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International Wound Journal logoLink to International Wound Journal
. 2019 Mar 5;16(3):813–826. doi: 10.1111/iwj.13101

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

Lea Peko Cohen 1, Zehava Ovadia‐Blechman 2, Oshrit Hoffer 2, Amit Gefen 1,✉
PMCID: PMC7948591  PMID: 30838792

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

1. INTRODUCTION

Non‐invasive ventilation (NIV) masks, also known as oxygen masks, are commonly prescribed to patients with acute or chronic respiratory insufficiency where intubation or surgical airway procedures can be avoided.1, 2, 3, 4 The use of NIV masks can reduce the risk of nosocomial infections and common tracheal intubation‐related complications (including the need for weaning) and overall shorten the length of hospital stays and reduce the associated medical costs, compared with invasive ventilation.4, 5

However, the prolonged use of NIV masks is a risk to facial tissue viability as these soft tissues are subjected to sustained deformations caused by the tightening of the rigid mask to the skin, which thereby also alters the microclimate conditions at and near the mask‐skin contact sites.6 Specifically, the mask applies compressive and shear forces to the skin at narrow contact sites, which then translate to compound loading states (compression, tension, and shear) including stress concentrations within sub‐dermal tissues.7, 8, 9, 10 The lack of biomechanical knowledge‐driven guidance for clinicians regarding safe application of NIV masks, as well as the generic mask designs containing traditional stiff polymer materials, which typically do not match the shape and biomechanical properties of the facial tissues, may lead to rapid and serious tissue damage.4, 11, 12, 13, 14, 15, 16

Recent studies have shown that approximately one‐third of all hospital‐acquired pressure ulcers (PUs) are associated with the use of medical devices, which led to the use of the term medical device‐related PUs (MDRPUs) in national and international PU classifications.8, 17 The incidence of NIV‐related PUs, in particular, depends on the duration of mask usage and varies within the 5% to 50% range for 2 to 4 hours of continuous use. After 48 hours of non‐stop use, the likelihood of developing a MDRPU caused by the mask increases to 100%.18, 19, 20, 21, 22, 23, 24

In addition to the standard practice of PU prevention (PUP), which is not specific to MDRPUs, that is, risk assessments, routine skin inspections, and repositioning protocols,17, 25 the specific risk of developing PUs associated with the use of NIV masks can be reduced by providing additional cushioning at the mask‐face contact areas. A potential, relevant preventive measure that is feasible and available for such facial tissue cushioning is dressings, such as Mepilex Lite dressings (Mölnlycke Health Care), which is a single‐layer foam dressing for general wound care. Unlike “border” dressings, the Lite dressing has been designed so that it would be easy to cut into pieces of desired shapes and sizes. Nurses have identified the potential of such dressings in protecting soft tissues from mask‐related PUs years ago. In different clinical settings, both acute and chronic, nurses often use cuts of the Lite dressing as standard practice to potentially protect against mask‐related PUs. They would then place the tailor‐made cuts under the contours of the mask to cushion certain sites of the mask‐face interface.26 It is noteworthy that, in the same context of PUP, the Mepilex Border prophylactic dressing designs (Mölnlycke Health Care) have been shown to successfully protect vulnerable tissue sites subjected to sustained bodyweight forces, for example, near the sacrum and calcaneal (heel) bones; their effectiveness in alleviating localised tissue loads has been demonstrated in multiple biomechanical computational studies, as well as in large‐scale randomised clinical trials.27, 28, 29, 30, 31, 32, 33, 34, 35

The ability to non‐invasively monitor changes in skin microcirculation improves both the diagnosis and treatment of certain diseases. It was already observed that cutaneous haemodynamic variables could reflect local and systemic changes and even predict the development of ischemic stress conditions.36, 37, 38, 39, 40, 41 Thermography, a non‐ionising, NIV, and low‐cost imaging modality, is based on the detection of infrared (IR) radiation inertly emitted from the surface of a measured object. Thermal imaging offers the great advantage of real‐time temperature measurement and has already been investigated for numerous medical applications.42, 43

In justification of the clinical practice of placing dressing cuts under NIV masks, we have experimentally and computationally evaluated, for the first time, facial tissue exposure to mechanical loads while using an NIV mask, with versus without dressing cuts as tissue protectors. We specifically investigated the biomechanical efficacy of such dressing cuts in alleviating facial tissue loads by means of (a) a custom‐made interface force measurement system used to collect subject data, (b) an anatomically realistic biomimetic computational head model used to simulate the effects of the measured facial forces on internal tissue exposure to loads applied by the mask, and (c) IR thermography to detect potential thermal changes in skin microclimate associated with the use of a mask. Our results quantify the biomechanical efficacy of dressing cuts placed by nurses between the mask and skin in reducing tissue exposure to focal intense loads, and hence, we demonstrate the value in following the above clinical practice of cushioning the mask‐face interface site.

2. METHODS

2.1. Subjects

This study was conducted as a pilot arm of a MDRPU research project (Medical Ethical Application Approval no. February 2, 2019‐1‐AFK; Afeka College, Tel Aviv, Israel). Six healthy volunteers (three females and three males), aged 25 ± 10 years (values are shown as mean ± SD throughout the article, unless otherwise stated), were recruited for this study and provided informed consent. The subjects were not obese or underweight according to the World Health Organization criteria. Exclusion criteria were respiratory obstructive disorders or disease, craniofacial anomalies, facial trauma or burns, skin diseases, or malignancy.

