Portal de Periódicos da CAPES

Masks, barriers, laundering, and gloving: Where is the evidence?

2006; Wiley; Volume: 84; Issue: 4 Linguagem: Inglês

10.1016/s0001-2092(06)63946-x

1878-0369

Nathan L. Belkin,

Radiation Dose and Imaging

Compared to the surgical environment that was commonplace half a century ago, today's ORs are a paradigm of sterility. Over the years, to accommodate the technological advances made in surgical science, AORN, in collaboration with other professional groups, has developed a number of recommended practices and guidelines.1 These recommendations are intended to benefit the welfare of patients by reducing the possibility of infection and the welfare of health care practitioners by protecting them from exposure to bloodborne pathogens. When information is available, these recommended practices and guidelines are evidence-based;2 however, some are predicated on what has been described as "strong theoretical rationale."3 Some practices commonly known as "sacred cows," however, have become so ingrained in perioperative practice that they continue to be performed even when they are shown to be unnecessary or ineffective.4-6 A practice cannot be justified on the basis of anecdotal experience or commercial interests; it must be evaluated by its influence on the outcome of surgical procedures and supported by scientific facts.7-9 wearing of surgical masks, universal use of barrier drapes, laundering of surgical scrubs, and gowning and gloving. The first study that supported the use of a mask in surgery was published in 1897 by a German physician who found bacteria in droplets expelled from the nose and mouth.11 In spite of these findings, masks were not commonly used in surgery for some time thereafter because it generally was believed that there was no need for improvement in OR techniques that were providing acceptable wound healing. It was the results of a study published in 1926 that showed the use of masks reduced the incidence of surgical site infections (SSIs),11 so the practice of wearing masks during surgery became more widespread. What is not generally known is that in a subsequent study published nine years later, the same author reported that the rate of infection with the use of masks was closer to 15% than the 2% to 5% range that had been anticipated.12 For some 25 years thereafter, with minimal research having been done on either the development or the filtering efficiency of the surgical mask, many institutions continued to use them. Whatever the mask's filtering capability, it was viewed as valuable for shielding the patient's wound from pathogenic bacteria expelled from the surgical team members' noses and mouths. Beginning in the 1950s, clinical investigators began to report the results of examinations of masks made of different materials. One group found that with a deflection-type mask, expired air that carried bacteria was deflected behind the wearer's head.13 This finding was reinforced when another group developed a testing method designed to demonstrate photographically the manner in which particles were spread when people coughed.14 What was particularly noteworthy was that the test clearly demonstrated that if people wearing masks had to sneeze or cough, it was better that they not turn their heads to one side as most people instinctively do. The mask and surgical infections. The key question that remains to be answered is what effect improvements have had on the masks of today. Have they contributed to a reduction in the incidence of SSIs? Several extensive in vitro studies have been published in an attempt to answer this question. Two studies showed that mask use did not contribute to a reduction in SSIs,15,16 and it should be noted that the rooms in which the studies were conducted employed high-efficiency particulate air (ie, HEPA) filtered air circulatory systems with 15 to 20 air changes per hour. The results of three other studies also challenged the standard practice of requiring all personnel in the OR, as well as those entering the surgical sterile area, to wear masks.17-19 One of the studies was performed in a theater equipped with a laminar flow air circulating system.19 The researchers concluded that air flow has a greater influence on bacterial counts than attire but recommended that personnel wear masks in ultraclean laminar flow ORs.19 More recently reported are the limited results of a study in which the authors found "no statistically significant difference in infection rates between the masked and unmasked groups" performing clean surgery.20 Thus, the researchers concluded that it was unclear whether wearing surgical masks results in any benefit to the patient during these procedures.20 It should be noted that in some countries today (eg, the United Kingdom, Finland), wearing of masks is optional for many procedures and personnel.21 The protective mask. With the advent of the era of HIV and the hazards associated with the transmission of bloodborne pathogens, the Occupational Safety and Health Administration's (OSHA's) final rule on occupational exposure to bloodborne pathogens22 identified the surgical mask in addition to a face shield and eye protection as "personal protective equipment" to be worn by health care providers in exposure situations. The need for a face shield was supported by the results of a comprehensive, multicenter study of more than 8,500 surgical procedures that indicated that approximately 26% of all the blood contacts occurred on the face and neck.23 Among those who sustained eye exposures, 83.7% wore surgical masks, including surgical masks with attached eye shields.