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Hip protectors can reduce the incidence of hip fractures. However, low user acceptance and compliance in use remain a major obstacle in the effective use of hip protectors, due to its discomfort and extra effort needed to wear it, etc. A leak-allowed air cushion is an air-bubble cushion designed to have one or some orifices on the side. In this cushion, an impact load is shunted to open air with airflow through orifice(s), and the energy is dissipated by the friction of the airflow. With the lightness, the flexibility, and the inexpensiveness, this cushion has a potential to be accepted by the target users at high levels of compliance. The purpose of this study was to evaluate a potential of the cushion as a hip-protector material by comparing with other three commercially-variable impact attenuation materials: polyethylene elastmer; silicon gel; and porous polyurethane. To this end, we performed impact tests for pads made of the materials using a falling-mass impact loader. The pad made of leak-allowed air cushions reduced the peak impact force from 7700N (recorded with no pad) to 1213 N, which was 38—64 % lower than the attenuated peak forces recorded in the other material pads. We concluded that the leak-allowed air cushion could be a novel hip protector material with high capacity of impact-force attenuation.

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.

We developed a gas-spring-powered device for assisting activities of sit-to-stand and stand-to-sit for the elderly andpersons with disability. The assistive device is fitted to both normal chair and wheelchairs, and is comprised of three mainparts; a seat, two support frames and two gas-springs. The assistive device was evaluated in comparison experimentswith or without this assistive device and commercially available assistive chair. Ten young healthy subjects aged from 21 to 24 yr-old had measurements of joint torque of knee and elbow using a force plate, load-cell attached on an armrest andposition of joint marker in video. In addition electromyography of upper arm and thigh were also measured. From theresults, maximum values of joint torque decreased by 29%-78%in both activities of sit-to-stand and stand-to-sit by usingthe assistive device. In addition, maximum and integrated values of electromyography output of upper arm and thighdecreased by50%-74%in both activities of sit-to-stand and stand-to-sit. In contrast, percentage decrease of commerciallyavailable device(joint torque: -7%-40%, EMG: -24-43%)was lower than the present device. We suggest that thenewly developed device could be a useful means for assisting sit-to-stand and stand-to-sit activities.

To measure blood hematocrit inside the magnetically suspended centrifugal pump, we have performed both forward and backward light scattering measurements using a specially designed optical cell. In the forward scattering measurement, an optical fiber was used to guide the near infrared light at 780 nm into a 250 microns gap region, and the light that forward scattered toward a detector fiber was measured using a phototransistor. The light intensity decreased exponentially with an increase in the hematocrit to around 20%. The forward scattering method suffered from sensitivity at the hematocrit levels around 25-45% due to the diffusion effect. By making the optical path length larger than several millimeters, the sensitivity of the forward scattering method in terms of hematocrit change can be improved. In the back scattering method, however, better sensitivity in terms of hematocrit change from 0-50% was obtained. By making the optical fiber separation distance less than 1 mm, the system will measure the first order back scattering from the shallow layer while, by making the fiber separation distance larger than several millimeters, the system will primarily measure the diffuse reflectance from the deeper layer. Both approaches will yield sensitive optical intensity change in terms of the physiological hematocrit range.

An ultracompact, completely implantable permanent use electromechanical ventricular assist device (VAD) and total artificial heart (TAH) intended for 50-60 kg size patients have been developed. The TAH and VAD share a miniature electromechanical actuator that comprises a DC brushless motor and a planetary roller screw. The rotational force of the motor is converted into the rectilinear force of the roller screw to actuate the blood pump. The TAH is a one piece design with left and right pusher plate type blood pumps sandwiching an electromechanical actuator. The VAD is one half of the TAH with the same actuator but a different pump housing and a backplate. The blood contacting surfaces, including those of the flexing diaphragm and pump housing, of both the VAD and TAH were made of biocompatible polyurethane. The diameter, thickness, volume, and weight of the VAD are 90 mm, 56 mm, 285 cc, and 380 g, respectively, while those of the TAH are 90 mm, 73 mm, 400 cc, and 440 g, respectively. The design stroke volume of both the VAD and TAH is 60 cc with the stroke length being 12 mm. The stroke length and motor speed are controlled solely based on the commutation signals of the motor. An in vitro study revealed that a maximum pump flow of 7.5 L/min can be obtained with a pump rate of 140 bpm against a mean afterload of 100 mm Hg. The power requirement ranged from 4 to 6 W to deliver a 4-5 L/min flow against a 100 mm Hg afterload with the electrical-to-hydraulic efficiency being 19-20%. Our VAD and TAH are the smallest of the currently available devices and suitable for bridge to transplant application as well as for permanent circulatory support of 50-60 kg size patients.

