Methods and systems for sterilization
Embodiments of the present disclosure relate to systems and methods for the application of vaporized chemicals in sterilization procedures, and systems and methods for controlling (e.g., distributing, moving, or exhausting) such chemicals. For example, embodiments of the present disclosure may relate to systems and methods for effecting terminal sterilization of medical products using vaporized hydrogen peroxide (VHP), and/or for the distribution of VHP to, or removal of VHP from, a sterilization system or parts thereof.
1 . A sterilization method comprising:
pre-conditioning a sterilization apparatus including a sterilization chamber comprising a sterilization load, wherein pre-conditioning the sterilization apparatus includes increasing a temperature of a portion of the sterilization apparatus to a temperature greater than a maximum temperature of the sterilization load, wherein the portion of the sterilization apparatus includes an inlet and a conduit connecting a vaporized hydrogen peroxide (VHP) injector to the inlet;
executing a sterilization phase, wherein the sterilization phase includes a plurality of sterilization pulses, wherein each sterilization pulse includes introducing vaporized hydrogen peroxide into the sterilization chamber via the inlet, and a temperature of the sterilization chamber is less than or equal to the maximum temperature of the sterilization load throughout the sterilization phase; and
executing an aeration phase, wherein the aeration phase includes a plurality of aeration pulses, wherein the plurality of aeration pulses includes:
a primary aeration pulse comprising:
achieving a first vacuum pressure within the sterilization chamber, wherein the first vacuum pressure is 500 to 800 millibar; and
after a first vacuum hold, increasing the pressure of the sterilization chamber to a pressure greater than 700 millibar; and
a secondary aeration pulse comprising:
achieving a second vacuum pressure within the sterilization chamber, wherein the second vacuum pressure is less than 650 millibar; and
after a second vacuum hold, adding air to the sterilization chamber while exhausting the sterilization apparatus.
2 . The sterilization method of claim 1 , wherein the plurality of aeration pulses includes a first primary aeration pulse, followed by a first secondary aeration pulse, followed by a second primary aeration pulse, followed by a second secondary aeration pulse.
3 . The sterilization method of claim 1 , wherein the sterilization load includes a semi-permeable envelope.
4 . The sterilization method of claim 1 , wherein each sterilization pulse comprises:
achieving a sterilization pressure within the sterilization chamber; and
when the sterilization chamber is at the sterilization pressure, adding vaporized hydrogen peroxide to the sterilization chamber.
5 . The sterilization method of claim 4 , wherein the sterilization pressure is less than or equal to 650 millibars.
6 . The sterilization method of claim 1 , further comprising:
after the sterilization phase and prior to the aeration phase, adding a dry air to the sterilization chamber.
7 . The sterilization method of claim 1 , wherein the sterilization chamber includes a piston or diaphragm configured to adjust the pressure of the sterilization chamber, and the method further comprises:
after the sterilization phase, creating a low frequency pressure wave with the piston or diaphragm.
8 . The sterilization method of claim 7 , wherein the low frequency pressure wave moves liquid hydrogen peroxide in contact with the sterilization load.
9 . A sterilization method comprising:
pre-conditioning a sterilization apparatus including a sterilization chamber comprising a sterilization load, wherein pre-conditioning the sterilization apparatus includes increasing a temperature of a portion of the sterilization apparatus to a temperature greater than a maximum temperature of the sterilization load, wherein the portion of the sterilization apparatus includes an inlet and a conduit connecting a vaporized hydrogen peroxide (VHP) injector to the inlet; and
executing a sterilization phase, wherein a temperature of the sterilization chamber is less than or equal to the maximum temperature of the sterilization load throughout the sterilization phase, the sterilization phase includes first, second, and third sterilization pulses, and wherein each sterilization pulse includes:
achieving a sterilization pressure within the sterilization chamber; and
when the sterilization chamber is at the sterilization pressure, adding an amount of vaporized hydrogen peroxide to the sterilization chamber via the inlet; and
executing an aeration phase comprising:
achieving a vacuum pressure within the sterilization chamber, wherein the vacuum pressure is less than 650 millibar; and
after a vacuum hold, adding air to the sterilization chamber while exhausting the sterilization apparatus;
wherein the amount of vaporized hydrogen peroxide added to the sterilization chamber during the first sterilization pulse is sufficient to establish a lethal concentration of hydrogen peroxide in the chamber;
the amount of vaporized hydrogen peroxide added to the sterilization chamber during the second sterilization pulse is less than the amount of vaporized hydrogen peroxide added to the sterilization chamber during the first sterilization pulse; and
the amount of vaporized hydrogen peroxide added to the sterilization chamber during the second sterilization pulse is less than the amount of vaporized hydrogen peroxide added to the sterilization chamber during the third sterilization pulse.
