FR2776070A1 - Method for detecting faults on medical washing or sterilizing machines - Google Patents

Abstract

Concentrates of cleaning, disinfecting and neutralizing agents (A,B,C) are stored in containers (8a,8b,8c). Test units (9a,9b,9c) capable of generating signals, measuring responses and evaluating algorithms transmit resistivity data to a processor (10) which also receives similar data from a sensor (12) in the washing machine tank (2). Additives are used to ensure that the concentrates and machine liquid are positively recognized.

Description

 The present invention relates to a method for the identification and quantification of concentrated active products for washing machines used in the medical field.

In these services, it is necessary to ensure excellent hygiene vis-à-vis the caregivers and patients, and reduce the risk of nosocomial infections. In order to ensure efficient cleaning and disinfection of hospital equipment without the risk of cross-contamination, the machine vessel must be supplied with specific active products in a specific order and in fixed and sufficient quantities.

In general, a washing machine requires the use of two to three different products that occur during the phases of the cycle. Possible products are detergent, disinfectant, neutralizer and sometimes rinsing agent. They are used in this order during cleaning, disinfection, neutralization and rinsing by the machine. Given the diversity of products, any anomaly in their use is a risk whose consequences would be harmful to the health care staff and patients. Also, it seems necessary for the user of the machine to be able to quickly and automatically control the loading of these products before they are introduced into the bath of the tank of the machine, therefore upstream of the treatment process.

Specifically, the invention relates to a method for determining formulas consumables whose analytical part is located in a rod and which allows to perform a series of successive steps when one of the supply rods of the machine is dipped in one of the containers in concentrated liquid active product. As soon as the machine is put into operation, the steps performed are as follows
a - analyzing the active product by measuring its resistivity,
b - compare the measured value with the set value:
if the measured value is equal to the setpoint in its safety interval, the product is considered to be in conformity, which validates the transition to step c
- if the measured value is outside the safety interval, the product is non-compliant, the system triggers an audible alarm and the machine does not start the cycle
c - when the product is considered compliant, authorize the collection of a fixed quantity. It will be sucked into the supply line to the bath of the tank by starting a pump
d - regularly measure the level of active substance contained in each Jerrican receiving the suction rod, before each cycle. This value is stored and analyzed.

This last measure will present the advantage
- to make sure of the good consumption of the product or to trigger an alarm with refusal to carry out the treatment if the value of average consumption goes beyond the limits of the pre-established instructions
- monitor the state of the stock to prevent any product shortage beforehand and automatically;
- follow the stock status at the beginning of a day of use of the machine to avoid a break in the work plan.

This protocol is therefore performed for each product used, corresponding to the number of feeding rods dipping in these products. The present invention is explained in more detail using FIGS. 1 and 2.

The implementation of this procedure carried out before the process of the machine offers the user the possibility of avoiding the positioning of a Jerrican active product inappropriate for the sake of quality assurance and security, on the one hand and, on the other hand, to check the average consumption of each product during the last cycles of treatment to avoid any abnormal consumption.

This present invention completes the use of another method of identifying and quantifying these same active products, this time diluted in the bath of the tank of a washing machine, which has been the subject of a prior patent application. It is a resistivity sensor capable of detecting diluted products, identifying them and verifying their dosing also connected to a security system. When a washing machine has these two processes placed before and during the process of processing the machine, none of the checks carried out can lead to conflicting messages.

 A first device known and commonly used in a procedure for sampling a quantity of liquid fixed by a supply rod is a float positioned at the bottom of a plunger positioned in a Jerrican. This float is mobile on 2 to 3 cm. When the container contains a liquid, it is positioned at the top of its moving stroke, and when it no longer contains it, it is positioned at the bottom, by simple gravity. The high position, like the low position, are recognized by a switch sending the information to a PLC.