2.2. Experimental test protocol

First, we developed a force measurement system consisting of five flexible, paper‐thin force sensors (Force Sensing Resistors; Interlink Electronics, Camarillo, California) connected to a microcontroller board (Arduino Uno R3, Ivrea, Italy) (Figure 1A). The reliability of these sensors is 2.3% to 6.6%, their repeatability is 5% to 10%, the drift ranges between 1.7% and 2.5%/logarithmic time, and their linearity is 1.9% to 9.9% for localised forces that are up to 50 g, which overall makes these sensors suitable for device‐skin interface studies.44, 45, 46, 47, 48, 49, 50 The sensors were calibrated with precision calibration weights (15–400 g) in order to obtain the force‐mass (N/g) graph for each sensor. The aforementioned system was used to experimentally determine local contact forces applied to the skin at the bridge of the nose (Sensor #1), cheeks (Sensors #2 and #3), and chin (Sensor #4) of the subjects while using a medium‐size NIV (NIV; AF531 Oro‐Nasal Single‐use; Phillips Respironics Inc., Murrysville, Pennsylvania) mask, with versus without cushioning using cuts of the Lite dressings (Figure 1B). Sensor #5 was placed on the back of the head between the mask straps and the skin, thereby assuring that the mask was fitted to subjects according to manufacturers’ instructions and clinical practice standards. An optimum fit was defined by tensioning the straps of the mask to an extent at which two fingers could slide between the straps and the skin.11 At this point, the measured force at Sensor #5 was approximately 2.2 N for each subject.

Figure 1.

Figure 1

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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

We repeated the above measurements thrice for each subject with versus without the Mepilex Lite dressing cuts, which were applied at the locations of Sensors #1 to 4 as shown in Figure 1B. During each measurement session, subjects were fitted with the NIV mask and allowed to acclimatise to it for 1 minute and then had 1‐minute break periods between measurements with versus without the dressing cuts.

We further studied changes in facial skin temperature distributions resulting from the use of the mask in two of the subjects (both females) using the IR camera Optris Xi 400 (Berlin, Germany), which has an IR resolution of 382 × 288 pixels with an image frequency of 80 Hz and object temperature range of 0 to 250°C. To maintain fixed environmental conditions, the room temperature was set to 24 to 25°C. Subjects were fitted with the mask, and the wearing time was up to 20 minutes depending on their comfort level and feedback. The first measurement session was taken before applying the mask to obtain baseline skin temperature distributions at the bridge of the nose, cheeks, and chin continuously for 15 minutes. A second measurement session followed immediately after removal of the mask1 to obtain the respective skin temperature distributions during the tissue recovery period, per facial site, continuously for 20 minutes. The thermal images were recorded every 5 minutes in each session.

2.3. Computational modelling

In this work, two comparable finite element (FE) model configurations were developed for providing insights regarding potential differences in facial skin and underlying soft tissue stresses and strain energy densities while an NIV mask is being used, with versus without the dressing cuts as tissue protectors.

Both FE model configurations used the same adult head that was built using the visible human (male) project image database (Figure 2A)51 and that has been applied and tested in previous research in our group concerning head protection.52, 53 Tissues in each transverse slice of the head model were segmented and then unified to create a three‐dimensional (3D) computational model using the Scan‐IP module of the Simpleware segmentation software package.54 The dimensions of the head were 16.5 cm ear to ear and 21.5 cm occiput to forehead, and its weight was 5 kg, all of which are representative anthropometric characteristics of a normative adult male head.55 The NIV mask was also created using the Scan‐IP module of Simpleware, and in one model configuration, in addition to the mask, we also generated dressing cuts as cushioning elements beneath the mask (Figure 2B).

Figure 2.

Figure 2

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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

The anatomical details of the brain, sinuses, optic nerves, and other soft tissue structures have been included in our general head modelling framework53; however, in the present study, they do not influence facial tissue loads. Thus, we do not provide information regarding their mechanical properties here (however, such information is available in our previously published work53). The mechanical properties of the relevant tissues of the head—the skin, the subcutaneous fat, and the bone tissue of the skull—were adopted from experimental work reported in the literature (Table 1). Specifically, the bone tissue of the skull was modelled as linear elastic isotropic material with Poisson's ratio of 0.2. Skin and fat tissues were represented using a Mooney‐Rivlin material model, with a strain energy density (SED) W function:

W=C1I1−3+C2I2−3−2C1+2C2lnj+λ2lnj2

Table 1.

Mechanical properties and element data for all the finite element model components

Model component Shear modulus (MPa) Bulk modulus (MPa) Elastic modulus (MPa) Poisson's ratio Number of mesh elements
Skina 0.031900 3.1794 ‐ ‐ 125 826
Fatb , c 0.000286 0.0285 ‐ ‐ 342 692
Skulld ‐ ‐ 6483.6 0.495 159 528
Vertebraee ‐ ‐ 10 000 0.29 37 253
Ventilation mask ‐ ‐ 0.12 0.49 13 700
Mepilex Lite dressings cut‐to‐shape ‐ ‐ 0.02675 0.258 16 490
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a

Data were adopted from the literature.56

b

Data were adopted from the literature.57

c

Data were adopted from the literature.58

d

Data were adopted from the literature.59

e

Data were adopted from the literature.60

where I 1 and I 2 are the first and second invariants of the right Cauchy‐Green deformation tensor, respectively, and J is the determinant of the deformation gradient tensor.

For mechanically characterising the Mepilex Lite dressing cuts, we have tested the product in uniaxial compression following the ASTM D3574 testing standard. The test results of the elastic properties of the dressing material are also specified in Table 1. The NIV mask was considered a linear elastic isotropic material with an elastic modulus of 120 kPa and Poisson's ratio of 0.49 (Table 1).

Using the FE modelling framework described above, we delivered the measured compressive forces to skin per facial site in the two head model configurations. For each model configuration, we created two variants that differ in the distribution of compressive forces applied per site of the face. For the first model variant, the boundary conditions set (BCS) were chosen so that pressure on the bridge of the nose exceeded the pressure on the chin (BCS1). For the second model variant, we swapped the aforementioned boundary conditions so that pressure on the chin exceeded pressure on the bridge of the nose (BCS2). These two model variants are aimed at better reflecting real‐world variation in facial structures as well as different strap orientations when mounting the NIV mask, as informed by our experiments and consultation with practicing clinicians. The mask displacements have been applied in the modelling perpendicularly to the surface of the face. The skull has been fixed for all translations and rotations. Contacts between the NIV mask and skin tissue, as well as contacts between the mask and the dressing cuts, were set as “tie.”

