It has been reported that approximately 400 kinds of medical devices are recalled every year in Japan. We analyzed Pharmaceuticals and Medical Devices Agency recall data from April 2008 to March 2013. In total, 2163 recalls were issued in five years. We investigated the recall cases and the length of recall time (the time between when the devices were sold and recalled), classifying by diagnosis device and clinical department. Radiology, cardiovascular, and clinical laboratory devices were heavily recalled. Thirty-one point six percent of recalls were class 3 and 4 specially controlled medical devices. Sixty-four percent of recalled devices were general devices (non-disposable), and 28% were disposable devices such as catheter and syringe barrel. The length of recall time was 37.7 months on average, but the time was shorter when the device risk level was high, and longer with a high risk recall. In particular, disposable device recalls occurred in a short period. In contrast, radiology and clinical laboratory device recalls occurred 55.1 months after delivery on average, and 10% of them were recalled after a decade or more. We investigated the length of recall time classifying by diagnosis device and clinical department, and found that there is a large difference between disposable devices and general devices.

View full abstract

This study investigated which alarm sound is easiest to distinguish from the background noise. The experiment measured the perception time of some alarm sounds such as: meaningful verbal alarms, meaningless verbal alarms, pulse sounds and melodic alarms.
The intensity of each alarm sound-type was increased stepwise against the level of background noise. It was discovered that the alarm sound could be distinguished when the peak value of the spectrum of the alarm sound was equal to or a little bit larger than the level of the spectrum of the background noise.
The sound level required for the different types of alarm sounds to be perceived was investigated. This investigation discovered that the pulse sound and meaningful voice alarm were easy to perceive but general melodic alarms were not easily perceived at the same sound level. It was estimated that a smaller alarm sound could be detected if the characteristics of the alarm sound are designed with the background noise taken into account.

View full abstract

During treatment of positive pressure ventilator, an intubation tube is inserted into the patient’s trachea. If the intubation tube is pulled out during the treatment, the patient condition may become critical. We reported on a system which enables an alarm before the tube might be pulled out by the patient’s hand. A detection electrode in the developed system is attached to the intubation tube and we proceeded to experiment with the system. Twelve healthy volunteers participated in the experiment, and were requested to place their hand at a distance of 10 cm, 5 cm, 2.5 cm, and 0 cm (contact), respectively, from the intubation tube. The preliminary result of this experiment showed that the oscillation frequency of the developed sensor changes accordingly to the distance between the electrode and the subject’s hand. By using the result, the threshold values for the alarm could be determined. In a practicability evaluation experiment, the system made alarms successfully; an attention lamp (yellow) was lit when the subject’s hand is in less than 5 cm from the intubation tube, and a warning lamp (red) was lit when the subject’s hand is contacted with the tube.

View full abstract

Tracheal suctioning has been studied without considering rheological aspects of the viscosity of the sputum. The volume of the fluid which travels in a tube is determined by the internal cross sectional area of the tube or catheter size, the velocity or vacuum pressure and the viscosity of the fluid. We investigated the effects of viscosity during tracheal suctioning using mucus simulants. We collected a total of 250 ml of sputum from 79 tracheostomized adult patients. The viscosity of the sputum decreased from 13,571 to 4,714mPa・s while increasing the speed of rotation of the viscometer from 4 to 20 rpm. The results indicated that the sputum was pseudoplastic non-Newtonian fluid similar to most of the liquid foods. The results allowed us to use 2, 4 and 6% of potato-starch solutions as mucus simulant for in vitro experiments. The viscosity was the most influential on suctioning volume over catheter sizes and vacuum pressures. The results obtained from a series of various combinations of the vacuum pressure of -10, -20, -30 and -40kPa and the catheter size of 8, 10, 12, 14 and 16Fr indicated that the best combination was -30kPa and 12Fr catheter. In terms of volume of mucus simulants suctioning we concluded that the above combination was clinically relevant while avoiding excess aspiration of air from the lungs.

View full abstract

Background: Single use devices (SUDs) are indispensable in clinical settings. However throughout the world, some of them are resterilised and reused. In the United States their reuse is strictly regulated, but in Japan their reuse is not so strictly regulated by law.
Objective: In the results of studies reported in 2000, 2003, 2005 and 2007 on the situations of reuse of SUDs in Japan, a decreasing tendency has been observed. Seven years have passed since the last surveillance, so here, the reuse of SUD was studied again in order to propose adequate ways of managing this issue in the future.
Methods: A questionnaire on the situation of reuse of SUDs was sent to 150 Certified Sterilisation Specialists (CSSs) of the Japanese Society of Medical Instrumentation who engaged in clinical central services.
Results: Replies to the questionnaire were received from 63/150 (42%). Of these 63 CSSs, 81% replied that some SUDs were reused in their facilities. Twenty seven facilities (43%) classified where the responsibility of reuse lied. Reuse of high-risk devices and opened but unused devices has been markedly decreased, although the population studied this time was a little different from those of the past four observations.
Conclusion: The reuse of SUDs is mainly for economical reasons, however, patient safety and ethical aspects should be considered further. In Japan too, the reuse of SUDs may become legally regulated in the near future. Patient safety should be considered more strictly by healthcare personnel.

View full abstract