A second known device is the floating magnet sensor. When immersed in the product, it can perform a measurement whose quantity is controlled by monitoring the height of the remaining liquid. This control is made possible by the sensor's own geometry. The elongated part of his body is composed of a juxtaposition of micro-detectors of magnetic fields capable of locating the position of the magnet on the surface of the liquid. The measurements made are then processed by software that determines the position of the magnetic float and the quantity of product taken. This device requires miniaturization difficult to achieve and is not currently implemented on washing machines whose consumables are cans of five or ten liters.

A third device known and used in this same type of procedure is the capacity sensor. This sensor is composed of two insulated conductive blades between which is measured the capacity of the product (in Faraday), a standardized physical quantity. The mechanical shape of the capacitor blades amplifies the capacitance value according to the level to be measured. The measurements made are also processed by software which determines the position of the liquid level and records the quantity of product taken. This device is unreliable and requires significant corrections depending on the capacity of the products.

In addition, these three devices do not allow the identification or recognition of products taken. In a cleaning procedure by a washing machine, when there are several consumables to be used, it is necessary to consider
- the containers may be interchanged with each other,
- that non-recommended containers having an external look confusable with those intended to perform the process can be used,
- that products degraded by mixtures, substitutions, dilutions. . can be used by the machine, resulting in inefficient treatment.

The present invention is intended to overcome these disadvantages. Its principle makes it possible to identify the concentrated active product by virtue of the properties attributed to the product (1, 2 or 3) and the supply rod of the machine (4) equipped with a suitable detection system (5 and 6), to validate its presence before sampling from a pump (7), to control the quantity of product withdrawn and that remaining in the original container (8), data accessible to the user of the machine.

Thus, as soon as the cane is immersed in the judiciously formulated concentrated active product, the machine performs an automated quality control before use, thus avoiding the risk of human error. In addition, this process allows a precise and regular traceability on the consumption of the products at each phase of cleaning, disinfection, neutralization and rinsing. A control of security, associated with a better management of the consumables and the time follows from it.

The principle of this invention requires
to modify the formulations of the consumable products in order to place them in a recognition scale (first phase), and
- to integrate jointly into each supply rod of the machine two detectors operating simultaneously
a resistivity sensor which allows the detection and identification of the active products (second phase) and
a level sensor which makes it possible to determine the quantity of product withdrawn and the quantity remaining (third phase).

The principle of the first phase of this invention consists in organizing the detergent, disinfectant, neutralizing and rinsing agent products by modifying their formulation or adding a tracer to allow their distinction according to their resistivity values in order to establish a scale of values. reference for their identification.

This scale of reference values is integrated in the program of a PLC of the machine and represents the set values. The automaton receives the values taken by a resistivity sensor, the second phase of this invention, which is adapted to product formulations and integrated in the supply rods of the machine, and compares these measured values with the set values.

If, as a result of these comparisons, a difference greater than the tolerances arises, the automaton activates an alarm and prohibits or stops the operation of the machine.

If no difference is found, the quality plan is accepted because each product behaves like the right product, placed at the right place in the machine's reserve because it is in contact with the appropriate supply rod. It will be picked accordingly as defined in the manufacturer's program.

A level sensor, third stage of this invention, is associated and the measurements will be taken into account according to the information given later.

Initially, the detergent, disinfectant, neutralizing and rinsing agent products are little characterized or hardly distinguishable by their resistivity value, the quantity of one or more components of their formulation is modified, or possibly a strong electrolyte acting as a Concentration marker is added to their formulations. These formulation modifications or additives imposed or modulated a product resistivity value different from the original one. The optimal amount of the component or marker is defined
to be able to position the active product in a value scale organized around a principle of grouping equivalent products by families,
- to make it possible to determine precisely the nature of the products,
- to preserve their initial detergent, disinfectant, neutralizing or rinsing properties.

The distribution of the products in the families takes into account their function during the treatment, which corresponds to the four families of products bringing together detergents, disinfectants, neutralizers and rinsing agents. Taking into account their characteristic physicochemical properties, the detergents are divided into four families, and the neutralisers split in two. This distribution then reveals eight distinct families of products. The content of each of them is detailed below.

