Facemasks have been widely used in surgical settings for a hundred of years and first use

documented in 1897 (Romney 2001) (Da Zhou, Sivathondan, and Handa 2015). This has

been ingrained in the definition of best practice in human health care although the use of

masks have been under review due to its controversial use. Evidence in its use has been

stated that in order to have a viable purpose it must satisfy three key elements:

1. Efficacy

2. Effectiveness

3. Cost effectiveness

(Da Zhou, Sivathondan, and Handa 2015)

These all point to the evidence of which the purpose of facemask is aimed to do rather than

just a personnel ritual in the surgical environment. (Datta 2010)

A facemask is a barrier device used as either a single method or part of a comprehensive

infection control regime to prevent healthcare providers from breathing or coughing on

patients. It is also equally used to prevent patient sneezes and sputum from making contact

with the healthcare providers face or eyes and from being inhaled.

It was first documented in its use in 1897 by a German surgeon, Johann von Mikulicz

Radecki, who defined a surgical face mask as a single layer of gauze. This was later found

to be proven as more effective when an extra layer of gauze was added at the same time

(Spooner 1967). It was initially believed bacteria in the form of droplets from the nose and

mouth of surgical / medical staff had a role to play in the formation of wound infections in the

postoperative stage. Even as early as the 1900, it was advocated that masks were sterilised

and replaced after each use. (Spooner 1967).

 

Evidence Review - Protective effects

Evidence has also shown that bacterial contamination of the surgical environment is reduced

when personnel are wearing such masks (Iqbal and Sarwar 2015).

It is even stated that the absence of surgical face masks could leave patients at risk of

wound infections through droplets contamination. (Iqbal and Sarwar 2015)

A surgical study in the United States involving 8500 cases concluded that 26% of all blood

exposures occurred on the face and neck. (White and Lynch 1993).

An alternative viewpoint is that skin shedding could be a cause of contamination as a result

of mask movement of the wearer. (Lipp 2003) In some cases incorrect fittings of surgical

face masks and unsuitable tension of tie backs are also a contributing factor of poor use and

compliance of personnel. Leakage often known as venting which could be a potential factor

from the sides of ill fitting masks causing airosals contaminants to escape. (Da Zhou,

Sivathondan, and Handa 2015). In some cases it was reported that some personnel don't

cover their nose when wearing face masks which can be contradictory and exacerbate the

issue. (Iqbal and Sarwar 2015).

There is also a psychological element to wearing such masks from both personnel and also 

to the surgical patient if in a human healthcare setting. From a personnel point of view, there

is reassurance that they are working in a safe environment and part of a professional

surgical team. In terms of patients, getting that reassurance and confidence that they are

receiving the best treatment possible is crucial to recovery. Communication and social

difficulties such as the ability to express emotions and expressions can pose difficulties from

clinicians when dealing with patients. (Roberson et al. 2012)

 

Potential risks

It has been documented that during a pandemic, there are concerns over promoting the use

of facemasks as this may offer the public a false sense of security and neglect social

distancing. There is also the potential that an ill-health stigma is attached to the wearer.

Compliance rates are high with compulsory measures rather than the voluntarily wearing of

face masks (Howard et al., 2020)

 

Filtration and practical aspects

In terms of filtration efficiency, there have been numerous documented studies evaluating

various types of masks and the results do vary from type to type. However, having said this, it

is interesting to note that the use of masks during prolonged periods of time or the build up

of moisture as a result, did not impair the efficiency of the mask in terms of filtration or

protection. (Romney 2001)

There are no current guidelines or methods of deciphering the quality or measuring the

efficiency of surgical face masks and they should always be used under the definition of

filters rather than actual barriers. It is anticipated that due to the huge range of variability

between different commercial surgical face masks, it should always be used as part of a 

wider PPE regime or even in some cases extending face mask to a full facial

protection. (Romney 2001)

In balance of this, the use of masks have always posed an issue to the wearer where some

people find them difficult to fit, unsuitable for the individual, wearing them incorrectly or

simply avoiding wearing them altogether. In one study, it was shown that a temperature

increase and the humidity build up in the personnel mask actually caused some discomfort

leading to mental impairment and ability to fulfil their performance to complete their role (Romney 2001).

In one paper it was stated that the importance of facemask must only formulate part of a

wider protection regime to include PPE for eye protection, gloves, gowns and also the

adequate training to use this properly. The same paper also suggested that non-aerosol

generating procedures in medical scenarios have shown that there is no benefit of

respirators over standard surgical masks other than to both use part of a wider

comprehensive protection and the ability to use this to maximum benefit. (Wilkinson 2020)

There are two main types of masks used, these being surgical and N95. The definition of

N95, is that masks of this type exclude 95% of non-oil-based sodium chloride particles, sized

at 0.3um in diameter. (Gralton and McLaws 2010)

There is controversial and conflicting evidence on the use of such masks, mostly due to

various evidence on the effectiveness in its use, an example is the valve and non-valve

valved N95 masks only offers filtration on inhalation and not exhalation. The

non-valved types filter both hence the reason for its use in health care settings.

