Summary A cardiotachometer has been devised to record the variation of the frequency of the sino-atrial node, but no apparatus has been reported which simultaneously records the frequency variations in atrioventricular conduction time and the sino-atrial node frequency.In an attempt to demonstrate how the sinus rhythm affects the A-V nodal conduction time, excitation conduction time between the right atrium and ventricle was recorded continuously by a newly devised A-V interval meter and compared with the variation in the length of the cardiac cycle (R-R interval).In the post-operative unanesthetized dog, the respiratory variation in A-V interval was from 7 to 13 msec while the R-R interval ranged from 350 to 500msec. The variations of the A-V and R-R intervals were in phase under nervous control but out of phase with pacing and pharmacological intervention. Both variations diminished in amplitude when the dog stood up or ate, when propranolol was administered intravenously, or when atropine was given.In the anesthetized animal right vagal stimulation caused an abrupt lengthening of the R-R interval after one second or less, while left vagal stimulation usually prolonged the A-V interval after more than one second. Stimulation of the left stellate ganglion resulted in a shorter A-V conduction time without a change in the R-R interval, while stimulation of the right stellate ganglion generally caused tachycardia.Neural control of the heart rate is mediated by vagal and sympathetic outflow to the cardiac pacemaker tissues (ANZOLA and RUSHMER, 1956;RUSHMER and WEST, 1957). Both the vagus and the sympathetic nerves are known to innervate the A-V node and to influence atrioventricular conduction (KUNTZ,

A new drip infusion solution monitoring system has been developed for hospital and care facility use. The system detects the fall of each drip chamber drop of fluid and also a free-flow situation. Three non-contacting copper foil electrodes are used. The electrodes are wrapped around the infusion supply polyvinyl chloride (PVC) tube from the solution bag, the drip chamber, and the infusion PVC tube from the drip chamber. Drip infusion fluids have electrical conductivity, so a capacitor is formed between the infusion fluid and each electrode. A thirty kHz sine wave is applied to the electrode wrapped around the infusion supply PVC tube from the solution bag. The capacity-coupled signal on the drip chamber electrode is the transducer output. When an infusion fluid drop is forming, its length and diameter, and therefore the drip chamber capacitance, are increasing, causing change in the output signal. The drip chamber electrode can detect the fall of each drip chamber drop of fluid. When the infusion solution becomes free-flow, an infusion fluid drop is not forming and the infusion fluid flows continuously. Therefore, the capacitance of the electrode around drip chamber does not change the output signal. On the other hand, the electrode wrapped around the infusion supply polyvinyl chloride tube under the drip chamber detects the thirty kHz sine wave conducted by the infusion fluid. The drip chamber electrodes and the infusion supply PVC tube under the drip chamber detect each drop of fluid and free-flow, respectively.

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.

A new safety support system has been developed to detect and transmit notification of a wandering elderly person's location. The system employs a low transmitting power mobile phone (PHS) and a personal computer (PC). The PHS is carried with the elderly person as a pendant. The PHS location is identified within 100 m from the receiving antenna ID. Therefore, the system can detect whether the wandering elderly person is in or out of their home. When the wandering elderly person is away from home, the system automatically informs the caregiver via voice mode and sends the wandering elderly person's location map by e-mail.

We have developed a remote drip infusion monitoring system for use in hospitals. The system consists of several infusion monitoring devices and a central monitor. The infusion monitoring device employing a Bluetooth module can detect the drip infusion rate and an empty infusion solution bag, and then these data are sent to the central monitor placed at the nurses' station via the Bluetooth. The central monitor receives the data from several infusion monitoring devices and then displays graphically them. Therefore, the developed system can monitor intensively the drip infusion situation of the several patients at the nurses' station.