Search

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.

山越, 憲一, 金沢大学ベンチャー・ビジネス・ラボラトリー, 金沢大学大学院自然科学研究科知的システム創成, Monitoring of posture change in sagittal plane and walking speed is important for evaluate the effectiveness of rehabilitation program or brace. We have developed a wearable device for monitoring human activity. However, in the previous system, there still remain several drawbacks for practical use such as accuracy in angle measurement, cumbersome cable arrangements, and so on. In order to improve these practical drawbacks, a new sensor system was designed, and its availability was evaluated. The results demonstrated that the accuracy of this system showed superior to that of the previous, and this system appears to be a significant means for quantitative assessment of the patient's motion. ©2006 IEEE.

In the super-aging society, daily healthcare monitoring has become increasingly emphasized as a possible approach for the early diagnosis and timely treatment of lifestyle-related diseases. A wide variety of information transfers and platforms have been developed for daily healthcare monitoring. Using these techniques, the commercially available devices for home healthcare are also networked. However, techniques for obtaining physiological information are unfocused, and in such a case, even useful data cannot be obtained even if the network system is applied. Given these considerations, the authors have investigated a new network system combined with new bioinstrumentation techniques, i.e., the fusion physiological sensing system and its applicability for the daily healthcare monitoring. In particular, as contributions towards the development of healthcare technology, two promising monitoring techniques, ambulatory and non-conscious physiological monitoring, have been developed. These methods can contribute to the fields of the personal healthcare, medical care, and rehabilitation through their fusion with information and communications technology. The utility of these systems are reported according to the results of practical use, in addition to the outline of the sensing techniques in this chapter.

A recently proposed optical method for a non-invasive in vivo blood glucose level (BGL) measurement named “pulse glucometry” is introduced. This method is based on near-infrared living body spectroscopy to accurately obtain blood information. The remarkable feature of the method is the measurement of both the total transmitted radiation spectra in wavelength ? (I?) and the cardiac-related pulsatile component (?I?). When ?I? is superimposed on I?, the differential optical density (?OD?), which includes only arterial blood information, is obtained, thus avoiding interference from living tissues other than arterial blood. Another feature is the ability to measure the differential optical density (?OD?) in multiple wavelengths to avoid interference from blood constituents other than the target blood chemical (glucose). To support this methodology, a very fast near-infrared spectroscopic system was developed to obtain a photoplethysmographic cardiac signal with a resolution of 8 nm over a wavelength range of 900 to 1700 nm at a 100 Hz sampling frequency. An example of an in vivo BGL measurement is shown and indicates good prediction capabilities. This method can be expanded to the measurement of other blood constituents.

Daily monitoring of health condition at home is important for an effective scheme for early diagnosis, treatment and prevention of lifestyle-related diseases such as adiposis, diabetes and cardiovascular diseases. While a number of commercially available devices for home healthcare monitoring are widely used, those are actually cumbersome in terms of self-attachment of biological sensors and self-operation of them. From this viewpoint, we have been developing a non-conscious physiological monitoring system without attachment of any sensors to the human body as well as any operations for the measurement. We developed some devices installed in a toilet, a bath, and a bed and showed their high measurement precision by comparison with simultaneous recordings of ordinary biological sensors directly attached to the body. In order to investigate those applicability to the health condition monitoring, we developed a monitoring system in combination with all of the monitoring devices at hospital rooms and previously carried out the measurements of patients' health condition. Further in this study, the health conditions were measured in 10 patients with cardiovascular disease or sleep disorder. From these results, the patients' health conditions such as the body and excretion weight in the toilet, the ECG during taking the bath and the pulse and respiration rate during sleeping were successfully monitored in the hospital room, demonstrating its usefulness for monitoring the health condition of the subjects with cardiovascular disease or sleep disorder.

