Draping has been a part of the surgical ritual since the 19th century, helping maintain the sterile field in the OR by creating a barrier to protect the patient from his own flora as well as bacteria in the room's air. The Centers for Disease Control and Prevention and the Association of periOperative Registered Nurses recommend draping the patient to prevent surgical site infections.1,2 But how much science is really behind these guidelines? Read on and then take our quiz on drapes, their benefits and drawbacks and the most effective ways to use them.

A barrier against bacteria
"Surgical drapes should establish an aseptic barrier," say the AORN guidelines for maintaining a sterile field. The drapes should also create a barrier against liquid suited to the procedure, based on how much fluid it will generate and its duration.

Studies show that disposable, non-woven drapes are more resistant to bacteria than reusable drapes. In 2000, British researchers at the University of Bristol sandwiched disposable and reusable drapes between a blood agar plate inoculated with bacteria and another that was free of bacteria.3 Ashley Blom, MD, PhD, and colleagues found that Streptococcus viridans and coagulase-negative Staphylococci penetrated reusable fabrics in 30 minutes but did not penetrate the disposable drapes.

But disposable drapes aren't always impermeable to bacteria. In 2007, Dr. Blom and colleagues tested the bacterial resistance of 6 brands of disposable drapes using the same double-plate technique and spores of coagulase-negative Staphylococci. After running the experiment 4 times, they found that each brand let bacteria pass though the barrier after 90 minutes at least once. Four of the 6 brands allowed bacteria to pass in as few as 30 minutes.4

Based on this and other data, the length of the procedure should be considered when draping. "Sterile fields should be prepared as close as possible to the time of use. The potential for contamination increases with time because dust and other particles present in horizontal surfaces over time," according to AORN.2

Does draping prevent infections?
Theoretically, covering the patient should reduce the risk of bacteria reaching the surgical site. But the limited peer-reviewed evidence shows mixed results. Even the CDC, which recommends using surgical drapes, admits that there is limited data linking drapes to fewer surgical site infections.1 "The wide variation in the products and study designs make interpretation of the literature difficult," says the CDC in its guidelines.

The move toward using disposable instead of reusable drapes began in the 1980s. But the results remain unclear. In 1987, researchers from Duke University found that using disposable drapes reduced surgical site infections to 2.8%, compared to 6.5% for reusable drapes, in 2,181 general surgical procedures. However, in 1999, surgeons at the Royal Brompton Hospital in London reported no added benefit from disposable drapes in 505 cases.6

Once you open drapes, handle them as little as possible. "Rapid movement of draping materials creates air currents on which dust, lint and other particles can migrate," say AORN guidelines.

In 1999, epidemiologist Charles E. Edmiston, Jr., PhD, CIC, and clinicians at the Froedert Lutheran Hospital in Milwaukee, Wis., sampled the OR air during 38 surgeries to measure the amount of bacteria and see whether the use of disposable drapes and gowns added to the amount of lint in the air, which could act as a vector for bacteria. In the air samples they found wood pulp fibers from disposable drapes and gowns and several pathogens that could cause surgical site infections, including Staphylococcus aureus and Staphylococcus epidermidis.7 These are floating around in the OR every day.

Drapes should be opened and placed by a team member wearing gloves. "During draping, gloved hands should be protected by cuffing the drape material over the gloved hands to reduce the potential for contamination," according to AORN guidelines.2 This helps keep the gloves sterile while transporting the drapes, says Gina Tamberino, RN, BSN, MSN, CNOR, manager of surgical services at St. Joseph Medical Center in Towson, Md. "The concept is that you don't touch anything that is not sterile." Likewise, drapes should be held as compactly as possible and held higher than the OR table. AORN calls for the patient to be draped closest to the surgical site first and then out towards the periphery. Once in place, the drapes should not be moved. "Shifting or moving the sterile drape can compromise the sterility of the field," says AORN.2

AORN recommends the use of fire-resistant drapes in its Recommended Practices for Selection and Use of Surgical Gowns and Drapes.8 Today many drapes are fire-resistant, but that doesn't mean that they can't catch fire.

Lasers can ignite drapes, especially in environments with higher O2 levels than in ambient air. In 1992, the ECRI Institute performed a study on the flammability of drapes when exposed to laser energy. Even at the lowest O2 level (ambient air at 21%) flame-resistant drapes caught fire. "Most lasers can ignite cellulose-based and cotton-based drapes in room air. Polymeric and synthetic drapes will melt away from the laser, and a high-power-density laser beam can penetrate most drapes without igniting them; in these cases, a patient injury or an unseen, smoldering fire could occur," write the ECRI researchers in their guidance report on fire safety: The Patient is on Fire! A Surgical Fires Primer.9

The combination of drapes and O2 supplied to the patient during anesthesia delivery can create a fire hazard if O2 accumulates underneath the drape. In 2000, anesthesia provider Angela Barnes, CRNA, MSN, and Rita Frantz, RN, PhD, FAAN, a professor of nursing at the University of Iowa, used a gas analyzer to record the O2 levels beneath drapes in simulated surgeries with and without supplemental O2. With supplemental O2 they found O2 concentrations as high as 45%, more than twice that of ambient air. Even when an O2 scavenger system was used, the average concentration was 34%, report Ms. Barnes and Ms. Frantz.10

Do adhesive drapes protect better?
Plastic adhesive-back drapes are commonly used to create an additional microbial barrier at the site of the incision. The logic behind this practice is to further isolate the site from exposed skin that can become re-colonized as the procedure progresses.11

But how well do these drapes work? Joan Webster, RN, BA, of the Royal Brisbane and Women's Hospital in Australia and Abdullah Alghamdi, MD, MSc, FRCSC, of the University of Toronto, performed a systematic review of 7 studies of adhesive drapes with a total of 4,195 patients. "[We] could find no evidence that adhesive drapes reduce surgical site infection rates and some evidence that they may increase infection rates," write Ms. Webster and Dr. Alghamdi. Patients in the group with adhesive drapes had a 23% greater chance of surgical site infection than those in the group without adhesive drapes. They found no difference in the rates of infection between iodine-impregnated adhesive drapes and plain plastic drapes, according to the review published in the Cochrane Library.

"If adequately disinfected prior to surgery, the patient's skin is unlikely to be a primary cause of SSI; so attempts to isolate the skin from the wound, using an adhesive drape, may be pointless and potentially harmful as excessive moisture under plastic drapes may encourage bacteria residing in hair follicles to migrate to the surface and multiply," write Ms. Webster and Dr. Alghamdi.

Medical devices
Although drapes are a common surgical supply that you order in bulk, it's important to remember that the FDA considers them medical devices. Recurring problems or failures of the drapes to work properly should be reported to the FDA's Medical Device Reporting program.12 AORN recommends reporting any problems with drapes to both the FDA and the manufacturer in order to alert other users that may be using the same drapes. "Any strike-through constitutes a threat of exposure to potentially harmful bloodborne pathogens," say AORN's guidelines for gowns and drapes.8

While the evidence doesn't always coincide with the theory that using drapes for invasive procedures reduces the risk of surgical site infection, drapes are still recommended by AORN and the CDC. Draping the patient does not guarantee protection from a surgical site infection, but in most cases, data suggest that it at least does no harm. Until more evidence comes out, the ritual will go on, so it's important that you know how and why you drape a patient.

Answers
1. a; 2. d; 3. b; 4. a; 5. a; 6. a; 7. d; 8. b