Biomechanical and Physiological Evaluation of Respiratory Protective Equipment Application

Abstract

Respiratory protective equipment is widely used in healthcare settings to protect clinicians whilst treating patients with COVID-19. However, their generic designs do not accommodate the variability in face shape across genders and ethnicities. Accordingly, they are regularly overtightened to compensate for a poor fit. The present study aims at investigating the biomechanical and thermal loads during respirator application and the associated changes in local skin physiology at the skin-device interface. Materials and Methods: Sixteen healthy volunteers were recruited and reflected a range of gender, ethnicities and facial anthropometrics. Four single-use respirators were evaluated representing different geometries, size and material interfaces. Participants were asked to wear each respirator in a random order while a series of measurements were recorded, including interface pressure, temperature and relative humidity. Measures of transepidermal water loss and skin hydration were assessed pre-and post-respirator application, and after 20 minutes of recovery. Statistical analysis assessed differences between respirator designs and associations between demographics, interface conditions and parameters of skin health. Results: Results showed a statistically significant negative correlation (p < 0.05) between the alar width and interface pressures at the nasal bridge, for three of the respirator designs. The nasal bridge site also corresponded to the highest pressures for all respirator designs. Temperature and humidity significantly increased (p < 0.05) during each respirator application. Significant increases in transepidermal water loss values (p < 0.05) were observed after the application of the respirators in females, which were most apparent at the nasal bridge. Conclusion:The results revealed that specific facial features affected the distribution of interface pressures and depending on the respirator design and material, changes in skin barrier function were evident. The development of respirator designs that accommodate a diverse range of face shapes and protect the end users from skin damage are required to support the long-term use of these devices.

Characterisation of superficial corneocytes in skin areas of the face exposed to prolonged usage of respirators by healthcare professionals during COVID-19 pandemic

“…Indeed, the disruption of the SC has been observed in in vitro histological studies, following 24 h of severe loading (200 mmHg) [ 34 ]. Recently, Caggiari et al observed high interface pressures at the nasal bridge (>70 mmHg) for four different respirators [ 4 ]. However, there has not yet been a study that has investigated the effects of persistent loading on the physiology of the SC.…”

“…However, the prolonged use of such devices can affect skin health, resulting in a variety of problems ranging from erythema, acne, dermatitis, and skin breakdown in the form of pressure ulcers (PUs) [ 2 , 3 ]. These adverse reactions are the result of non-uniform pressure, shear, and frictional forces at the skin–respirator interface [ 4 ], together with changes in the microclimate, which includes increased moisture and temperature from excess sweating due to mental and physical stress [ 5 ]. Indeed, moisture is known to increase skin friction [ 6 , 7 ] and has been attributed to an increase in the contact area due to its plasticising action [ 6 , 7 ] that reduces the stiffness and strength of the skin layers [ 8 , 9 ].…”

A combined imaging, deformation and registration methodology for predicting respirator fitting

“…In a recent study the authors also demonstrated an association between the interface pressure exerted on the nasal bridge and the alar width, with narrow noses shape subjected to higher pressures [ 5 ]. This highlights the importance of integrating respirator-face biomechanical interactions, intelligent algorithm for fitting prediction, and anthropometric measures to support efficient respirator fitting and characterise the GoF to individual face shapes in an objective manner.…”

“…nasal bridge and cheeks. In a recent study [ 5 ] the authors demonstrated an association between the interface pressure exerted on the nasal bridge and facial anthropometrics, with narrow nose shapes subjected to higher pressures. This highlights the importance of an effective fitting process prior to use, and the potential issues where face geometry do not conform with the design and material of the respirator.…”