Every month, Andersen’s Ted May will explore topics like safety, history, emissions and even molecular science related to medical device gas sterilization. These articles are published as part of Beyond Clean’s “Expert Series”—articles written by medical experts tackling some of the most pressing issues facing Sterile Processing departments.
Beyond Clean is the global voice for sterile processing, connecting individuals through innovative and disruptive platforms such as podcasting, social media and new technology.
Hospital EO and the automobile – the race for gas efficiency
How are automobiles and ethylene oxide (EO) sterilizers similar? The answer may surprise you.
The post-World War II era saw a dramatic growth in automobile sales and broad adoption of EO sterilizers in US hospitals. In both cases, these early models were inefficient. In 1935 average fuel efficiency for American autos was around 14 miles per gallon (mpg) and that number dropped to only 12 mpg in the 1960s and early ‘70s (thanks, muscle car era!).1 Fuel efficiency simply was not valued during this period.
Likewise, early hospital EO systems were not concerned with gas efficiency. Ethylene oxide had been extensively tested in the 1930s and 1940s and was recognized as a promising sterilizing agent. The widespread introduction of plastics in the 1950s to medical instrumentation required a low temperature method of sterilization compatible with these new materials and EO fit the bill nicely.
Early hospital EO systems were typically fed by large 50lb tanks, kept on-site in specially ventilated storage rooms. Ethylene oxide is flammable and explosive in concentrations above 3%. Manufacturers of these tank systems reduced the potential danger by mixing EO with inert gases. The mixes, however, introduced their own problems – they were far less efficient and (unlike EO) the inert gasses used were discovered to be greenhouse gasses.
By the 1970s things began to change. The oil crisis of 1973 spurred a move toward automotive fuel efficiency that continues to this day.2 By 1980, average fuel economy for cars had reached 20 mpg. By 2008, it was over 25 mpg.3
For EO sterilizers, the impetus for change was the creation of OSHA in 1971 and a growing awareness of the potential dangers of chemicals in the workplace. The early 1980s saw the introduction of single-use cartridge based EO sterilizers. These systems, which used 100–170 grams of EO per cycle, represented a major step forward in gas efficiency and reduced risk over the tank-based systems.
Modern cars have an average fuel efficiency over 30 mpg with some hybrid models reaching near 60 mpg combined.4 EO has advanced even further. FDA recently cleared a new EO sterilization process that uses only 17.6g of EO per cycle – 90% less gas than any other system on the market.
Both technologies have continually innovated over the last 60 years. So just as you would not confuse a modern hybrid with the gas guzzlers of the ‘60s, do not confuse modern, high-efficiency EO sterilizers with the tank systems of yesteryear.
Deeper Dive: Want to know more?
At Andersen, we are so proud of our EO – Flexible Chamber Technology (EO-FCT). It’s the proprietary technology that makes the astonishingly small, micro-dose of EO we use in our sterilizers so effective.
You see, we don’t sterilize “dead space.” A special sterilization liner bag encloses the items to be sterilized, the 17.6g gas cartridge and sterility indicators and that’s it. Any extra air is pulled out of the bag before the cartridge is activated.
We recently received several national awards for EO-FCT.
EO-FCT is also most likely one reason our upcoming EOGas 4 – 6 hour sterilizer recently achieved the ONLY FDA-clearance for terminal sterilization of duodenoscopes and colonoscopes – for lumens up to an 11.6 feet long and down to just 1.2mm in diameter! More Andersen FDA clearances.