Performance qualification is documented evidence to prove that equipment/system is performing under specified condition. It involve in taking trial under “loaded condition”.
The different tests are follows for qualification of autoclave are
. Vacuum leak test
· Bowie-dick test
· Heat distribution study
· Heat penetration study
Vacuum leak test:
Objective:
To verify the leakage in sterilization chamber during vacuum hold time when the sterilizing chamber is empty.
Principle:
These tests are designed to show that the sterilizer chamber does not leak in empty chamber. Leakage of air into the chamber is not acceptable for two reasons:
1. The presence of air inhibits penetration of the load by the sterilant (Steam) and prevents sterilization.
2. Air leaking into the chamber during the sterilization and drying cycle are not passed through the bacteria retentive filter, and therefore there is a risk of contamination of the load.
The test is performed by measuring the change in vacuum in the chamber when all the valves leading to it have been closed and the vacuum source is isolated.
Procedure:
Ensure that the chamber temperature is stable at ambient and compressed air is on with high pressure and ensure that gasket lubrication is proper and switch provided on panel board. Start the vacuum leak rate test cycle and observe the pressure in the pressure gauge of steam sterilizer and Cycle allow the pressure to drop down. Machine will close all the valves connected to the chamber and stop the vacuum pump and note the time and pressure (P1). Wait for stabilization period of 5 minute (±10 second) and note down the pressure again (P2) and Wait for another 10 minute (± 10 second) and note down the pressure third time (P3). Return to atmospheric pressure and continue to run for next cycle where vacuum leak rate should not be more than acceptance criteria.
Acceptance criteria:
Vacuum leak rate should be NMT 0.013 bar / 10 minutes.
Frequency:
Run the test for 3 consecutive cycles at the time of Initial Qualification.
Bowie- Dick test:
Objective:
To ensure that the vacuum pulses applied before the sterilization hold period are sufficient to remove the entrapped air or non-condensable gases so as to facilitate the event and rapid steam penetration into all parts of load and maintaining this condition during sterilization holding time.
Principle:
Sterilization is achieved by the rapid and even penetration of steam into all parts of the load and the maintenance of these conditions for the specified holding time. To ensure this, it is essential to remove air from the chamber and load, and to provide a steam supply which contains a minimal volume of Non-condensable gases .The Bowie Dick test shows whether or not steam penetration is taking place by testing the presence of Non condensable gases in the chamber, but it does not confirm that the sterilization condition in the load is achieved or not.
Procedure:
Place the Bowie Dick test paper on the bottom shelf of the sterilizer just above drain point (100mm over the drain) Air removal study shall be performed in empty chamber by placing the Bowie Dick test paper. it consist of standard paper pack and indicator sheet Start the cycle by pressing enter key After the cycle is over open the door from control area side and take the sterilized test paper from the autoclave and check the indicator paper for uniform colour change As Bowie Dick test paper is designed to simulate the garment pack, it used to test the efficiency of the air removal from the steam sterilizer Three cycle of air removal study shall be performed (initially) by using fresh indicator paper This test shall be performed by using Bowie Dick test cycle. To fulfil the maximum exposure requirement, the sterilization cycle shall have 17 minutes at 121°C to 123°C sterilization period.
Set Parameters:
17 minutes cycle at a temperature of 121°C
Place of keeping Bowie -Dick Indicator:
Place the Bowie dick indicator approximately 100 mm to 200 mm above the sterilization chamber base.
Acceptance criteria:
The Bowie dick indicator should show uniform color change (Yellow to Brown / black) after the cycle.
No change or no uniform change or air entrapment (bubbles) spot on the test sheet indicates inadequate air removal from the sterilization base chamber.
Frequency:
Run the test for 3 consecutive cycles at the time of Initial Qualification.
Heat distribution study (empty chamber)
Objective:
To verify the temperature uniformity throughout the chamber and to locate the cold spot in Empty Chamber.
The sterilizer is capable attaining a temperature of 121° C throughout the sterilizing hold period in Empty Chamber.