Both head model configurations (with versus without dressing cuts) were meshed using the Scan‐IP module of Simpleware. All elements were of the tetrahedral type; numbers of elements in each model component are specified in Table 1. The simulations were solved using the Pardiso FE solver (version 2.5) and post‐processed using PostView (version 1.10.2), which are both FEBio modules (University of Utah, Salt Lake City, Utah).61, 62 The runtime of each model configuration was between 5 and 10 minutes, using a 64‐bit Windows 7‐based workstation with a CPU comprising Intel Xeon E5645 2.40 GHz (2 processors) and 64 GB RAM.

We obtained descriptive statistics (means and SDs) of the force values measured in the subject group while wearing the NIV mask, with versus without the dressing cuts applied as tissue protectors, per anatomical location of Sensors #1 to 4. We then conducted one‐tailed paired t tests,2 separately for each sensor location, to determine whether local contact forces per site of the face differed significantly while using the dressing cuts, in comparison with the no‐dressing case. As no left‐to‐right cheek force differences were identifiable, force data from the two cheeks were pooled. P < 0.05 was considered statistically significant.

As outcome measures that evaluate tissue exposure to mechanical loads, we selected the effective stresses in skin and fat tissues as well as SEDs. All the above are scalar tissue load measures, which reflect both a compound loading state in the tissues and tissue/device mechanical property gradients, which are highly relevant in the present analyses. Furthermore, we compared volumetric exposures of skin and fat tissues to elevated effective stresses and SED values in relevant areas of interest, that is, for BCS1 at the bridge of the nose and for BCS2 at the chin (Figures 3 and 4, upper frames). For this purpose, we calculated the percentage reduction in area bounded under the curve of tissue exposure to mechanical loads when dressing cuts have been applied as tissue protectors. Furthermore, for consistency in comparisons of exposures to elevated loads across the simulated cases, we used the upper quartile (75th percentile) of each stress/SED scale, separately for the effective stress and SED domains and per BCS case in the corresponding anatomical area of interest.

Figure 3.

Figure 3

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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.

Figure 4

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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

A comparison of the distributions of effective and maximal shear stresses that develop in the soft tissues at the back of the head on the Z‐Flo head positioner versus the medical foam support are shown in Figures 5, 6, 7. For both model variants, stresses in skin and fat peaked at the occiput (Figure 5). The average and peak effective stresses at the soft tissues covering the occipital region when using the Z‐Flo versus the medical foam are detailed in Table 3. The skin at the back of the resting head is subjected to greater stress values with respect to fat; however, the Z‐Flo positioner reduced the exposure of both skin and fat tissues to elevated stresses considerably, compared with the medical foam support (Table 3, Figures 5, 6, 7). It is further shown that, across all stress levels, the Z‐Flo head positioner substantially decreased the volumetric exposure of skin tissue to stresses with respect to the extent of decrease achieved by means of the medical foam (Figure 8). For fat tissue, the Z‐Flo has been shown to be mostly effective in reducing the volumetric exposure to stresses at the high stress domain.

Figure 5.

Figure 5

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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.

Figure 6

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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.

Figure 7

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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.

Figure 8

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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

A comparison of the distributions of effective and maximal shear stresses that develop in the soft tissues at the back of the head on the Z‐Flo head positioner versus the medical foam support are shown in Figures 5, 6, 7. For both model variants, stresses in skin and fat peaked at the occiput (Figure 5). The average and peak effective stresses at the soft tissues covering the occipital region when using the Z‐Flo versus the medical foam are detailed in Table 3. The skin at the back of the resting head is subjected to greater stress values with respect to fat; however, the Z‐Flo positioner reduced the exposure of both skin and fat tissues to elevated stresses considerably compared with the medical foam support (Table 3, Figures 5, 6, 7). It is further shown that, across all stress levels, the Z‐Flo head positioner substantially decreased the volumetric exposure of skin tissue to stresses with respect to the extent of decrease achieved by means of the medical foam (Figure 8). For fat tissue, the Z‐Flo has been shown to be mostly effective in reducing the volumetric exposure to stresses at the high stress domain.

3. RESULTS

The body mass index across the study group was 21.8 ± 2.8 (mean ± SD). Descriptive statistics of the force values measured in the study group while wearing the NIV mask are shown in Figure 5. The maximal contact forces developed on the chin were 3‐fold and 10‐fold greater than the forces at the bridge of the nose and at the cheeks, respectively. The application of dressing cuts facilitated significantly lower local contact forces at the chin, which were approximately 10% less than for the no‐dressing cases (P < 0.05). At the bridge of the nose, we measured a 25% decrease in contact forces after applying the dressing cuts, which was at the edge of statistical significance (P < 0.1); however, the effect of dressing cuts on the cheeks was statistically indistinguishable (Figure 5).

The IR images of facial skin temperature distributions associated with use of a ventilation mask in one female subject are shown in Figure 6: (a) prior to applying the mask, (b) immediately after removal of the mask, and (c) 10 minutes after removal of the mask. The IR thermography images demonstrated physiologically significant temperature changes3 at the mask‐skin contact sites after removal of the mask compared with baseline conditions (Figure 6). The greatest temperature increases occurred at the cheeks of both subjects (Δ = 0.7‐0.8°C) immediately after removal of the mask. The bridge of the nose was also altered in the two subjects, inconsistently however, demonstrating Δ = 0.6°C decrease for one subject but a similar increase in the other (which is potentially related to the anatomical protrusion, hence the individual localised heat transfer pattern at that site). The chin temperatures associated with use of the mask changed negligibly for both subjects. The temperatures at all facial skin sites returned to near their basal levels (Δ ≤ 0.2°C) approximately 10 minutes into the recovery period (Figure 6C).

