Process validation,

routine controls & maintenance

The purpose of process validation is to ensure that all reprocessing steps, from point of use reprocessing to storage before use, are effectively and reproducibly executed. As it is not possible to individually control the sterility of each medical device, process validation is the only way to minimize the risk of a non sterile product.

International standards define validation as the documented procedure for obtaining, recording and interpreting the results required to establish that a process will consistently yield product complying with predetermined specifications

A prerequisite to validation is to design each reprocessing step according to a risk based approach (see quality management).

Validation observation and data are objectively collected and evaluated to ensure that consistent and reliable levels of quality are obtained.

Process validation includes the qualification of the equipments used by the process. Qualifications of equipment consist of installation qualification (IQ) , operational qualification (OQ) and performance qualifications (PQ).

Installation qualification (IQ) is intended to confirm that the services associated with the equipment (water, electricity, etc.) and any accessories and safety devices are installed in accordance with manufacturer’s instructions.
Operational qualification (OQ) is carried after successful IQ. It verifies that the equipment performs according to manufacturer specifications.
Performance qualification (PQ) takes place after successful IQ and OQ on an equipment in routine operating conditions. All factors that may have an influence (operators and environment) are taken into account

Requalification takes place at predefined periodicity (often yearly) or after a major event (e.g. relocation, major modification or breakdown of an equipment used by the process).

Routine controls and maintenance of equipment ensure that process effectiveness is maintained over time.

Some routine controls are performed at each cycle, other are scheduled at defined periodicity (daily, weekly, monthly quarterly). Preventive maintenance calendar is according to equipment manufacturer recommendations.

International standards propose validation plans for sterilizers, automated washer-disinfectors and packaging. No ISO framework exists for manual cleaning and ultrasonic baths but principles defined for automated washer-disinfectors validation may be adapted.

Process validation operations are adapted to need and locally available resources

Requalifications may be simplified compared to initial qualifications (e.g. IQ will not be repeated if the equipment was not relocated).
Requalification performed after a major event is according to analysis (e.g. a complete IQ will not be necessary if the equipment was not relocated but partial IQ may be required if connection to water or air was modified or repaired).
Plans proposed by international may be too ambitious for some countries and may be progressively implemented

The validation, routine controls plans define the operations, methods and schedules as well as the responsibilities, training and, as needed, accreditations of the personal in charge.

Documentary verification may be considered as a prerequisite to qualification operations or as being part of IQ.

The documents to be made available by the manufacturer vary according to the type of equipment.

Before installation, the supplier:

communicates the characteristics of the equipment and its accessories (weight, dimensions, noise level) to adapt the access and the space around the equipment and, if necessary, to reinforce supporting structures,
specifies the associated service needs: electricity, chemical and possibly microbiological characteristics of the water, drainage, extraction, temperature and humidity control.
draws attention on precautions for safe use and protection of personnel,

In return, the future user specifies any installation constraints (e.g. quality of the water available) and, if applicable the specific test method(s) to be used.

After installation, the user checks:

the conformity of marking and availability of certificates: calibration of the measurement system, verification of safety devices, compliance with applicable standards and, where applicable, certificate of essential tests,
the availability of instructions for use (with description of the functions and cycles of the equipment, alarms and measures to be applied, list of consumables and accessories, cleaning and disinfection instructions),
the availability of the maintenance manual (with electrical and hydraulic diagrams, safety functions, list of spare parts, instructions for preventive maintenance, periodic checks and calibration of equipment, software checks), warranty certificates and maintenance or technical assistance contract and contacts.

Language in which the user and service manual must be provided is defined by local regulation.

Validation, requalifications and maintenance operations may be subcontracted by the healthcare facility to the sterilizer manufacturer or a skilled service provider; However the healthcare facility must review and sign the reports. Calibration verifications are usually made during preventive maintenance.

Routine controls are performed by the healthcare facility

Validation principles may be graphically summarized as follows:

Validation routine controls and maintenance of cleaning processes

Cleaning processes can be automated (with washer-disinfectors), manual or assisted by ultrasonic cleaners.

