Sterilization, Disinfection, Decontamination and Antisepsis
SURGICAL HAND SCRUB
Hand hygiene is a critical component of an infection prevention program. Nowhere is this principle more fundamental than in the operating room. Health care personnel must receive formal education and training, and then undergo competency validation on surgical hand hygiene products and procedures. They should perform a surgical hand scrub before donning sterile gloves for surgery or other invasive procedures.2
Members of the surgical team who have direct contact with the surgical field and/or sterile instruments must perform a surgical scrub.
Choice of antiseptic
An antimicrobial surgical scrub agent, intended for surgical hand antisepsis, or an alcohol-based antiseptic surgical hand rub, with documented persistent and cumulative activity that has met U.S. Food and Drug Administration (FDA) regulatory requirements for surgical hand antisepsis, is acceptable. The active components of antiseptics that are available in the U.S. include alcohol, CHG, iodine/iodophors, para-chloro-meta-xylenol (PCMX), or triclosan. Alcohol-based agents show an immediate reduction of 95% of the resident flora and a 99% reduction with repeated applications. However, products containing alcohol are generally used less frequently than other antiseptics due to their inflammability.
CHG rapidly reduces both skin flora and transient bacteria. Additionally, CHG has residual activity on the skin that helps to prevent rapid regrowth of skin organisms and enhances the duration of skin antisepsis.
Most data indicate that povidone-iodine and CHG have equal efficacy in decreasing the bacterial contamination of the skin, but CHG has a longer effect, is less toxic in open wounds, and causes less skin irritation with prolonged use.
Scrubbing technique, duration of the scrub, condition of the hands, and techniques used for drying and gloving all may influence the effectiveness of the surgical scrub.
Current recommendations for surgical scrub with antimicrobial soap are as follows:
∙ Remove all hand or arm jewelry.
∙ Keep nails short and do not wear artificial nails.
∙ Clean under each fingernail prior to performing the first scrub of the day and for any visible foreign material.
∙ Scrub the hands and forearms up to the elbows for the length of time recommended by the manufacturer of the antimicrobial soap in use (typically 2-5 minutes).
∙ After performing the surgical scrub, keep the hands up and away from the body with the elbows flexed.
∙ Dry hands with a sterile towel, ensuring that the towel touches only the parts being dried. Start drying the fingers of one hand and then the other. Next, dry each hand using a different part of the towel that has been kept away and clean. Finally, work up each arm toward the elbow, again keeping contaminated parts of the towel away from each successive area being dried.
∙ Don a sterile gown and gloves using a technique that preserves the hands’ antisepsis.
∙ When using an alcohol-based surgical handrub that has sustained activity, strictly follow the manufacturer’s instructions:
a. Adhere to recommended application times.
b. Apply the product to dry hands only.
c. Do not combine other surgical hand scrub products with alcohol-based surgical handrub.
d. After application of the alcohol-based handrub, allow hands and forearms to dry thoroughly before donning a sterile gown and gloves.
PATIENT SKIN ANTISEPSIS/SKIN PREP
The CDC provides the following evidence-based recommendations for surgical skin preparation:
1. Thoroughly wash and clean at and around the incision site to remove gross contamination before performing antiseptic skin preparation.
2. Apply perioperative antiseptic skin preparation in concentric, enlarging circles, moving from the incision towards the periphery. The prepared area must be large enough to incorporate any likely extension of the incision or creation of additional incisions or drain sites, if necessary.
Choosing an agent
The optimal antiseptic skin preparation agent should:
1. Significantly reduce microorganisms on intact skin
2. Be broad spectrum
3. Be fast-acting
4. Have persistent effect
5. Be non-irritating
The CDC has not issued a recommendation as to which antiseptic should be used preoperatively to prevent SSIs. The most commonly used antiseptic skin preparation agents include CHG, alcohol-based solutions, and iodophors, such as povidone-iodine.
While both CHG and iodophors have broad spectrum antimicrobial activity, CHG’s effect lasts longer with greater residual effect after a single application. Overall, it achieves greater reductions in skin microflora and is not inactivated by contact with blood or serum.
Current clinical evidence confirms CHG’s superiority over povidone-iodine for preoperative antisepsis. A recent study of 897 patients found CHG and alcohol surpassed cleansing with povidone-iodine for preventing SSI within 30 days after surgery, and demonstrated a greater than 40% reduction in SSI.
SURGICAL ATTIRE AND DRAPES
While evidence about the relationship between surgical attire and the shedding of live microorganisms from operating room personnel exists, only a few controlled studies have evaluated the relationship between the use of surgical attire and the incidence of SSIs. Nevertheless, personal protective equipment, including scrub suits, masks, surgical caps, hoods, and shoe covers, should all be used in accordance with federal and state regulations, as well as professional society guidelines.