Maximal effective stress distributions in facial soft tissues for both model variants BCS1 and BCS2, with versus without the dressing cuts, are shown in Figures 7 and 8, respectively. Peak effective tissue stresses occurred at the bridge of the nose and at the chin in BCS1 and BCS2, respectively. For both model variants BCS1 and BCS2, the application of the dressing cuts considerably reduced the peak stresses in facial soft tissues. Specifically, peak effective stresses and SED were reduced by approximately 20% and 35%, respectively, in both model variants while using the dressing cuts as tissue protectors (Figures 7 and 8).

Consistent with the above findings, it is further shown that the application of the dressing cuts substantially lowered the volumetric exposure of soft tissues at the bridge of the nose and chin to elevated effective stress and SED values (Figures 3 and 4). Specifically, for BCS1 at the bridge of the nose, the dressing cuts yielded 75% and 27% reduction in tissues exposures to the high (upper quartile) effective stresses and SEDs, respectively (percentage reduction has been calculated as reduction in the area under the respective curve of volumetric tissue exposure to mechanical loads following application of dressing cuts for the upper quartile of each scale) (Figure 3). Furthermore, for BCS2 at the chin, the dressing cuts lowered the volumetric exposure of facial tissues by 91% and 78% in the high effective stress and high SED domains, respectively (Figure 4).

4. DISCUSSION

In the present study, we developed a multiple‐force‐sensor measurement system to experimentally determine local contact forces applied to the skin at the bridge of the nose, cheeks, and chin while using NIV mask, with versus without dressing cuts. For two subjects, we have also obtained IR thermography data prior‐ and post‐application of the mask. Furthermore, we developed two comparable 3D anatomically realistic FE model configurations of the 3D adult head wearing the NIV mask, with versus without the dressing cuts, in order to compare the biomechanical efficacy of such dressings in alleviating tissue deformations developed in facial tissues, with respect to the no‐dressing case.

We found that the application of the dressing cuts was effective in reducing measured skin contact forces while wearing the NIV mask with respect to the no‐dressing case in each of the tested facial sites. Specifically, the greatest reduction of local contact forces offered by the use of the dressing cuts was at the bridge of the nose. These findings are consistent with previously published research demonstrating that the nose is the most common location for NIV mask‐related PU development.4, 11, 63 Anatomically, the bridge of the nose is characterised by curved geometry with minimal soft tissue coverage, hence with structural tendency to greater tissue deformations. Application of the dressing cuts provides additional localised cushioning at the mask‐skin contact sites, which thereby facilitates an effectively softer and thicker support interface to accommodate the mask and redistribute mask‐tightening loads. Hence, deformation of the dressing cuts absorbs a share of the mechanical energy transferred via the mask, which is then taken off from the skin and underlying tissues. This further demonstrates that, from a PUP perspective, a larger contact area and a more compliant interface layer between the skin and rigid mask structure is a desirable design feature in NIV masks.26 Hence, application of the dressing cuts, particularly over the bony prominent areas of the face, is effective in preserving tissue thickness and reducing soft tissue exposure to elevated deformations and stresses. The risk for developing PUs associated with the use of a nasal NIV mask can also be reduced through the selection of a different mask design, for example, a full‐face or under‐the‐nose mask, which better protects the vulnerable tissues at the bridge of the nose.16, 64, 65, 66

Interestingly, we found that the maximal mask‐inflicted contact forces developed at the chin area, despite the chin not being clinically reported to be the most common site for facial, mask‐related PUs. During the current study, we used a four‐point headgear with a crown strap, which originates at the top of the head and circles around the back of the head, with a dual‐density foam forehead pad. These unique strap orientations and the forehead pad structure appear to have been designed to relieve some of the pressure applied at the bridge of the nose. The crown strap is particularly helpful in lowering pressures by partially taking the weight of the mask off from the bridge of the nose and redirecting it to the top of the head. In addition, the foam forehead pad of the mask, which was applied directly above the nose, facilitated further redistribution of tissue loads, specifically relieving contact pressures applied by the mask directly at the bridge of the nose. While this specific strap design appears to protect soft tissues at the bridge of the nose from sustained tissue deformations and mechanical stresses, it is clear that the contact loads still need to be physically transferred from the mask to the skin and underlying soft tissues, which means that there are greater loads developing in the other sites of the face. Considering that the area at the bridge of the nose was less loaded, we identified a small but apparently important rotation of the mask position towards the chin, which created greater interface pressures at the chin than at any other site of the face. Hence, it can be well expected that the contact loads would shift towards the chin, which confirms our present experimental findings. The anatomy of the chin is such that it is typically less curved and more soft‐tissue‐padded than at the bridge of the nose; hence, the anatomy of the chin appears to be structurally more tolerable to sustained soft tissue deformations and stresses, which could explain why mask‐related PUs are in fact less common at the chin. This points to a possible biomechanical strategy for mitigating mask‐related PUs by shifting mask loads from the apparently more vulnerable bridge of the nose to less vulnerable facial sites, that is, the chin and cheeks. The above concept is actually used routinely in other fields of clinical practice, such as prosthetic socket design, diabetic footwear design, and total contact casts and so should be considered in the prevention of device‐related PUs as well.

The contact forces developed at the cheeks were considerably lower than those developed at the bridge of the nose or at the chin, being consistent with previously published literature.11, 12, 63, 67 Moreover, we found that the effect of the dressing cuts on the cheeks was indistinguishable across the experimental study group, possibly because, as stated above, the cheeks contain thicker soft tissue masses and are relatively distant from bony prominences.