Recommendations for the validation of processes performed in automated washer-disinfectors are proposed by international standards ISO 15883-1 and subsequent parts (2 to 7). There is no ISO suggestion for validations of manual cleaning and ultrasonic cleaners but ISO 15883-1 principles may be adapted.

Installation qualification (IQ) verifies that the equipments (washer disinfector, ultrasonic bath or manual cleaning workstation) and utilities (power, water, drain, dosing systems etc..), are installed according to manufacturer specifications, that the equipment is safe for use and that all documentation is made available.
Operational quafication (OQ) verifies chemistry dosing, temperature for thermal washer-disinfector, cavitation for ultrasonic baths, drying, absence of leaks). Controls are visual for visible surface and quantitative (e.g. protein tests) for complex device with hidden surfaces. Test methods, artificial test soils and acceptance criteria are described in international standards (see below).
Performance qualification (PQ) is performed with actual loads or devices contaminated by clinical use. Validated surrogate devices and test soils may however be used when real devices are difficult to sample. Load or device used for PQ are selected to present the highest cleaning challenge for a given family. Controls are visual for external surfaces, carriers and loads and quantitative for complex devices with hidden surfaces. Test methods, artificial test soils and acceptance criteria are described by international standards (see below).

Test methods, and acceptance criteria for tests soils used for OQ and PQ are described in international standard ISO 15883-5 (see below)

ISO 15883-5 ^, proposes control methods based on the quantitative analysis of various chemical subtances (analytes), that can be found and measured in artificial and clinical soils.

For each analyte, alert levels and action levels are defined (for example 3 μg/cm² and 6,4 μg/cm² respectively for the residual protein analyte).

The alert level is an early warning of a deviation. The action level necessitates immediate action.

Examples of analytes with corresponding alert and action levels are displayed in the table below.

PQ controls are done with natural soils. For OQ controls, artificial test soils considered as representative of real soils are suggested in Annex A of ISO 15883-5 (for example coagulated blood for general surgery).

Analyte	Alert level, target value of analyte.	Action level maximum value of analyte not to be exceeded.
Protein (reference)	≥3 μg/cm²	≥6,4 μg/cm²
Total organic carbon	≥6 μg/cm²	≥12 μg/cm²
Carbohydrate	≥ 0,9 μg/cm²	≥ 1,8 μg/cm²
Haemoglobin	≥ 1,0 μg/cm²	2,2 μg/cm²
ATP	≥ 10 femtomoles of ATP/cm2	22 femtomoles of ATP/cm2
Endotoxin	≥ 2,2 EU/cm2	≤20 EU/device

Local guidelines may have some specific requirements. For example UK has defined cleanliness target per device, instead of per cm²

ISO 15883-1 and subsequent part propose validation for automated washer-disinfectors (Thermal or chemical, critical and semi-critical or non critical devices).

Operational and Performance requalifications are commonly annual.

An example of validation and routine control plan for thermal washer-disinfectors is displayed below. This example is based upon ISO 15883 and may be adapted by applicable guidelines or in accordance to locally available resources.

Validation of automated thermal washer-disinfector processAccording to ISO 15883	IQ	OQ	PQ	rQ	RoutinePeriodic
Documentary verification	P			P
Verification of installation conformity a. If the equipment was moved or connection to services was modified	P			P ^a
Cleaning efficacy. For thermal WD, cleaning efficacy tests are performed after sucessful completion of thermometric tests (see below). Test soils, quantitative method, action and alert levels for OQ, and PQ according to ISO 15883-5 (2021). Part of PQ and OQ may be repeated at predefined periodicity (for example quarterly). a. OQ: actual test load or representative.Test soils on walls of the chamber, carriers and load. For each cleaning program and carrier configuration b. PQ: actual load contaminated by clinical use or surrogate device. For each cleaning program and carrier configuration c. Identical to initial OQ or simplified after risk analysis d. Routine tests: systemetic visual controls of cleanliness and dryness. Part of		P ^a	P ^b	P ^c	P ^d
Thermometric tests – Thermal disinfection. In most unfavorable starting conditions either by deactivating the washing phase or by adjusting the T°C at the end of the washing phase to the lower limit of the specifications. First test: at least 60 min. after the last use of the machine (cold start). Reproducibility: 3 cycles at 15 min. intervals at most (hot start) a. Representative test load or actual load. For each program/carrier configuration). For details of T°C sensor locations and requirements see ISO 15883-1. b. Actual load. For details of T°C sensors locations and requirements see ISO 15883-2. PQ controls that the targeted time/temperature combination or A₀is obtained (see below) c. Requalification is identical to initial OQ and PQ or simplified after appropriate risk analysis d. Quarterly on tanks and load. Chamber wall and load carrier optional		P ^a	P ^b	P ^c	P ^d
Chamber leak proof		P		P
Door interlock a. Quarterly		P		P	P^a
Chemical dosing a. Quarterly		P		P	P^a
Water quality a. optional		P		P	P ^a
Air quality a. optional		P		P	P ^a
Load dryness			P	P	P
Process residuals			P	P
Load carrier and trolley (fitting, force to move, alignment)			P	P