A novel calibration method using support vector machines regression (SVMsR) of pulse oximetry was proposed and attempted. Conventional calibration method of pulse oximetry that based on an optical density ratio of transmitted visible red light and infrared radiation whereas a proposed method here was not based on the optical density ratio directly. In theory, conventional calibrations using the ratio can be considered as a technique for nonlinear problem: nonlinear relation between two optical densities (red and IR) and oxygen saturation could be linearized by the ratio calculation. We thought, that nonlinear problem could be solved by using nonlinear analyses. Among them, the support vector machines regression method that has been studied well in this decade was attempted to be applied for pulse oximetry calibration. As an experiment, two photo plethysmograms (PPGs) by red and IR were measured on five subjects. Simultaneously, oxygen saturation (SpO(2)) level was measured by a commercial pulse oxymeter. SpO(2)) level was controlled by breathing 10% oxygen gas obtaining 98-75% SpO(2) level. Sequentially, feature points of two PPGs were extracted in beat by beat. Convex peaks and concave valleys on waveform and DC levels of PPGs were selected as feature points. Then, nonlinear regression using SVMs were attempted to obtain relationship between SpO2 by meter (regressand) and feature points of PPG (regressor). In result, a regression model was constructed from training data that is three fourths of measured cardiac data by using SVMsR. Finally, the constructed calibration model was evaluated by other one third data (validation data). The root mean squared error for the validation data is 1.90 [SpO(2)) level %] and 89% of validation data fell within +/- 2 % of SpO(2) level by the meter. In conclusion, SVMsR might be applicable on calibration for pulse oximetry.

金沢大学理工研究域機械工学系, 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.

A novel calibration method using support vector machines regression (SVMsR) of pulse oximetry was proposed and attempted. Conventional calibration method of pulse oximetry that based on an optical density ratio of transmitted visible red light and infrared radiation whereas a proposed method here was not based on the optical density ratio directly. In theory, conventional calibrations using the ratio can be considered as a technique for nonlinear problem: nonlinear relation between two optical densities (red and IR) and oxygen saturation could be linearized by the ratio calculation. We thought, that nonlinear problem could be solved by using nonlinear analyses. Among them, the support vector machines regression method that has been studied well in this decade was attempted to be applied for pulse oximetry calibration. As an experiment, two photo plethysmograms (PPGs) by red and IR were measured on a subject. Simultaneously, oxygen saturation (SpO2) level was measured by a commercial pulse oxymeter. SpO2 level was controlled by breathing 10% oxygen gas obtaining 98–76% SpO2 level. Sequentially, feature points of two PPGs were extracted in beat by beat. AC and DC components were separated then convex peaks and concave valleys on AC waveform and DC levels of PPGs were selected as feature points. Then, nonlinear regression using SVMs were attempted to obtain relationship between SpO2 by meter (regressand) and feature points of PPG (regressor). Parameters of SVMsR were obtained by trial-and-error method. In result, a regression model by training data derived from 1408 cardiac beats was obtained and evaluated by validation data of 202 beats. The root mean squared error for the validation data is 1.309 [%] and 197 of 202 validation data fell within ± 2 % of SpO2 level by the meter. In conclusion, SVMsR might be applicable on calibration for pulse oximetry.

A prototype endoscopic system for observing inner wall of aorta was developed and tested in vivo using swine. The purpose of this system is to visualize the inner wall of aorta without stopping aortic flow for the use of an assistive technique for endovascular interventions such as stent-graft placement for aortic aneurysm. The technique newly introduced for this purpose was the use of intermittent high-pressure saline jet synchronized to heart beat (diastolic phase). For preliminary studies, a commercially available bronchoscope having an outer diameter of 5mm with a biopsy channel was used, and a discharging system for intermittent high-pressure saline jet was constructed using a high-speed solenoid valve and a pressurizing tank. From in vitro tests, it was confirmed that we could obtain sufficient amount of saline jet (about 1ml) within short period of time (about 100 ms) with the driving pressure of 0.1 MPa. Based on these results, we conducted in vivo tests using swine with the body weight of about 30 kg. The tip of the endoscope was introduced from the abdominal aorta and inserted proximally about 30 cm. At this point, the saline jet was discharged (period: 200 ms, driving pressure: 0.2 MPa), and then we could clearly observe the aortic bifurcations during the flushing period. This result strongly suggests an availability of the present method as an assistive technology for the endovascular interventions in aorta.