The four families of detergents stand out from each other as follows
- foaming detergents (bearing the trade names "TED 4", "DDN 250" and "TFD 9") recommended mainly for manual washing, to be avoided in a washing machine because of the risk of foam, overflow and inefficiency that entails,
- alkaline detergents ("TFD 7") used in the machine for the degreasing and cleaning of glassware and surgical instruments,
- acid detergents ("CA5P" and "NA 6") to unclog scaled objects such as urinals and animal cages,
- endoscope washers ("TFD 75") specially formulated for the cleaning of endoscopes by suitable washing machines.

Disinfectants ("ENDEX 25") are distinguished from all other product families for their characteristic antimicrobial properties and whose action is effective only on sufficiently clean material, therefore recommended following a cleaning phase.

Neutralizers, which are acidic solutions, are used as a result of the washing or disinfection phase and allow the dissolution of limescale deposits and the neutralization of traces of alkaline detergents. They are distinguished mainly by their function
- acid neutralizers ("PHOS PHAX") which are recommended for the neutralization of the washing baths of laboratory glassware, baby bottles, urinals and animal cages.

 - neutralizers for instruments ("NEUTRAX") suitable for the neutralization of the washing and disinfection baths of the endoscope washing machine and the surgical instrument washing machine.

The rinsing agents that intervene in the last phase of the cycle washing machines urinals to facilitate their drying, or washing machines surgical instruments to protect their surface ("MOUILLOL" and "LUBRIX").

Each of these product families is therefore characterized by a reference resistivity value, placed in a scale called "Scale of pure products". These values are collated in the table below, specifying the minimum and maximum limits of their reference value.

<Tb>

<SEP> FAMILIES <SEP> OF <SEP> value <SEP> value <SEP> of <SEP> value
<tb><SEP> PRODUCTS <SEP> minimum <SEP> reference <SEP> maximum
<tb><SEP> (Ohms) <SEP> | <SEP> (Ohms) <SEP> | <SEP> (Ohms)
<tb> NEUTRALIZING <SEP> 7 <SEP><SEP> 8 <SEP> 9 <SEP>
<tb><SEP> ACID
<tb><SEP> DETERGENT <SEP> 12.5 <SEP> 14 <SEP> 15.5
<tb><SEP> FOAMING
<tb><SEP> DETERGENT <SEP> 16.5 <SEP> 18 <SEP> 19.5
<tb><SEP> ALCALIN
<tb><SEP> DETERGENT <SEP> 22 <SEP> 27 <SEP> 32
<tb><SEP> ACID
<tb><SEP> DETERGENT <SEP> 61 <SEP><SEP> 66 <SEP> 71
<tb> LAVA <SEP>
<tb><SEP> ENDOSCOPE
<Tb>

<tb> NEUTRALIZING <SEP> 123 <SEP> 134 <SEP> 145
<tb><SEP> INSTRUMENT
<tb> DISINFECTANT <SEP> 515 <SEP> 560 <SEP> 615
<tb><SEP> LAVA <SEP>
<tb><SEP> ENDOSCOPE
<tb><SEP> AGENT <SEP> 900 <SEP> 1000 <SEP> 1100
<tb><SEP> RINCING
<Tb>
These reference resistivity values correspond to pre-recorded setpoint values accessible to the resistivity sensor to enable the identification of pure products. In the case where the parameter taken by the sensor is different from the setpoint and is outside its safe interval, the operation of the machine is interrupted and an alarm intended to warn its user is triggered. The predefined setpoints are within a safety interval that takes into account inaccuracies of any kind.

If, for example, in the case of a washing machine and disinfect the endoscopes (9), the parameter taken by the resistivity sensor indicates a value equal to (66 + / 5) W, this indicates that the analyzed product has a high probability of being the proper detergent for the machine. The check is validated by continuing the analysis.

