Researchers at Imperial College London found the best lubricants for frontline healthcare workers who are wearing personal protective equipment (PPE) during the Covid-19 pandemic are those that do not absorb into the skin, creating a long-lasting layer of protection between skin and PPE.
In a study published online ahead of print in the journal PLOS ONE (Sept. 24, 2020) researchers discovered that non-absorptive creams such as coconut oil, cocoa butter, or beeswax mixtures, and powders such as talcum powder, are most likely to provide those wearing PPE such as face visors, goggles and respiratory protective equipment with long-lasting skin protection.
“We think of moisturizers as good for our skin, but commercial skin creams are often designed to absorb into the skin without leaving any residue,” said Dr. Marc Masen, the study’s lead author, in a press release. Dr. Masen is a senior lecturer at Imperial's department of mechanical engineering.
“While this is fine for everyday moisturizing, our study shows that a greasy residue is precisely what is needed to protect skin from PPE friction,” Dr. Masen added.
According to the study’s investigators, extended PPE use, particularly on the face, can cause friction and shear injuries such as skin tears, blistering, ulcers and hives.
The effects of friction and shear can be reduced by lubricants, which workers are advised to apply every half hour. However, the study’s authors suggest half-hourly applications can be impractical during shift work and may expose workers to the virus. Additionally, the researchers said many typical moisturizers do not last long as they are designed to be absorbed into the skin for a 'non-greasy feel'.
In an effort to identify the best lubricants, the researchers built a custom tribometer—an instrument that assesses friction between two surfaces—and used it to test the friction between skin and polydimethylsiloxane (PDMS), which is a common component of PPE.
The researchers used the tribometer to test commercially available products to measure how they changed the friction between PDMS and the inner forearm skin of a healthy 44-year-old male participant. They tested friction upon application, and then one, two and four hours after application.
The study’s investigators found that while most products initially reduced friction by 20%, some silicone-based and water-and-glycerin-based lubricants increased friction levels over time by up to 29% compared to dry skin.
Researchers found two products that reduced friction. Talcum powder reduced friction by 49% on application and 59% at four hours. A commercially available product comprised of coconut oil, cocoa butter and beeswax reduced friction by 31% on application and 53% at four hours. A mixture of petrolatum and lanolin reduced friction by 30% throughout the testing.
While testing commercial moisturizers, the study’s authors found that friction on application was low, but increased drastically within 10 minutes of application. The researchers suggest this is because the active ingredients—humectants—attract water like magnets from the lower layers of skin to the upper ones, leaving it soft, unlubricated and breakable.
“Friction can be incredibly damaging for the skin, particularly when applied for an extended period,” said Dr. Masen. “We hope our study will save healthcare workers and other frontline PPE wearers from suffering with the painful and damaging effects of skin friction.”