Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using disinfecting or sterilizing substance
Reexamination Certificate
2000-02-17
2002-04-02
Warden, Sr., Robert J. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using disinfecting or sterilizing substance
C422S116000, C422S300000
Reexamination Certificate
active
06365103
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method of sterilizing endoscopes and in particular hollow endoscopes.
BACKGROUND OF THE INVENTION
The development of endoscopic instruments has greatly advanced the ability of the medical profession to diagnose and treat diseases in relatively inaccessible regions of the body. The first examinations that could be considered “endoscopic” in the modern sense were probably the rectal inspections conducted in the 18th century. The physician peered through a rigid tube inserted into the patient's rectum and relied on candles or gas lamps to illuminate the interior. By today's standards the physician saw very little; however, endoscopic examinations continued and endoscopes of various designs were invented and have revolutionized many medical procedures.
As is well known to one skilled in the art, endoscope tubes often include mechanisms for turning the tip in four directions, up, down and from side to side, to facilitate passage of the instrument around angles and allow visualization of all surfaces. An additional viewing channel, coupled to a separate eye piece, for simultaneous direct viewing by a second observer is also available. In addition, the tubes contain channels for air insufflation and water instillation, so that lenses can be cleaned during a procedure, and to allow passage of biopsy instruments and fulguration instruments. Tube channels may also be provided for passage of light from a laser for ablation/photo dynamic therapy, spray catheters, polypectomy snare wires etc.
A typical endoscope, as found in a physician's office or hospital, is used repeatedly. Thus, it is imperative that endoscopic tubes must be completely sterilized between each use to avoid the transmission of diseases, such as AIDS, Hepatitis, etc. Typically, a sterilization fluid is passed through the water and air ducts of the instrument to sterilize the internal surfaces. This sterilization fluid is at times supplied from a bottle which temporarily replaces the water bottle used with the endoscope. As is evident to one skilled in the art, conduits (internal surfaces) within the endoscope are the most difficult parts of the endoscope to sterilize. Endoscopic materials are also often heat sensitive and do not lend themselves to heat sterilization techniques.
In light of the ubiquitous use of the endoscope by the medical profession and intricate internal surfaces of the endoscope, an efficient method for sterilizing the endoscope at ambient temperatures is required.
U.S. Pat. No. 4,862,872 issued to Yabe et al. on Sep. 5, 1989 discloses an endoscope and a washing apparatus for an endoscope. The endoscope comprises an elongate insertable part having an observation window and illuminating window in the tip part, an observation means for observing an object by receiving a returning light from the object which enters through the observing window, an illuminating light output means emitting an illuminating light from the illuminating window and a memorizing means capable of memorizing the information on washing. The washing apparatus is provided with a read-out means for reading out the information memorized by the memorizing means of the above mentioned endoscope and a control means controlling the conditions of washing the above mentioned endoscope by the information read out by this read-out means. This endoscope washing apparatus is relatively complex and likely expensive to manufacture.
U.S. Pat. No. 5,297,537 issued to Savitt et al. on Mar. 29, 1994 discloses a disposable liquid supply kit for use with an endoscope that comprises a closed liquid container for connection to an endoscope prior to use. With a disposable unit of this type, a fresh supply of sterile water is installed in the endoscope between each use with a patient. The liquid supply system is preferably sealed at the factory to insure complete sterilization. Obviously, a medical facility using such a kit requires inventory and incurs expense as a result of maintaining and monitoring the inventory.
U.S. Pat. No. 5,534,221 issued to Hillebrenner et al. on Jul. 9, 1996 entitled “Device and system for sterilizing objects” discloses a hollow cassette for holding an item to be sterilized, for example an endoscope. The cassette is a sealable cassette in which an endoscope or other medical device is placed. The cassette has input and output fluid sealing ports for the introduction and removal of a sterilizing fluid. The cannula of the endoscope is coupled either to the input or output port. The cassette is formed of two identical halves which are placed in superimposed sealable relationship with each other to form a hollow chamber. A latch is placed on one or more handles on the cassette to create a presealing condition to allow a vacuum to be introduced at the outlet port. The cassette is then placed in an outer oven-like container or warming chamber where the temperature is properly maintained. Connections are made to open the input and output ports on the cassette such that the sterilizing agent may be introduced through a first port to bathe the outside of the medical endoscope, while one end of the endoscope is coupled to the output port where a vacuum is supplied external to the cassette to pull the sterilization agent into the cassette and through the interior passageways of the endoscope. When the sterilization process is completed, the warming chamber is opened and the sterilizing cassette is simply removed from the chamber with the input and output ports being uncoupled from their respective sources. A tight seal is maintained and the object remains in the sterilized interior of the cassette until the cassette is opened or the device is to be used. This represents a sterilization system which is relatively costly to produce and use.
It would be advantageous to provide a method for endoscopic sterilization that is inexpensive and operatively simple. It would also be advantageous to provide a method that can be used with a sterilizing chamber that is used to sterilize many different articles and not just for endoscopic sterilization per se. It has now been found that by applying principles of pressure equilibration it is possible for an endoscope's conduit(s) and external surfaces to be sterilized.
Conventional sterilization procedures for medical instruments involve high temperature (such as steam and dry heat units) or toxic chemicals (such as ethylene oxide gas, EtO). Steam pressure sterilization has been the time-honoured method of sterilization. It is fast and cost effective. However, the autoclave destroys heat-sensitive instruments such as arthroscopes and endoscopes.
Ethylene oxide sterilization is used to cold-sterilize heat-sensitive instruments and can be used as a sterilization gas. However, it has been deemed by national health and safety organizations to be carcinogenic and neurotoxic, and requires long sterilization and aeration periods.
Ozone is a more efficient, safer, and less expensive sterilization agent and is easily generated from oxygen, preferably hospital grade oxygen. Ozone is widely used in industry as an oxidising agent to bleach paper pulp, treat drinking water, and sterilize sewage water and food products. Ozone generally acts on chemical compounds in two ways. Either by direct reaction or through hydroxyl radical species formed during the decomposition of ozone (Encyclopaedia Of Chemical Technology, Vol. 17, Ozone page 953 to 964). The amounts (concentrations) of ozone required in the sterilization gas for water purification are low, generally less than 36 mg/l (milligram per liter). Significantly higher concentrations are required to make ozone gas an effective sterilant of micro-organisms, and those high concentrations of ozone gas are generally combined with critical levels of humidity during the entire sterilization cycle to improve sterilization efficiency. The activity of ozone increases rapidly with increased relative humidity. The resistance of spores to ozone varies from strain to strain, but the differences become comparatively
Brinks Hofer Gilson & Lione
Conley Sean E.
Technologies of Sterilization with Ozone TSO3 Inc.
Warden, Sr. Robert J.
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