… In the remainder of cases, some form of eye protection was worn, including goggles, face shields, or eye shields attached to masks, but the protective eyewear was, in these instances, inadequate to prevent eye exposures.25(p991) Summary. As indicated in the literature, the use of a surgical mask has been perpetuated because its influence on the incidence of SSIs is perceived but is not supported by evidence. Rather than mask use, which can easily be abused (eg, by masks not being worn properly, worn hanging loosely around the neck, or worn for prolonged periods of time), perhaps the perioperative nurse community should focus on protecting the wearer from hazards associated with the transmission of bloodborne pathogens. Toward that end, further study is needed to investigate whether masks could be replaced with what are described as "splash shields."26 A properly designed and constructed item of this nature could safely be used by those personnel in the immediate vicinity of the sterile field and would simultaneously deflect the air expelled by the wearer behind his or her head, thus protecting the patient. The use of surgical gowns and drapes evolved as a standard of practice more than a century ago with their primary purpose being to protect the sterile field from microbial invasion. For the most part, the items were made of a loosely woven, readily permeable, reusable, all-cotton fabric generically known as muslin.27 It was not until 1952 that a renowned surgeon and researcher, William C. Beck, MD, FACS, alerted the perioperative nurse community that the material failed to provide an effective bacteriological barrier after it became wet.28 Nevertheless, for some time thereafter, hospitals continued to use muslin. Lacking scientific evidence to support the need for a more impenetrable fabric, the community relied on industry to provide clinical data for proof of its benefits. there are limited data that can be used to understand the relationship of gown or drape characteristics with SSI risk. The wide variation in products and study designs make interpretation of the literature difficult.33(p262) The CDC's position is further supported by a published review of experimental, clinical, and epidemiological studies of gowns and drapes in which the authors concluded that the studies were of "limited relevance because of methodological flaws and product improvements."34(p256) A "standard" of performance. With the emergence of the era of the hazards associated with the transmission of bloodborne pathogens, whatever "strike-through" prevention of available barrier materials that may have been tolerated in the past no longer was acceptable. With a pressing need for a valid and reliable test method, the American Society for Testing Materials (ASTM) modified one of its existing tests that determined the effectiveness of protective clothing worn by chemical workers. The existing methodology was incorporated into two new tests—one for liquid penetration and one for viral penetration.35,36 Under the auspices of the American National Standards Institute (ANSI) and the Association for the Advancement of Medical Instrumenta-tion (AAMI), a standard was established.37 To accommodate the selection of a barrier material suitable for the "level of anticipated exposure," the standard classified a barrier's performance capability into four levels. For levels 1, 2, and 3, water is used to measure the levels of resistance to penetration. For the most resistant, level 4, the ASTM's test is used. For surgical drapes and accessories, the material must meet the liquid challenge; surgical gowns must pass both liquid and viral penetration tests. The test results for level 4 are reported on a pass/fail basis rather than the amount of pressure (ie, 2 psi) at which a material was tested. It should be noted that although the manufacturer may use a "pass" to characterize a material as being "impervious" or "liquid-proof," the literature indicates that the levels of pressure experienced in both in vitro and in vivo situations exceed that level of pressure.38-41 With the trend toward small incisions and minimally invasive procedures, how vital is it that drapes be made of a level 4 "pass" quality material? A survey of draping practices found that almost two-thirds of respondents use incise drapes.42 Why then is it necessary for the drape to be made of a level 4 fabric? If a drape is to be considered an item of protective clothing for the patient, should it not be chosen based on the same factors (eg, the level of exposure anticipated for the patient) on which the surgeon's gown is chosen? Data released by the American Hospital Association in 2003 indicate that 16,700,000 (61%) of the 27,200,000 surgical procedures performed in hospitals were performed on an outpatient basis.43 An increasing number of procedures also are being performed in office surgery centers and freestanding ambulatory surgery centers. In these situations, how vital is it for drapes to be made of costly barrier quality level 4 materials? The influence of barrier drapes on the outcome of a surgical procedure is not evidence based. There also is little real, empirical evidence demonstrating protection for the surgical team. Thus, there remains a need for unbiased, statistically valid conclusive research.44 Until such data become available, the use of barrier drapes cannot be indisputably defended. safer and better that all (surgeons) should put on a complete change of costumes rather than simply don a sterilized coat and pair of trousers over the ordinary clothes.45(p54) During that period, nurses wore dresses that were made of either linen or a calico fabric and that were described as being long sleeved, belted in, and fastened down the back.46 No mention is made about who laundered the garment, where it was laundered, or how laundering was to be done. Scrubs today are the most practical alternative to wearing street clothing. As stated in AORN's "Recommended practices for surgical attire," "scrub clothing is worn to promote