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N95 Respirators (HEPA or High-Efficiency-Particulate-Air Filter Respirators) as Personal Protective Equipment (PPE)

N-95 and HEPA respirators  

Information provided regarding N-95 Respirators (HEPA or High-Efficiency-Particulate-Air Filter Respirators) comes from:

Why is PPE important for otolaryngologists during the COVID-19 Pandemic?

  • According to the American Academy of Otolaryngology, "otolaryngologists are among highest-risk group when performing upper airway surgeries and examinations"
    • Viral density and replication rate greatest in the nose and nasopharynx
    • Surgeries and endoscopic examinations often require applications of sprays and use of instruments which can aerosolize viral particles
  • As per CDC recommendations (3-21-2020 CDC): "N95 respirators or respirators that offer a higher level of protection should be used instead of a facemask when performing or present for an aerosol-generating procedure":
    • Aerosol-Generating Procedure (AGP) - procedures likely to induce coughing (e.g., open suctioning of airway)
    • Recommended PPE for an AGP: N-95 respirator (or APR with higher level of protection), eye protection, gloves, gown, hair protection
    • Limit personnel to only essential HCPs; do not allow visitors during procedure
    • Perform AGPs in AIIR if possible

What is an N-95 respirator, and what alternative types of Air-Purifying Respirators (APRs) are available to be used as PPE? 

  • N-95 and other Particulate Filtering Facepiece Respirators (FFRs):
    • Disposable half facepiece respirators worn to filter out particles
    • Nomenclature:
      • NIOSH classification system (recognized by US, Canada, Mexico and Chile) - 9 total available mask combinations:
        • Letter (N, R, and P) refers to filter's ability to protect against oils
          • N - Not resistant to oil
          • R - somewhat Resistant to oil
          • P - strongly resistant to oil (oil Proof)
          • Note: while coronaviruses do have viral envelopes composed of lipids, the quantity of oil is insufficient to affect the efficacy of "N"-labeled FFRs
        • Number (95, 99, and 100) refers to filter to minimum percentage of airborne particles filtered out by the mask
          • 95 - filters at least 95% of particles
          • 99 - filters at least 99% of particles
          • 100 - filters at least 99.97% of particles
        • Surgical N95 - filters 95% of airborne particles; not resistant to oil; not all N95's are cleared by FDA as 'surgical masks' see:  https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/n95list1.html  (accessed 3-30-2020)
        • Those N95's with a exhalation valve protects the person wearing the mask but not the subject being evaluated/operated on.
      • ‘Conformité Européen’ (CE) classification system:
        • FFP1 - filters at least 80% of airborne particles
        • FFP2 - filters at least 94% of airborne particles
        • FFP3 - filters at least 99% of airborne particles
    • CDC Guidelines for Isolation Precautions in Hospitals recommends healthcare workers protect themselves from any disease spread by airborne transmission by wearing a respirator at least as protective as an N-95 respirator (N-95 or FFP3 would qualify)
    • 3 requirements for effective use:
      • Must be put on correctly and worn throughout entire exposure
      • Must fit snugly on user's face to ensure no gaps between skin and respirator seal (see CDC guide for User Seal Check)
      • 95% of particles from air passing through respirator must be captured 
  • Elastomeric half- or full facepiece air purifying respirators
    • Reusable
    • Facepiece is cleaned and reused; filter cartridges discarded and replaced after use
    • Assigned same protection classifcation as N95s
    • EHFRs = "Elastomeric Half-Facepiece Respirators
  • Powered Air Purifying Respirators (PAPRs)
    • Battery-powered blower filters air through attached and replaceable filter, cartridge or canister
      • Fitted with High Efficiency Particulate Air (HEPA) filter - considered to be as efficient as P-100 filters (99.97% of particles)
      • Efficiencies usually exceed those of EHFRs or N95s
    • Loose-fitting hooded/helmeted PAPRs do not require a fitting and can be used with facial hair
    • Reusable - require cleaning and disinfection prior to re-use

Tracheostomy guidelines for PPE use

Airway management PPE recommendations, per

What alternatives are available in times of N95/respirator shortage?  Need to individualize by institution - dependent on many factors.