An example of manual cleaning process validation inspired by ISO 15883-1 and ISO 15883-5 may be as follows:

Validation of manual cleaning process	IQ	OQ	PQ	rQ	RoutinePeriodic
Documentary verification	P			P
Verification of workstation and equipments installationa. As needed.	P			P ^a
Cleaning efficacy: Visual control of instruments and baths. Quantitative controls for device with hidden surfaces (for example lumen device) with test soils, method and action levels according to ISO 15883-5 (2021). a. Representative test devices or actual hollow or hinge devices. b. Real devices selected as most challenging contaminated by clinical use. c. Identical to initial OQ or simplified according after appropriate risk analysis d. systematic visual control and repeat PQ and OQ quarterly		P ^a	P ^b	P ^c	P ^d
Chemical dosing if the manual bench is equipped with dosing pump. a. quarterly.		P		P	P ^a
Water quality a. Quarterly control or as per applicable guidelines		P		P	P ^a
Drying air quality a. optional		P		P	P ^a
Dryness			P	P	P
Process residuals			P	P

Validation of ultrasonic cleaning baths must be adapted to the use of the type and objective of the ultrasonic cleaning process.

If the ultrasonic bath is used in preparation to manual cleaning, it will be considered as a preparation to manual cleaning process and cleaning efficacy control do not have to be performed.
If the ultrasonic bath is the final stage before disinfection or sterilization of the Medical device the procedure should be according to ultrasonics system features.

Cavitations test can be performed using:· An aluminum foil (according to the international technical rule IEC / TR 60886: 1987-03), Assessment of the effectiveness of the waves is according to the deteriorations and perforations observed in the aluminum foil. This test is only indicative and is not reproducible,· commercialized colorimetric tests,· ultrasonic analyzer,· cavitometer.

An example of a validation plan for ultrasonic bath may be as follows:

Validation of ultrasonic cleaning process In bracket corresponding paragraph of ISO 15883-1	IQ	OQ	PQ	rQ	Routine
Documentary verification	P			P
Verification of conformity of the installation of ultrasonic cleanera. If needed. Content according to need and after risk analysis	P			P ^a
Cleaning efficacy – if applicable and according to ultrasonic bath features. Visual control of instruments and baths and quantitative controls for device with hidden surface (for example lumen device) with test soils, quantitative method and action level according to ISO 15883-5 (2021) a. Representative test devices or actual hollow or hinge devices. b. Real devices selected as most challenging contaminated by clinical use. c. Repeat OQ and PQ d. Systematic visual control and Repeat PQ and OQ quarterly		P ^a	P ^b	P ^c	P ^d
Thermometric tests a. For example 6 sensors: in each angle, 1 center, 1 next to reference sensor. Cleaning phase: specified T°C ± 5°C – Thermal disinfection if applicable 90°C < T°C < 95°C – Variation on 1 sensor < 2°C – Variation between sensors < 4°C		P ^a		P ^a
Cavitations tests		P ^a		P ^a
Chemical dosing according to 6.9, if applicable		P		P
Water qualitya. Quarterly control or as per local guidelines		P		P	P ^a
Drying air quality, if applicable		P		P
Load dryness. if applicable			P	P	P
Process residuals. if applicable			P	P

Validation, routine controls and maintenance of packaging process

Packaging validation is guided by international standard ISO 11607-1 (packaging system), 11607-2 (packaging process) and guided by ISO 16775.

