Using compact 24 GHz microwave radar system, we developed a sleep apnea syndrome screening system for clinical practice. For six sleep apnea syndrome suspects (five male /one female, 65±14 years old), our system had 89% success in detecting respiratory disorder events, which were determined by a reference CO₂ monitor.

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Work analysis based on quantitative data is required in order to gain a proper understanding of the burdens that are placed on nurses. To this end, this study developed a movement analysis system which utilizes ultrasonic tags and RFID tags. The goal of this study was to analyze the flow of nursing staff working in operating room through field experiments, thereby gaining an understanding of specific nursing duties, while at the same time verifying the efficacy of the system. The experiments focused on 18 operating room nurses over a twenty day observation period.
The results indicated that all 18 nurses were involved with the preparation of surgical instrument container sets in the central supply department. In particular, it was noted that 6 nurses worked exclusively in this department. The accumulated time spent by nurses in the central supply department over a 20 day period till 10:00 was 36.8 hours and totaled 49.2 hours by 11:00 when container sets had been completed.
It was also revealed that the operating room was at its busiest between 14:00~16:00 and between 13 nurses were involved in operating room duties. On the other hand, the accumulated time spent by nurses in the operating room area over a 20-day period from 17:00 onwards was 166.1 hours and approximately 5 nurses were assigned to this area.
This system enables us to grasp in real time the precise location of nursing staff in relation to the map information of the operating room, by mapping their positions via the ultrasonic tags. In other words, simply by using the ultrasonic tags, it is possible for us to automatically grasp the movement paths (routes) of nursing staff, therefore proving effective in work analysis.

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The Luciferin/Luciferase/Aadenosine Tri-Phosphate (ATP) bioluminescent method is commonly used for cleanliness verification of medical instruments. In Japanese Society of Medical Guideline for assessing the cleanliness of medical instrumentations in healthcare setting, the ATP measurement method is adopted as one of swabbing test methods. As the advantages of ATP method, high sensitivity, easy measurement and rapid readout capability are cited in this document. The guideline consecutively describes the ATP swabbing test method is not suitable to verify the cleanliness of narrow and lumen structure because it has limitation on access there. To solve this limitation of the ATP swab test method, we developed a test method of measuring residual soil from whole instrument surface using extract liquid. 3M^TM Clean-Trace^TM ATP Monitoring Systems of Water ATP liquid test (Product Code: H2O) and Luminometer (Product Code: NGi) were used. To verify the performance of the extract liquid, we investigated the influence of the extract liquid on the measurement result and the performance of the extract liquid. ATP stability of two types of commercially available preserved sheep blood (heparinized or Alsever solution added) were examined. A soil model device was prepared by applying mixture of sheep blood and 1.0% sulfate protamine to forceps box lock and drying. Using the selected extract liquid, the contaminant was extracted with ultrasonic cleaning process at 50 °C for 30 min and quantitatively thorough extraction was confirmed by protein measurement. ATP value of each diluents of sheep blood was measured, and the correlation between protein and ATP was evaluated.

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High frequency surgical equipments have been reported to exert electromagnetic interference on implanted cardiac pacemakers because of the conductive currents. We proposed a methodology to evaluate the electromagnetic interference possible to simulate the complex anatomy using the Finite Element Method (FEM) and examined its feasibility. We performed an inhibition test and an asynchronous test using a phantom as the standardized Irnich human body model. We injected 10W of electrical energy (515 kHz, 270mA_RMS) using a high frequency surgical equipment, and measured the potential at 18 measuring electrodes placed in the phantom and the voltage between the electrodes of the pacemaker. A three-dimensional FEM model of phantom had been developed using 193 slices of X-ray CT images taken in 2mm pitch. Electrical potentials at each electrode were estimated using the FEM model and compared with experimental results. If output of the high frequency surgical equipment became more than 7W, the asynchronous test was positive. The maximum error was 25% between measured voltages and estimated voltages using FEM analysis, and average error was 13%. Those results demonstrate that the FEM analysis method is useful to investigate the electromagnetic interference on pacemakers by conductive currents, determining the presence or absence of electromagnetic interference.

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Heat and moisture exchanger filters (HMEFs) are commonly used in mechanical ventilation practices. We described the performances of HMEF in extreme conditions which may decrease expected moisture returns from HMEF. The experiments with dry gases were performed on the model lung-ventilator system. The test lung with soaked cotton inside was placed in the incubator where temperature was maintained at 37 °C.
Relative (RH) and absolute humidity and temperature of the circuit was measured electronically (Maphy+, S.K.I. Net, Inc.).
The results showed, firstly, RH went down below 90% when minute volume exceeded 12L/min. Secondary, air leak of 20% of the inspiration volume decreased RH below 90% when inspired minute volume exceeded 8L/min. Thirdly, addition of unheated cascade humidifier kept RH of the circuit at 100% in both of the above conditions throughout the minute volume of up to 20L/min by providing additional humidity of between 6 and 12 mg/L. We also reported additional effects of the atmospheric humidity as turbine ventilator inspired room air instead of dry gasses. Water content of HMEF increased approximately 8grams in seasons of high humidity whereas, that with dry gases was constantly 1.5±0.3grams(n=39). HMEF with water content of 8grams increased the inspiratory airway resistance by 33%.

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The prevention of occurrence and recurrence of the incidents and accidents involving medical equipment is important in order to provide safe and quality medical care. Since medical gases that are used by medical professionals in the daily clinical setting are often compressed in cylinders, we assessed the incidents and accidents that occurred in relation to medical gases contained in cylinders in this study.
By using published data search on the Japan Council for Quality Health Care website, 102 cases that occurred in relation to medical gases contained in cylinders were extracted, and the causes of occurrences and methods to prevent recurrences were subsequently examined based on the occurrence summary.
The details of the occurrences included: not realizing that the oxygen cylinder had become empty, forgetting to open the valve of the cylinder, forgetting to set the gas flow, not being able to use the oxygen cylinder in an emergency, and damaging the flowmeter.
Multiple staff members from different occupations are involved in the usage of medical gases in cylinders, and the communication of information between medical professionals and between the patient, and error prevention through information sharing are extremely important to prevent the occurrence and recurrence of accidents.

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