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Quiz: PPE Options for Urgent Surgical Cases

Karen M. Tobias, DVM, MS, DACVS, University of Tennessee

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Published Thursday, March 26, 2020, at 11:00 AM CST

The COVID-19 pandemic has resulted in a shortage of personal protective equipment (PPE) for veterinarians as current disposable material stocks are being diverted to human healthcare workers. Many veterinarians are searching for other options, particularly for emergency surgical procedures. Although recent high-quality medical studies are limited, available published information can help guide veterinary professionals in the decision-making process.

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Quiz: COVID-19 & PPEs

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Surgical Masks

In the operating room, the purpose of a surgical mask is to prevent spread of droplets from the nose or mouth of the mask wearer into a surgical wound or onto a sterile surface. A secondary benefit is to protect the wearer’s nose and mouth from blood or fluid spatters originating from the patient. However, the importance of masks in preventing surgical site infection (SSI) is debatable. There was no evidence that use of a mask reduced postoperative SSI in humans in a systematic review comparing use of disposable face masks with no face masks during clean surgeries.1 This suggests that well-fitting, reusable cloth masks may provide sufficient protection for most veterinary surgical procedures. 

However, cloth masks do not provide reliable protection against respiratory infection from other humans. In a randomized trial of effectiveness of cloth and medical masks, medical workers using cloth masks had a 13-times greater risk of developing influenza-like illness significantly higher than workers wearing medical masks (relative risk, 13; 95% CI 1.69 to 100.07) and a 1.72-times greater risk of developing laboratory-confirmed influenza (relative risk, 1.72; 95% CI, 1.01 to 2.94).2 The trial additionally suggested that even a well-fitting cloth mask will allow particle penetration. Use of N95 respirators compared with surgical masks was not associated with prevention of laboratory-confirmed influenza, possibly because of low compliance.3 N95 respirators are more uncomfortable and ill-fitting than surgical masks; wearers unaccustomed to these masks tend frequently to take them on and off, increasing the chance of contamination. 

True or False?

Reusable cloth masks may provide adequate SSI protection for most veterinary surgical procedures. 

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Surgical Gowns

Surgical gowns prevent transference of perspiration particles, skin cells, lint, and other materials from the surgeon to the patient, as well as blood from the patient to the surgeon. Depending on construction and care, cloth gowns can offer sufficient patient protection for most routine veterinary surgeries. In a Level 1 SSI study in humans, no difference was noted in SSI rate when comparing use of disposable and woven cotton gowns, although implant surgeries were not evaluated.4 In another prospective, randomized, blinded study of human patients undergoing coronary artery bypass, no difference in sternal or leg wound infection rates were noted when comparing the use of disposable drapes and gowns with the use of reusable cloth materials.5

The ability of a cloth gown to repel fluids depends on the fabric thread count, thread size, weave characteristics, thickness, mass, and repellency.6 Multifilament, woven, 100% polyester gowns with pore size <7 microns and thread count of 175 to 280 provide maximal water repellency. These fabrics also provide greater resistance to bacterial strike-through than do cotton or cotton-blend fabrics6; however, they result in increased thermal discomfort with long wear, as they lack breathability and retain heat. Because fabrics gradually break down with repeated washing, a tracking system should be instituted if cloth surgical gowns are used. Manufacturers often suggest a maximum number of laundering cycles; in general, most reusable gowns can be used for 50 or more laundering cycles.7

True or False?

Studies have suggested that reusable cloth gowns may provide adequate SSI protection for most veterinary surgical procedures. Most gowns should be discarded after 10 laundering cycles. 

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Surgical Drapes

Reusable drapes should be sufficient for routine surgeries in veterinary medicine, assuming they are appropriately constructed and are discarded when damaged by use or frequent laundering.4,5 A systematic literature review described reductions in SSIs with switches from cloth to disposable drapes in several initial, uncontrolled studies.8 In these studies, however, hospitals used old-style linen drapes, which likely affected outcomes. Subsequent controlled studies reported no difference in infection rates between reusable and nonreusable materials, except when implants were placed.4,5,9 Alternative sources of pathogens (eg, patient skin, instruments, room air) may be greater factors in development of SSIs as compared with a loss of physical barrier, as suggested in the systematic review.8 Addition of adhesive drapes is unlikely to reduce infection rates, assuming the skin is appropriately prepared.10,11

As with surgical gowns, materials for surgical drapes should be free of punctures and tears, resistant to fluid penetration, lint-free, flame-resistant, and easily sterilized.12 Manufacturers should be able to provide information regarding (1) the efficacy of their drapes as fluid and microbial barriers based on standards published by the American Society for Testing and Materials (ASTM), and (2) the level of barrier efficacy based on resistance to impact and hydrostatic penetration.13  

ANSI/AAMI PB 70:12 Classification of Barrier Performance

  • Level 1 material has minimal resistance to water and is therefore less effective as a drape when moisture from blood or lavage solutions is expected. 
  • Level 2 material has low water resistance under constant contact with increasing pressure, although has some resistance to water spray. 
  • Level 3 material has moderate water resistance, even with some constant contact and pressure. 
  • Level 4 material is resistant to blood and viral penetration.14 

Because blood has a lower surface tension than water, it can penetrate materials more easily.14 Impervious drapes, or drapes that are impervious in critical areas, such as around fenestrations, are therefore recommended if large amounts of fluid are expected during surgery.15 If drapes have been treated with fluid-repellent chemicals, purchasers should request information from the manufacturer as to whether the barrier is nontoxic and will tolerate multiple laundering cycles.  