ISO 11607-2 concerns packaging processes such as forming, sealing and assembly of preformed sterile barrier systems, sterile barrier systems and packaging systems. ISO 16775 provides guidance on ISO 11607-1 and -2 and suggests validations plans and checklists for each type of packaging (wraps, pouches and reels and containers).

The user is not expected to repeat the type tests already performed by the manufacturer. Instead, certificates of compliance to applicable standardized tests should be requested.

The packaging validation plan define the controls to be applied to the various types of packaging (wraps, pouches, reels, containers) and packaging equipment (heat sealers).

The installation qualification (IQ) controls that:
- the packaging workstations and environment are adequate: layout, ergonomics (operator position), light appropriate for visual controls, air quality, temperature and humidity level. Cleaning and disinfection procedures are defined for the workstations and their environment
- maintenance plans are in place for equipment, in particular heat sealers,
- the documentation is verified for each model and brand of packaging (including evidence of compatibility with sterilization cycles, certificates of compliance with applicable standards, storage conditions).
- standard operating procedures are available for each type of packaging and operator training are up to date,

The operational qualification (OQ) verifies the correct implementation of various packaging, controls that heat sealers meet manufacturer specifications (with dye and peel tests) and checks that containers are operational and maintained according to plans.
The performance qualification (PQ) controls the entire packaging circuit from preparation to aseptic presentation. Performance qualification is performed with actual content representing the most challenging packaging and handling, transport and storage conditions. It confirms, through practice, the risk analysis carried out when defining the packaging system suitable for each RMD or family of RMD’s.

Within each family of packaging (sheets, pouches / sheaths, containers) several variants, specific to each hospital, may exist (according to the type of DMR, sterilization methods, size, brand etc…). In practice, it is accepted to limit operational and performance validations to representative configurations selected by apropriate risk analysis.

International standard ISO 16775 provides guidance to determine the size of OQ samples. ISO 16775 suggests 3 evaluations for each type of packaging (i.e. 3 loads and 3 sterilization cycles. One of them corresponds to the conditions considered to be the most challenging. If destructive checks are carried out (dye test or peel test), the number of samples tested is increased accordingly.

The chemical indicators affixed to the packaging should comply with international standard ISO 11140-1.

Requalification may be simplified compared to the initial validation. A risk analysis will determine if a requalification is required after an incident or a voluntary modification (e.g. change of supplier).

Routine and periodic tests include:

Systematic visual checks of packaging, before sterilization, after sterilization and before opening
periodic checks of the execution quality of packaging systems and in particular checks on the effectiveness of the seals

Validation of manual cleaning packaging process	IQ	OQ	PQ	rVQ	Routine
Documentary verification	P			P
Verification of installation of packaging worstation and sealers a. If needed. Content according to need and after risk analysis	P			P ^a
For each type of packaging (wraps, pouches and reels, containers) before and after sterilization cycleFor OQ and PQ and rQ sample size determined by risk analysis a. before and after sterilization with most challenging content. Visual controls of wraps and container. Dye and peel test for pouches and reels b. Whole packaging circuit from preparation, transport to aseptic presentation, with actual content selected to represent the most challenging packaging. Covers all the variant including operators c. Repeat OQ and PQ. Revalidation can be simplified compared to the initial validation after appropriate risk analysis. d. Systematic visual controls of packaging, before sterilization, after sterilization and before opening and periodic repetition of OQ or PQ (simplified if allowed by risk analysis)		P ^a	P ^b	P ^c	P ^d

Validation, routine controls and maintenance of sterilization processes

Validation and routine controls of sterilization processes are described by international standards, specific to each sterilization modality.

Installation qualification (IQ) verifies that the services (water supply when needed, power, supporting structure, etc.) are in accordance with manufacturer’s specifications and that documentation (Instruction for use, maintenance, calibration certificates) is available. Conformity to applicable regulations for emissions into the environment (chemical processes) or pressure vessel (steam) is controlled
Operational Qualification(OQ) is performed with empty chamber or standardized loads (depending on sterilization modality).
Performance Qualification (PQ) is performed for each cycle, with the most challenging routine load or a challenge pack more challenging than routine loads. Packaging must be equivalent or more challenging than routine.