The recommended consumable for the next cycle is the endoscope washer disinfectant. If the sensor does not detect the expected resistivity value equal to (560 +/- 45) Q, but a value equal to (134 +/- 11) Q, this being included in the "Scale of pure products" , and corresponding to a known active product, its identification is possible. A logic system incorporated in the method then makes it possible to indicate in error message that Ae produced is the neutralizer for washing machine endoscopes and surgical instruments, necessary for the neutralization phase and unsuited to those washing or disinfection, and that its place is inverted with that of the disinfectant. An alarm for the user is triggered simultaneously and the machine interrupts its analysis. The operator only has to return the consumables to their proper place, and manually validate the move to the next analysis.

If the value detected by the sensor is not identifiable to any of the products placed in the "Scale of pure products", it is either a deteriorated product, or any product that may not be adapted to the use of the machine. An error message intended for the user of the machine then specifies that the analyzed product is unknown and an alarm is triggered simultaneously. It remains for the operator to exchange the consumable and re-engage the product analysis.

The second sensor mounted on the supply rod (4) together with the resistivity sensor, is the level sensor. Its operating principle is also based on measuring the resistivity of the liquid product, in opposition to an insulating reference product such as air.

This level sensor consists of a series of resistivity sensors installed on the elongate portion (10) of the body of the supply rod, allowing a level measurement every centimeter.

The operating principle of this invention combines two different technical fields: chemistry and electronics. The chemical and electronic studies are described successively below.

The chemical study shows that the concentrated solutions of detergent, disinfectant, neutralizer and rinsing agent have higher or lower resistivity values, and sometimes confused. In order to be able to differentiate these products from one another, an electrolyte acting as a marker is added to their formulation, or a modification of the content of one of their constituents is carried out.

The labeling is carried out by the addition of a strong electrolyte composed of interfering ions such as potassium chloride (KCl) and sodium nitrite (NaNO2). They possess at a very low concentration a very important conductivity; they do not cause any negative reaction on any of the constituents of the detergent, disinfectant, neutralizer and rinse agent. They are non-corrosive to the concentrations used. The optimal amount of the label is set at 0.25 W (KCl) or 0.33% (NaNO 2).

When the marker causes a variation on the value of the original resistivity that is insignificant or when it is incompatible with the nature of the active product because it forms an insoluble complex with one of the constituents, it is possible to modulate the amount of one of the compounds in the formulation. Tests have shown that the potassium hydroxide, methanol, and phosphoric acid contained in the active products considered have a strong influence on their resistivity. It is then sufficient to increase or decrease in a small amount the content of one of these compounds according to the desired resistivity without considering that the formulation is modified.

The maintenance of the physico-chemical properties of the resulting active product is verified in a series of comparative analyzes. They include colorimetry studies (determination of free alkalinity, active ingredients), pH-metry, corrosion, determination of the foaming power or wetting power of the active products.

When the quantifiable differences are less than 2, it is considered that the effectiveness of the product is not impaired. Otherwise, the product is discarded.

These two resistivity modulations techniques products not only ensure a resistivity specific to each of them but also maintain invariant in time.

Thus, by adding a marker to the washer-disinfectant, its resistivity becomes more than eight times greater than that of the detergent used for the same washing machine. By reducing the amount of potassium hydroxide contained in foaming detergent by 7%, its resistivity is different from that of a 30% machine alkaline detergent and 370% detergent for a lava-endoscope.

These differences in resistivities are sufficiently important to allow the detection of each of the products as well as their identification without risk of confusion.

The so-called "C2" electronic detection device is incorporated in the supply rod and in the control system of the machine. The supply rod supports the entire liquid level detection device (5), ie the probe (10), the electronic circuit and the software. The control system contains part of the product identification device (6) being the circuit and the software, the sensor being installed on the probe (10) in the cane.

