Method of sterilization

Details Method of sterilization Method of sterilization

2001-11-16

2003-02-18

Thornton, Krisanne (Department: 1744)

Chemical apparatus and process disinfecting, deodorizing, preser

Process disinfecting, preserving, deodorizing, or sterilizing

Using disinfecting or sterilizing substance

C422S032000, C422S033000, C422S109000, C422S116000

Reexamination Certificate

active

06521180

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to the sterilization of thermosensitive instruments and, more specifically, to a method for sterilizing thermosensitive instruments while preferably exposing the instruments to substantially room temperatures during the sterilization process.
Current methods for sterilizing instruments include using steam autoclaves, using ethylene oxide, or using irradiation. While these methods are effective for sterilizing instruments, none of these methods are suitable for performing instrument sterilization at a patient side location while exposing the instrument to substantially room temperatures during the sterilization process.
Steam autoclaves operate at temperatures ranging between two hundred-forty degrees Fahrenheit and two hundred seventy-five degrees Fahrenheit for extended periods of time. The high temperatures used by steam autoclaves have been known to damage thermosensitive instruments, such as the turbines of a dental handpiece, and tend to reduce the useful life of the thermosensitive instruments. This results in the associated medical instruments requiring more frequent and expensive refurbishing.
Ethylene oxide is a carcinogenic, flammable, and highly toxic substance. Expensive ventilation systems are required before the discharge resulting from the ethylene oxide sterilization process is released to the atmosphere. Thus, the use of ethylene oxide raises safety issues with regard to the sterilization of instruments at a patient-side location. Problematic environmental issues are also associated with the use of ethylene oxide.
The use of irradiation for sterilization is not a practical solution for normal patient-side applications. Irradiation sterilization requires large and expensive installations and protective measures which makes irradiation sterilization unsuitable for use at a patient-side location.
Currently, the pre-cleaning of soiled medical instruments prior to the exposure of the instrument to the actual sterilizing heat, chemicals, or radiation depends on manual cleaning which is performed by medical personnel. The reliance on medical personnel for the manual cleaning of instruments increases the chance of inadequate cleaning due to human error or due to the omission of pre-cleaning all together.
Chemical sterilization can be used to sterilize instruments at room temperature, but it is difficult and hazardous to manually perform. One method of overcoming the difficulties of manual sterilization is to automate the process. However, one problem with automating a chemical sterilizing process is ensuring that the instrument is sterilized according to the U.S. Food and Drug Administration (“FDA”) standards with all of the pathogens and spores killed and removed from every surface of the instrument being sterilized. If the chemicals used to sterilize the instrument are not correctly applied to the instrument, the instrument will not be sterilized as defined by the FDA. The FDA requires that a sterilizer have a STERILITY ASSURANCE LEVEL (SAL) of 10
−6
. The SAL number represents the probability of a non-sterile unit (e.g., a contaminating micro organism or the like) surviving the sterilization process. Thus, a sterilizing apparatus having a SAL rating of 10
−6
is capable of sterilizing an instrument bearing one million contaminating units with no more than one non-sterile unit surviving the process. The difficulty in meeting current FDA standards is exacerbated when sterilizing dental handpieces or other instruments having lumens or internal passages.
What is needed, but so far not provided in the sterilizing art, is method of applying chemicals to dental handpieces, and other instruments having internal passages, which results in the elimination or destruction of life, including micro organisms, on the dental handpiece at least in accordance with a STERILITY ASSURANCE RATING of 10
−6
as currently set forth by the FDA.
BRIEF SUMMARY OF THE INVENTION
One aspect of the present invention is a method of sterilizing an instrument in a chamber of a sterilizing apparatus. The instrument has an exterior and a proximal end. The method comprising applying to the instrument a first application of a sterilizing fluid at a first predetermined flow rate and applying to the instrument a second application of the sterilizing fluid at a second predetermined flow rate. The first application comprises a first predetermined sequence of pulses of the sterilizing fluid and a driving fluid. The second application comprises a plurality of pulses of the sterilizing fluid.
Another aspect of the present invention is a method of sterilizing an instrument in a chamber of a sterilizing apparatus. The instrument has an exterior and a proximal end. The method comprises: washing the instrument with a rinse fluid; removing bio-burden from the instrument with a bio-burden removing fluid; stabilizing a sterilization temperature at which sterilization of the instrument occurs; sterilizing the instrument; a first rinsing of the instrument with the rinse fluid; and a first drying of the instrument. The sterilizing step comprises: applying to the instrument a first application of a sterilizing fluid at a first predetermined flow rate and applying to the instrument a second application of the sterilizing fluid at a second predetermined flow rate. The first application comprises a first predetermined sequence of pulses of the sterilizing fluid and a driving fluid. The second application comprises a plurality of pulses of the sterilizing fluid
Still another aspect of the present invention is a method of sterilizing an instrument in a chamber of a sterilizing apparatus. The instrument has an exterior and a proximal end. The method comprises: washing the instrument with a rinse fluid; a first drying of the instrument; removing bio-burden from the instrument with a bio-burden removing fluid; a first rinsing of the instrument with the rinse fluid; a second drying of the instrument; stabilizing a sterilization temperature at which sterilization of the instrument occurs; sterilizing the instrument; a second rinsing of the instrument with the rinse fluid; and a third drying of the instrument. The sterilizing step comprises applying to the instrument a first application of a sterilizing fluid at a first predetermined flow rate and applying to the instrument a second application of the sterilizing fluid at a second predetermined flow rate. The first application comprises a first predetermined sequence of pulses comprising the sterilizing fluid and a driving fluid. The second application comprises a plurality of pulses of the sterilizing fluid.


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