How to Sterilize Medical Supplies
A significant factor in the quality of medical care given in austere settings is the level of cleanliness of the equipment used. You may have heard of the terms “sterile” and “clean”. Certainly, ideal conditions warrant both, but they are actually two different things. Do you know the difference?
Sterile Vs. Clean
When it comes to medical protection, “sterility” means the complete absence of microbes. Sterilization destroys all microbes on a medical item to prevent disease transmission associated with its use. To achieve this, we want to practice “sterile technique”, which involves special procedures using special solutions and the use of sterile instruments, towels, and dressings. Sterile technique is especially important when dealing with wounds in which the skin has been broken and soft tissue exposed.
Of course, it may be difficult to achieve a sterile environment if you are in the field or in an extremely austere setting. In this case, we may only be able to keep things “clean”. Clean techniques concentrate on prevention of infection by reducing the number of microorganisms that could be transferred from one person to another by medical instruments or other supplies. Meticulous hand washing with soap and hot water is the cornerstone of a clean field.
If you are going to be medically responsible for the health of your people off the grid, you will have to strike a balance between what is optimal (sterility) and what is achievable (clean).
The “Sterile” Fieldfenestrated drape
When you’re dealing with a wound or a surgical procedure, you must closely guard the work area (the “sterile field”) to prevent contact with anything that could allow micro-organisms to invade it. This area is lined with sterile “drapes” arranged to allow a small window where the medical treatment will occur. Although there are commercially-prepared drapes with openings already in them (“fenestrated drapes”), using a number of towels will achieve the same purpose, as long as they are sterile.
The first step is to thoroughly wash any item you plan to reuse before you sterilize it. Using a soft brush removes blood, tissue particles, and other contaminants that can make sterilization more difficult. Consider using gloves, aprons, and eye protection to guard against “splatter”.
Ways To Disinfect and Sterilize Instruments
Now, the question of how to sterilize your medical supplies: There are a number of ways that you can accomplish this goal:
• Simply placing them in gently boiling water for 30 minutes would be a reasonable strategy, but may not eliminate some bacterial “spores” and could cause issues with rusting over time, especially on sharp instruments like scissors or knives. Also, there’s the matter of how much fuel is used to achieve the goal.
(Note: always sterilize scissors and clamps in the “open” position)
• Soaking in bleach (Sodium or Calcium Hypochlorite). 15-30 minutes in a 0.1% solution of bleach will disinfect instruments (but no longer or rusting will occur). Instruments must be rinsed in sterilized water afterward.
• Soaking in 70% isopropyl alcohol for 30 minutes is another option. Some will even put instruments in a metal tray with alcohol and ignite them. The flame and alcohol, or even just fire itself (if evenly distributed) will do the job, but eventually causes damage to the instruments.
• Chemical solutions exist that are specifically made for the purpose of high-level disinfection (not necessarily sterility) in the absence of heat, something very important if you have items that are made of plastic. A popular brand is Cidex OPA, a trade name for a solution with phthalaldehyde or glutaraldehyde as the active ingredient. Insert the instruments in a tray with the solution for 20 minutes for basic disinfection. Soaking overnight (10-12 hours) gives an acceptable level of “sterility” for survival purposes. There are test strips which identify when the solution is contaminated. If negative, you can reuse it for up to 14 days. As an alternative, some have recommended using 6-7.5% hydrogen peroxide for 30 minutes (household hydrogen peroxide is only 3%, however).
• Ovens are an option if you have power. For a typical oven, metal instruments are wrapped in aluminum foil or placed in metal trays before putting them in the oven. The oven is then heated to 400 degrees Fahrenheit for 30 minutes or, alternatively, 325 degrees Fahrenheit for 2 hours.
Although ovens and microwaves have been used to sterilize instruments, probably the best way to guarantee sterility in an austere setting is a pressure cooker. Hospitals use a type of pressure cooker called an autoclave that uses steam to clean instruments, surgical towels, bandages, and other items. All modern medical facilities clean their equipment with this device (I hope).
Having a pressure cooker as part of your supplies will allow you to approach the level of sterility required for minor surgical procedures. As you can imagine, this isn’t easy to lug from place to place, so it’s best for those who plan to stay in place in a disaster scenario. Here’s a link to the procedure:
A significant development in the quest to put together a portable and reliable method to sterilize instruments comes from a recent study commissioned by the military. The study, published in the journal Wilderness and Environmental Medicine, explored the use of UVC light as a survival medical tool.
In this study, instruments laden with MRSA and other bacteria were first scrubbed with Chlorhexidine (Hibiclens) for 30 seconds, and dried with a sterile gauze 4 x 4. Then, an ultraviolet C (UVC) wand was passed within 4 inches over the instruments for 45 seconds. Evaluation afterwards revealed a 100% reduction of bacteria and achieved levels of sterilization acceptable for use in the field. If the instruments were not used right away, rapid vacuum sealing extended the life of sterility.
In most survival settings, “clean” may be as good as it gets, but is that so bad? Modern medical facilities have the ability to provide sterility, so there is very little research that compares clean vs. sterile technique. In one study, an experiment was conducted in which one group of patients had traumatic wounds that were cleaned with sterile saline solution, another group with tap water. Amazingly, the infection rate was 5.4% in the tap water group as opposed to 10.3% in the sterile saline group. Another study revealed no difference in infection rates in wounds treated in a sterile fashion as opposed to clean technique. Therefore, clean, drinkable water is acceptable for general wound care in survival scenarios. That doesn’t mean that you shouldn’t use antiseptic solutions if you have them, however, especially for the first cleaning.
We’ll discuss antiseptics in more detail in a future article.
Joe Alton, MD
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