In this study, the power output and contraction length of trained and untrained canine latissimus dorsi (LD) muscles were measured using a roller screw linear muscle actuator (RSLMA). The RSLMA consisted of a roller screw-nut assembly and translation unit to convert the linear pull force of the muscle into an axial displacement of the roller screw. When a cable wound around a spool attached at each end of the roller screw nut was pulled in either direction, the nut was rotated which in turn advanced the roller screw in the axial direction. Under anesthesia, a Telectronics myostimulator (Model 7220) was implanted in the subcutaneous area of the canine left thoracic region with its bipolar intramuscular leads implanted around the thoracodorsal nerve and the distal muscle. A total of 6 dogs went through the myostimulator implantation, followed with 8 weeks of continuous stimulation. After completion of the training, the contraction lengths of the trained and untrained LD muscles were measured, and they were 4.25 and 5.5 cm, respectively, while the instantaneous power outputs were 4.24 and 8 W, respectively. Although untrained muscles could provide much higher instantaneous power immediately following the start of the stimulation, it diminished rapidly. On the other hand, the trained muscle showed prolonged fatigue resistance. The thoracolumbar and humeral approaches in attaching the actuator cable did not show a difference with respect to muscle power output. The trained LD muscle can provide sufficient power in the range of 3-4 W to drive a left heart assist device, but its long-term evaluation awaits development of an appropriate muscle-device interface for chronic in vivo application.

Instantaneous non-invasive blood pressure (BP) measurement in dorsalis pedis artery as a measuring site, which can be applied to the patient monitoring in a hospital bed, was attempted based on previously proposed the volume-compensation technique. The measurement system mainly consists of a partial pressurization cuff with a pair of LED and photo-diode for the detection of arterial volume, a micro-computer-based PID servo control circuitry, a hydrostatic compensator of the pressure difference between the dorsal artery of foot and the heart level to obtain the dorsal arterial BP at heart level. Using healthy subjects, the performance and accuracy of this system were evaluated through comparison experiments with the indirect BP simultaneously measured from the radial artery. It was demonstrated that the compensated BP values in dorsal artery of foot were well coincident with those in radial artery and that the short-term BP responses such as instantaneous slight hypotension and its recovery during the changes in body positions from supine to sitting were clearly observed in both measuring sites. Dorsal BP was also measured during the Valsalva maneuver test then showed typical BP response in the maneuver. The mean error of BP measured in dorsalis pedis from radial artery are −3.0α6.88 mmHg in SBP and 0.4α6.84 mmHg in DBP. The Bland-Altman plots of systolic (SBP) and diastolic BP (DBP) values in dorsalis pedis and radial artery showed almost consistent results. The instantaneous BP measurement technique in dorsalis pedis artery appears promising as a useful means for the patients restrained in a bed during hemodialysis, bedridden patients with spinal cord injuries and with severe diseases, and others.

A prototype endoscope for observing inner wall of large arteries was specially designed and evaluated through in vitro and in vivo tests. The purpose of this endoscope is to visualize the inner wall of large arteries, e.g., an aorta, without blocking off the blood stream aiming 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 studies using commercially available bronchoscopes, we confirmed the validity of the system utilizing this technique [1, 2]. Based on these findings, in this study, we have specially designed a new endoscope with two channels, one for saline discharge and the other for forceps, and evaluated its performance through in vitro and in vivo tests. From the results of in vitro tests using a mock circulation system, it was confirmed that the newly designed endoscope was capable of visualizing a target installed on an inner surface of the mock system. Also confirmed through in vivo tests using swine was that we could observe bifurcation in descending aorta, e.g., left renal artery, without stopping off the blood stream. © 2011 IEEE.