The IR thermography has demonstrated physiologically significant facial skin temperature changes caused by the application of the mask in the two examined subjects despite the relatively short (up to just 20 minutes) time of application. These temperature data (Figure 6) demonstrate, for the first time in the literature, that there are localised microclimate changes at the mask‐skin contact sites that differ across facial regions and should be considered in addition to, and coupled with, the mechanical (force and deformation) factors in the context of preventing MDRPUs. We found that the greatest temperature increases occur at the cheeks, and this likely relates to tissue thickness and composition and the associated thermal conductive properties and perfusion‐related heat convection at these sites. At the chin area, temperature changes were considerably lower compared with those recorded at the bridge of the nose and cheeks, which interestingly matches with the chin being an atypical injury site in mask users. It is possible that the convection of heat at the chin is more efficient than at the bridge of the nose given the thicker soft tissue mass at the chin, which contains more blood vessels than the tissues covering the bridge of the nose, and hence, transport and clearance of heat away from the contact site with the mask is performed more effectively at the chin. Overall, these interesting pilot findings warrant thermal imaging studies in larger groups and using different mask designs, but clearly, the skin microclimate needs to be characterised per mask design.

In agreement with our previous computational modelling work with regard to the biomechanical function of dressings in PUP,27, 28, 33, 34, 35, 68, 69, 70, 71 here, we found that application of the dressing cuts considerably reduced peak stresses in facial soft tissues for both model variants BCS1 and BCS2, in comparison with the respective no‐dressing cases. Furthermore, use of the dressing cuts substantially reduced the volumetric exposure of facial soft tissues to elevated effective stresses and SED values, for BCS1 at the bridge of the nose and for BCS2 at the chin. This confirms that the application of the dressing cuts provides effective tissue protection. The protective quality of the dressing cuts is particularly evident for the dangerous, high‐end stress domains.27, 28, 52 We attribute this protective efficacy of the dressing cuts to the localised cushioning, as well as the stable attachment of the dressing cuts to the skin, which prevents relative mask‐skin movements and associated frictional forces and tissue distortions in shear.

The present work clearly shows that application of the dressing cuts provides protection from elevated, sustained tissue strains and stresses. Nevertheless, as always, there are inherent limitations related to the experimental work, as well as to the computational modelling. For example, because of ethical considerations, we did not ventilate our healthy subjects, particularly because the primary focus of the work was to quantify the extent of facial tissue distortions and the associated tissue loads at and near the face‐mask contact contours, which did not require actual ventilation. The influence of pumping air through the mask on the studied biomechanical interaction phenomena should therefore be small, if any: the air pressure does not act to detach the mask from the face, particularly because a nurse should always ensure that the mask does not leak (typically by further tightening the straps if needed).11, 26, 72 Furthermore, we note that the skin temperature indeed changed at the centre of the nose as a result of air circulation within the mask (Figure 6) but could have been affected differently in an actual ventilation process where pressurised air is being circulated. Furthermore, in our experiments, the mask was applied for relatively short time periods compared with real‐world clinical scenarios, which may affect how tissues behaved biomechanically, including the potential development of an inflammatory response and localised oedema under the mask, which would then elevate tissue stiffness, contact forces, and stresses.73 Limitations with regard to the modelling are associated primarily with the assumptions and the omissions made. The mechanical properties of soft tissues were adopted from animal studies because of a lack of specific literature providing empirical properties of fresh human facial tissue components. The head anatomy and tissue mechanical properties represent healthy conditions and do not account for anatomical variants or pathologies. In addition, importantly, the present results cannot be directly extrapolated to the paediatric population as neonate or toddler heads are not miniature adult heads with respect to head anatomy, tissue physiology, and soft tissue mechanical properties.53

5. CONCLUSIONS

We found that the application of the dressing cuts was biomechanically effective in reducing exposure of facial tissues to elevated mechanical loads. The use of the dressing cuts considerably reduced deformations and stresses in facial soft tissues in the two model variants, which represented (a) variation in strap orientations when fitting the NIV mask and (b) different distributions of skin‐mask contact forces applied per facial site. Accordingly, the present work provides scientific justification and biomechanical evidence supporting the efforts of nurses in applying dressing cuts to the faces of patients in clinical practice prior to mounting NIV masks. Now that we have demonstrated the combined use of face‐mask contact force measurements, IR thermography, and computational modelling as related to MDRPUs, we propose, as a next step in this research line, to develop multi‐physics (structural‐thermodynamic) modelling and simulations of face‐mask interactions. This will facilitate analyses of the resulting soft tissue distortions when coupled with tissue heating, using the multi‐physics modelling approach in PU research that was recently introduced by our group.74 Taking such a multi‐physics approach would be highly relevant for considering the altered microclimate conditions imposed by the NIV mask, in addition to the local tissue deformations and stress concentrations.

ACKNOWLEDGEMENTS

The work was funded by an unrestricted educational grant from Mölnlycke Health Care, from which A.G. received speaker honoraria.

Peko Cohen L, Ovadia‐Blechman Z, Hoffer O, Gefen A. Dressings cut to shape alleviate facial tissue loads while using an oxygen mask. Int Wound J. 2019;16:813–826. 10.1111/iwj.13101

Funding information Mölnlycke Health Care

ENDNOTES

1

No measurements were taken during wearing of the mask as the presence of the mask blocks the true thermal emittance from the affected regions of the skin.

2

One‐tail tests were considered adequate since dressing cuts applied as tissue protectors act as cushioning elements between the skin and mask and therefore can only decrease skin‐mask contact forces (hence the 1‐tail effect).

3

Physiologically significant temperature changes are defined here as temperature differences greater than the healthy core body day‐to‐day or day/night temperature changes, that is, changes equal or exceeding 0.5 °C.