PQ can be parametric only (steam) or a combination of parametric and bacteriological indicators (for low temperature sterilization processes).

When bacteriological indicators (BI) are used there are placed at the most challenging locations in the load (when PQ is performed with a real load) or at positions determined by the manufacturer (when a challenge pack is used).

Bacteriological indicators may be placed in a process challenge device representative of the most challenging device approved for reprocessing.

PQ is repeated 3 times for each cycle being tested.

In healthcare facilities, PQ is done according to the overkill principle at full cycle (steam), or ½ cycle (vH2O2 and EO). As low temperature steam formaldehyde cycles cannot be divided in 2 equivalent portions, OQ is performed at full cycle.

Systematic control and recording of cycle parameters after each cycle is required.

international standards define the variables to be measured by sterilizing equipments (for example, temperature (T°C), pressure (P) and time (t) for saturated steam. The cycle parameters are the values reached by each variables along the cycle. Cycle parameters controls consist in verifying that those value are within tolerances specified by the sterilizer manufacturer.

Periodic control (e.g. air removal and penetration test for saturated steam sterilization) are performed at periodicity defined by local guidelines and with test items complying to international standards.

Bacteriological and chemical indicators used for validation or routine control comply to international standards.

Most guidelines recommend a visible type 1 chemical indicators on each package to differentiate processed from non processed items. Type 3, 4, 5 or 6 indicators may also be placed within packages. Chemical indicators types are defined by International standard ISO 11140-1.

Frequency of use of bacteriological indicators is country and sterilization modality dependent

Validation, routine controls and maintenance of steam sterilization processes

Validation of steam sterilization process is carried out according to international standard ISO 17665. EN 285 defines the performance requirements and test methods for large steam sterilizer (chamber > 60 L). EN 13060 defines the performance requirements and test methods for small table top steam sterilizer (chamber < 60 L).

Installation Qualification verifies and documents the conformities of the services to manufacturer’s specifications (water supply, steam supply if applicable, power, supporting structure, etc.) and checks the documentation and execution of pressure vessel safety tests required by local regulation.

Operational qualification controls include steam quality, air leakage flow rate, thermometric test, air detector if fitted, steam penetration, load dryness. OQ and routine penetration test are performed with standardized porous load and/or hollow load process challenge devices complying to international standards

Performance qualification Thermometric tests are performed with the most challenging loading configurations. Advice on characterizing for difficulty should be available from the medical device manufacturer(s) and/or sterilizer manufacturer. Element to be considered when defining the most challenging load are mass (tray or container with the highest mass, the material and geometry (hollow devices), packaging (wrap, pouches, container).

Experience has shown that for a typical health care sterilization load and chamber usable space (ca. 400 l), 5 to 12 temperature sensors are sufficient. There are distributed next to the sterilizer control sensor and on/i the load. Some sensors are placed on parts of the medical device where steam penetration/air removal is most difficult to achieve.

Routine controls are performed at each cycle, daily, weekly or quarterly

Each cycle: dryness and integrity of all packaging and chemical indicators (if used). Control that cycle parameters are in accordance with validation data.
Daily: visual control of corrosion and stain in chamber, gaskets, control of operating means and recorders, Bowie Dick test (chemical or electronic).
Weekly: Air leakage flow rate in some countries and calibration of air detector (if fitted).
At least quarterly: Air leakage flow rate (if not specified by country guidelines and unless the sterilizer is fitted with an automated leak tests active at each cycle).

The Bowie-Dick test was developed to evaluate steam penetration and air removal in porous textile load. Over time, various chemical or electronical versions complying to international standard ISO 11140-4 became available. Process challenge devices complying to EN 867-5 were designed as an alternative to Bowie-Dick for small sterilizers complying to EN 13060. Chambers were too small to host the Bowie-reference package. EN 867-5 test devices were adopted by EN 285 to verify penetration in hollow items. EN 867-5 however showed deficiencies that were corrected by ISO 11140-6. Like Bowie-Dick, EN 867-5 and 11140-6 check that standardized penetration and air removal performance are met but are not intended to simulated a real medical device.

