Steam sterilizers are the most prevalent sterilization devices in use today. They're also the most likely to be affected by errors of familiarity. Think about it. Your staff activates the steam autoclave, hears the reassuring whoosh of steam entering its chamber and moves on to prepare the next set of instrument packs. But do they really know what makes the device tick? Can they recognize potential problems before they jeopardize instrument sterilization and patient safety?

Routine observation is key to keeping autoclaves running effectively, day after day, load after load. They require regular attention and constant maintenance. They'll provide years of quality service if you take the time to match your steam sterilizer's performance against the manufacturer's maintenance guidelines as well as universal ones (see "6 Upkeep Basics for Your Autoclave" ). Here's a review of the basics we all tend to forget when working with arguably our most reliable method of sterilization.

Routine maintenance
The advantages of steam sterilization are well known, including economy, safety, simplicity, reliability and familiarity. You are also likely familiar with steam's limitations: the item sterilized must be able to withstand time in the sterilizer amid high temperatures and saturated steam.

A well-maintained steam sterilizer, therefore, starts with a well-maintained steam system. Whether you use a tabletop sterilizer that generates its own steam, a self-contained steam generator or a hospital-wide boiler, the steam must be monitored and maintained according to the sterilizer manufacturer's instructions. Quality steam begins with quality water. Tabletop sterilizers use di-ionized or distilled water while self-contained sterilizers and boilers rely on water provided by commercial sources. Test the water's hardness, pH balance and condensate return in self-contained units and carefully review the chemicals used for boiler applications.

Staff working with a steam boiler or a self-contained steam generator must work in tandem with the plant engineering technicians responsible for assuring the quality of the steam these sources produce. The amount of moisture in steam should be 2 percent to 3 percent liquid water. Any variations in moisture content will result in poor steam quality, wet instrument loads, superheating within the sterilizer's chamber or trouble with the sterilizer's pressure-reducing systems.

Don't assume that a new sterilizer will work properly. The initial assessment of steam quality should be made upon purchase of a new device, and steam piping must be insulated and installed in a general fashion that doesn't allow condensate to flow in the same direction as the steam. Steam traps - devices that drain water while keeping steam within the sterilizer system - should be accessible and added to the sterilizer's preventative maintenance schedule.

Make sure your new sterilizer comes with maintenance and instruction manuals, as they include all maintenance schedules and systems for its monitoring. Retain these as long as you own the device. In addition to keeping these instructions safely in a permanent file, make a copy that your entire staff can easily access.

Trained and authorized repair technicians must perform general and emergency repairs and routine maintenance. Always ask for the training records of your service provider. Review your expectations of service and make sure they are spelled out in the contract or agreement you reach with outside repair firms. At the very minimum, the stipulations outlined in your sterilizer's service contract should exactly match the required services - and frequency of those services - listed in the manufacturer's guidelines. Also ensure the terms of the service contract guarantee a quick response to repair requests and the use of factory-authorized parts in all repairs. Always follow the manufacturer's instructions and recommendations for preventative maintenance regardless of who actually performs the routine service.

Keep all maintenance records for the life of the sterilizer. They should include the device's model and serial numbers, the purchase date of the device, its location within your facility, service contract information, the documentation of preventative maintenance performed and a history of repair calls, including the names of the employees who requested the repairs.

Quality controls
A discussion of sterilizer maintenance would not be complete without a rundown of the quality controls used to monitor sterilizer performance. Here's an overview by function type. These three functions, when taken as a whole, ensure the efficacy and quality of the sterilization process.

• Mechanical. This review verifies that parameters of the sterilization cycle have been met. It includes a visual check of pressure gauges, temperature gauges and pressure graphs, charts and recording charts. Here's a tip: Review chart or computer printouts after each load for a real-time check of the sterilizer's performance and to verify that temperature and pressure parameters comply with your facility's policies and the manufacturer's instructions.

As you know, today's newer sterilizers have recording systems to monitor physical properties. Your staff must check that all recording devices are ready for use at the start of each day and before each load or cycle. They should maintain paper and ink levels and ensure that the recording device is set to the correct date and time. At the end of each load the user should review the recording documentation, verify the correct temperature was reached for the correct duration and initial the record. If your sterilizer doesn't have a recording device, the user is responsible for reporting the following data at the completion of each load: date, temperature reached and actual length of the cycle at the required exposure temperature. Whoever monitors the sterilization process must sign this report.

• Chemical. These indicators respond to changes in the sterilizer's chamber and assist in the identification of errors in the sterilizer's function by verifying that at least one parameter of the cycle has been met. The Association for the Advancement of Medical Instrumentation categorizes chemical controls into five classes.
  • Process indicators Class 1. These external chemical indicators are used with all packages to determine if individual items have been exposed to the sterilization process.
  • Indicators for use in specific test Class 2. These include Bowie-Dick type indicators or dynamic air removal tests. They should be used upon installation of the autoclave, after repairs or on a daily basis with pre-vacuum sterilizers.
  • Single parameter indicators Class 3. Designed to react to one parameter, these can be used as internal chemical indicators.
  • Multi-parameter indicators Class 4. Designed to react to two or more parameters, these can be used as internal chemical indicators.
  • Integrating indicators Class 5. Designed to react to all critical parameters, these can be used as internal chemical indicators.

You should use Class 3, 4 or 5 indicators in each instrument package as part of general monitoring of the sterilizer, load configuration and packaging. The indicators should be placed in the area of the package where steam penetration is the most difficult. Internal chemical indicators (Class 3, 4 or 5) should also be used for random quality testing of the sterilizer's performance.

• Biological. These indicators verify that conditions were adequate to kill a known quantity of microorganisms. Biological indicators are designed to verify that the conditions in the sterilizer were present to achieve sterilization. Many commercially produced biological indicators are available. Each must be validated for the cycle in which they're to be used. It's essential to review and to follow exactly the individual manufacturer's instructions on use, handling, storage and incubation protocol.

Manufacturers' instructions, in most cases, require you to perform a biological control at least daily. Perform three consecutive biological tests in each cycle and each container configuration upon initial installation, relocation or any large repair of the steam sterilizer. Run a biological daily, or at least weekly, in every sterilizer and in any load that contains an implant. It is important to record and maintain results of all routine and installation testing, including the lot numbers of controls and biological indicators.

Stay vigilant
Establish your own policies and procedures for steam sterilizer maintenance. They should be driven by manufacturers' guidelines for service, preventative maintenance, inspection and quality controls, and AAMI standards. Sterilizer records must be kept according to your state's regulations. Document the personnel who maintain your autoclaves, how often they perform that upkeep and the methods they use.

Stay in tune with your staff's performance of autoclave maintenance. Constant monitoring can be as simple as firsthand observations made during regular passes through sterile processing or as involved as designing random audits to measure adherence to your facility's policy and procedures. Review your autoclave's performance on a monthly or quarterly basis, depending on the number and severity of reported problems. Include the users, repair technicians, plumbers, plant engineering technicians and infection control practitioners when reviewing your sterilization records as they all play a part in the sterilizer's performance.

Above all, make sure staff is well trained and experienced. Steam sterilizers have been in the medical and science fields for generations, but sterilization problems still persist. Educate your sterile processing team on core competencies, re-demonstrate required skills, monitor their progress and test their steam sterilizer maintenance knowledge with random audits.

References:
The Association for the Advancement of Medical Instrumentation. "Steam sterilization & sterility assurance in health care facilities." ANSI/AAMI, ST46-2002. J. J. Perkins. Principles and Methods of Sterilization in Health Sciences. 2nd ed.,1969.