REFERENCES

  • 1. NICE . Chronic Obstructive Pulmonary Disease in Adults (QS10). London, England: National Institute for Health and Care Excellence; 2011. [Google Scholar]
  • 2. Hess DR. Noninvasive ventilation for acute respiratory failure. Respir Care. 2013;58(6):950‐972. [DOI] [PubMed] [Google Scholar]
  • 3. Zhan Q, Sun B, Liang L, et al. Early use of noninvasive positive pressure ventilation for acute lung injury: a multicenter randomized controlled trial. Crit Care Med. 2012;40(2):455‐460. [DOI] [PubMed] [Google Scholar]
  • 4. Munckton K, Ho KM, Dobb GJ, Das‐Gupta M, Webb SA. The pressure effects of facemasks during noninvasive ventilation: a volunteer study. Anaesthesia. 2007;62(11):1126‐1131. [DOI] [PubMed] [Google Scholar]
  • 5. Demoule A et al. Changing use of noninvasive ventilation in critically ill patients: trends over 15 years in francophone countries. Intensive Care Med. 2016;42(1):82‐92. [DOI] [PubMed] [Google Scholar]
  • 6. Kottner J, Black J, Call E, Gefen A, Santamaria N. Microclimate: a critical review in the context of pressure ulcer prevention. Clin Biomech. 2018;59:62‐70. [DOI] [PubMed] [Google Scholar]
  • 7. Wolverton CL, Hobbs LA, Beeson T, et al. Nosocomial pressure ulcer rates in critical care: performance improvement project. J Nurs Care Qual. 2005;20(1):56‐62. [DOI] [PubMed] [Google Scholar]
  • 8. Black JM, Cuddigan JE, Walko MA, Didier LA, Lander MJ, Kelpe MR. Medical device related pressure ulcers in hospitalized patients. Int Wound J. 2010;7(5):358‐365. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 9. Lemyze M, Mallat J, Nigeon O, et al. Rescue therapy by switching to total face mask after failure of face mask‐delivered noninvasive ventilation in do‐not‐intubate patients in acute respiratory failure. Crit Care Med. 2013;41(2):481‐488. [DOI] [PubMed] [Google Scholar]
  • 10. Visscher M, King A, Nie AM, et al. A quality‐improvement collaborative project to reduce pressure ulcers in PICUs. Pediatrics. 2013;131(6):e1950‐e1960. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 11. Worsley PR, Prudden G, Gower G, Bader DL. Investigating the effects of strap tension during non‐invasive ventilation mask application: a combined biomechanical and biomarker approach. Med Devices (Auckl). 2016;9:409‐417. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12. Weng MH. The effect of protective treatment in reducing pressure ulcers for non‐invasive ventilation patients. Intensive Crit Care Nurs. 2008;24(5):295‐299. [DOI] [PubMed] [Google Scholar]
  • 13. Navalesi P, Fanfulla F, Frigerio P, Gregoretti C, Nava S. Physiologic evaluation of noninvasive mechanical ventilation delivered with three types of masks in patients with chronic hypercapnic respiratory failure. Crit Care Med. 2000;28(6):1785‐1790. [DOI] [PubMed] [Google Scholar]
  • 14. Rozzini R, Sabatini T, Trabucchi M. Non‐invasive ventilation for respiratory failure in elderly patients. Age Ageing. 2006;35(5):546‐547. [DOI] [PubMed] [Google Scholar]
  • 15. Visscher MO, White CC, Jones JM, Cahill T, Jones DC, Pan BS. Face masks for noninvasive ventilation: fit, excess skin hydration, and pressure ulcers. Respir Care. 2015;60(11):1536‐1547. [DOI] [PubMed] [Google Scholar]
  • 16. Shikama M, Nakagami G, Noguchi H, Mori T, Sanada H. Development of personalized fitting device with 3‐dimensional solution for prevention of NIV oronasal mask‐related pressure ulcers. Respir Care. 2018;63(8):1024‐1032. [DOI] [PubMed] [Google Scholar]
  • 17. European Pressure Ulcer Advisory Panel . Pressure Ulcers Treatment: Quick Reference Guide. Washington, DC: National Pressure Ulcer Advisory Panel (NPUAP); 2014. [Google Scholar]
  • 18. Gregoretti C, Confalonieri M, Navalesi P, et al. Evaluation of patient skin breakdown and comfort with a new face mask for non‐invasive ventilation: a multi‐center study. Intensive Care Med. 2002;28(3):278‐284. [DOI] [PubMed] [Google Scholar]
  • 19. Rocco M. Noninvasive ventilation by helmet or face mask in immunocompromised patients: a case‐control study. Chest. 2004;126(5):1508‐1515. [DOI] [PubMed] [Google Scholar]
  • 20. Keenan SP, Powers C, McCormack DG, Block G. Noninvasive positive‐pressure ventilation for postextubation respiratory distress: a randomized controlled trial. JAMA. 2002;287(24):3238‐3244. [DOI] [PubMed] [Google Scholar]
  • 21. Carron M, Freo U, BaHammam AS, et al. Complications of non‐invasive ventilation techniques: a comprehensive qualitative review of randomized trials. Anaesthesia. 2013;110(6):896‐914. [DOI] [PubMed] [Google Scholar]
  • 22. Conti G, Marino P, Cogliati A, et al. Noninvasive ventilation for the treatment of acute respiratory failure in patients with hematologic malignancies: a pilot study. Intensive Care Med. 1998;24(12):1283‐1288. [DOI] [PubMed] [Google Scholar]
  • 23. Antonelli M, Conti G, Pelosi P, et al. New treatment of acute hypoxemic respiratory failure: noninvasive pressure support ventilation delivered by helmet ‐ a pilot controlled trial. Crit Care Med. 2002;30(3):602‐608. [DOI] [PubMed] [Google Scholar]
  • 24. Schettino G, Altobelli N, Kacmarek RM. Noninvasive positive pressure ventilation reverses acute respiratory failure in select "do‐not‐intubate" patients. Crit Care Med. 2005;33(9):1976‐1982. [DOI] [PubMed] [Google Scholar]
  • 25. Duncan KD. Preventing pressure ulcers: the goal is zero. Jt Comm J Qual Patient Saf. 2007;33(10):605‐610. [DOI] [PubMed] [Google Scholar]
