When I arrived at The Big Fix Animal Hospital in Gulu, Uganda, Dr. Arnold was abnormally pleased with my arrival. Although we became friends and are keeping in touch about medical cases, Dr. Arnold was beyond pleased because I was bringing a pressure cooker autoclave.
Since the late 1800’s and Sir Joseph Lister, Bt. We have known that surgical sterility of instruments, wounds, and hands was important. Indeed King Edward the Third credited his life to an aseptic appendectomy surgery in 1902. In other words, Lister’s procedures saved his life. (Aseptic literally means no infection.)
While Lord Lister used carbolic acid (phenol) to spray on the instruments and on the human tissues, Louie Pasteur’s work in microbiology proved that heat, chemicals or filtration was required to remove or inactivate microbes. The carbolic acid was used on sewage waste spread on fields to decrease the stench and Lord Lister decided to try the chemical on a badly fractured wound. Although it saved the boy’s life, carbolic acid is very caustic and we now know it can cause cancer.
In 2018, I take sterility for granted. We have four autoclaves in the hospital. One that is used routinely with an appropriate amount of bells and whistles. One is a back up that we purchased from a hospital that was going out of business and the other two have been retired. At the same time that I was in Africa, ours needed a new steam valve. Stephanie called the repair guy, scheduled the visit and authorized the repairs. The first time I knew anything about it was when the bill appeared on my desk. It was so important that she knew I would insist on it being repaired regardless of the cost. We are serious about sterility here.
Sterilization for instruments and surgical attire can only be accomplished by heat or chemical. Although both have advantages, heat sterilization is effective, safer and cheaper once set up. Ethylene oxide is a gas treatment that is commonly used to sterilize instruments that cannot be subjected to the intense heat needed to steam sterilize. Ethylene oxide treatment is generally carried out between 86 and 140 °F and a gas concentration between 200 and 800 mg/l. The process lasts for several hours and is highly effective, but it is flammable, toxic, and carcinogenic. That last part is why we do not use it at Guardian Animal.
Of course, steam sterilization is cheaper at Guardian Animal, because we own an autoclave and electricity is not a problem. That was not the same case in Africa. Power came from solar panels and the sun does not always shine. Autoclaves pull some serious amps. It is not that the struggling clinic has the two to three thousand US dollars for an autoclave in the first place.
So, Dr. Arnold was happy to see me because I brought a 41-quart sterilizer that could be used over a charcoal fire. His eyes were glistening as he looked past me into my footlockers and saw that the sterilizer had indeed arrived.
Pressurized steam is ideal for sterilization. The microorganisms are killed by coagulation (think boiled egg) or oxidation (think burnt egg). (Or as Harry Truman once said: “If you can’t stand the heat, get out of the kitchen.”) The high-pressure steam transfers the heat energy into the microorganism and quickly and effectively overloads their system to kill them. Although a proper cycle takes longer, pressurized steam accomplishes in three minutes what dry heat does in two hours. The autoclave uses saturated steam under pressure of approximately 15 psi to achieve a chamber temperature of at least 250°F for 30–60 minutes with an additional 20 to 40 minutes of drying time.
Dr. Arnold knew that spraying chemicals on instruments that were then rinsed and wrapped in a hand washed towel was not ideal, but it is all he had. It is not just the vet clinic that was having issues with sterilization. I talked with volunteers at two other health organizations in Uganda. One surgery clinic used boiling water to sterilize instruments. While it is better than nothing, it does not kill all the bacteria, viruses, fungi and prions. The other clinic used dry heat. This could work, but requires multiple cycles of heat and ventilation and requires temps of 374 for two or more hours. That really doesn’t happen in a manual environment in a third world country. Even at the University, Dr. Arnold had seen an autoclave, but not actually touched one.
We were even on that score. I had owned the pressure cooker autoclave for a few decades. It had been given to me, I think when I opened my clinic in 1991. I knew I wouldn’t use it, but thought it might be handy some day. From when it was given to me until I was told one was needed in Uganda, it had sat in various storage places. When I sent Austin to the attic to get it, we found that it had all the original instructions for instruments or canning. (Luckily, Dr. Arnold Googled and found a youtube video on how to use it in the way we were going to.)
On the little tin stove that was lined with fire block mud, we lit a charcoal fire and placed rocks on top to get air to the bottom of the sterilizer. Then we took too long to get it boiling and then it was in danger of being too cool. Being veterinarians, we added more charcoal and then it was too hot. We told Franco, his assistant, that we were testing the relief valves. And I did feel better that they worked even though we ducked and covered when it went off. We achieved about 265 degrees with about 20 psi for most of the cycle.
Lister’s work led to a reduction in post-operative infections and made surgery safer for patients, distinguishing him as the “father of modern surgery.” Now The Big Fix has a better, safer system for sterilizing the instruments. One that I suggested to some of the folks that were working with the human side of medicine there. They thought it was brilliant and a better solution than what they had. One health means animal and human medicine work together. Sometimes animal medicine leads human medicine and sometimes we steal from human medicine. Regardless, I was extremely pleased to get an email a few days after I got back from Dr. Arnold: “The Autoclave is working very well, we sterilized every tool that has to be sterilized! I am so grateful!”
Yes. Yes, I can see that. Good luck, Dr. Arnold!
Dr. MJ Wixsom owns and practices at Guardian Animal Medical Center on Bellefonte Road in Flatwoods, KY. 606.928.6566 and online at www.GuardianAnimal.com and has her fourth book out.