Due to the extended use of personal protective equipment (PPE) during the COVID-19 pandemic, healthcare workers experience skin injuries. These injuries result from high shear stresses acting on the skin caused by friction with the PPE.
The effects of friction and shear can be reduced by lubricants, which workers are advised to apply every half hour. Half-hourly applications can be impractical during shift work. They may expose workers to the virus, and many typical moisturizers don’t last long as they are designed to be absorbed into the skin for a ‘non-greasy feel.’
A new study by the Imperial College London investigated which products create the longest-lasting protective layer between PPE and skin. The study suggests that the best lubricants to use are those that don’t absorb into the skin, creating a long-lasting protection layer between skin and PPE.
Scientists found that non-absorptive creams like coconut oil-cocoa butter beeswax mixtures, and powders like talcum powder, are most likely to provide PPE wearers long-lasting skin protection.
Lead author Dr. Marc Masen, of Imperial’s Department of Mechanical Engineering, said: “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. While this is fine for everyday moisturizing, our study shows that a greasy residue is precisely what’s needed to protect skin from PPE friction.”
Friction-thwarting lubricants could save PPE wearers’
For the study, scientists especially built a tribometer to identify best performing lubricants. A tribometer is an instrument that assesses friction between two surfaces. It is used to test the friction between skin and polydimethylsiloxane (PDMS), a common PPE component.
Using a tribometer, scientists tested commercially available products to measure how they changed the friction between PDMS and the healthy 44-year-old male participant’s inner forearm skin. They tested conflict upon application, and then one, two, and four hours after application.
While most products initially reduced friction by 20 percent, some silicone-based and water-and-glycerin based lubricants increased friction levels over time by up to 29 percent compared to dry skin.
However, two products reduced friction as time went on. Talcum powder reduced friction by 49 percent on the application and 59 percent at four hours. A commercially available product comprising coconut oil, cocoa butter, and beeswax reduced friction by 31 percent on the application 53 percent at four hours. A mixture of petrolatum and lanolin reduced friction by 30 percent throughout testing.
When it comes to moisturizers, the application’s friction was low but increased drastically within ten minutes of application. This is because the active ingredients, known as humectants, attract water like magnets from the lower layers of skin to the upper ones, leaving it soft, unlubricated, and breakable.
Co-author Dr. Zhengchu Tan, also of the Department of Mechanical Engineering, said: “The products that don’t absorb easily into the skin are the ones that provide a protective layer. In fact, for PPE wearers, it’s best to actively avoid creams and moisturizers which advertise a ‘non-greasy feel.’”
Dr. Masen said: “Friction can be incredibly damaging for the skin, particularly when applied for an extended period. We hope our study will save healthcare workers and other frontline PPE wearers from suffering with the painful and damaging effects of skin friction.”
Marc A. Masen et al. Evaluating lubricant performance to reduce COVID-19 PPE-related skin injury. PLOS ONE, 2020; 15 (9): e0239363 DOI: 10.1371/journal.pone.0239363