N95 EXTENDED USE, REUSE AND STERILISATION
Courtes my friend Dr Shiv Kumar Singh, sr Intensivist 🇬🇧 UK
In the present situation of shortage of PPE, this question is often asked. Please read till the end
This is based on CDC recommendations and some research on sterilisation.
I hope this information will be helpful to everyone who is caring for COVID-19 Patients. I will also share a PDF file so that it can be widely distributed.
For extended use of N95 respirators limit potential surface contamination (e.g., use of barriers to prevent droplet spray contamination) and consider additional training and reminders (e.g., posters) for staff to reinforce the need to minimize unnecessary contact with the respirator surface, strict adherence to hand hygiene practices, and proper Personal Protective Equipment (PPE) donning and doffing technique.
Healthcare facilities should develop clearly written procedures to advise staff to take the following steps to reduce contact transmission after donning:
Discard N95 respirators
· Following use during aerosol generating procedures.
· If contaminated with blood, respiratory or nasal secretions, or other bodily fluids from patients.
· Following close contact with, or exit from, the care area of any patient co-infected with an infectious disease requiring contact precautions.
Consider use of a cleanable face shield (preferred3) over an N95 respirator and/or other steps (e.g., masking patients, use of engineering controls) to reduce surface contamination.
Perform hand hygiene with soap and water or an alcohol-based hand sanitizer before and after touching or adjusting the respirator (if necessary for comfort or to maintain fit).
Extended use alone is unlikely to degrade respiratory protection. However, healthcare facilities should develop clearly written procedures to advise staff to:
Discard any respirator that is obviously damaged or becomes hard to breathe through.
RESPIRATOR REUSE RECOMMENDATIONS
There is no way of determining the maximum possible number of safe reuses for an N95 respirator as a generic number to be applied in all cases.
Safe N95 reuse is affected by a number of variables that impact respirator function and contamination over time.
If reuse of N95 respirators is permitted, limit potential N95 respirator surface contamination as mentioned above and consider additional training and/or reminders to reinforce the need to minimize unnecessary contact with the respirator surface, strict adherence to hand hygiene practices, and proper PPE donning and doffing technique, including physical inspection and performing a user seal check.
Healthcare facilities should develop clearly written procedures to advise staff to take the following steps to reduce contact transmission:
· Discard N95 respirators as mentioned for extended use.
· Reduce surface contamination of the respirator by using a cleanable face shield (preferred) or a surgical mask over an N95 respirator
· Hang used respirators in a designated storage area or keep them in a clean, breathable container such as a paper bag between uses.
To minimize potential cross-contamination, store respirators so that they do not touch each other and the person using the respirator is clearly identified. Storage containers should be disposed of or cleaned regularly.
· Clean hands with soap and water or an alcohol-based hand sanitizer before and after touching or adjusting the respirator (if necessary for comfort or to maintain fit).
· Avoid touching the inside of the respirator. If inadvertent contact is made with the inside of the respirator, perform hand hygiene as described above.
· Use a pair of clean (non-sterile) gloves when donning a used N95 respirator and performing a user seal check. Discard gloves after the N95 respirator is donned and any adjustments are made to ensure the respirator is sitting comfortably on your face with a good seal.
Preliminary data suggests limiting the number of reuses to no more than 5 uses per device to ensure an adequate safety margin.
Management should consider additional training and/or reminders for users to reinforce the need for proper respirator donning techniques including inspection of the device for physical damage (e.g., Are the straps stretched out so much that they no longer provide enough tension for the respirator to seal to the face? Is the nosepiece or other fit enhancements broken?, etc.).
Healthcare facilities should provide staff clearly written procedures to:
· Follow the manufacturer’s user instructions, including conducting a user seal check.
· Follow the employer’s maximum number of donnings (or up to 5 if the manufacturer does not provide a recommendation) and recommended inspection procedures.
· Discard any respirator that is obviously damaged or becomes hard to breathe through.
· Pack or store respirators between uses so that they do not become damaged or deformed.
Secondary exposures can occur from respirator reuse if respirators are shared among users and at least one of the users is infectious (symptomatic or asymptomatic). Thus, N95 respirators must only be used by a single wearer.
To prevent inadvertent sharing of respirators, healthcare facilities should develop clearly written procedures to inform users to:
· Label containers used for storing respirators or label the respirator itself (e.g., on the straps) between uses with the user’s name to reduce accidental usage of another person’s respirator.
STERILISING N95 RESPIRATORS
To be useful, a decontamination method must eliminate the viral threat, be harmless to end-users and retain respirator integrity
Many methods, as listed below, have been described and believed to be effective for destroying viruses, but not all of them were good ideas.
– Heat in an oven for 30 minutes at 58 degrees Fahrenheit (70 degrees Celsius)
– Use ultraviolet light for 30 minutes
– Soak the mask in 75% ethyl alcohol, then let it dry
– Clean the mask with liquid or vapour hydrogen peroxide
– Clean the mask with bleach
– Steam the mask with hot vapour from boiling water
– Microwave the mask
– Use extreme heat in an oven or autoclave
– Soak in soap and water
DO NOT use ALCOHOL AND CHLORINE [bleach]-based disinfection methods. These will remove the static charge in the microfibers in N95 facial masks, reducing filtration efficiency. In addition, chlorine also retains gas after de-contamination, and these fumes may be harmful.
MICROWAVES tended to melt the masks and render them useless.
HYDROGEN PEROXIDE AND ULTRAVIOLET radiation appeared to be at least somewhat more effective, but it is not known if they would retain filtration, material strength and airflow integrity with repeated use.”
AUTOCLAVES, 320 degree F [160 degree C] ovens, and soap and water soaking, all appeared ineffective.
However, 70 degree C / 158 degree F HEATING IN A KITCHEN-TYPE OF OVEN for 30 min, or HOT WATER VAPOUR FROM BOILING WATER for 10 min, are additional effective decontamination methods.