Laird Harrison

October 31, 2017

SAN DIEGO — Cloth skullcaps protect against contamination of operating rooms better than can disposable skull caps or bouffant hats, a new study suggests.

The finding could bolster surgeons' resistance to the shower-cap style of bouffant hats required by some hospitals.

"We saw that the cloth hats seemed to be the best of all," Troy Markel, MD, told Medscape Medical News. Dr Markel, an assistant professor of pediatric surgery at Indiana University Health in Indianapolis, presented the finding at the American College of Surgeons (ACS) Clinical Congress 2017.

Until recently, professional guidelines were vague about what people working in operating rooms should wear on their heads.

However, in 2013, the Association of Perioperative Registered Nurses specified  that "ears, scalp skin, sideburns, and nape of the neck" should be covered. The organization reasoned that people might shed uncovered hair, spreading bacteria.

Since then, many hospitals have required bouffant hats in the operating room, Dr Markel said. But some surgeons have bridled because of the tradition behind the tie-in-the-back skullcaps, because they find the bouffant caps hotter, and because they believe they can't hear as well when their ears are covered.

In 2016, the American College of Surgeons voiced its objection to the bouffant requirement, arguing that skullcaps leave only minimal skin and hair exposed and that "the skullcap is symbolic of the surgical profession."

To see whether the choice of hats makes a difference, the research team, which included a microbiologist, engineers specializing in ventilation, an industrial air hygienist, and a surgeon, placed particle detectors, air samplers, and settle plates in an operating room. A surgical team then conducted 1-hour mock operations. They followed a script, closely simulating surgery. But instead of operating on a real patient, they performed electrocautery on raw steaks to disperse particles into the air.

The researchers tested bouffant-style hats, disposable skullcaps, and freshly laundered cloth skullcaps in three 1-hour experiments for each hat at two hospitals, for a total of 6 hours of testing for each hat. Both operating rooms had high-efficiency air-cleansing ventilation systems, according to the researchers.

They measured more particles in the air when the surgical team was wearing either of the two disposable hats than with the cloth skullcap. In a couple of experiments, for particles of 0.5 µm and 1.0 µm, the difference reached statistical significance (P = .03).

The researchers tested the permeability of the different types of hat and found that the two disposable types had more porous crowns than the cloth skullcaps.

In the settle plates, more colony-forming microbes gathered when the operating room personnel were wearing bouffant hats than when they were wearing either type of skullcap. The difference was statistically significant (P < .05).

The researchers did not capture any hairs in their measuring devices.

"The long and short is that the cloth hats are probably best of the three," Dr Markel said. But he noted that he washed all the cloth skullcaps used for the experiments in his washing machine at home. Hospitals don't generally have procedures for laundering skullcaps, and it's not clear how sanitary a cloth cap can remain while kept unwashed in a dresser drawer between operations. The ACS recommends that caps be cleaned or replaced daily.

The finding will raise surgeons' hopes of hanging on to the skull caps traditionally associated with their profession, said session moderator Leslie Kobayashi, MD, an associate professor of surgery at the University of California in San Diego.

"I think people have pretty strong loyalties to what they are using," she told Medscape Medical News. "I know in our hospital when they did away with the skullcaps it was greeted with cries of dismay."

Yet, the study won't put an end to the controversy, she said. "I think that in order to create any kind of policy you're going to need more than one study, regardless of how well constructed it is. I think that a lot of people who are proponents of only one type of headgear are going to request a more real-world situation looking at things that definitively impact patient outcomes like surgical site infections."

Dr Markel reported that he is one of the principles of Onsite, a company that is commercializing the techniques used in the study to test air quality in operating rooms. Dr Kobayashi has disclosed no relevant financial relationships.

American College of Surgeons (ACS) Clinical Congress 2017. Presented October 25, 2017.

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