10 . The method of claim 9 , wherein the first sterilization pulse is repeated at least once before the second sterilization pulse.
11 . The method of claim 9 , wherein the third sterilization pulse is repeated at least twice.
12 . The method of claim 9 , wherein the amount of vaporized hydrogen peroxide added to the sterilization chamber during the first sterilization pulse includes at least 0.1 moles of hydrogen peroxide per cubic meter of volume of the sterilization chamber.
13 . The method of claim 9 , wherein each sterilization pulse further includes:
(i) adding gas into the sterilization chamber to increase the pressure to a hold pressure, wherein the hold pressure is greater than 700 millibar; and
(ii) decreasing the pressure of the sterilization chamber to the sterilization pressure.
14 . The method of claim 13 , wherein step (i) takes more time than step (ii).
15 . The method of claim 14 , wherein each sterilization pulse further comprises:
before step (i), maintaining the pressure of the sterilization chamber for a first hold time;
after step (ii), maintaining the pressure of the sterilization chamber for a second hold time;
wherein the second hold time is longer than the first hold time.
16 . The method of claim 9 , wherein the sterilization chamber includes a distribution manifold, an inlet, and a chamber wall, and the method further comprises:
during the first, second, and third sterilization pulses, maintaining a temperature of the chamber wall to be approximately the same as a temperature of the inlet or a temperature of the distribution manifold.
17 . A sterilization method comprising:
pre-conditioning a sterilization apparatus including a sterilization chamber comprising a sterilization load, wherein pre-conditioning the sterilization apparatus includes increasing a temperature of a portion of the sterilization apparatus to a temperature greater than a maximum temperature of the sterilization load, wherein the portion of the sterilization apparatus includes an inlet and a conduit connecting a vaporized hydrogen peroxide (VHP) injector to the inlet; and
a first sterilization pulse including adding a first amount of vaporized hydrogen peroxide to the sterilization chamber via the inlet, wherein the first amount is sufficient to establish a lethal concentration of hydrogen peroxide in the sterilization chamber;
a plurality of second sterilization pulses, wherein each second sterilization pulse includes adding a second amount of vaporized hydrogen peroxide to the sterilization chamber via the inlet, wherein the second amount is less than the first amount; and
a plurality of third sterilization pulses, wherein each third sterilization pulse includes adding a third amount of vaporized hydrogen peroxide to the sterilization chamber via the inlet, wherein the third amount is less than the second amount;
wherein, throughout the sterilization method, a temperature of the sterilization chamber is less than or equal to the maximum temperature of the sterilization load throughout the sterilization phase.
18 . The method of claim 17 , wherein the sterilization chamber comprises a load, and the load includes a semi-permeable material defining an interior of the load and an exterior of the load; and
wherein after the plurality of third sterilization pulses, a concentration of hydrogen peroxide in the interior of the load is approximately equal to a concentration of hydrogen peroxide in the exterior of the load.
19 . The method of claim 17 , further comprising executing an aeration pulse including:
(i) lowering the pressure of the sterilization chamber to a first aeration pressure, wherein the first aeration pressure is less than 650 millibar; and
(ii) increasing the pressure of the sterilization chamber to a second aeration pressure, wherein the second aeration pressure is greater than 700 millibar;
wherein a rate of pressure change in step (ii) is at least 100 millibar per minute faster than a rate of pressure change in step (i).
20 . The method of claim 19 , further comprising, prior to the aeration phase, removing moisture from the sterilization chamber by passing the contents of the sterilization chamber through a condenser.
21 . A method for sterilizing a syringe, the method comprising:
placing the syringe inside a sterilization chamber; and
subjecting the syringe to the sterilization method of claim 1 .
22 . The method of claim 1 , wherein pre-conditioning the sterilization apparatus includes increasing the temperature of the portion of the sterilization apparatus to at least 110° C.
23 . A method for sterilizing a syringe, the method comprising:
placing the syringe inside a sterilization chamber; and
subjecting the syringe to the sterilization method of claim 17 .