The differences of the two masks is that the surgical face mask prevents contamination of

the surgical site / field where N95 masks were used in the healthcare setting to offer

protection to the personnel from inhaling particles from infected patients. (Table 2)

The effectiveness of N95 masks have been documented in one study which found that N95

masks were found to have less filter penetration, less total inward leakage along with less

facial seal leakage to the wearer in comparison to normal surgical masks. (Smith et al. 2016)

The effectiveness was also further investigated for comparison in another study between the

two masks with the aim of using in scenarios where influenza virus is concerned, The results

of this study from the collection efficiency have shown that N95 filtering facepiece respirator

masks were superior compared to standard surgical face masks. Face seal leakage seems

to be one of the persisting factors that needs to be addressed through further research.

(Richardson and Hofacre 2010)

The use of FFP (Filtering Facepiece masks) are in use and certified by the European Union

and so these are most commonly found in european countries. The EN149 classifies the

efficiency of masks into three categories such as FFP1, FFP2 and FFP3. The FFP2 is the

closest equivalent to the N95 masks. (See Table 1)

The table one shows the effectiveness of typical face masks available for surgical use.

Table 1 Filtering face piece mask (EN 149 standard):

Face Mask Type

Aerosol Filtration

Internal Leak rate

Uses

FFP1

80% min

22% max

Low level dust for DIY

FFP2

Equivalent to N95)

94%>

8% max

Serves as protection against SARS, influenza viruses

FFP3

99%>

2%

 

Asbestos and fine particles - does not offer protection against gases.

(Lee et al. 2016) (Ciotti, Bouvet, and Abiteboul 2008)

Table 2 Differences between Surgical Masks and N95 Respirator:

 

Surgical face mask

N95 respirator

Uses

Offers protection to the personnel against large droplets or any hazardous liquids such as blood or bodily fluids. This also offers protection to the patients when in close proximity due to respiratory concerns.

Offers protection against particles which could be aerosol in origin.

 

Fitting

Fitting Ear Looped or tie back

Adjustable fitting to ensure a seal around the mask.

Filtration

Limited filtration.

95% of airborne particles filtration.

Leakage

Apparent around edges of mask

 

Upon tight fitting, this should be minimal.

Reusability

Disposable - limited use

Some are designed to be reusable Guidance on some types can be re sterilised:

UV light 67 J/m2 of UV-C will inactivate SARS-CoV-2**

Oven heat - 70C (148F) heat for between 5 and 30 minutes**

 

Fit testing requirements

No

Yes

Design

3 ply design (3 layer). ‘Melt blown’ layer in the middle for filtration.

 

Usually valved although do come in non-valved designs. (Valved versions only filters inhalation and not exhalation which not commonly used in health care workers)

 

Safety rating

No

Yes

** Both may cause some low-level damage to the respirator.

 

Points to take away In pandemic situations it is known that PPE becomes a scarce resource. Laboratory

based evidence have shown that household masks have some filtration capacity

which offer some protection.

Household materials had between 49 and 86% filtration rate for 0.02um exhaust

particles in comparison to the effectiveness of 89% of surgical face masks. (Davies et

2013) Sterilisation and reuse of masks can be effective and suitable handling to prolong its

use. (Man et al. 2020)

Masks wearing is most effective when compliance is high and therefore stopping the

spread of viruses.

Masks should formulate as part of a comprehensive personal protection regime

within the veterinary practice both for veterinary surgeons and nurses.

Best practice should always be followed such as aseptic techniques, infection control

procedures alongside the use of PPE.

 

Key facts for information:

Coronavirus - 0.06 - 0.14 microns

Influenza - 0.08 - 0.12 microns

Droplets - 5um - 10um

Speech - 1um

(Bouvier and Palese 2008) (Howard et al. 2020)

 

Written by Albert Holgate BSc (Hons) CVN, Dip AVN, RVN and Faye Ashcroft RVN.

Albert qualified as a veterinary nurse in 2007 and also gained the advanced diploma in 2013 at Myerscough College. Albert has also completed his BSc (Hons) Clinical Veterinary Nursing in 2014. Currently employed as Clinical Manager at R.S.P.C.A Greater Manchester Animal Hospital where he oversees the responsibility of a team of nurses at various levels some of which are actively undergoing their own training as part of ongoing status as a role of qualified assessor. An active council member of the BVNA and also have a special interest in research and development in anaesthesia and shelter medicine.

Faye qualified as a veterinary nurse in 2018 at Proco Wigan. Currently employed as a Staff nurse at R.S.P.C.A Greater Manchester Animal Hospital. Faye has an interest in shelter medicine and anaesthesia.


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