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

AORN Journal,  Oct, 2006  by Nathan L. Belkin

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Compared to the surgical environment that was common-place 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)

"Courage is the power to let go of the familiar." (10) It is the intent of this article to play devil's advocate and offer a perspective that supports the need for further investigation of four basic perioperative practices:

* wearing of surgical masks,

* universal use of barrier drapes,

* laundering of surgical scrubs, and

* gowning and gloving.

The Surgical Mask

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)