What to know and what to wear

by Scott Harrison

 In operating rooms (ORs) across the United States, there are countless boxes of facemasks sitting on scrub sinks—all varying to some degree from the box just beside it. Some masks have foam, while others have tape. Some come with shields, while others do not. Flat construction. Bill construction. Vertical or horizontal ties. And N95 respirators may add to the confusion.

Many times, healthcare workers select facial protection based on comfort or looks. Sometimes, the choice is based on knowing which mask fogs goggles or shields the least. But there is more to the selection than user preference.

Historically, selecting a mask based on user preference has been a common practice in the OR. Face masks were originally designed to protect the patient from microorganisms expelled from the mouth during talking, sneezing and coughing. ¹ In other words, face masks were designed to protect the patient from the healthcare practitioner, not the other way around.

But clinicians now are more aware of the prevalence of epidemiologically significant diseases such as hepatitis B, acquired immune deficiency syndrome (AIDS) and the H1N1 flu increases. And they now recognize the hazards of surgical smoke. So much of the thinking around face masks has begun to change. ¹

            Indeed, healthcare workers are wearing face masks and other respiratory protection devices to protect themselves from the patient as much as they are wearing them to protect the patient. To protect both effectively, it is important to have appropriate products available and to educate staff thoroughly on the topic of facial protection selection.

Performance Characteristics of Facial Protection Devices: Fluid Resistance, Filtration and Fit

To select an appropriate mask, clinicians must first consider the level of protection the procedure requires. Manufacturers of surgical masks are required to test all masks against several key criteria—the results of which help healthcare workers determine which mask is most appropriate.

Bacterial Filtration Efficiency (BFE)

BFE measures the ability of the mask’s materials to prevent the passage of aerosolized bacteria. It is expressed as the percentage of bacteria that does not pass through the mask’s layers at a fixed aerosol flow rate. A low barrier mask will achieve a BFE score of ≥95%, while medium and high barrier masks will achieve a BFE score of ≥98%.²

Particulate Filtration Efficiency (PFE)

PFE measures the ability of the mask’s material to filter sub-micron particles as small as 0.1 micron in size. Much like the BFE score, PFE is expressed as the percentage of particulate that do not pass through the face mask materials.

A low barrier mask is not required to pass the PFE test. Medium and high barrier masks must achieve a PFE score of ≥98%.³ This means that medium and high barrier masks will filter out at least 98% of particulate that are 0.1 micron is size or larger. For reference, laser plume ranges in size from 0.1 microns to 0.8 microns.

Fluid Resistance

Fluid resistance measures the ability of the mask’s construction and materials to resist the penetration of blood and other fluids. A mask that does not score well on the fluid resistance test may allow fluid to pass through the mask and come in contact with the wearer.

To test fluid resistance, a mask is sprayed for 0 to 2.5 seconds with a fixed volume of synthetic blood at three pre-set levels: 80mm/Hg, 120mm/Hg and 160mm/Hg. These levels correspond with low, medium and high velocity, respectively. Any visual evidence of synthetic blood penetration to the inside of the mask constitutes failure. At least 29 of 32 mask samples must pass the test for the mask to pass at the given velocity.⁴

Which Mask is Correct?

If the clinician does not face a threat of exposure to fluids or smoke, most surgical masks available will provide sufficient protection. According to the Association of periOperative Registered Nurses’ (AORN) recommended practices, “all individuals entering restricted areas of the OR suite should wear a mask when open sterile items and equipment are present.” Masks should fully cover both the nose and mouth and be secured in a manner that prevents venting.⁵ All ties on the mask should be secured appropriately.

Though most masks on OR scrub sinks are appropriate for general use, procedures in which healthcare workers run the risk of contact with blood or other fluids necessitate the use of a fluid resistant mask. It is important to note that many masks on the market today are not fluid resistant, and not all “fluid resistant” masks pass at the highest level of testing. In fact, not all masks that pass the fluid resistance test are an appropriate choice for procedures that have a risk of exposure to fluid.

According to the Association for Professionals in Infection Control and Epidemiology (APIC), a face mask with a fluid resistance level of 160mm/Hg should be worn for all procedures during which there is any risk of exposure to bodily fluids.⁶ Fluid and splash resistant mask packaging should carry information about fluid resistance levels. If it does not, representatives from the manufacturing company can provide the information.

During procedures that generate surgical smoke or laser plume, clinicians should select masks that provide a high level of particulate filtration (PFE). Smoke plume generated during surgical procedures will range in size from 0.1 to 0.8 microns, so it is necessary to use a mask capable of filtering at this level.

AORN’s Recommended Practices for Laser Safety in Practice Settings state that, “personnel working in the laser environment should avoid exposure to smoke plume generated during laser surgery” and further advise that healthcare practitioners participating in these procedures should wear surgical masks designed to filter smoke plume.⁷ When selecting a mask for use in laser procedures, practitioners should pick a mask that achieves a PFE score of ≥99% or higher—meaning that the mask filters out at least 99% of all particles 0.1 microns in size or larger.

Some masks have PFE data included on their packaging. As is the case with fluid resistance levels, data not presented on the packaging should be available from a representative from the manufacturing company.

To ensure that a surgical mask is providing adequate protection, it is imperative for the healthcare worker to wear the mask correctly. Unfortunately, it is not uncommon in the OR for healthcare workers to leave their masks partially untied, loose or otherwise inappropriately secured.