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.

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.

Prolonged monotonous driving may lower a driver's awareness level as well as increasing their stress level due to the compulsion to maintain safe driving, which may result in an increased risk of a traffic accident. There is therefore an opportunity for technological assessment of driver physiological status to be applied in-car, hopefully reducing the incidence of potentially dangerous situations. As part of our long-term aim to develop such a system, we describe here the investigation of differential skin temperature measurement as a possible marker of a driver's stress level. In this study, healthy male (n=18) & female (n=7) subjects were investigated under environment-controlled conditions, whilst being subjected to simulated monotonous travel at constant speed on a test-course. We acquired physiological variables, including facial skin temperature which consists of truncal and peripheral skin temperatures (T s ) using thermography, beat-by-beat blood pressure (BP), cardiac output (CO), total peripheral resistance (TPR), and normalized pulse volume (NPV) used as an indicator of local peripheral vascular tone. We then investigated the driver's reactivity in terms of skin temperatures with this background of cardiovascular haemodynamics. We found that the simulated monotonous driving produced a gradual drop in peripheral T s following the driving stress, which, through interpretation of the TPR and NPV recordings, could be explained by peripheral sympathetic activation. On the other hand, the truncal T s was not influenced by the stress. These findings lead us to suggest that truncal-peripheral differential T s could be used as a possible index indicative of the driver's stress.

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.

We describe further development of a novel method for non-invasive measurement of blood glucose concentration (BGL), named Pulse Glucometry, based on differential near infrared spectrophotometry. Sequential temporal differences of infrared transmittance spectra from the radiation intensity (I(lambda)) emerging from a fingertip containing an arterial pulse component (DeltaI(lambda)) are analysed. To perform the measurements we developed a new high-speed spectrophotometer, covering the wavelength range from 900 to 1700 nm, scanning at a maximum spectral rate of 1800 spectra/s, with a minimum exposure time of 20 micros. Spectra related only to the pulsatile blood component are derived, thus minimising influences of basal components such as resting blood volume, skin, muscle and bone. We have now improved the performance of the spectrophotometer and in the present paper we describe new in vivo measurements carried out in 23 healthy volunteers undergoing glucose tolerance tests. Blood samples were collected from the cephalic vein simultaneously with radiation intensity measurements in the fingertip every 10 min before and after oral administration of glucose solution for 120 min. BGL values were then predicted using a PLS calibration model and compared with blood values determined by colorimetric assay. The precision and accuracy of the non-invasive determinations are encouraging.

A new technique for swiftly determine a servo reference value (Vo) of the volume-compensation method was developed. To determine the Vo values, high frequency vibration (frequency: 20 Hz, pulse pressure: 10 mmHg) was superimposed on cuff pressure (Pc), and artificially produced arterial wall oscillation was detected as photoplethys-mographic (PG) pulsation signal. In this signal, maximum oscillation points were observed when the mean value of Pc is equal to blood pressure, and Vo value was then determined from the mean level of PG signal at this maximum point. The values obtained by this method coincide well with those obtained by the previous method (the volume-oscillometric method), indicating the validity of the present method.