True or False?

Level 1 material is resistant to blood and viral penetration. 

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Surgical Caps & Booties

The primary purpose of disposable shoe covers or booties is to prevent gross contamination of footwear in the operating room, preventing the tracking of material to other areas of the hospital.16,17 Use of shoe covers has not been proven to reduce SSI risk or infection rates in intensive care units.18-20 Shoe covers also do not decrease bacterial contamination of floors.21

Disposable surgical caps reduce the amount of air contamination and bacterial sedimentation in experimental situations.22 However, there is no evidence that use of full coverage headgear, including hoods and beard covers, reduces the SSI rate as compared with skullcap-style head coverings.23 The American College of Surgeons (ACS) supports the use of skullcaps if minimal hair is exposed.24 Interestingly, study results have suggested that disposable bouffant caps yielded higher levels of particles and microbial shed than cloth skull caps, likely because of the larger bouffant pore size.25 As with surgical scrubs and lab coats, the ACS recommends that cloth caps are changed daily, even if they do not appear soiled.24 

True or False?

Full coverage headgear is not superior to skullcap-style coverings.

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Surgical Gloves

Because surgical gloves are considered essential PPE in human surgery, there are few modern studies on SSI rates when no gloves are used. Glove punctures double the chances of SSI, but only when surgical patients do not receive perioperative antimicrobial prophylaxis.26 This means that properly-disinfected hands, along with antimicrobial prophylaxis, can reduce the risk of infections when gloves are perforated.

What should veterinarians do when disposable sterile surgery gloves are no longer available? Some veterinarians have considered using examination gloves as a replacement. Examination gloves from a newly opened box are not necessarily sterile: in one study, microbial growth was identified on 48% of tested gloves.27 Contamination likely increases as the gloves are donned; however, these gloves may still be sufficient when used for minor procedures (eg, simple skin wounds) in which appropriate surgical site and hand preparation and instrument sterilization are concurrently employed. Overall, infection rates for simple excisions and laceration repairs in humans are similar when performed with sterile or clean gloves28; however conflicting study results suggest more complicated and longer procedures would benefit from use of sterile gloves.29,30  

Some veterinarians have considered washing and re-sterilizing their disposable surgery gloves. During a surgical glove shortage in the 1940’s, rubber gloves were successfully sterilized for reuse in a pressurized steam autoclave.31 Glove construction has changed, however, with current surgical gloves made of thinner materials to improve dexterity. Information about effects of surgical glove resterilization is not readily available. 

Some examination gloves can, however, be sterilized. In one study,27 surface disinfection of latex and nitrile exam gloves with 1% hydrogen peroxide and 0.08% peracetic acid (HP-PA) effectively reduced bacterial contamination at a rate similar to that of single-use, disposable surgical gloves; however, similar results were not found using 70% alcohol, thus alcohol sterilization is not recommended. The same study evaluated the use of autoclaved latex and nitrile exam gloves and found that all of the nitrile gloves could be donned after autoclaving, while 23% of the latex gloves failed because of adhesions or tearing.27 During a second stretch test, about 2.5% of the nitrile gloves failed, a result similar to that expected of disposable surgical gloves during their first use. Although this study did not look at infection rates, it appears that sterilized nitrile examination gloves may be a good option for emergency sterile surgery.

Fit of the gloves will be important, since gown cuffs are more vulnerable to strike-through.7 Variations in quality can also occur based on the manufacturing; in one study of disposable exam gloves worn in ICUs, perforations were noted in 13.9% of latex gloves and 6.6% of nitrile gloves.32 Perforations or contamination occurred more often at the fingers of latex gloves and the palms and cuffs of nitrile gloves; the latter was likely because of the poorer fit of nitrile gloves.32 Because of the risk for perforations, urgent surgeries that require implant placement (eg, fracture repair) are best performed with disposable gloves. 

True or False?

Glove punctures always double the risk of SSI.

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Quiz: COVID-19 & PPEs

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Conclusion

During times of limited PPE availability, veterinarians must consider other options for urgent surgical cases. Cloth gowns, caps, masks, and drapes serve as effective replacements for disposable items. Although disposable surgical gloves are considered best practice, sterilized examination gloves could be considered for some emergency soft tissue procedures. 

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

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