N.A | Information on types of face mask available for hospital staff | Which Medical Device

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From Which Medical Device

PPE has never been as important to health care professionals as it is now in the era of novel Corona viruses. 

Most of us had never heard of PPE or FFP3 masks a few months ago, but now ours and our patient's lives may depend on the correct choice. This choice of equipment is very much dependent on local availability and the vagaries of national supply or indeed lack of supply. This means that as clinciains we very much have to use what we are given. I believe that we should be using the correct equipment and to do that you need to know what types of equipment are available ie specifically what class/type of mask you are being given. You cannot always rely on the supply chain staff or people ordering equipment to get it right! You cannot even rely on your government to order the best equipment.

Face Mask Standards and what they mean:

The American Standard:  ASTM (American Society For Testing and Materials), Levels 1-3

The European Standard (EN14683) for fluid resistant surgical masks type 2R

The ASTM standards:

Level 1 masks are low barrier and not suitable for operating theatre use

level 2 masks are moderate barrier

Level 3 masks are considered high barrier and used for procedures with a higher amount of aerosol/spray exposure, these however are not sufficient for aerosol generating procedures in COVID/supected COVID patients.

 

This excellent diagram from Cardinal health illustrates the different features very well:

 

The European Standard (EN14683) :

These fluid resistant surgical masks are classes as type 2R and are equivalent to ASTM level 2 masks

Type 2 EN14684 masks are appropriate for situations where exposure to blood/body fluids from the patient or work environment is not a risk for the healthcare worker, they are intended to prevent large particles expelled by the wearer from reaching the patient/work environment.

ASTM Level 2/3 masks and EN14683 type 2R masks are suitable for operating theatre use and will provide some protection from splash risk. They also minimise contamination from the wearer to the patient/environment. They are not sufficient for protection from COVID-19 and other viruses.

If there is a risk of infection from a patient due to close/prolonged contact or when performing an aerosol generating procedure then an N95 (or better, US standard) of FFP2/FFP3 filtering face piece should be worn. These are otherwise known as respirators and contain a filter suitable to trap small particles. There should be an air tight seal around the edges of the mask.

All operators should be fit tested with the mask they are supplied with to ensure the seal is adequate and a fit check should be performed on each occasion a respirator mask is worn. Different operators may suit different types of mask and different makes may need to be tried to obtain a correct fit.

 

Respirator Masks:

US standard N95 and European standard FFP2/3 are the most commonly used masks/respirators.

The following is from an excellent detailed discussion and explanation of face masks by Dr John Campbell, The full discussion can be found HERE and I would highly recommend you read it:

Respirator Standards

Standard	Filter capacity, x% of partciles 0.3 microns or larger
FFP1 and P1	at least 80%
FFP2 and P2	at least 94%
N95	at least 95%
N99 and FFP3	at least 99%
P3	at least 99.95%
N100	at least 99.97%

 

 

 

 

 

 

 

 

Respirator masks are valved and non valved.

Valved masks allow easier exhalation and are therefore more comfortable but do not protect the patient.

Non valved masks filter in inhalation and exhalation and protect the patient and the wearer.

There is much debate about what constitutes an aerosol generating procedure or AGP where infection risk to the operator is greatest. The following is a list of such procedures (from Public Health England) but is by no means comprehensive:

• intubation, extubation and related procedures, for example, manual ventilation and open suctioning of the respiratory tract (including the upper respiratory tract)
• tracheotomy or tracheostomy procedures (insertion or open suctioning or removal)
• bronchoscopy and upper ENT airway procedures that involve suctioning
• upper gastro-intestinal endoscopy where there is open suctioning of the upper respiratory tract
• surgery and post mortem procedures involving high-speed devices
• some dental procedures (for example, high-speed drilling)
• non-invasive ventilation (NIV); Bi-level Positive Airway Pressure Ventilation (BiPAP) and Continuous Positive Airway Pressure Ventilation (CPAP)
• High Frequency Oscillatory Ventilation (HFOV)
• induction of sputum
• high flow nasal oxygen (HFNO)

In addition we would consider the following AGPs more specific to Intervcentional Radiology:

• Enteral feeding tubes of any type, 
• Oesophageal/tracheal dilatation
• Bronchial artery embolization
• Lung/mediastinal biopsy
• Procedures requiring intubation/extubation in IR
• Combined IR and endoscopic procedures
• Oxygen therapy with a face mask, any form of ventilatory assistance
• Procedures performed on a patient with tracheostomy
• Procedures where airway compromise or suctioning is likely, CPR is likely
• Procedures that provoke respiratory difficulty or heavy coughing
• Procedures that require the operator to be near to the airway e.g. Central lines

When in doubt operators should make their own risk assessments in individual cases.

 

 

N95 FFP2 and FFP3 Masks explained, an interesting page with plenty of useful references

GEST COVID-19 Learning from global experience, an excellent webinar that we should all watch!

There is NO emergency in a pandemic, experience of emergencies during Ebola

Preparing for a COVID-19 pandemic: a review of operating room outbreak response measures in a large tertiary hospital in Singapore

Radiology Department Preparedness for COVID-19: Radiology Scientific Expert Panel

Public Health England COVID-19: infection prevention and control

NHS England Guidance on supply and use of Personal protective Equipment, updated 4th April 2020

World Health Organisation Country and technical Guidance-Coronavirus disease (COVID-19)

CIRSE COVID-19 Resource Centre

CIRSE-APSCVIR joint checklist to prepare IR depratments for COVID-19

Society of Interventional Radiology COVID-19 FAQ