  • Alternative classes of FFR
  • Elastomeric half- or full facepiece air purifying respirators - reusable (see images at top of page)
  • Powered air purifying respirators (PAPRs) - reusable
  • Conservation of FFRs for high-risk scenarios and HCPs at high risk:
    • Aerosol-generating procedures
    • Care of patients with other high-risk infections requiring respiratory protection (tuberculosis, measles, varicella)
  • Extended use/limited reuse of disposable N95 respirators (per CDC/NIOSH recommendations for Pandemic Planning):
    • N95 respirators typically can function within specifications for 8 hours of continuous or intermittent use
    • Extended use - preferred over limited reuse as it involves less touching of respirator and therefore decreased risk of contact transmission
      • "Extended use alone is unlikely to degrade respiratory protection"
      • Ensure adherence to controls to limit respirator surface contamination (e.g., use of face shield to limit droplet spray, strict hand hygiene practices)
      • Steps to reduce contact transmission: discard following AGP, contamination with bodily fluids
        • Discard N95 respirators following AGPs, contamination with bodily fluids, following contact with patient requiring contact precautions
        • Consider additional steps to reduce surface contamination: use of cleanable face shield, masking patient
        • Hand hygiene with soap and water or alcohol-based sanitizer before and after touching or adjusting respirator
      • Discard any respirator that becomes contaminated or difficult to breathe through
    • Limited reuse
      • Number of reuses determined by variables that affect respirator function and contamination over time
      • Specifications regarding reuse varies from individual manufacturers of N95 masks 
      • Only the original wearer should be reusing the N95 respirator
      • Steps to reduce contact transmission:
        • Follow employer's maximum number of donnings (up to 5 if manufacturer does not provide recommendation)
        • Discard N95 respirators following AGPs, contamination with bodily fluids, following contact with patient requiring contact precautions
        • Use cleanable faceshield (preferred) or surgical mask over N95 respirator (and/or other steps including masking patient) to reduce surface contamination
        • Between uses:
          • Hang in designated storage area or keep in clean, breathable container (e.g., paper bag)
          • Avoid cross-contamination: ensure user identified, avoid respirators touching each other
        • Hand hygiene with soap and water or alcohol-based sanitizer before and after touching or adjusting respirator
          • Avoid touching inside of respirator
        • Use clean (non-sterile) gloves when donning used N95 respirator and performing user seal check (see above). Dispose of gloves after donning and ensuring adequate seal
      • Pack or store respirators between uses so to as to avoid damage that might affect seal

Surgical masks

  • High filtration laser surgical masks when worn by a health care worker protects the patient from infectious agents in the worker's mucus and saliva and the worker from body fluid coming from the patient
  • As per Benson et al (Benson 2013) the FDA does not independently test face masks, but reviews the manufacturere's testing data for filter efficiency / breathing resistance / flammability / and fluid resistance
  • Benson et al (Benson 2013) identified that filtration efficiency of a surgical laser mask can be as high as that of a surgical N95 respirator, but, as tested by Oberg and Brosseau, found the adequacy of the fit of surgical masks to be low - and none considered equivalent to a surgical N95 respirator.  Commenting that without an adquate seal to the face, inhaled breath flows around the gaps and not through the filter - leading Benson et al (2013) to conclude that surgical and high-filtration surgical laser masks do not provide the degree of protection to be considered respiratory PPE.

University of Iowa Hospitals and Clinics Guidelines for Conservation of PPE (https://medcom.uiowa.edu/theloop/2019-novel-coronavirus-covid-19)

Short version

Terminology and abbreviations

For more extensive descriptions

see: Abbreviations Addressing COVID-19 Explained

FFR Filtering Facepiece Respirator
aerosols or droplet nuclei small respiratory droplets
HCP Health Care Personnel*
PAPRs Powered Air Purifying Respirators
AIIR

Airborne Infection Isolation Room

(formerly known as negative pressure isolation room)

CDC definition of HCP *"Health Care Personnel": all persons in healthcare setting with potential for direct or indirect exposure to patients or infectious materials including body substances; contaminated medical supplies, devices, and equipment; contaminated environmental surfaces; or contaminated air.

Samannan et al (2020) recently tested wearing of surgical masks to compare a 'normal' (housestaff physicians) group to patients with COPD identifying that "gas exchange is not significantly affected by the use of surgical mask, even in subjects with 
severe lung impairment" and identified this finding to be in contrast to "the use of N-95 masks, in which pCO2 may increase in lung-healthy users however without major physiologic burden". citing Roberge et al (2010)

 

References:

 


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