Wearing a mask clearly protects the health care worker’s face from exposure, but some studies have raised questions about their efficacy and cost-effectiveness with regard to reducing SSIs. Nevertheless, the protection afforded the surgical staff warrants their use.5 The Occupational Safety and Health Administration (OSHA) requires that masks and protective eye wear be worn whenever splashes can be anticipated.
Furthermore, the AORN states that all individuals entering restricted areas of the operating room suite should wear a mask when open sterile items and equipment are present.
Hoods, caps, and shoe covers
Surgical caps reduce contamination of the field by organisms shed from the hair and scalp. Personnel should cover their head and facial hair when in the semirestricted and restricted areas of the surgical suite.
Shoe covers are used to maintain sanitation and, when badly soiled, should be removed before leaving the operating room.
Shoe covers have not been shown to reduce SSI risk and footwear dedicated for use in the operating room can be worn in lieu of shoe covers. Again, the underlying principle is sanitation and even dedicated OR shoes, when soiled, should be cleaned or discarded.
Sterile gloves must be worn when performing all sterile procedures, including those on tissues that should be sterile, such as open wound dressing changes. Non-sterile, medical grade gloves can be used for non-sterile activities.
In the operating room, sterile gloves are worn (a) to minimize the transmission of microorganisms from the surgical team’s hands to the patient, and (b) to prevent exposure of the team members’ hands to the patient’s body fluids and tissues. Sterile gloves should be inspected immediately upon donning and before contact with sterile supplies and tissue. They should be changed:
• After each patient contact;
• When a visible defect is noted;
• When suspected or actual contamination occurs;
• When a suspected or actual perforation occurs;
• Immediately following direct contact with uncured methyl methacrylate (bone cement);
• If the wearer receives an electrical shock from an electrosurgical unit;
• When gloves begin to swell or expand; and
• According to institutional policy.
Double-gloving has been shown to reduce the wearer’s risk of exposure to blood
and fluids. The AORN, the CDC, the American College of Surgeons, and the American Academy of Orthopedic Surgeons all recommend that health care providers double- glove during invasive procedures. Upon completion of the invasive procedure, both pairs of gloves should be discarded and hand hygiene should be performed.
Gowns and drapes
Sterile surgical gowns and drapes create a barrier between the surgical field and potential sources of bacteria. They should be chosen based on the type of the operation, its estimated duration, and the amount of blood loss expected. Additional considerations include their impermeability, comfort, and cost. They should have the ability to maintain an isothermic environment for patients and health care workers. Surgical gowns and drapes should be low-linting, since lint particles spread into the environment where bacteria attach to them and pose a potential for increased postoperative complications.
Surgical gowns should be selected according to their barrier characteristics and the expected exposure to blood and body fluids, in accordance with OSHA guidelines for the use of personal protective equipment (PPE).2 OSHA regulations require that if blood or other potentially infectious materials penetrate a garment, the garment shall be removed immediately or as soon as feasible.
Adhesive incise drapes have been evaluated in several studies, and have not been shown to be superior in controlling wound infections when compared with standard skin preparation and draping. However, it has been shown that the infection rate increases if the adhesive drape becomes separated from the skin during the operative procedure.
The operating room environment plays an important role in reducing the threat of SSI. A number of activities that occur in this environment are controlled by the surgical team. Attention to these factors may affect the patient’s risk of developing a surgical site infection.
Standards for airflow and ventilation in the operating room are intended to protect patients from SSIs and health care workers from acquiring infection from patients.
Air in the operating room environment contains microbe-filled dust, lint, skin particles, and respiratory droplets, with the majority of the airborne bacteria coming from the skin of the patients and the staff.
Airflow and ventilation
To prevent SSIs, clean air under positive pressure is supplied to the operating room. Maintaining operating rooms at positive pressure prevents airflow from less clean areas into cleaner areas. Heating, ventilation, and air conditioning systems remove air contaminants and control air flow patterns, which are designed to minimize contamination of the sterile field. Disruptions in the airflow patterns within the operating room can redirect contaminants into the sterile field, increasing the risk of SSI.
The air quality in the operating room should be sequentially filtered through two filters.
The first filter should be rated as 30% efficient, and the second should be 90% efficient. The operating room should be maintained with a minimum of 15 air exchanges per hour with a recommended range of 20 to 25 air exchanges per hour. Laminar air flow and the use of ultra-violet (UV) radiation have been suggested as additional measures to reduce SSI risk; however, intraoperative UV radiation has not been shown to reduce overall SSI risk.
SSI rates following certain procedures increase when a patient is permitted to become hypothermic. Therefore, it is important to monitor the ambient temperature in the room and maintain it at a level that does not induce hypothermia. Generally, the temperature in the operating room should be kept between 68⁰ F and 73⁰ F (20⁰ C and 23⁰ C). The room temperature should be increased when
directed forced-air heating alone is insufficient to maintain normothermia, such as when large areas of body surface are exposed during surgery. Procedures that include significant exposure to evaporative heat loss include open abdominal procedures, due to the large surface area of exposed visceral and parietal peritoneum, and large area tangential excisions and split thickness skin grafting for burn wound care. (Refer to section on Hypothermia under “Intraoperative Issues” for more information on preventing hypothermia.)
