HI Jeremy-

The issue of disinfection of PAPRs remains a knowledge gap and continued logistical need.

Aside from manufacturer instructions, which have improved in relation to healthcare guidance since before the start of the pandemic, there is limited published data on efficacy of the disinfection practices suggested by the manufacturers.

For loose-fitting PAPRs, really the only thing published come from the Heimbuch/Applied Research Associates 2019 report to the FDA: https://www.ara.com/wp-content/uploads/MitigateShortageofRespiratoryProtectionDevices_3.pdf

The disinfection description starts on p88, based on a hospital protocol from Oregon Health and Sciences University.  Basically, involves disinfecting all the surfaces of hood, hose, belt, blower with Sanicloth along with a sponge moistened with detergent.  The process was effective for elimination of viable influenza virus - and same results whether they cleaned w detergent + disinfected w wipe OR just used a wipe.

There has also been one study published that described impact of using SteraMist iHP on PAPR hoods and hoses.  Also worked. https://doi.org/10.1038/s41598-021-81365-7

So - there is limited laboratory-based evidence to support these practices - but - it has not been studied in a clinical setting.

For Halo, CleanSpace has updated their manufacturer instructions for decontamination significantly since the beginning of the pandemic to address additional means to decon face masks, such as Steris vHP.  Otherwise, the guidance for those facemasks is similar to other guidance for decon of elastomeric respirators.

We have done some research with the CleanSpace Halo - both in laboratory settings and in clinical practice settings.  In the laboratory setting, we compared only wiping all of the respirator surfaces with a disinfectant wipe vs. cleaning (w/detergent) AND wiping with disinfectant.  With Halo, we found that virus was more consistently eliminated if detergent was also used.  That is described in our paper in the Journal of the International Society for Respiratory Protection, here: https://www.isrp.com/index.php?option=com_docman&view=document&alias=1139-vol-37-no-1-2020-jisrp&category_slug=isrp-journals-archive&Itemid=240

More recently, we assessed surface contamination on Halo respirators being used in an ICU, including in care of COVID-19 patients.  The practice at that hospital was for each worker to wipe the surfaces of the respirator with disinfectant wipe after each use.  Then, at the end of shift, they dropped the Halo Face Mask off for centralized cleaning/disinfection, performed according to manufacturer instructions.  The Halo blower units, themselves, stayed in the clinical units.  We found no evidence for surface contamination with SARS CoV-2.  We did find, however, a couple samples positive for S. aureus - and this was detected after the worker had handled the face mask at the beginning of shift, before first use - and then after they came out of a patient room, but before wiping down the face mask with a disinfectant wipe. We think this reflected contact transfer of S. aureus, emphasizing the importance of hand hygiene.  That paper has been accepted for publication in Workplace Health & Safety, but not published yet.  Conference abstract is here: https://www.atsjournals.org/doi/pdf/10.1164/ajrccm-conference.2022.205.1_MeetingAbstracts.A1695

Versaflo:

We have used the Versaflo at University of Maryland Medical Center for the last several years, including during the pandemic. Disinfection protocols are based on the manufacturer instructions:

I have to say - I don't think any ever does Step 3.e. I'm sure not doing that likely decreases the lifespan of the PAPR.

CleanSpace Halo:

We just published a paper on User Acceptance of Halo among use at some of our System hospitals in AJIC. Overall, well received.   Link is here: Redirecting

We are now looking at reported use practices among Halo users, i.e. how often did they actually wipe down the surfaces of the respirator, how often do they notice cleaning product residue or odor, how often the respirator is actually present, charged, and ready to go.  Stay tuned for that.  Results look good.

But - I will reiterate  - there are definite gaps in the literature describing what best practices are for PAPR decontamination and reuse.  This is a research need to inform clinical practice.

Stella Hines, MD, MSPH

Division of Occupational and Environmental Medicine

Division of Pulmonary and Critical Care

University of Maryland School of Medicine