Medical accidents have potentially included many cases associated with medical instruments as one of background factors. Aiming to keep personnel’s awareness on medical safety as one of hospital management and administration schemes, we explored and statistically analyzed two grounds of medical accident reports from the viewpoint of the safety management supervisor on medical instruments. One was contexts of reported accidents related to medical instruments in our hospital. And the other ground was varied medical incidents and accidents independent on medical instruments from Japanese open database. In our hospital, 10.8% accidents were associated with medical instruments and most of these were use failures of medical instruments. Analyzing the open database, we found that numbers of accidents related to medical instruments were linearly correlated with total numbers of medical accidents. Considering these results, risk management about medical instruments based on the accident reporting system would be important for continuously improving and maintaining quality of medical care.

呼吸器リハビリテーション用のデバイスでは，動脈血の二酸化炭素の濃度は呼気値から推定される．我々は呼気中の二酸化炭素分圧が，伝播する音波の速度を遅らせる効果に鑑み音響式の呼気二酸化炭素計を開発した．この論文は我々の知る限り呼気中の音響速度の測定に基づく最初のオリジナルな方法である．したがって二酸化炭素識別用のどんなセンサも省略できる．この方法は呼気二酸化炭素計が極めて安価に作られ，リハビリテーションの目的で広く用いられる可能性がある．

デバイスは円筒形の小さなサンプル用空洞があり，超音波発・受信システム，音速決定のための電子回路ならびにデータ処理用のマイクロプロセッサーからなる．このシステムを確かめるべく12 名の肺疾患の患者を集め，終末呼気の二酸化炭素分圧のデバイス値を動脈血ガス分析装置の値と比較すると，結果は関心領域（40 －60 トル）で直線相関を示した．したがって動脈血の二酸化炭素濃度は呼気中の音速の測定値から推定できることが分かった．

Nosocomial infection mainly derives from contacting the microorganisms spread from environmental surfaces and the medical devices. To prevent and control hospital infections from the circumstances, this study aimed to evaluate the sterilization effect of an ion-less hypochlorous acid water. We compared with no hand wiping (control), hand wiping and hand wiping plus sprayed hypochlorous acid water. We investigated the bacteriocidal effects of 12 points in the dialysis center (165m³) (Bed side/ dialysis equipment monitor, bed mat, side table, Nurse station/ PC keyboard, mouse, and work desk) using a contact plate method. As a result, the hypochlorous acid water significantly reduced bacterial colony forming units (CFU) on the surfaces of various places than those of hand wiping method (p<0.05). There were fluctuations in the density of the bacteria in the hand wiping group. The hypochlorous acid water showed a broad-spectrum virucidal activities. We concluded that this hypochlorous acid water was useful and applicable for disinfection of the various places’ surfaces and is a key method of controlling the spread of nosocomial infection.

When placed in an environment with the magnetic flux density higher than a certain value, cardiac implantable electronic devices (CIEDs) possibly show magnet response and affect patients’ safety.

In this study, we investigated the magnetic flux density at which magnet response works in six types of CIEDs. Further, we measured the magnetic flux density of the radio wave utilization equipments generally used in the hospital and investigated the relationship with magnet response.

Among the investigated CIEDs, Cobalt (Medtronic) ICD showed magnetic response at the minimum value of the magnetic flux density larger than 1 mT. In addition, the magnetic flux density exceeded 21 mT in all of the radio wave utilization equipments.

Our findings suggests that the investigated CIEDs are possibly affected by magnet response when the magnetic flux density is larger than the minimum value of 1 mT, and therefore CIEDs are possibly affected by all the target radio wave utilization equipments. For the medical safety management, it is necessary to disseminate and share information with patients, their families, and medical staffs to make them aware of this risk.

In infusion therapy, flow rate errors are caused by changes in the droplet volume dripped from drip chamber. The purpose of this study is to determine the change in droplet volume when surface tension, viscosity, density, and flow rate are varied. The droplet mass in a continuous drip is precisely measured and the droplet volume and standard deviation are determined for each 100 drops. At drip nozzle A, the rate of change in droplet volume was -44.78% at the change in surface tension, -12.14% at the change in viscosity, -5.70% at the change in density, and 8.14% at the change in flow rate. The volume change rate when double the surface tension, viscosity, and density were changed was 43.18% at the change in surface tension, -2.87% at the change in viscosity, and -16.10% at the change in density. The volume change rate affected by the viscosity change was slight. An experimental equation was tried to calculate the droplet volume of each condition. Since a change in surface tension causes a significant change in droplet volume, infusion therapy used drugs with significantly different surface tensions needs to pay attention to flow rate errors. It is recommended that the surface tension of drugs used for infusion is written on the package insert.

The results of our previous study using the hands-free manual for emergency dialysis cessation suggested a higher operational accuracy and usefulness of the hand-free manual as compared with a paper manual. However, its contents were excessively detailed and a jump function was required for speedup. Since use of a jump function that skips manual pages could cause mistakes due to false assumptions, we attempted to develop an automatic inspection method. Assuming that image recognition using a Neural Network Console (NNC) might be effective for the automatic inspection, images from a previous study in which mistakes were often made were collected and the results revealed an accuracy rate of only 37%. In order to improve the accuracy, we considered that the amount of information would need to be reduced. Therefore, we set the detection images as those showing the forceps position on the puncture needle, the relative angle between them, and the forceps grasp, and evaluated the potential merits of using a NNC, and this analysis yielded an accuracy rate of 67%. For further improvement, we conducted pre-processing, in which the level of the line connecting the centers of gravity of the markers and the midpoint of the line were moved to the center of the screen; this action yielded an accuracy of 100%, suggesting the usefulness of pre-processing.

The authors have been developing a generator for Nasal-CPAP (HNCPAP) using an air-curtain capable controlling nasal high frequency oscillation. The experiment was performed using a breathing mode simulating healthy lung of the spontaneous breathing simulator for newborns (PT-2: manufactured by Atom Medical) equipped with HNCPAP, and the MAP (mean airway pressure) was changed with constant tidal volume. The experimental conditions were that the respiratory rate and the tidal volume were constant at 50 times/minute and 7 ml, respectively, and the experiment was performed by changing every 100 Pa within the MAP (mean airway pressure) range (300 Pa to 900 Pa). The NDPAP experiments were also performed in the same breathing mode. From biphasic CPAP pressure synchronized with CPAP pressure (Cpap) of HNCPAP, biphasic characteristics were inferred as follows.

・The inspiratory Cpap waveform at CPAPhigh should indicate the physiological inspiratory state.

・By setting CPAPhigh, the effect of lung recruitment during inhalation, the effect of discharging nostril side flow due to entrainment during the first half of expiration, and the effect of preventing collapse the alveoli during the second half of expiration are improved. From the above results, we were able to present the possibility of biphasic CPAP synchronized with spontaneous breathing as a new usage of HNCPAP.