The relative humidity in the operating room should be maintained between 30% and 60%. Low humidity increases the risk of electrostatic charges, which pose a fire hazard, increase the potential for dust, and increase the rate of evaporation leading to heat loss and hypothermia. High humidity, on the other hand, increases the risk of microbial growth and can be uncomfortable for the fully gowned surgical team.
The microbial level in operating room air is directly proportional to the number of people moving about in the room. Therefore, efforts should be made to minimize personnel traffic during operations. Operating room doors should be closed, except as needed for movement of patients, personnel, supplies, and equipment.
The number of personnel entering the operating room should be limited as much as feasible and traffic into and out of the operating room should be minimized through pre-planning. Consideration, therefore, must be given to the location and quantity of supplies stored inside and outside the operating room; the location of flash sterilizers; and the equipment and supplies that are opened and assembled before the start of the case.
DISINFECTION AND STERILIZATION
Disinfection and sterilization of medical devices and surgical instruments are essential to reduce transmission of infectious pathogens to patients. Health care policies must identify, primarily on the basis of the items’ intended use, whether cleaning, disinfection, or sterilization is indicated.
Then, appropriate processing and reprocessing guidelines must be followed. Medical devices and surgical instruments needing reprocessing can be divided into three categories:
a) Critical items
b) Semicritical items
c) Non-critical items
Items which enter normally sterile tissue or the vascular system are categorized as critical and should be sterile when used.
Items that come in contact with mucous membranes or skin that is not intact are considered semicritical and should receive high-level disinfection, at a minimum, prior to use.
High-level disinfection kills all microorganisms with the exception of bacterial spores. (Disinfection levels are defined below).
Items that come in contact with intact skin should receive intermediate-level disinfection, low-level disinfection, or cleaning.
Cleaning, Disinfection, and Sterilization Cleaning
Cleaning is the removal of visible soil from objects and surfaces, which is normally accomplished using water with detergents or enzymatic products. Thorough cleaning is essential before high-level disinfection and sterilization. Effective sterilization cannot take place without effective cleaning. The process of sterilization is impeded by the relative number (i.e. bioburden), type, and resistance of microorganisms on the items to be sterilized. The manufacturer’s written instructions for handling and reprocessing should be used to determine how to replicate the validated cleaning an the recommended cleaning procedures can lead to decreased susceptibility to disinfectants.
Disinfection describes a process that eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects. In health care settings, items are often disinfected by liquid chemicals or wet pasteurization. 5 There are three levels of disinfection:
1. a) High-level disinfection: A process that kills all microorganisms, with the exception of high numbers of bacterial spores and prions
2. b) Intermediate-level disinfection: A process that kills microorganisms, most viruses, and tuberculosis bacteria, with the exception of high
numbers of bacterial spores or prions
3. c) Low-level disinfection: A process by which most bacteria, some viruses, and some fungi are killed
Sterilization describes the use of a physical or chemical procedure to eliminate all microbial life, including highly resistant bacterial endospores.35
The AORN offers the following recommendations for sterilization:
1. Saturated steam under pressure should be used to sterilize heat- and moisture- stable items, unless otherwise indicated by the device manufacturer.
2. Flash sterilization should be used only in select clinical situations and in a controlled manner. Flash sterilization should be used only when there is insufficient time to permit processing by the preferred wrapped or container method, and should not be used as a substitute for maintaining sufficient instrument inventory. Flash sterilization should be performed only if all the following conditions are met:
• The device manufacturer’s instructions are followed;
• Items are disassembled and thoroughly cleaned with detergent and water;
• Lumina are brushed, then flushed under water with a cleaning solution, and rinsed thoroughly;
• Items are placed in a closed sterilization container or tray, validated for flash sterilization in a manner that allows steam to contact all instrument surfaces;
• Measures are taken to prevent contamination during transport from the sterilizer to the sterile field.
3. Ethylene oxide sterilization is a low-temperature process that is appropriate for heat- and moisture-sensitive surgical items, when indicated by the device manufacturer.
4. Low-temperature hydrogen peroxide gas plasma sterilization should be used for moisture-sensitive and heat-sensitive items, when indicated by the device manufacturer.
5. Sterilization systems using peracetic acid as a low-temperature liquid sterilant is appropriate for heat-sensitive surgical items that can be immersed, when indicated by the device manufacturer.
6. Sterilization systems using ozone should be used for moisture- and heat-sensitive items, when indicated by the device manufacturer.
7. Dry-heat sterilization should be used to sterilize waterless items that can withstand high temperatures, when indicated by the device manufacturer.
The American Society for Gastrointestinal Endoscopy (ASGE) offers information for patients in their “Ensuring the Safety of Your Endoscopic Procedure” brochure, click here: http://www.asge.org/patients/patients.aspx?id=404