A novel calibration method using support vector machines regression (SVMsR) of pulse oximetry was proposed and attempted. Conventional calibration method of pulse oximetry that based on an optical density ratio of transmitted visible red light and infrared radiation whereas a proposed method here was not directly based on the optical density ratio. From theoretical point of view, conventional calibrations using the ratio can be considered as a method for nonlinear problem: nonlinear relation between two optical densities (red and IR) and oxygen saturation could be partly linearized by the ratio calculation. We thought, that nonlinear problem could be directly solved by using nonlinear analyses. Among them, the support vector machines regression method was attempted to make a calibration for pulse oximetry. As an experiment, two photo plethysmograms (PPGs) by red and IR were measured on three healthy male subjects. Simultaneously, oxygen saturation (SpO2) level was measured by a commercial pulse oxymeter. SpO2 level was controlled by breathing 10% oxygen gas for obtaining 98-76% SpO2 level. Sequentially, feature points of two PPGs were extracted in beat by beat. Convex peaks and concave valleys on PPG waveforms and moving averages of red and IR PPGs of each cardiac beat were selected as feature points. Then, nonlinear regression using SVMs were attempted to obtain relationship between SpO2 by the oxymeter (regressand) and feature points of PPG (regressor). Parameters of SVMsR were obtained by trial-and error method. In result, a regression model by trained by three-quarters of cardiac beats (teaching data) was obtained and evaluated by validation data of other one-quarter beats (validation data). As an example, 89 of 103 validation data of a subject (86% of validation data) fell within ± 1.5 % of SpO2 level by the meter. In conclusion, SVMsR could be applicable on calibration for pulse oximetry.

In order to evaluate the efficacy of rehabilitation for persons with hemiplegia, a therapist usually makes judgment by directly observing posture changes, walking speed, activities not only in hospital, but also during daily living. Therefore, quantitative assessment of activities is most desirable. From this viewpoint, we have developed a device for ambulatory monitoring of posture changes, walking speed and activity scenario and evaluated its measurement accuracy by simultaneous recordings of a digital video camera. In order to investigate its applicability to a patient’s activity monitoring, we have further developed a new monitoring system which can display static and dynamic motion pictures as well as detailed angle changes of the trunk, thigh and calf. This system makes a therapist to easily understand the patient’s motion during training in rehabilitation center and activities during daily living. By evaluation on 6 patients with hemiplegia, the patients’ motions were successfully monitored during walking in the rehabilitation center and daily living at their own home. The results clearly demonstrated that the system could detect detailed motion characteristics, indicating that the system appears useful for evaluating quantitatively the efficacy of rehabilitation.

Biological Exposure Indices (BEIs) are reference for a chemical or its metabolite in the biological specimen. BEIs give guidelines for the evaluation of potential health hazards or for diagnosis of occupational illnesses. Among them, urine hippuric acid (HA) that is a metabolites of toluene is considered as the BEIs of toluene exposure for human and measured from workers using toluene. In this study, we attempted to develop a brief measurement of urine HA by using near-infrared spectroscopy. As the first step, water solutions of hippuric acid of several concentrations (0-250mg/dl) are measured. Afterward, artificial urines conditioned by adding glucose and urine to HA solutions were measured and analyzed. The solvents are optically measured within near infrared region (750-2500nm) obtaining optical absorption. Then, differential absorbance were calculated by subtraction of analyte absorbance from ion-exchange water absorbance and analyzed. As a result, for HA solutions, a calibration equation from absorbance in two wavelengths can be obtained by using multiple regression (R 2 =0.935). However, this calibration cannot provide a good estimation for artificial urines. Secondary, another calibration from three wavelengths was obtained and providing a good regression (R 2 =0.934). This result suggests that a brief urine constituents measurement using near-infrared spectroscopy can be developed.