Long hours of automobile driving under monotonous situations may cause the lowering of what we term a driver's activation state (DAS) or in other words the production of drowsiness, resulting in an increased risk of a traffic accident. There is therefore a need to create a newly advanced system focused on the DAS in-car, hopefully thus avoiding potentially dangerous situations. In order to develop such a system as a final goal, we have firstly set out to acquire such cardiovascular variables as beat-by-beat blood pressure (BP), RR interval from ECG and normalized pulse volume (NPV) used as a peripheral vascular tone of alpha-adrenergic sympathetic activity, during presentation to the driver of a screen movie simulating monotonous travel at constant speed on a test-course. Subsequently, we have investigated the reactivity in terms of the driver's cardiovascular hemodynamics. Through the successful monitoring of cardiovascular parameters during the movie presentation obtained in 11 healthy male subjects, the following results were obtained: The monotonous driving produces a statistically significant gradual rise in BP following drowsiness, which could be explained by enhancement of sympathetic activity using a time-frequency analysis of BP and RR. This finding strongly indicates that continuous driving in such monotonous situations can make a driver considerably stressful and thus may cause a gradual increase in BP, and that this gradual BP increase may be used as a possible index relevant to the DAS. This finding was also confirmed by the analysis of NPV, suggesting that the gradual increase in BP during the monotonous driving would be rather caused by a regulation of peripheral vasomotor constriction. Language: en

For the noninvasive and accurate measurement of instantaneous blood pressure (BP) in the radial artery, the performance of a device based on the principle of volume-compensation was assessed by comparison with simultaneous measurement of direct (invasive) radial artery pressure in nine healthy subjects. Bias and precision of systolic BP (SBP) and diastolic BP (DBP) derived from Bland-Altman plots of data from the present system and the direct method averaged -0.5 plusmn 2.1 mmHg and 0.6 plusmn 1.8 mmHg respectively, over a wide range of SBP and DBP. These results clearly indicate that, using this system, instantaneous radial artery pressure can be measured noninvasively with high accuracy.

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.

Recently, several studies revealed that daily slow-breathing exercise lowered blood pressure and increased baroreflex sensitivity. With this interesting finding, we have been contemplating to design a compact breath-controllable device for relaxation to stress reaction during daily living for home as well as ambulatory use, as a final goal, towards reduction of cognitive hemodynamic disorders, hypertension, and acute stress-induced hemodynamic disorders. The present study thereby describes, as a first step, to design a prototype system combining a compact multipurpose non-invasive beat-by-beat cardiovascular monitor developed previously with a wrist-type vibrator to make a respiration rhythm, and to assess an effect of slow-breathing relaxation on the cardiovascular hemodynamics in response to acute stressful conditions. The cardiovascular hemodynamic monitor can measure beat-by-beat systolic (SBP), mean (MBP) and diastolic (DBP) pressure in a finger based on the volume-compensation method, cardiac output (CO) by the electrical admittance method and the other hemodynamic-related parameters (e.g., total peripheral resistance (TPR=MBP/CO), heart rate (HR), respiratory rate, pulse wave velocity, etc.). The wrist-type vibrator can give various breathing rhythms quietly to a subject using a small vibration motor. The stressful tasks loaded to healthy volunteers (3 males, 23-34 yrs.) in the experiments were cold pressor and arithmetic ones as a representative of daily passive and active coping tasks, respectively, under conditions with (respiratory rate of 6 1/min) and without breath control. The results showed that the slow-breathing technique could have a significant effect on improvement of the hemodynamic changes following the acute stressful tasks, especially in the passive coping task. The prototype system combining the cardiovascular monitor with the breath controller appears to be useful and helpful in terms of self-monitoring of hemodynamic changes as well as self-care for the improvement of the cardiovascular function during daily living.

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.

Monotonous automobile driving for a long stretch of time and/or over a familiar route may cause the lowering of what we term a Driver’s Activation State (DAS), or in other words the awareness level, resulting in an increased risk of a traffic accident. There is therefore a need to create a newly advanced system focused on the DAS in-car, hopefully thus avoiding potentially dangerous situations. In order to develop such a system as a final goal, we have firstly set out to acquire such cardiovascular variables as beat-by-beat blood pressure (BP), RR interval from ECG and normalized pulse volume (NPV) used as a peripheral vascular tone of α-adrenergic sympathetic activity, during presentation to the driver of a screen image simulating monotonous travel at constant speed on a test-course. Subsequently, we have investigated the reactivity in terms of the driver’s cardiovascular hemodynamics. Through the successful monitoring of cardiovascular parameters during the image presentation obtained in 11 healthy male subjects, we have obtained the following interesting findings: That is, the monotonous driving produces a significantly gradual rise in BP, which could be clearly explained by enhancement of sympathetic activity using a time-frequency analysis of BP and RR. Additionally, it is suggested that this rise in BP during a monotonous situation may be caused by a regulation of peripheral vasomotor constriction rather than by cardiac-related control. This BP finding strongly indicates that the continuous driving in such monotonous situation makes a driver considerably stressful and thus may cause a gradual increase in BP, and that this gradual BP increase might be used as a feasible index relevant to the DAS.

