Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
2001-03-21
2002-06-25
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S031040, C073S049200, C422S033000, C422S119000, C422S112000, C134S022120, C134S102200
Reexamination Certificate
active
06408682
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a leak detector for lumened instruments. It finds particular application as a leak detector for endoscopes of the watertight type. It will be appreciated, however, that the invention is also applicable to the detection of leaks in other lumened devices.
Endoscopes and other lumened medical instruments are typically subjected to a thorough cleaning and antimicrobial decontamination between each use. During endoscopic procedures, the devices become coated with blood and other protein-rich body fluids. The endoscopes have a watertight structure in which elements that are sensitive to water, detergents, and antimicrobial agents are contained so that it is possible to wash and sterilize the whole body of the endoscope by immersion or spraying in a washing liquid and an antiseptic solution. However, when there are defects in the watertight structure of the sensitive elements, or pinholes and cracks in a sheath of the endoscope's flexible tube, washing and antiseptic solutions can leak into the inside of the water tight portions of the endoscope. This may lead to corrosion of the operating devices, or leakage of the solutions into the bundle of optical fibers, resulting in hindrance of transmission of light. In addition, patients could be harmed if trapped washing or antiseptic liquids later leak from the inside of the endoscope while in use.
To minimize these problems, methods have been developed to detect for leaks in an endoscope. In a conventional leak test procedure, a source of compressed air is attached to the endoscope. The source exhaust port is closed and the endoscope pressurized until a pressure gauge registers that the pressure within it is within a predetermined “pressure hold” range (typically 1140 to 220 mm of mercury). An observation is made to verify that the scope holds this pressure without falling outside the range. Falling outside this range would indicate a gross leak. The endoscope is then totally submerged in a tub of warm water. If the pressure drops, the endoscope is considered leaky and the test discontinued. If the pressure is maintained in the pressure hold range, the operator is instructed to articulate the control handle knobs of the endoscope to flex the distal tip of the endoscope, and visually inspect the device for bubble generation. An inability to maintain pressure during the pressure hold phase, or the generation of a single bubble in a period of one to two minutes is considered to be an endoscope failure. The operator is instructed to discontinue endoscope reprocessing until the device has been inspected and repaired.
The manual leak check procedure is prone to human error, especially with the increasing demand for rapid reprocessing and turnaround of endoscope devices. For example, bubbles may not become evident until two to three minutes into the pressure hold phase. This is well beyond the one to two minutes time frame allotted for the typical leak check. Another problem with the manual leak check procedure is the potential for the operator to leave the endoscope pressurized during subsequent reprocessing. If this occurs, the distal tip will inflate, as the internal pressure increases in the elevated temperature of the processing solution (typically about 50° C.). This can lead to extensive endoscope damage and costly repairs.
Some automated reprocessing systems include a leak check step prior to disinfection of the endoscope. However, changes in ambient temperature can lead to increases in the internal pressure within the endoscope and lead to erroneous assessments. The reprocessing vessel is frequently warm from a prior reprocessing procedure and the internal temperature of the endoscope often rises, as a result, during the leak check.
Even if a leak detection test is conducted at the beginning of a reprocessing cycle, leaks may develop during the cycle which permit the cleaning fluids to enter the sealed portions of the endoscope during the cycle, or subsequently permit blood or other body fluids to enter during reuse of the endoscope in a surgical procedure.
Continuous leak detection during a reprocessing cycle suffers from inaccuracies, in most cases, since the device being reprocessed is typically subjected to varying temperatures and pressures. To have a test which operates under the variations in temperature experienced results in the test being able to measure only large variations in internal pressure due to relatively large leaks. The test, therefore, may not detect small, pin-hole sized leaks. If the test is designed to be sensitive enough to detect these small leaks, there is a high probability that the device would fail a test where no leak was present.
The present invention provides a new and improved leak detection method, which overcomes the above-referenced problems and others.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a method for reprocessing an endoscope is provided. The method includes supplying a quantity of gas under pressure to an internal passage of the endoscope to pressurize the internal passage. The temperature and pressure of the gas within the internal passage are measured at a first time. After holding the quantity of gas within the internal passage, the temperature and pressure of the gas within the internal passage are measured at a second time. From the measured temperatures and the measured pressures of the gas within the internal passage at the first and second times it is determined whether leakage of the gas from the internal passage has occurred. In response to determining that the endoscope does not have leaks, a decontamination solution is supplied to contact and decontaminate the endoscope. During decontamination, the pressure of the gas within the endoscope is maintained within a range which is above ambient pressure but below a pressure at which damage to the endoscope may occur.
In accordance with another aspect of the present invention, a method of reprocessing endoscopes is provided. The method includes positioning an endoscope in a reprocessing region and connecting a leak detector to the endoscope. A quantity of compressed gas is supplied to an internal passage of the endoscope to pressurize the internal passage. The method further includes electronically calculating whether the endoscope has leaks from changes in the temperature and pressure of the gas with time. A portion, but not all of the gas within the endoscope is released, such that the pressure of the gas is at an above ambient pressure during decontamination. In response to determining that the endoscope does not have leaks, an antimicrobial fluid is supplied to the reprocessing region to contact and decontaminate the endoscope.
In accordance with another aspect of the present invention, an apparatus for processing endoscopes is provided. The apparatus includes a structure which receives an endoscope to be reprocessed, a pressurized gas source, a means for supplying the pressurized gas from the gas source to an internal passage of the endoscope for selectively pressurizing the internal passage and for holding a quantity of gas in the internal passage fixed. A gas temperature and pressure measuring means is provided for repeatedly measuring a temperature and pressure of the fixed quantity of gas in the internal passage. A leakage determining means receives the measured temperatures and pressures and determines, from changes in the measured temperature and pressure, whether the gas in the internal passage is leaking at a rate greater than a predicted acceptable leakage rate. A source of antimicrobial fluid and a means for supply the antimicrobial fluid to the structure and for contacting and decontaminating surfaces of the endoscope with the antimicrobial fluid are provided. The pressurized gas supplying means supplies pressurized gas to the internal passage to maintain the pressure of the gas in the internal passage above an ambient pressure in the structure while the antimicrobial fluid is contacting and decontaminating the surf
Fay Sharpe Fagan Minnich & McKee LLP
Steris Inc.
Wiggins David J.
Williams Hezron
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