Abstract
Medical apparatuses and devices used for the procedure, treatment or surgery for a patient are stained with body fluid such as blood. In order to prevent infection and maintain smooth operation of apparatuses and devices, it is crucial to remove these stains completely. For this reason, washer disinfectors and ultrasonic washers are widely used. Defects of parts caused by prolonged operation are an inevitable accompaniment to these devices, and factors such as the cubic measurement of devices to be washed have a great influence on the cleaning efficiency. Although the cleanliness level of devices after washing is evaluated visually or with the protein staining method using amido black, these methods have trouble with objectivity and quickness. Even if a person in charge of washing had doubt about whether the cleaning performance was really sufficient, it was impossible to improve the washing procedure on each occasion by checking the level in a simple and easy way in real time.

In the present study, we applied blood components to stainless steel plates, and checked the cleaning efficiency before and after the overhaul of a washer disinfector using a dried cleaning efficiency indicator for washer disinfectors. We also made experiments on the cleaning efficiency when overlapping devices were washed. As a result, it has become evident that the use of an indicator enables us to take an objective view of machine disorders, and provides us with information on the need for modification of the washing procedure for better cleaning efficiency.

Thus, we confirmed that the use of a cleaning efficiency indicator was very useful for daily washing operations.