Procedure:
Insert 16 no of temperature sensors inside the chamber through the validation port of sterilizer. Seal the port with silicon sealant to ensure that no steam leakage during operations of sterilizer. Fix all the probe at different location in the sterilizer so that sensors do not touch the metallic surface of the chamber. Connect the temperature sensors to the data logger, which can scan and print the actual temperature and pressure at different locations.
After completion of sterilization cycle check the thermograph in the data logger for attaining set temperature and pressure during the sterilizing hold period. If any deviation observed repeat the cycle after taking necessary correction.
Acceptance criteria:
Temperature distribution within the chamber must be between 121°C to 123°C at all location during the sterilization period (dwell time)
There should not be any slowest heating point (cold spot) in the autoclave chamber and equilibrium time should not be more than 30 second.
Heat distribution study (loaded chamber)
Objective:
To verify the temperature uniformity throughout the chamber and to locate the cold spot in loaded Chamber.
The sterilizer is capable attaining a temperature of 121°C throughout the sterilizing hold period in loaded Chamber.
Procedure:
Insert 16 no of temperature sensors inside the chamber through the validation port of sterilizer. Seal the port with silicon sealant to ensure that no steam leakage during operations of sterilizer. Fix all the probe at different location in the sterilizer so that sensors do not touch the metallic surface of the chamber. Load the article as per loading pattern in the autoclave chamber. Loaded chamber heat distribution study shall be performed separately for all loading patterns. One cycle shall be performed for each loading type for loaded chamber heat distribution study Connect the temperature sensors to the data logger, which can scan and print the actual temperature and pressure at different locations.
After completion of sterilization cycle check the thermograph in the data logger for attaining set temperature and pressure during the sterilizing hold period. If any deviation observed repeat the cycle after taking necessary correction.
Acceptance criteria:
Temperature distribution within the chamber must be between 121°C to 123°C at all location during the sterilization period (dwell time) There should not be any slowest heating point (cold spot) in the autoclave chamber and equilibrium time should not be more than 30 second.
Heat penetration study
Objective
In order to verify sterilizing temperature has been reached in each load subjected to moist heat sterilization, it is necessary to conduct heat penetration studies. This study is conducted to ensure that the coolest unit within a pre-defined loading pattern (including minimum and maximum loads) will consistently be exposed to sufficient heat lethality (minimum "F0").
Procedure:
Insert 16 no of temperature sensors inside the chamber through the validation port of sterilizer. Seal the port with silicon sealant to ensure that no steam leakage during operations of sterilizer. Fix all the probe at different location in the sterilizer so that sensors do not touch the metallic surface of the chamber. Load the article as per loading pattern in the autoclave chamber. Loaded chamber heat distribution study shall be performed separately for all loading patterns. Arrange the load as specified keep at least 15 biological indicators and 10 thermo chemical indicators shall be used for each cycle. Load placed at the identified cold points must have indicator and temperature sensor in all three runs. One biological indicator and thermo chemical indicator along with external temperature sensor shall be placed at drain point in all three cycle. Perform the sterilization by operating the program specified for each load type as per standard operating procedure and start the data logger and steam sterilizer simultaneously. After the sterilization cycle is completed, stop data logger and open the sterilizer and take out the biological indicator and thermo chemical indicator from load and send to microbiological lab for testing. The biological indicator shall aseptically inoculate into sterile soybean casein digest media (SCDM) and incubated at 55 - 60deg.C and liquid load at 35 - 39deg.C for 7 days and check the thermo chemical indicator for the compliance as per manufacturer recommendation for colour change (i.e. Brown).
Take out temperature chart/data logger and inbuilt temperature recorder, report of biological indicator. Check against acceptance criteria for compliance and determine the Fo value and compare against acceptance criteria.
Take out external temperature sensor from the chamber and perform vacuum leak rate test.
Acceptance criteria
Temperature distribution within the chamber must be between 121°C to 123°C at all location during the sterilization period (dwell time) Sterilization temperature should be maintained for NLT 15 minute for minimum 10 thermo couple during hold time. Biological indicator (Geobacillus Stearothermophillus) should show complete sterilization (i.e. no growth after incubation)
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