An example of a validation and routine control program for sterilizer complying to EN 285 is displayed below:

Validation of steam sterilization processes	IQ	OQ	rQ	Routine
Documentary verification	P		P ^a
Verification of installation and safety tests: Electrical, plumbing, pressure vessels controls a. Specified by the sterilizer manufacturer and local regulation for pressure vessel	P	P	P^a
Steam quality· Non condensable gas in the steam affects air dilution in the sterilizer chamber. £ 3.5 % by volume of non-condensable gas; ·Moisture in the steam affect residual moisture in the sterilizer load. Dryness ³ 95 % (5 % moisture) for a sterilizer load containing metal ·Superheat in the steam delays the presence of saturated steam. Superheat when expanded to atmospheric pressure ≤ 25 °C · Contaminants can cause corrosion and deposit toxic substances on the product. Tests in condensated are performed by certified laboratories (See ISO 17665 for control of contaminants causing corrosion or contamination in condensates) a. or certificates of work test by the manufacturer for non condensable gas, Moisture and superheat. Contaminants tests performed by accredited laboratory b. Annually. Sooner for contaminants if deposits or traces appearing on surface of DMRs or packaging (check reverse osmosis installation beforehand). Local recommandations may allow to not perform test every year for condensable gas, moisture and superheat		P^a	P^b
Thermometric tests. Acceptance criteria: · Sterilization T°C £ T°C measured £ sterilization T°C + 3°C · Equilibration time < 15 s for chamber 800 l and 30 s for chamber ³ 800 l · During the plateau period T°C above the test pack £ T°C at reference point + 5°C for the first 60 s and £ T°C at reference point + 2°C for the remaining period – Omitted for full load · During the Holding time: all sensors wihin T°C at the reference point within the sterilization T°C band and max 2°C difference between sensors. · Holding time ³ 15 min, 10 min and 3 min for sterilization temperatures of 121 °C, 126 °C and 134 °C respectively. a. With full and small load (ISO 17665-2 : A.4. – Description of Standard test pack in A.3). 5 sensors at different levels within the std test pack around the vertical axis. Performed by the manufacturer as a work test before delivery. Request certificate.With most challenging real load and devices (or process challenge device) – repeated 3 times for each cycle and most challenging load configuration (may be simplified for rPQ after appropriate risk analysis)		P ^a,b	P ^a,b
Bowie and Dick test (ISO 11140-4) a. At least daily		P	P	P ^a
Hollow load (ISO 11140-6)		P	P
Calibrationa. Request calibration certificatesb. Can be part of maintenance	P^a		P^b
Dynamic pressure test. Verifies that the rate of pressure change in the sterilizer chamber will not cause damage to packaging. Average pressure change for any 3 s interval during the sterilization process £ 1,000 kPa/min (10 bar/min)a. Part of work test performed by the manufacturer before delivery. Request certificateb. Need and periodicity, specified by the manufacturer		P ^a	P ^b
Air leakageLeakage impairs steam penetration and create risk of contamination during drying. Pressure rise £ 0.1 kPa/min (1.3 mbar/min) at a chamber pressure of 6kP (60mbar) or less. a. At least Quarterly.		P	P	P^a
Air detector (if fitted)Used to detect an excess of non-condensable gas or a lack of air extraction. a. Active at each cycle. Checks / calibrations of air detector are carried out on a weekly		P	P	P^a
Load dryness ( A.8)visual inspection and mass increase a. With small and full load textile and metal load Increase of Humidity level ≤ 1% for textile and 0.2 % for metal b. Visual		P		P^a

Validation, routine controls and maintenance of low temperature sterilization vaporized H202 processes (vH2O2)

Validation and routine control of vH₂O₂ sterilization process are carried out according to international standard ISO 22441

ISO 22441 was published in 2022. It has or will progressively replace ISO 14937 as the reference norm for vH2O2 processes. Adoption calendar is country or region dependent. Like other ISO sterilisation process standards already available for steam, EO or LTSF, it uses the structure and principles of ISO 14937 and adds informations specific to VH2O2. In particular it specifies that the 4 variables that should be measured by a vH2O2 process are pressure, temperature, time and H2O2 concentration. Manufacturers may add other variables. Concerning H2O2 concentration, ISO 22441 indicates that it can be measured directly (i.e. via an H2O2 monitor) or indirectly (for example via pressure increase in the chamber or other combination of methods).