Daily monitoring of health condition at home is very important not only as an effective scheme for early diagnosis and treatment of cardiovascular and other diseases, but also for prevention and control of such diseases. From this point of view, we have developed a prototype room for fully automated monitoring of various vital signs. From the results of preliminary experiments using this room, it was confirmed that (1) ECG and respiration during bathing, (2) excretion weight and blood pressure, and (3) respiration and cardiac beat during sleep could be monitored with reasonable accuracy by the sensor system installed in bathtub, toilet and bed, respectively.

Ubiquitous healthcare is very important subject not only as an effective scheme for early diagnosis of cardiovascular and other diseases, but also for prevention and control of such diseases. For this purpose, we have developed two kinds of non-invasive physiological monitoring systems. One is the systems utilizing furniture and furnishings in home to detect biosignals under daily life, and the other is portable systems for ambulatory monitoring of physiological valuables including blood pressure, cardiac output, posture change, walking speed, and so on.. In this paper, structure and performance of these systems are briefly described.

We have developed a wearable system for monitoring static and dynamic posture in sagittal plane together with walking speed, and reported its usefulness in the rehabilitation field. However, in the previous system, there still remain several drawbacks for practical use such as accuracy in angle measurement, cumbersome cable arrangements, and so on. In order to improve these practical drawbacks, a new sensor system was designed, and its availability was evaluated. Using 11 healthy subjects (21 to 75 yrs) and 14 patients with hemiplegia (61 to 87 yrs) under their informed consent, the measuring accuracy of the improved system was evaluated by simultaneous recordings of a digital video. The results demostrated that the accuracy of this system (angle change; r=0.997, walking speed; r=0.992) showed superior to that of the previous system (angle change; r=0.986, walking speed; r=0.960). It is clearly shown through the practical monitoring that this system appears to be a useful and significant means for quantitative assessment of the human motion during rehabilitation programs.

Measurement of physical activity is one of the key subjects in the field of ambulatory cardiovascular monitoring using such as Holter ECG and so called "ambulatory blood pressure monitor (ABPM)". Rehabilitation and gerontology will also be another fields for the application of the activity monitor. From this point of view, we have developed a portable device for monitoring human posture and walking velocity in ambulatory subjects. In this paper are described, a new sensor system for this purpose using three accelerometers and one gyroscope, its availability for the accurate measurement of human posture and walking velocity, and results of preliminary study using a prototype system for ambulatory monitoring.

The importance of human posture monitoring is well recognized in the field of rehabilitation, in order to evaluate quantitatively the effectiveness of rehabilitation by a physical therapist. The activity monitoring is also well recognized as being useful in the field of certification of eligibility for long-term care. Assessment of the actual physical condition of the applicant tends to be difficult when determining the level of need for long-term care. Taking these circumstances in consideration, we attempted to measure the activities of patients in rehabilitation using a wearable device for monitoring human activity. The results clearly demonstrated that detailed motion characteristics could be detected during standing up, walking and sitting up as angle changes between specific body segments and as trunk motion acceleration

金沢大学理工研究域機械工学系, We have been developing an endoscopic system for observing inner wall of large arteries. The purpose of this system is to visualize the inner wall of large arteries, e.g., an aorta, without blocking off the blood stream for the use of an assistive technique for endovascular interventions such as stent-graft placement for aortic aneurysm. The technique newly introduced for this purpose was the use of intermittent high-pressure saline jet synchronized to heart beat (diastolic phase). In the previous paper [1], we reported performance of a prototype system using a commercially available bronchoscope having an outer diameter of 5mm with a biopsy channel. A discharging system for intermittent high-pressure saline jet was also constructed using a high-speed solenoid valve and a pressurizing tank. In this study, we tried to introduce a special hood (we call "Hemo-visor") on the tip of the endoscope in order to more clearly observe the target (inner wall of artery). From in vitro tests using a mock circulation system, it was confirmed that the Hemo-visor was highly effective for keeping saline solution around the endoscope tip against the blood stream, and for improving the quality of the picture obtained. © 2010 IEEE.