Dressings cut to shape alleviate facial tissue loads while using an oxygen mask

Abstract

Non-invasive ventilation (NIV) masks are commonly used for respiratory support where intubation or a surgical procedure can be avoided. However, prolonged use of NIV masks involves risk to facial tissues, which are subjected to sustained deformations caused by tightening of the mask and microclimate conditions. The risk of developing such medical device-related pressure ulcers can be reduced by providing additional cushioning at the mask-face interface. In this work, we determined differences in facial tissue stresses while using an NIV mask with versus without using dressing cuts (Mepilex Lite; Mölnlycke Health Care, Gothenburg, Sweden). First, we developed a force measurement system that was used to experimentally determine local forces applied to skin at the bridge of the nose, cheeks, and chin in a healthy sample group while using a NIV mask. We further demonstrated facial temperature distributions after use of the mask using infrared thermography. Next, using the finite element method, we delivered the measured compressive forces per site of the face in the model and compared maximal effective stresses in facial tissues with versus without the dressing cuts. The dressings have shown substantial biomechanical effectiveness in alleviating facial tissues deformations and stresses by providing localised cushioning to the tissues at risk.

Keywords: finite element modelling; medical device-related pressure ulcer; non-invasive ventilation; pressure injury; prophylactic dressings.

Figure 1

Measurements of the contact forces applied by the mask. A, a force measurement system consisting of five force sensors (Force Sensing Resistors; Interlink Electronics) connected to a microcontroller board (Arduino Uno R3) with versus without cushioning using cuts of the Mepilex Lite (Mölnlycke Health Care) dressings. B, The aforementioned system was used to experimentally determine local forces applied to the skin at the bridge of the nose (Sensor 1), cheeks (Sensors 2 and 3), and chin (Sensor 4) while using a medium‐size non‐invasive ventilation (AF531 Oro‐Nasal Single‐use; Phillips Respironics Inc.) mask

Figure 2

Computational modelling of the head‐mask interaction. A, Configuration of the finite element modelling with boundary and loading conditions for the head model. The mask displacements have been applied perpendicularly to the surface of the face model. The skull has been fixed for all translations and rotations. B, The head model configurations in frontal view with (right frame) versus without (left frame) the dressing cuts applied as cushioning

Figure 3

Cumulative percentage of soft tissue exposures to (A) effective stress and (B) strain energy density for the model variant with boundary conditions set #1, where pressure on the bridge of the nose exceeds pressure on the chin. The volume of interest at the bridge of the nose is indicated using a dashed box

Figure 4

Cumulative percentage of soft tissue exposures to (A) EFFECTIVE stress and (B) Strain energy density for the model variant with boundary conditions set #2, where pressure on the chin exceeds pressure on the bridge of the nose. The volume of interest at the chin is indicated using a dashed box

Figure 5

Mean force values with SDs measured in the study group while using a non‐invasive mask, with versus without the dressing cuts applied as tissue protectors. The force data for the cheeks were calculated as the average between the measured force values of the right and left cheeks (*Significance level: p<0.05)

Figure 6

The infrared images of facial skin temperature distributions associated with the use of a ventilation mask in one female subject: (A) prior to applying the mask, (B) immediately after removal of the mask, and (C) 10 minutes after removal of the mask. The values specified on the thermal images are the local temperatures at the sites of interest (bridge of the nose, two cheeks, and chin), averaged in the respective marked regions (bounded by ellipses). All temperature values are in degrees Celsius

Figure 7

Effective stress distributions developed in facial tissues for the model variant with boundary conditions set #1, where pressure on the bridge of the nose exceeds pressure on the chin. Effective stresses are shown on a frontal view of the head model (upper frames), as well as in a transverse cross‐section of the head at the height of the bridge of the nose and eyes (lower frames). Regions in the cross‐sections where stress concentrations apply are magnified. Data presented at the left and right columns are for the model configurations without versus with the dressing cuts applied as tissue protectors, respectively

Figure 8

Effective stress distributions developed in facial tissues for the model variant with boundary conditions set #2, where pressure on the chin exceeds pressure on the bridge of the nose. Effective stresses are shown on a frontal view of the head model (upper frames), as well as in a transverse cross‐section of the head at the height of the chin (lower frames). Regions in the cross‐sections where stress concentrations are applied are magnified. Data presented at the left and right columns are for the model configurations without versus with the dressing cuts applied as tissue protectors, respectively