Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2001-03-12
2002-12-03
Boyer, Charles (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S245000, C510S356000, C510S384000, C510S391000, C510S421000, C510S504000, C510S510000, C510S511000
Reexamination Certificate
active
06489276
ABSTRACT:
TECHNICAL FIELD
The present invention concerns compositions for cleaning instruments and the like. More particularly, it is concerned with compositions for removal of body fluid from surgical instruments and other surfaces such as operating tables and instrument trays.
BACKGROUND OF THE INVENTION
In medical environments, there are several types of soils which contaminate surgical instruments and surfaces in or around an operating theatre. The invention relates to compositions for washing such surfaces, and is particularly concerned with an improved method and composition for the removal of body fluids and soils from surgical instruments and similar medical equipment.
Blood is the most difficult type of stain to deal with in that it contains complex iron molecules i.e. hemoglobin molecules. Blood stains are difficult to remove because they tend to harden and become fixed by conventional detergent mixtures.
A number of chemical methods have tried to reduce staining by the action of hemoglobin on metals and other surfaces. For reasons which are not understood, the iron content within the hemoglobin tends to become more insoluble in the presence of surface active agents.
Fats are another type of stain frequently encountered. These are easily solubilised or emulsified by conventional detergents. However, in the presence of iron i.e. hemoglobin which acts as a catalyst, liquid fats can harden. Thus fats in conjunction with blood can be difficult to remove. In this state, inert soils such as surgical lubricants, usually silicones, can become embedded and thus difficult to remove. Similarly, other soils including soluble and semi-soluble carbohydrates can also become bound up.
Biological soils such as pus and other waste from microbic activity also often encountered in these environments. These type of soils are insoluble in water and surfactants and thus their removal causes problems.
As a consequence of the technical advances in medicine over the last few years there is now a wide range of materials used in the manufacture of surgical instruments. Hence there are a number of substrates on which soils can be deposited which include metals such as stainless steels, plastics, ceramics and glass.
A wide range of surfactant formulations are known for removing body fluid soils. These are varying effectiveness. Apart from body fluid soils, problems arise with the formation of insoluble deposits arising from water and from the presence of metals, such as aluminium which leads to the formation of alumina scale. Iron oxide or rust staining is also a problem which arises from the presence of hemoglobin in blood stains. Certain sequestering agents are commonly used to inhibit scale formation but these may suffer from instability which presents a safety problem as the decomposition products may be harmful or render the sequestering agent ineffective.
Conventional surfactants include polyphosphates. These essentially function as sequestering agents for hard water salts ie they act as a water softener. However, such conventional surfactants are not capable of dissolving rust stains, nor are they capable of preventing the formation of alumina scale.
Another common cleaning agent is the complexing agent EDTA. This is perfectly suitable for sequestration of calcium and particularly for the prevention of precipitation of more highly insoluble calcium salts such as calcium phosphate. However, this compound can be unstable at high pH, with the breakdown products being corrosive. This agent also has no effect on rust stains.
Other sequesterants have been used, but they all suffer disadvantages in one way or another and frequently there is less than 100% removal of soils arising from body fluids.
Conventional soil removal systems are generally high pressure high temperature washing machines such as autoclaves. There are other machines which work at lower temperatures for cleaning heat labile equipment. Hand-hot water is used for hand washing instruments and similar equipment.
A commonly used method of washing large numbers of surgical instruments is by batch washing or continuous washing in a suitable machine such as an autoclave or the equivalent to a domestic washer. Also certain instruments are cleaned by ultra-sonic equipment containing either a water based cleaning solution or an organic solvent.
Conventional methods of cleaning instruments suffer the problem that a thin layer of material frequently remains on the instrument after cleaning. Although this material may be rendered inactive by the cleaning agent and thus be unable to propagate, there is still the problem that any layer of material which remains on the instrument after cleaning will act as a nutrient for any microbial organisms which come into contact with the instrument, thereby representing a potential health hazard.
Once cleaned by a conventional method, the instruments are sterilised by heat with or without chemical support.
It is during the heat-sterilising process that any soiling left on the instruments will carbonise. This has the disadvantage that the presence of carbonised deposits could have an adverse effect on the performance of the instrument.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide improved cleaning compositions which are capable of removing substantially all contaminating material from surgical instruments. It is also an aim of the invention to provide compositions which are compatible with a wide range of materials encountered in the medical field. It is a further object to provide compositions. which are effective at ambient room temperature and/or at elevated temperatures such as those found in hospital washing equipment. It is thus intended that the compositions of the present invention effect substantially complete and safe removal of soiling. It is hence an aim that the compositions of the invention are easy to handle and use and do not in themselves present a health risk.
It is also an aim of the invention to overcome the disadvantages of conventional cleaning agents as described above. In particular, instruments cleaned using the compositions of the present invention may not need a further heat sterilising treatment.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention there is provided a method for cleaning medical equipment and surgical instruments; the method comprising applying to the medical equipment and surgical instruments a composition comprising by weight:
a metal silicate or silicate complex
2.0 to 20.0%;
a metal phosphate or polyphosphate,
1.0 to 50.0%;
or orthophosphoric acid
a non-ionic or amphoteric surfactant
1.0 to 15.0%;
a quaternary ammonium salt
1.0 to 3.0%;
with the balance of the composition
comprising de-ionised water or a
solid bulking agent;
the composition optionally including
one or more of:
a sequestering agent
0.5 to 3.0%;
an oxygen donor
0.1 to 50.0%;
an alcohol
5.0 to 25.0%;
a polysaccharide
0.01 to 0.50%;
cationic surfactant or source of
1.0 to 3.0%;
cations
and; colours, fragrances, and/or
as required.
anti-foaming agents
The substantially complete and safe removal of soiling is achieved by using this method in a number of ways including physiochemical and chemical transformation or alteration of the soiling to enable removal. These compositions are directed solely towards soil removal from surgical instruments and associated equipment. Soiling in this context refers to all types of contamination usually encountered in such circumstances and ranges from inorganic materials to microbic organisms. In the medical field, the main criterion is safety, followed by effectiveness and ease of use. The compositions of the present invention provide exactly these benefits.
Preferably, the metal cation in the silicate or silicate complex is an alkali metal cation or an ammonium cation. More preferably, the cation is sodium. In the case of liquid formulations, preferably there is 2.0 to 6.0% of the silicate or meta-silicate present; and in the case of solid formulations there is preferably 15.0 to 20.0% present.
Boyer Charles
Ebiox Limited
Jenkins & Wilson, P.A.
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