Installation Qualification (IQ) verifies and documents the conformities of the services to manufacturer’s specifications (power) and checks the availability of documentation and certificates of essential type tests.

In particular the healthcare facility verifies that H₂O₂ emission tests according to IEC 61010-2-040 were performed by the manufacturer and that they take into account the applicable time weighted avarage for H₂O₂ (usually 1 ppm or 0.5 ppm over 8 hours)

OQ tests verify that the value delivered by each cycle are in accordance with manufacturer specifications. vH2O2 cycles profiles and parameters are specific to each manufacturer. PQ tests are commonly performed in an empty chamber.

PQ is performed for each cycle with the most challenging load or a challenge pack. Criteria for the determination of the most challenging load are multiple. The challenge test pack is commonly proposed by the manufacturer. Evidence must be provided that it is more challenging/absorbent than the most challenging load approved for reprocessing. Bacteriological indicators, possibly placed in process challenge devices are placed at the most challenging locations in the load or at locations recommended by the manufacturer.

There is no normative requirement to place temperature, pressure or H₂O₂ concentration sensors in the load for OQ or PQ. However evidence must be provided by the sterilizer manufacturer that a relationship has been established between cycle parameters and achievement of conditions for SAL through the various load and device configurations approved for reprocessing. P, T°C and H₂O₂ concentration measured directly or indirectly at chamber level guarantees that conditions for SAL are obtained on all surfaces of medical devices. OQ or PQ controls are best achieved by placing sensors as close as possible to sterilizer sensors.

Due to the complexity of devices commonly reprocessed by vH₂O₂ processes, validation of sterilization efficacy and compatibility with each VH₂O₂ cycle recommended in medical device manufacturer is essential

Validation of vH₂O₂ processes In bracket corresponding paragraph of ISO 17665-2, EN 285 or other applicable standards	IQ	OQ	PQ	rQ	Routine
Documentary verification
Verification of installation a. If needed	P^a			P^b
Verification that cycle parameters are within tolerances defined by manufacturer a. Commonly with empty chamber		P^a		P^a
Verification that conditions for the 10^-6 SAL are met for each cycle a. Performance validation is performed for each cycle with the most challenging routine or with a challenge test pack more challenging that the more challenging routine load for each cycle. Biological indicator, possibly placed in PCD more challenging than the most challenging device approved for reprocessing are placed at most challenging locations in the load or at location determined by sterilizer manufacturer			P^a,b	P^c
Control of Process parameters, bacteriological and chemical indicators a. Control of process parameter at each cycle. b. Use of chemical and biological indicators are according to local recommendations. It is often recommended tio have at least a type 1 chemical indicator on each item. Bacteriological indicators according to applicable guidelines ( each cycle, daily or weekly)					P^a,b

WFHSS key recommendations for process validation, routine controls and maintenance

As sterility of each RMD cannot be individually controlled, the validation of all reprocessing steps (from point of use cleaning to storage) is essential to minimize the risk of a non sterile device.
Validations plans include the installation, operational and performance qualification (IQ, OQ, PQ) of equipments and scheduled or event related requalifications (rQ). Routine controls (systematic or at defined periodicity) and equipment maintenance (preventive and corrective) ensure that process effectiveness is maintained over time.
International standards detail the validation of automated cleaning and disinfection, packaging and sterilization processes. No standardized guidance exist for ultrasonics and manual cleaning processes, but principles of automated cleaning controls may be adapted. Although common principles may apply, validation of sterilization process is specific to each modality. International standards do not assign responsibility but remind that they must be established. In practice IQ and OQ are often carried out by equipment supplier. PQ is performed by the users, suppliers or qualified third parties. In all cases validation report are reviewed and approved by the healthcare facility and recorded.

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