The probe (10) is constituted in its elongate portion of a set of stainless steel rods distributed at regular intervals. The first rod placed at the bottom end of the probe is the current-receiving electrode (R), the others are the emitting electrodes (eg, with i = 0.1.2 ..31 and the electrode E31 is placed at the high end of the probe). The identification of the product is carried out by means of the receiving electrode and the emitting electrode which is juxtaposed with it (Eo). The detection of the level requires the receiving electrode and the following emitting electrodes (E1 to Ex). The probe is fully integrated in the cane through walls preserving its tightness.

The electronic circuit of the product identification device (6) comprises a series of variable amplitude and offset operational amplifiers, a variable frequency square and symmetrical voltage generating system, and a microcontroller for executing the algorithms logic, the manipulation of electronic circuit settings, and the transmission of information externally through a network protocol. The system for producing a square signal with variable amplitude and frequency makes it possible to inject a symmetrical current into the emitting electrode El. The frequency of the injected signal and the reading amplitude are determined in order to have the best reading comfort in the measuring medium. During this phase, the digital potentiometers controlling the operational amplifiers of the circuit are adjusted. Then, the digital potentiometers controlling the feedback loops of the operational amplifiers are also adjusted, this having the effect of adapting the sensitivity of the circuit.

The associated software performs averages and error corrections for better reliability of the result. It carries out communication tasks with other external circuits according to an information transmission protocol and network commands for advanced systems or by Morse code for primary systems. It executes orders coming from the outside: to take a measurement and to give the value of the resistivity of the active product.

The electronic circuit of the level detection device (5) supplies the emitters (E2 to Ei) alternately with a square electric signal by means of a clockless multiplexing and zero-component system thanks to a set of appropriately placed capacitors. .

The adjustable frequency power of these emitters is regulated by diodes. When they are not powered, they are in high impedance state. Thus, the current can flow only from the single excited transmitter. When the liquid reaches the level of this emitter, the current can flow to the receiver. It is then amplified and converted into a logic signal to be processed by the software.

The software associated with it implements probe scanning and verification of measurement consistency.

It successively controls each transmitter and tests the logic signal at the output of the receiver. It converts it to liquid height in centimeters. It then checks before validating the measurement that if the level Ni is not detected, the higher level Ni + 1 is not either. In the case where the measurement can not be validated, the software sends an error message to the user of the machine.

The uncertainty on the measurement of the liquid level is evaluated to +/- 0.5 cm. When there is agitation and foaming on the surface of the liquid, the error generated is greater.

The advantage of the electronic detection device once tested and validated is its perfect reliability and long service life.

 The method can be used for surgical instrument washing machines and laboratory glassware to detect, identify and control the removal of detergent, neutralizer and rinse agent.

The method can be used for a washing machine and disinfect the endoscopes (9) to detect, identify and control the removal of detergent, disinfectant and neutralizer.

The method can be used for a urinal basin washing machine to detect, identify and control the removal of detergent and rinsing agent.

The method can be used for a baby bottle washing machine to detect, identify and control the removal of detergent, neutralizer and rinsing agent.

The method can also be used for an animal cage washing machine to detect, identify and control the removal of detergent and neutralizer.

The method can be used for any other washing machine requiring a quality control of the same criteria.

The process may be used by extension for any other industrial application requiring the identification, control, or removal of concentrated chemical products involved in the process of washing, disinfecting, neutralizing or rinsing.

Claims (18)