To ensure a secure fit, the wearer should tie the top set of ties at the crown of the head and the lower set of ties around the back of the neck. The mask should fit underneath the mouth and conform to the shape of the cheekbones. The nose wire should be formed across the bridge of the nose. The fit should assure there are no gaps around the edges that would allow dispersion or entry of microbes.⁸ 

However, some patient settings and procedures require more than a secure fit. When this is the case, practitioners should wear N95 respirators.

N95 Respirators

Though surgical masks provide enough protection to healthcare workers for most procedures, there are instances when practitioners need a greater degree of protection. The filtration capabilities of N95 respirators exceed those of traditional surgical masks and are designed to form a tight seal around the mouth and nose that provides a physical barrier from the surrounding environment. According to APIC, a properly fitted (fit tested) N95 respirator should be used when there is potential for exposure to tuberculosis or other airborne viruses.⁹

However, there is debate within the medical community over N95s and their ability to stop global flu pandemics. During the H1N1 pandemic of 2009, the official Centers for Disease Control (CDC) recommendation was to use respirators when treating patients affected with the illness to stop the spread of the virus. Initially, APIC and the Society for Healthcare Epidemiology of America (SHEA) supported the CDC recommendation; however, a recent study showed respirators and standard surgical masks to be equally effective in preventing the spread of H1N1. As a result, SHEA and APIC both changed positions and supported the use of surgical masks for the treatment of patients infected by the H1N1 virus.¹⁰

In addition, there is also controversy in the medical community over fit testing of N95 respirators. Fit testing is required, and is intended to identify a properly fitting respirator for each healthcare worker exposed to airborne viruses.

Unfortunately, available masks may not always fit properly. Today there are two means of fit testing N95 respirators: quantitative and qualitative.

Quantitative fit testing uses a machine to measure the number of particles on the inside and outside of a respirator that is being worn. To simulate a normal environment, the respirator wearer performs certain mouth and body movements such as talking or turning the head. If the respirator does not fit properly, these movements will allow particles to enter the mask chamber, resulting in test failure.

With qualitative fit testing, a large chamber is placed over the head of an individual being tested. A sweet smelling aerosolized solution is then introduced into the chamber. If the individual detects the smell, the fit test is considered to have failed.

However, the accuracy of fit testing has drawn criticism. Because individuals engaged in the fit testing process are actively trying to find a mask that fits well, they are predisposed to ensure a secure fit. Although the prescribed movements made during the fit test process are designed to mimic a real world setting, healthcare workers may try to limit those movements to ensure the fit stays secure. As a result, a N95 respirator seemingly never will fit better than it does during the fit test. So it is possible for a healthcare worker to pass a fit test with a mask that would not pass in real world situations.

Unfortunately, there are no statistics suggesting what the average success rate of fit tests in a facility might be. It is possible for some hospitals to have much higher failure rates than others. And N95s that have a high fit test success rate in one facility might fare poorly in another facility. But hospitals must continue fit testing until each employee is equipped with a properly fitting mask.

There are many N95 respirators available on the market, and all are slightly different in terms of shape and fit. Finding a mask to fit each healthcare worker in need can be a daunting task. There is an acute need in the market today for an N95 respirator that truly fits all face shapes.

Concerns about fluid resistance, laser plume and issues with N95 fit testing make it especially apparent that comfort of a mask or user preference should not be the only factors considered when selecting the appropriate facial protection device.

Though comfort and anti-fogging capabilities are important considerations, the most critical consideration is the level of protection the mask provides.

For now, this means that healthcare facilities need to have several masks available to clinicians, including those that achieve the highest level of fluid resistance and a high PFE score. Though it would be convenient to have one mask that achieves all ends, facilities will not be able to reduce the number of masks available to employees until manufactures develop a mask that combines protection with comfort and anti-fogging capabilities.

References

1. Cardinal Health. Continuing Education Program; Understanding Facial Protection:  What to know and What to Wear; 2010
2. ASTM. ASTM F2101 – 07 Standard Test Method for Evaluating the Bacterial Filtration Efficiency (BFE) of Medical Face Mask Materials, Using a Biological Aerosol of Staphylococcus aureus. West Conshohocken, PAA; ASTM International; 2007.
3. ASTM. ASTM F2100-04 Standard Specification for Performance of Materials Used in Medical Face Masks. West Conshohocken, PAA; ASTM International; 2004.
4. ASTM. F1862-05 Standard Test Method for Resistance of Medical Face Masks to Penetration by Synthetic Blood (Horizontal Projection of Fixed Volume at a Known Velocity). West Conshohocken. PAA: ASTM International; 2005.
5. AORN. Recommended practices for surgical attire. Perioperative Standards and Recommended Practices. Denver, CO: AORN, Inc; 2009; 299-305
6. APIC Personal protective equipment (PPE) education. Washington, DC: APIC; 2005
7. AORN. Recommended practices for laser safety in practice settings Perioperative Standards and Recommended Practices. Denver, CO: AORN, Inc; 2009; 367-372.
8. Understanding Facial Protection: What to know and What to Wear. Cardinal Health CE program, 2010.
9. APIC Personal protective equipment (PPE) education. Washington, DC: APIC; 2005
10. Infection Control Today. Groups ask Obama to Rethink N95 issue. Available at: http://www.infectioncontroltoday.com/hotnews/rethinking-n95-respirator-issue.html. Accessed January 22,2010

Scott Harrison is a marketing research consultant at Cardinal Health, where his team focuses on clinician protection so that clinicians can focus on infection-free procedures.