OSAKA REPORT
A) Importance of the cleaning test
B) University
of Osaka
Department of Medicine
Ryo Fushimi
C) Introduction
During use surgical instruments become soiled with blood, liquids, and other substances. In order to guarantee correct use of these instruments and to avoid infections one must clean them properly, eliminating all residue.
We
are in charge of the cleaning of these instruments, and we are searching for an
even more efficient way to clean them.
We are discussing the subject--particularly washing/disinfecting
machines and the use of enzymatic detergents—in our meetings and conferences.
Until
now quality control could only be done visually or with the “Amido-black”
method, both of which are quite unreliable.
Recently
we have had the opportunity to try the TOSI indicator. We would like to report the results of
validation.
D) Materials and Methods
1)
Washer/disinfector: WDT-21CS / Hamo
Detergent:
Farmint + J. and Liquid 54
Temperature:
40 C without prerinse
Cleaning time:
1 min. – 3 min. – 5 min.
Drying time:
5 min.
Repetition of this procedure after servicing
2)
Cleaning
efficiency indicator
After using bovine blood on steel we tested TOSI.
Two pieces of metal have been situated on each level
of the 3-level washer, and on each piece of metal we put 6 TOSI with the same
distance between them.
We controlled the results two ways:
1.
Visual
check
2.
Amido
black, Ninhydrin, Rodamin
E)
Results
Table
1 shows the
composition of the TOSI test soil.
Table
2 shows the
different levels of TOSI evaluation.
Table
3 records
the results of the visual validation under the following conditions:
WDT-21CS
Enzymatic detergent
Cleaning: 1 min./3 min./5 min.
Results
after 1 min. (mean value)
Upper level:
3.33 remaining fibrin
Middle level:
2.38 remaining fibrin
Lower level:
1.96 remaining fibrin
Results
after 3 min. (mean value)
Upper level:
1.67 remaining fibrin
Middle level:
0.96 remaining fibrin
Lower level:
1.17 remaining fibrin
Results
after 5 min. (mean value) (normal cleaning time in the hospital)
Upper level:
0.75 remaining fibrin
Middle level:
0.35 remaining fibrin
Lower level:
1.33 remaining fibrin
The
washer WDT-21CS we use in our ward has been in use for seven years and has
never required service.
Table
4 explains
the results after the service and how they improved.
Table
5 shows
results with alkaline detergent. Note
there is not a big difference between enzymatic detergent and alkaline
detergent; however, we did achieve better results with the alkaline detergent
when using the washer for one minute.
Tables
3 – 5 contain the results of the visual evaluation after the washing; however,
only an expert can evaluate the remaining fibrin on the stainless steel.
Figure
1 shows the results of an alternate method—Amido black, Ninhydrin and Rodamin.
We
suppose that the person who uses the washer daily knows that it doesn’t work
perfectly in certain points. Thus it is
important to use an indicator to find these points.
TOSI
is a steel plate on which albumin, hemoglobin, and fibrin are applied. Since we
are washing instruments soiled with blood, we consider TOSI a very accurate
control. In fact, as is illustrated in
Table 3, the washer we have used in our ward for the past seven years show the
following results after a five-minute wash on the upper level:
0/0/2/0/0/2/2/1/2/2/2/2
This
clearly demonstrates that there are parts of the washer that are not cleaning
perfectly. After servicing (Table 4),
the results were much improved, with values from 0.0 to 1.0 These results should be reassuring to anyone
who has doubts about the efficiency of a particular washer. Because the
rotating arm on the washer works at high speed it is only natural that it may
break down over time.
Until
recently we did not know if there was a difference between alkaline and
enzymatic detergent, but now we see (Table 5) that we can achieve better
results with alkaline detergents for the short washing times and with enzymatic
detergents for the longer washing times.
F) Conclusion
Thanks to the TOSI we are now able to determine whether our washers are working perfectly to clean our instruments.
We
believe it is very important to use TOSI daily.