a high-level of cleanliness and hygiene within the surgical environment."47(p451) Soiled versus contaminated. AORN's recommended practices contain definitions of two very important and distinctively different terms: contaminated and soiled. A contaminated garment is one in which "the presence of pathogenic organisms on or in the material" is observed.47(p455) A soiled garment is one that may be "smirched or stained by body perspiration, body oils, or other substances."47(p455) The difference is not emphasized when discussing home laundering, however. It is a violation of OSHA's final rule on occupational exposure to bloodborne pathogens22 to remove a contaminated garment from the health care facility premises, let alone take it home to be laundered. There is no evidence, however, that a soiled garment cannot be safely and effectively laundered in the home environment. the mechanical action of the laundry equipment, water flow, water temperature, time, and chemicals used. These are supplemented by agitation, dilution, and the addition of a disinfecting agent (eg, chlorine bleach).48 Chlorine bleach is one of the eight oxidizing types of bleaches, and it is recognized as being the most effective bacteria-killing agent commonly used by the laundry industry.49,50 Whereas use of one of the other bleaches, such as hydrogen peroxide, may sanitize a garment (ie, result in a reduction in the garment's microbial population), it will not disinfect it (ie, kill or destroy nearly all the disease-producing microorganisms on it).51,52 It should be noted that the material of which the greatest percentage of these garments are made is a blend of 45% polyester and 55% combed cotton percale such as is commonly used in bed linen. The only difference is that when the material is used for scrubs, the laundry process should include a cycle with chlorine bleach to assure its disinfection (ie, not simply having body odors, body oils, and perspiration removed). Summary. Although the CDC's "Guidelines for the prevention of surgical site infections" state that "there are no well-controlled studies evaluating scrub suit laundering as an SSI risk factor,"33(p262) AORN does not recommend the practice of home laundering.47 Nevertheless, those facilities that have permitted their OR personnel to launder their apparel at home would have ceased doing so long ago had they found any evidence that the practice was detrimental to either the patients' welfare or the home environment of their staff members. Considering the fact that surgical gloves did not become a part of the surgeon's armamentarium until the turn of the last century, it is not surprising that the technique for donning them did not appear in a nursing text until 1916,53 and that the open and closed techniques so commonplace today were not described in print until 1940.54 It was not until 1975, some time after the introduction of barrier materials, that the community's attention was alerted that the design and construction of the gown was such that it permitted "leakage" at the gown/glove interface.55 With the emergence of the era of the hazards associated with the transmission of bloodborne pathogens, this leakage became an issue of concern. The ANSI/AAMI standard for the performance of barrier materials defines the critical zone as an "area of protective apparel or surgical drape where direct contact with blood, body fluids, and otherwise potentially infectious material is most likely to occur."37(p2) One of the critical zone areas of the surgical gown is obviously at the gown/glove interface. In examining the protective gowns available today, researchers found that leakage occurred in an overwhelming percentage of them in the hand area.56 Nevertheless, it is on the list of exclusions as one of the items that the standard does not cover. excluded this subject because the standard is for the barrier properties of the gown and drapes, especially in the critical zone, and it is not possible to determine how an individual would select a gown that assured him that there would not be a potential problem with this [gown/glove] interface.57 What is particularly noteworthy is that in a study published in the mid-1990s, the researchers proposed a solution to this problem area that has yet to be pursued commercially.56 The solution entails a complete redesign of the interface to eliminate the stockinette cuff and equalize the circumference of the sleeve and cuff by producing a smooth dart to achieve an interface of the quality that approximates that of the gown or glove.56 changes in the gown's construction, changes in the glove's construction, or a combination of changes in both. Aseptic technique can best be described as an aggregation of reasonable practices performed in the surgical suite as part of the overall methodology for controlling or minimizing the possibility of a surgical infection. The key words in this definition are aggregation and reasonable. The real question is whether the perioperative nurse community is prepared to reconsider and reassess the importance of unproven, theoretical practices, some of which have been traditional for as many as 100 years. Albert Einstein said, "The important thing is not to stop questioning."58 Two major questions to be asked are: does the practice make sense today, and can the practice be changed without impairing the outcome of the procedure? From the evidence submitted here, it appears that a departure from their universal application may not compromise the quality of care rendered to the surgical patient or harm health care practitioners and at the same time, could prove to be economically advantageous. Additional research needs to be conducted to determine whether these practices are beneficial for patients and practitioners. Those practices that are not evidence-based are not defensible.