiments, we propose a model of information systems for residential healthcare, and technical guide to select available hard and software technologies. An implementation is described, based on Emails. The system is under experimentation within the framework of the French national project AILISA.

VTAMN--a smart clothe for ambulatory remote monitoring of physiological parameters and activity.

The prototype of a communicating underclothe for medical remote monitoring was realized. It delivers physiological information on the subject (Cardiac Frequency, Breathing Frequency, surface and mid-temperature) as well as the environment and activity parameters (ambient temperature, fall detection). It also enables the automatic data transfer on event, with the localization of the subject.

ACTIDOM--a microsystem based on MEMS for activity monitoring of the frail elderly in their daily life.

A "ambulatory activity recorder" was developed, with 3 accelerometers and 3 magnetometers, to detect and qualify the elementary activities of a person, such as walking and transfers. The signal processing is explained, along with the preliminary results obtained on young and older healthy subjects. This work open the way to continuous and automatic monitoring of the level of mobility.

Telemonitoring of vital parameters with newly designed biomedical clothing.

The paper describes the development of biomedical clothing for ambulatory telemonitoring of human vital parameters. VTAM (Vetement de Tele-Assistance Medicale) presents a T-shirt made from textile with woven wires and incorporating four smooth dry ECG electrodes, a breath rate sensor, a shock/fall detector and two temperature sensors. The garment is equipped for the signal pre-computing and transmission through a miniature GSM/GPRS module kept on a belt together with the power supply. Three VTAM prototypes have been tested on persons in a normal state of health using a medical protocol to assess the biomedical data that include an ECG reading, a pneumogram, temperature and fall detection in mobile situations.

An experimental health smart home and its distributed internet-based information and communication system: first steps of a research project.

We present a study and whole experimental tele-monitoring and medical tele-surveillance system for maintaining patients at home. The project features networked sensors, in a fully equipped apartment, operated by an advanced information and communication system based on Internet, Java, and object oriented modeling. The sensors are connected, mainly wirelessly, with a in-home software module devoted to signals analysis and detection of critical situation such as falls, sickness, sudden palsy, stroke, hypothermia, etc. This module communicates, either via modem or ethernet network, with a remote medical control station in charge of appropriate response to received information and alarms. The system is designed to be a powerful information and communication tools for medical and social workers. It offers a series of functions such as medical file management, user profiles and rights management, drafting and management of ordinances and visit notes, confidentiality of medical information, and management of scenarios of detectable events. The access to the system is allowed to authorized users only (physicians, emergentists, social workers, etc.), and is available on as much authorized computers as needed, by means of a Java applet invoked from any traditional web browsers.