Development of a fully automated network system for long-term health-care monitoring at home

Electrodes array for contactless ECG measurement of a bathing person - a sensitivity analysis

An applicability of a remote (contactless) electrocardiogram (ECG) measurements in a bathtub is presented in the paper. Possibility of ECG measurements in shallowly filled tube with a water was examined. A bathing person was, both, sitting and lying during experiments performed. The problem became non-trivial when the bathing person was moving in reference to a fixed set of electrodes and located at the longer walls of the bathtub. However, the results obtained indicate that the sensitivity of a developed electrode array could enable such measurements. However, a spatial sensitivity distribution determines, both, the recorded ECG signal parameters and quality.

Measurement of electrocardiograms in a bath through tap water utilizing capacitive coupling electrodes placed outside the bathtub wall

BACKGROUND

Taking a bath sometimes poses a risk for subjects with chronic cardiopulmonary disorders, due to the thermal effect and water pressure on his/her body. The ECG measurement would be helpful for the early recognition of abnormal cardiac beats and respiratory conditions. This paper describes a new attempt to improve on previous bathtub ECG measurement techniques that had electrodes placed inside the bathtub that were intrusive to the subjects' bathing experience. This study is concerned with the initial development of a method to measure an electrocardiogram (ECG) through tap water without conscious awareness of the presence of electrodes that are placed outside the bathtub wall.

METHODS

A configuration of capacitive coupling electrodes placed outside the bathtub was designed so that the electrodes could be hidden. The capacitive coupling was made from the electrodes to the water through the bathtub wall. Two electrodes with an active shielding amplifier covered further by an electromagnetic shield were fixed to the outside surface of the bathtub wall, near the bather's right scapula and left foot. The potential difference between these two electrodes, similar to the bipolar lead-II ECG, was amplified to obtain raw signals inclusive of ECG/QRS components. Respiration intervals were also derived from ECG/RR intervals. Comparison experiments between this bathtub method and conventional direct methods with spot-electrodes and a chest-band sensor were made using 10 healthy male volunteers (22.2 ± 0.98 years).

RESULTS

The ECG signal was detectable through tap water as well as water with differing conductivity resulting from mixing bathwater additives with the water. ECG signals and respiration curves derived from ECG/RR intervals were successfully obtained in all subjects. The intervals of the ECG/RR and respiration obtained by the bathtub system and by the direct method were respectively agreed well with each other.

CONCLUSION

The ECG signal, in particular ECG/QRS components, were successfully detected utilizing capacitive coupling electrodes placed outside the bathtub wall. Also, the ECG/RR and respiration intervals were determined with reasonable accuracy as compared with the conventional direct methods.

Development of a network system combined with ambulatory and non-conscious physiological measurements for supporting challenged kids - a new proposal of a gait monitoring system for use in rehabilitation

Various physiological measurement techniques have been developed to support healthcare and daily living of adult including elderly. However, in light of the rapid growth of the declining birth rate, promotion in care and life support for children are not enough. Especially in rehabilitation for disabled children, i.e., challenged kids, it is important for therapist to evaluate the efficacy of rehabilitation and the health condition. Share of these information with educational, welfare, and government institutions are also needed for accurate life support. Therefore, the quantitative data of the activities and daily health status are helpful. From these viewpoints, we are developing a new network system for monitoring the activities and the health status of children using ambulatory and non-conscious physiological measurements as well as data browse at anytime and anywhere. Firstly, we propose a wearable gait monitoring system to support evaluation for the efficacy of rehabilitation. In this study, the present system can successfully detect the characteristics of postural changes in children with disorder of movement, demonstrating its usefulness and availability to the evaluation for the effect of the brace attached to the subject's lower limb.

In the Spotlight: BioInstrumentation

This review briefly introduces three topics from recent publications in this field. These are: 1) new concepts of measurement methods; 2) noteworthy improvements of existing methods; and 3) feasible applications of bioinstrumentation.

A system for monitoring cardiac vibration, respiration, and body movement in bed using an infrared

We have developed a non-invasive system for monitoring cardiac vibrations, respiration and body movement of in-bed hospitalized patients and elderly people who need constant care. These physiological parameters are recorded by an infrared emitting diode and a photo transistor, which are attached between spring coils in bed mattress. The infrared emitting diode diffuses infrared light into the mattress. The diffusion of this energy is changed by mattress shape variations and spring coil vibrations, which modulate the intensity of the received infrared signal. The intensity is also modulated by physiological parameters such as heart pulse, respiration and body movement. The physiological parameters are detected from the received infrared intensity signal by low, high and band pass filters.