The blood hematocrit is well recognized as the versatile index of various physiological conditions especially for anemia, polycythemia and dehydration. However, the conventional method of the hematocrit measurement was conducted with the direct blood sampling. In this study, based on the similar principle of the pulse oximetry, a simple principle of optical noninvasive hematocrit measurement method, pulse hematometry, was introduced. And the performance of the optical sensor evaluated with healthy subjects was also reported. Because of its simplicity, the pulse hematometry would be promising technique as patients monitoring and daily healthcare.

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.

In order to develop a simple and reliable assessment method of the stress induced psychosomatic and hemodynamic responses against various stress situations, especially for evaluating of the effectiveness of stress reduction methods, a multipurpose non-invasive continuous cardiovascular monitoring system was developed. The monitoring system could measure beat-by-beat finger blood pressure (SBP, MBP, DBP based on the volume-compensation method), cardiac output (CO, electrical admittance method), total peripheral resistance (TPR=MBP/CO), and the other hemodynamic related parameters (e.g. RR-interval, respiratory rate, pulse wave velocity, etc.). As controlled stress conditions, the human subjects would be exposed to the various stresses such as flash video display, electrical stimulation and so on. In this study, after 5 minutes resting, the stress induced hemodynamic responses were measured during 10-min presentation of floating vertical stripes image using 5 healthy subjects. The image presentation was discontinued when the subject gave his/her self-assessment due to considerable discomfort. The results showed that although BP increased during the presentation in all the subjects, there observed two types of cardiovascular responses; one is a type of increase in CO (or of almost unchanging or decrease in TRP), and the other of increase in TPR. These results strongly suggested that the detection of the change in TPR might be an important factor for the evaluation of stress conditions. Further investigations would be required for the reasons why these two types were observed in the same stressful condition.

Monotonous automobile operation in our daily life may cause the lowering of what might be termed an activation state of the human body, resulting in an increased risk of an accident. We therefore propose to create a more suitable environment in-car so as to allow active operation of the vehicle, hopefully thus avoiding potentially dangerous situations during driving. In order to develop such an activation method as a final goal, we have firstly focused on the acquisition of physiological variables, including cardiovascular parameters, during presentation to the driver of a monotonous screen image, simulating autonomous travel of constant-speed on a motorway. Subsequently, we investigated the derivation of a driver's activation index. During the screen image presentation, a momentary electrical stimulation of about 1 second duration was involuntarily applied to a subject's shoulder to obtain a physiological response. We have successfully monitored various physiological variables during the image presentation, and results suggest that a peculiar pattern in the beat-by-beat change of blood pressure in response to the involuntary stimulus may be an appropriate, and feasible, index relevant to activation state.

The objective of this study was the development of a reflectance pulse oximeter sensor for broader clinical applications, specifically for broader arterial oxygen saturation (SaO/sub 2/) measurement from various body portions. To enhance the reflectance pulse amplitude from any body surface and eliminate the effect of tissue inhomogeneity, the new sensor incorporated ten LED chips for each wavelength mounted symmetrically at the radial separation distance of 7 mm around a photodiode chip. Based on the photon diffusion theory, the wavelength combination, 730/880 nm, was determined to obtain a linear relationship between the reflectance ratio and broader SaO/sub 2/ range from 100% to 30%. The improved linearity of the new sensor was evaluated in dogs (n=5) in comparison to the 665/910 nm conventional wavelength sensor. Additionally, this new reflectance sensor was applied to various body surfaces in healthy human adults (n=30). The relative reflectance pulse amplitudes from the fingertip, forehead, and chest were 1.0, 0.3, and 0.1 as normalized to the fingertip at each wavelength. These results will broaden the application sites of the reflectance pulse oximeter sensor in the hospital and home healthcare.