claims  1. Method for controlling the protocol for washing instruments and medical objects using liquid active products used in a hospital environment intended for a washing machine, characterized in that it consists first of all in detecting and identifying the active products in their respective containers placed upstream of the process of treatment of the machine by comparison between the measured resistivity values and those of setpoint which are pre-recorded and delimited by a safety interval, which are dependent on the family of the active product under consideration and of its concentration, and in a second step to regularly measure the level of active product remaining in its container before each cycle by comparison between the resistivity values of the active products and that of a reference insulator.  2. Method according to claim 1 characterized in that the instruments and medical objects concerned are endoscopes, surgical instruments and accessories, baby bottles, laboratory glassware, animal cages and urinal ponds.  3. Method according to any one of the preceding claims characterized in that the active products are liquid washing agents, disinfection, neutralization and rinsing.  4. Method according to any one of the preceding claims, characterized in that the active products used for washing, disinfection, neutralization and rinsing have a slightly modified formulation or comprises in their original formulation one or more compounds to be able to modulate intentionally their natural resistivity.  5. Method according to claim 4 characterized in that the compounds intended to intentionally modulate the natural resistivity of the active products contain electrolytes, and in particular KCl and NaNO2, compatible with these products.  6. A method according to any preceding claim characterized in that the resistivity values of the active products range from 7 Q to 1100 Q.  7. Process according to any one of the preceding claims, characterized in that the active products can be classified into eight families grouping each of the products having the same function in the treatment and the same physico-chemical properties and which are the family of acidic neutralizers. foaming detergents, alkaline detergents, acidic detergents, detergents for the endoscope, instrument neutralizers, disinfectants for endoscope washers and rinsing agents.  8. A method according to claim 7 characterized in that the family of foaming detergents containing the detergents recommended for manual washing is defined by a resistivity value within a safety interval of 14 +/- 1.5 Q.  9. A method according to claim 7 characterized in that the family of alkaline detergents combining the detergents recommended for washing machines laboratory glassware and surgical instruments is defined by a resistivity value within a safety interval of 18 + / - 1.5 Q.  10. A method according to claim 7 characterized in that the family of acid detergents bringing together the detergents recommended for urinal washing machines and animal cages is defined by a resistivity value within a safety interval of 27 + / - 5 Q.  11. A method according to claim 7 characterized in that the family of detergents for endoscope washing bringing together the detergents recommended for washing machines endoscopes is defined by a resistivity value within a safety interval of 66 +/- 5 Q  12. A method according to claim 7, characterized in that the family of disinfectants for endoscope washers containing the disinfectants recommended for washing machines endoscopes is defined by a resistivity value within a safety interval of 560 +/- 45 Q.  13. A method according to claim 7 characterized in that the family of acid neutralizers containing neutralizing agents recommended for the neutralization of washing baths washing machines laboratory glassware, baby bottles, urinals and animal cages is defined by a resistivity value within a safety interval of 8 +/- 1 Q.  14. A method according to claim 7 characterized in that the family of neutralizers for instruments bringing together the neutralizing agents recommended for the neutralization of washing baths and disinfection of endoscope washing machines and surgical instruments and accessories is defined by a value of resistivity within a safety interval of 134  15. A method according to claim 7 characterized in that the family of rinsing agents bringing together the rinsing agents for the last phase of the cycle washing machines urinals to facilitate their drying or washing machines surgical instruments to protect their surface is defined by a resistivity value within a safety interval of 1000 +/- 100 Q.  16. A method according to any one of the preceding claims, characterized in that it uses a resistivity detector associated with a level detector incorporated together with each supply rod of a washing machine and that it implements the following sequences of operations as many times as there are diving rods in the containers of active product  - measurement of the resistivity of the active product,  - identification of the active product,  - authorization to take the active product produced according to the predefined protocol  measuring the level of the liquid active product remaining in the container, with its storage and analysis.  17. Device for implementing the control method as defined in any one of the preceding claims, characterized in that it consists of a washing machine using active products (1, 2 or 3 ) to be diluted in the washing, disinfecting, neutralizing and rinsing baths (11), comprising a resistivity detector associated with a level detector (10) incorporated in the supply rod (4) immersed in the containers (8) washing, disinfecting, neutralizing and rinsing agents, implementing a series of operations connected to a safety system to prevent the washing, disinfection, neutralization and rinsing process when the resistivity the active product measured in its original container reaches a value different from the pre-recorded set value and delimited by a safety interval, thus allowing a control q ualitative and quantitative use of products upstream of the machine process.  18. Device according to the preceding claim characterized in that the washing machine is intended for washing and disinfection of medical instruments and objects and in particular endoscopes, surgical instruments and accessories, baby bottles, laboratory glassware, animal cages and urinal ponds.