Development of a ubiquitous healthcare monitoring system combined with non-conscious and ambulatory physiological measurements and its application to medical care

The demand for ubiquitous healthcare monitoring has been increasingly raised for prevention of lifestyle-related diseases, acute life support or chronic therapies for inpatients and/or outpatients having chronic disorder and home medical care. From these view points, we developed a non-conscious healthcare monitoring system without any attachment of biological sensors and operations of devices, and an ambulatory postural changes and activities monitoring system. Furthermore in this study, in order to investigate those applicability to the ubiquitous healthcare monitoring, we have developed a new healthcare monitoring system combined with the non-conscious and the ambulatory measurements developed by us. In patients with chronic cardiovascular disease or stroke, the daily health conditions such as pulse, respiration, activities and so on, could be continuously measured in the hospital, the rehabilitation room and subject's own home, using the present system. The results demonstrated that the system appears useful for the ubiquitous healthcare monitoring not only at medical facility, but also during daily living at home.

A fully automated health-care monitoring at home without attachment of any biological sensors and its clinical evaluation

Daily monitoring of health condition is important for an effective scheme for early diagnosis, treatment and prevention of lifestyle-related diseases such as adiposis, diabetes, cardiovascular diseases and other diseases. Commercially available devices for health care monitoring at home are cumbersome in terms of self-attachment of biological sensors and self-operation of the devices. From this viewpoint, we have been developing a non-conscious physiological monitor installed in a bath, a lavatory, and a bed for home health care and evaluated its measurement accuracy by simultaneous recordings of a biological sensors directly attached to the body surface. In order to investigate its applicability to health condition monitoring, we have further developed a new monitoring system which can automatically monitor and store the health condition data. In this study, by evaluation on 3 patients with cardiac infarct or sleep apnea syndrome, patients' health condition such as body and excretion weight in the toilet and apnea and hypopnea during sleeping were successfully monitored, indicating that the system appears useful for monitoring the health condition during daily living.

Detection of respiratory waveforms using non-contact electrodes during bathing

The aim of this study is to develop a method for measuring the respiratory waveform using non-contact electrodes during bathing. To determine the most appropriate electrode arrangement, we modeled a composite system consisting of a body submerged in bath water. We calculated the frequency dependence of the impedance amplitude using a three-dimensional finite difference method (3D-FDM). The simulation results showed that an increase in chest size due to inspiration caused a decrease in the impedance amplitude in the frequency range of 0.1 Hz to 1 MHz. Next, bioelectric impedance (BEI) was measured in the frequency range of 4 kHz to 4 MHz at the maximum-end-expiration and maximum-end-inspiration stages. BEI results were consistent with those obtained from the model simulations. We found that 1 MHz was the appropriate frequency for measuring the respiratory waveform, and the time dependence of the impedance amplitude was measured at 1 MHz. The impedance amplitude agreed well with the respiratory waveform obtained from rubber strain gauge plethysmography, which was used as a reference.

A remote monitor of bed patient cardiac vibration, respiration and movement

We have developed a remote system for monitoring heart rate, respiration rate and movement behavior of at-home elderly people who are living alone. The system consists of a 40 kHz ultrasonic transmitter and receiver, linear integrated circuits, a low-power 8-bit single chip microcomputer and an Internet server computer. The 40 kHz ultrasonic transmitter and receiver are installed into a bed mattress. The transmitted signal diffuses into the bed mattress, and the amplitude of the received ultrasonic wave is modulated by the shape of the mattress and parameters such as respiration, cardiac vibration and movement. The modulated ultrasonic signal is received and demodulated by an envelope detection circuit. Low, high and band pass filters separate the respiration, cardiac vibration and movement signals, which are fed into the microcontroller and digitized at a sampling rate of 50 Hz by 8-bit A/D converters. The digitized data are sent to the server computer as a serial signal. This computer stores the data and also creates a graphic chart of the latest hour. The person's family or caregiver can download this chart via the Internet at any time.