  • 26. Dellweg D, Hochrainer D, Klauke M, Kerl J, Eiger G, Kohler D. Determinants of skin contact pressure formation during non‐invasive ventilation. J Biomech. 2010;43(4):652‐657. [DOI] [PubMed] [Google Scholar]
  • 27. Levy A, Schwartz D, Gefen A. The contribution of a directional preference of stiffness to the efficacy of prophylactic sacral dressings in protecting healthy and diabetic tissues from pressure injury: computational modelling studies. Int Wound J. 2017;14(6):1370‐1377. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 28. Levy A, Frank MB, Gefen A. The biomechanical efficacy of dressings in preventing heel ulcers. J Tissue Viability. 2015;24(1):1‐11. [DOI] [PubMed] [Google Scholar]
  • 29. Kannon GA, Garrett AB. Moist wound healing with occlusive dressings. A clinical review. Dermatol Surg. 1995;21(7):583‐590. [DOI] [PubMed] [Google Scholar]
  • 30. Butcher M, Thompson G. Can the use of dressing materials actually prevent pressure ulcers: presenting the evidence. Wounds UK. 2010;6:119‐125. [Google Scholar]
  • 31. Clark M, Black J, Alves P, et al. Systematic review of the use of prophylactic dressings in the prevention of pressure ulcers. Int Wound J. 2014;11(5):460‐471. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32. Butcher M, Thompson G. Dressings can prevent pressure ulcers: fact or fallacy? The problem of pressure ulcer prevention. Wounds UK. 2009;5:80‐93. [Google Scholar]
  • 33. Kalowes P, Messina V, Li M. Five‐layered soft silicone foam dressing to prevent pressure ulcers in the intensive care unit. Am J Crit Care. 2016;25(6):e108‐e119. [DOI] [PubMed] [Google Scholar]
  • 34. Santamaria N, Gerdtz M, Sage S, et al. A randomised controlled trial of the effectiveness of soft silicone multi‐layered foam dressings in the prevention of sacral and heel pressure ulcers in trauma and critically ill patients: the border trial. Int Wound J. 2015;12(3):302‐308. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 35. Santamaria N, Gerdtz M, Liu W, et al. Clinical effectiveness of a silicone foam dressing for the prevention of heel pressure ulcers in critically ill patients: border II Trial. J Wound Care. 2015;24(8):340‐345. [DOI] [PubMed] [Google Scholar]
  • 36. Ovadia‐Blechman Z, Meilin A, Rabin N, Eldar M, Castel D. Noninvasive monitoring of peripheral microcirculatory hemodynamics under varying degrees of hypoxia. Respir Physiol Neurobiol. 2015;216:23‐27. [DOI] [PubMed] [Google Scholar]
  • 37. Ovadia‐Blechman Z et al. Noninvasive evaluation of microcirculatory hemodynamic changes during hemorrhage followed by saline or blood. Transfus Shock. 1995;4(2):96‐101. [DOI] [PubMed] [Google Scholar]
  • 38. Ovadia‐Blechman Z, Avrahami I, Weizman‐Shammai E, Sharir T, Eldar M, Chouraqui P. Peripheral microcirculatory hemodynamic changes in patients with myocardial ischemia. Biomed Pharmacother. 2015;74:83‐88. [DOI] [PubMed] [Google Scholar]
  • 39. Ovadia‐Blechman Z, Gavish B, Levy‐Aharoni D, Shashar D, Aharonson V. The coupling between peripheral microcirculation and slow breathing. Med Eng Phys. 2017;39:49‐56. [DOI] [PubMed] [Google Scholar]
  • 40. Ovadia‐Blechman Z, Gritzman A, Shuvi M, Gavish B, Aharonson V, Rabin N. The response of peripheral microcirculation to gravity‐induced changes. Clin Biomech. 2018;57:19‐25. [DOI] [PubMed] [Google Scholar]
  • 41. Lustig M, Ayelet L, Kara K, Ovadia‐Blechman Z, Gefen A. Beware of the toilet: The risk for a deep tissue injury during toilet sitting. J Tissue Viability. 2018;27(1):23‐31. [DOI] [PubMed] [Google Scholar]
  • 42. Bagavathiappan S et al. Infrared thermal imaging for detection of peripheral vascular disorders. J Med Phys. 2009;34(1):43‐47. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 43. Hoffer OA, Ben‐David MA, Katz E, et al. Thermal imaging as a tool for evaluating tumor treatment efficacy. J Biomed Opt. 2018;23(5):1‐6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 44. Ferguson‐Pell M, Hagisawa S, Bain D. Evaluation of a sensor for low interface pressure applications. Med Eng Phys. 2000;22(9):657‐663. [DOI] [PubMed] [Google Scholar]
  • 45. Wilson DR, Apreleva MV, Eichler MJ, Harrold FR. Accuracy and repeatability of a pressure measurement system in the patellofemoral joint. J Biomech. 2003;36(12):1909‐1915. [DOI] [PubMed] [Google Scholar]
  • 46. Polliack AA, Sieh RC, Craig DD, Landsberger S, McNeil DR, Ayyappa E. Scientific validation of two commercial pressure sensor systems for prosthetic socket fit. Prosthet Orthot Int. 2000;24(1):63‐73. [DOI] [PubMed] [Google Scholar]
  • 47. Wilharm A, Hurschler C, Dermitas T, Bohnsack M. Use of Tekscan K‐scan sensors for retropatellar pressure measurement avoiding errors during implantation and the effects of shear forces on the measurement precision. Biomed Res Int. 2013;2013(6):829171. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 48. Komi ER, Roberts JR, Rothberg S. Evaluation of thin, flexible sensors for time‐resolved grip force measurement. Proc Inst Mech Eng C. 2008;221(12):1687‐1699. [Google Scholar]
  • 49. Nikonovas A, Harrison AJL, Hoult S, Sammut D. The application of force‐sensing resistor sensors for measuring forces developed by the human hand. Proc Instn Mech Engrs. 2004;218(2):121‐125. [DOI] [PubMed] [Google Scholar]
