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A Look Inside Low-Temp Sterilization
6 points to keep in mind about reprocessing heat-sensitive instruments.
Kevin Anderson
Publish Date: May 7, 2018   |  Tags:   Infection Prevention
Nasal Injection
UNDER AN HOUR Shorter cycle times is one key benefit vaporized hydrogen peroxide sterilization has over over ethylene oxide.

Besides not knowing how to get there, the biggest mystery about the sterile processing department might be low-temperature sterilization. Allow me to clear the air about how heat- and moisture-sensitive instruments get back into your ORs, sterile and ready to use on the next patient — but perhaps not as quickly as you'd like.

1. Why low-temp? Nothing destroys bacteria, fungi and spores like steam sterilization, which is also the most cost-effective and simplest sterilization method. But many of today's heat-sensitive instruments can't withstand the higher temperatures or moisture of steam. Enter low-temp sterilization.

2. EtO vs. VHP. Your main choices in low-temp sterilization processes are ethylene oxide (EtO) or vaporized hydrogen peroxide (VHP). Besides being toxic, carcinogenic and explosive, EtO gas has an excessively long sterilization cycle that's incompatible with the pace of outpatient surgery. Including the required aeration to remove EtO residue, the EtO cycle ranges from 14 to 30 hours. Very impractical. Who's got that kind of time to reprocess instruments when the most efficient and safest form of low-temp sterilization that eliminates contaminating microbes in a fraction of the time is available?

With VHP, the most common cycle is 28 minutes — with no aeration necessary. Some items such as lumened flexible scopes may stay in for an hour-long extended cycle. It's simple to operate, install (all you need is a 208 V outlet) and monitor. It's also safe for the environment and compatible with most medical devices. Here's how it works: The sterilization chamber is evacuated and hydrogen peroxide solution is injected from a cassette and vaporized in the sterilization chamber.

3. EtO hasn't gone away. I'm the manager of the sterile processing department at Henry Ford Wyandotte (Mich.) Hospital. We service 11 ORs, 3 procedure rooms and 18 off-site clinics. We reprocess 2,500 to 3,000 instrument trays per month. In addition to 3 steam sterilizers, we have 2 VHP sterilizers and 2 EtO sterilizers. Surprised? Let me explain.

Some instruments are only EtO-compatible. If you have an outdated endoscope inventory, for example, certain flexible scopes might not be validated with VHP. If given the choice to upgrade their instrument inventory or keep their EtO sterilizer in good working order, many OR managers would choose to keep the old instruments in play. With flexible scopes costing the same as a car ($30,000) and low-temp sterilizers ranging in price from $80,000 for certified pre-owned to $180,000 for new, it's something to consider. Side note: EtO could extend the life of your heat- or moisture-sensitive instruments because it's non-corrosive to plastic, metal and rubber materials.

4. Call for backup. Why do we have 2 of each? In case 1 breaks down, we won't miss a beat. If you rely heavily on an EtO sterilizer and something happens to it, where do you go for back-up? When I started here about 18 months ago, we only had 1 VHP sterilizer. When it broke down, we had to run instruments back and forth to a surgery center a couple cities away. Incredibly disruptive. No matter the size of your facility, I encourage you to invest in a backup low-temp sterilizer — even if it's a half-sized unit.

5. Don't overpack. Ideally, you'd load 1 sterilizer with items that need a half-hour cycle and load another with items that need a 1-hour cycle. It's not efficient to mix loads in which a battery that only needs 30 minutes is in with a scope that needs an hour. If you have only 1 sterilizer, however, you might be forced to run longer loads throughout the day. The danger in running mixed loads is overpacking. Yes, you always want to pack your sterilizer to max capacity per manufacturers' guidelines, but not to the point where the sterilant can't reach everything.

6. They'll be ready in 1 hour, right? We get this question a lot in sterile processing: "I gave you those instruments an hour ago — how come they're not back yet?" When OR staff hear that VHP cycles are 1 hour or less, they assume we'll get the instruments back to them in 60 minutes. Not the case. Turnaround time for instruments includes a lot more than the sterilization cycle time. There's a long list of steps before we place instruments in the sterilizer: manual cleaning, possible automated washing and sonication. Then we wrap or place instruments into a container. Then we inspect during the preparation and sterilization phase. Before you think of asking sterile processing staff to cut corners, keep in mind that we are bound to manufacturers' reprocessing instructions.

Find your way

While steam is an effective and cost-efficient way to sterilize surgical instruments, low-temp sterilization methods are still an absolute necessity in today's fast-paced surgical department. Hopefully, you now have a better understanding of low-temp sterilization. Now if you can just find out how to get to the sterile processing department. OSM

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