An ultracompact, high-performance, completely implantable permanent electromechanical total artificial heart (TAH) intended for physically smaller populations like the Japanese has been designed, utilizing the desirable features of the TAHs that are already being developed elsewhere. The design specifications include: (1) it should fit in 60–65 kg adults, (2) it should have 4–51/min average pump output with a maximum flow of 81/min, (3) system efficiency should be 15%–20%, and (4) durability should be 3–5 years. The TAH is a one-piece design with left and right pusher-plate type blood pumps (55 cm3 stroke volume) sandwiching a miniature electromechanical actuator consisting of a smaller-size planetary roller screw in combination with a d.c. brushless motor. The blood-contacting surfaces, including the inner surface of the pump housing, flexing diaphragm, and inflow/outflow valves, were fabricated with polyurethane, Bio-Span. The pump housings were fabricated with carbon fiber. Two sets of 16-bit microprocessors were incorporated to operate the TAH in the left and right alternately ejecting mode, based on the commutation sensor pulses and pusher-plate position signals. Energy is transmitted inside the body using a transcutaneous energy transmission system. The left and right flow difference is compensated for by the implantable compliance chamber. The diameter of the pumping unit is 88–90 mm with the thickness being 73 mm. The overall fabrication cost has also been reduced through incorporation of built-in polyurethane valves. This ultracompact, high-performance, completely implantable TAH is expected to be suitable for permanent replacement of the failing heart of end-stage cardiac patients.

In patients with severe heart failure, the ventricular assist devices (VAD) have proved their usefulness for temporary bridging to heart transplantation and for more permanent usage [1,2]. Patients implanted with the mechanical devices can go home and return to work while waiting for heart transplantation. The currently available mechanical circulatory assist devices, Novacor (Division of Baxter Health Care, Oakland, CA, USA) and TCI (Thermo Cardio Systems, Woburn, MA, USA), both use an external power source, chemical batteries. The skin transformer is used to deliver transcutaneously electrical power inside the body. The external batteries usually last from 7 to 8 h before needing to be recharged. As an alternative, biological energy sources such as skeletal muscle power have been also investigated since the 1950s. In 1958, Kantrowitz wrapped the diaphragm around the left ventricle to assist its contraction [3,4].

A new reflectance pulse oximeter sensor for lower arterial oxygen saturation (Sa)2) measurement has been designed and evaluated in animals prior to clinical trials. The new sensor incorporates ten light emitting diode chips for each wavelength of 730 and 880 nm mounted symmetrically and at the radial separation distance of 7 mm around a photodiode chip. The separation distance of 7 mm was chosen to maximize the ratio of the pulsatile to the average plethysmographic signal level at each wavelength. The 730 and 880 wavelength combination was determined to obtain a linear relationship between the reflectance ratio of the 730 and 880 nm wavelengths and Sa)2. In addition to these features of the sensor, the Fast Fourier Transform method was employed to compute the pulsatile and average signal level at each wavelength. The performance of the new reflectance pulse oximeter sensor was evaluated in dogs in comparison to the 665/910 nm sensor. As predicted by the theoretical simulation based on a 3D photon diffusion theory, the 730/880 nm sensor demonstrated an excellent linearity over the SaO2 range from 100 to 30 percent. For the SaO2 range between 100 and 70 percent, the 665/910 and 730/880 sensors showed the standard error of around 3.5 percent and 2.1 percent, respectively, in comparison to the blood samples. For the range between 70 and 30 percent, the standard error of the 730/880 nm sensor was only 2.7 percent, while that of the 665/910 nm sensor was 9.5 percent. The 730/880 sensor showed improved accuracy for a wide range of SaO2 particularly over the range between 70 and 30 percent. This new reflectance sensor can provide noninvasive measurement of SaO2 accurately over the wide saturation range from 100 to 30 percent.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

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.