  • 50. Pavlovic JL, Takahashi Y, Bechtold JE, Gustilo RB, Kyle RF. Can the Tekscan sensor accurately measure dynamic pressures in the knee joint. 17th Annual Meeting, American Society of Biomechanics, Iowa City, IA, 1993; pp. 135–136.
  • 51. Visible Human Project Gallery . Visible Human Project (VHP) of the U.S. National Library of Medicine. Bethesda MD: U.S. National Library of Medicine; 1994. [Google Scholar]
  • 52. Katzengold R, Gefen A. What makes a good head positioner for preventing occipital pressure ulcers. Int Wound J. 2018;15(2):243‐249. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 53. Friedman R, Haimy A, Gefen A, Epstein Y. Three‐dimensional biomimetic head model as a platform for thermal testing of protective goggles for prevention of eye injuries. Clin Biomech. 2018; pii: S0268‐0033(18)30344‐9. 10.1016/j.clinbiomech.2018.04.012 [DOI] [PubMed] [Google Scholar]
  • 54. Simpleware® Ltd . ScanIP, +FE, +NURBS and +CAD Reference Guide ver 5.1. 2012. http://www.simpleware.com/software/. Accessed February 12, 2019.
  • 55. Goldstein JP. The effect of motorcycle helmet use on the probability of fatality and the severity of head and neck injuries a latent variable frame‐work. Eval Rev. 1986;10(3):355‐375. [Google Scholar]
  • 56. Linder‐Ganz E, Shabahin N, Itzchak Y, Gefen A. Assessment of mechanical conditions in sub‐dermal tissues during sitting: a combined experimental‐MRI and finite element approach. J Biomech. 2007;40(7):1443‐1454. [DOI] [PubMed] [Google Scholar]
  • 57. Sopher R, Nixon J, Gorecki C, Gefen A. Exposure to internal muscle tissue loads under the ischial tuberosities during sitting is elevated at abnormally high or low body mass indices. J Biomech. 2010;43(2):280‐286. [DOI] [PubMed] [Google Scholar]
  • 58. Gefen A, Haberman E. Viscoelastic properties of ovine adipose tissue covering the gluteus muscles. J Biomech Eng. 2007;129(6):924‐930. [DOI] [PubMed] [Google Scholar]
  • 59. Moore DF, Jérusalem A, Nyein M, Noels L, Jaffee MS, Radovitzky RA. Computational biology‐ modeling of primary blast effects on the central nervous system. Neuroimage. 2009;47(Suppl 2):T10‐T20. [DOI] [PubMed] [Google Scholar]
  • 60. Greaves CY, Gadala M, Oxland TR. A three‐dimensional finite element model of the cervical spine with spinal cord: an investigation of three injury mechanisms. Ann Biomed Eng. 2008;36(3):396‐405. [DOI] [PubMed] [Google Scholar]
  • 61. Maas SA, Ellis BJ, Ateshian GA, Weiss JA. FEBio: finite elements for bio‐mechanics. J Biomech Eng. 2012;134(1):5‐11. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 62. FEBio . Finite element for biomechanics, theory manual ver. 1.5. 2012. http://mrl.sci.utah.edu/software/febio. Accessed February 12, 2019.
  • 63. Maruccia M, Ruggieri M, Onesti MG. Facial skin breakdown in patients with non‐invasive ventilation devices: report of two cases and indications for treatment and prevention. Int Wound J. 2015;12(4):451‐455. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 64. Willson GN, Piper AJ, Norman M, et al. Nasal versus full face mask for noninvasive ventilation in chronic respiratory failure. Eur Respir J. 2004;23(4):605‐609. [DOI] [PubMed] [Google Scholar]
  • 65. Chungmei S, McCarthy E, Merrlan K, Bliss K. Reducing pressure injuries related to positive airway pressure ventilation masks. Stanford Health Care, Stanford Medicine. Poster session represented at EPUAP Conference, Rome, Italy; 2018.
  • 66. Riquelme H et al. Face protective patches do not reduce facial pressure ulcers in a simulated model of non‐invasive ventilation. Rev Chil Pediatr. 2017;88(3):354‐359. [DOI] [PubMed] [Google Scholar]
  • 67. Ahmad Z, Venus M, Kisku W, Rayatt SS. A case series of skin necrosis following use of non invasive ventilation pressure masks. Int Wound J. 2013;10(1):87‐90. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 68. Levy A, Gefen A. Assessment of the biomechanical effects of prophylactic sacral dressings on tissue loads: A computational modeling analysis. Ostomy Wound Manage. 2017;63:48‐55. [PubMed] [Google Scholar]
  • 69. Levy A, Gefen A. Computer modeling studies to assess whether a prophylactic dressing reduces the risk for deep tissue injury in the heels of supine patients with diabetes. Ostomy Wound Manage. 2016;62:42‐52. [PubMed] [Google Scholar]
  • 70. World Union of Wound Healing Societies (WUWHS) Consensus Document . Role of dressings in pressure ulcer prevention. Wounds Int. 2016:3‐24. [Google Scholar]
  • 71. Gefen A, Kottner J, Santamaria N. Clinical and biomechanical perspectives on pressure injury prevention research: The case of prophylactic dressings. Clin Biomech. 2016;38:29‐34. [DOI] [PubMed] [Google Scholar]
  • 72. Schettino GP, Tucci M, Sousa R, Barbas C, Amato M, Carvalho C. Mask mechanics and leak dynamics during noninvasive pressure support ventilation: a bench study. Intensive Care Med. 2001;27(12):1887‐1891. [DOI] [PubMed] [Google Scholar]
  • 73. Racca F, Appendini L, Berta G, et al. Helmet ventilation for acute respiratory failure and nasal skin breakdown in neuromuscular disorders. Anesth Analg. 2009;109(1):164‐167. [DOI] [PubMed] [Google Scholar]
  • 74. Zeevi T, Levy A, Brauner N, Gefen A. Effects of ambient conditions on the risk of pressure injuries in bedridden patients – multi‐physics modelling of microclimate. Int Wound J. 2017;15(3):402‐416. [DOI] [PMC free article] [PubMed] [Google Scholar]

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