Determinants of skin contact pressure formation during non-invasive ventilation

[Non-invasive Mechanical Ventilation in Acute Respiratory Failure. Clinical Practice Guidelines - on behalf of the German Society of Pneumology and Ventilatory Medicine]

The guideline update outlines the advantages as well as the limitations of NIV in the treatment of acute respiratory failure in daily clinical practice and in different indications.Non-invasive ventilation (NIV) has a high value in therapy of hypercapnic acute respiratory failure, as it significantly reduces the length of ICU stay and hospitalization as well as mortality.Patients with cardiopulmonary edema and acute respiratory failure should be treated with continuous positive airway pressure (CPAP) and oxygen in addition to necessary cardiological interventions. This should be done already prehospital and in the emergency department.In case of other forms of acute hypoxaemic respiratory failure with only mild or moderately disturbed gas exchange (PaO2/FiO2 > 150 mmHg) there is no significant advantage or disadvantage compared to high flow nasal oxygen (HFNO). In severe forms of ARDS NIV is associated with high rates of treatment failure and mortality, especially in cases with NIV-failure and delayed intubation.NIV should be used for preoxygenation before intubation. In patients at risk, NIV is recommended to reduce extubation failure. In the weaning process from invasive ventilation NIV essentially reduces the risk of reintubation in hypercapnic patients. NIV is regarded useful within palliative care for reduction of dyspnea and improving quality of life, but here in concurrence to HFNO, which is regarded as more comfortable. Meanwhile NIV is also recommended in prehospital setting, especially in hypercapnic respiratory failure and pulmonary edema.With appropriate monitoring in an intensive care unit NIV can also be successfully applied in pediatric patients with acute respiratory insufficiency.

The prevalence and risk factors of facial pressure injuries related to adult non-invasive ventilation equipment: A systematic review and meta-analysis

To systematically assess the prevalence of facial pressure injuries related to adult non-invasive ventilation equipment, and risk factors of facial pressure injuries. PubMed, Cochrane Library, Web of Science, Embase, China Knowledge Resource Integrated Database, Wanfang Database, Chinese Biomedical Database and Weipu Database were comprehensively searched for observational studies investigating the prevalence and risk factors of facial pressure injuries related to adult non-invasive ventilation equipment from inception to May 16th, 2022. Filter articles based on inclusion and exclusion criteria. The quality of the included studies was evaluated independently by two investigators. Meta-analysis was conducted using Stata 16.0 software package. In total, 2835 articles were screened and data from 12 studies were used in meta-analysis. The prevalence of facial pressure injuries related to adult non-invasive ventilation equipment was 25% (95% confidence interval, CI:15% to 37%, I²  = 97.34%, P < 0.0001). After controlling for confounding variables, the following risk factors of facial pressure injuries: use equipment form, with diabetes, fever, cumulative time of using equipment, facial skin oedema and Glasgow score. Understanding the risk factors of facial pressure injuries can provide the healthcare personnel with the theoretical basis for the management and treatment of the patients.

Comparing the quantitative fit-testing results of half-mask respirators with various skin barriers in a crossover study design: a pilot study

Background

Clinicians around the world are experiencing skin breakdown due to the prolonged usage of masks while working long hours to treat patients with COVID-19. The skin damage is a result of the increased friction and pressure at the mask–skin barrier. Throughout the COVID-19 pandemic, clinicians have been applying various skin barriers to prevent and ameliorate skin breakdown. However, there are no studies to our knowledge that assess the safety and efficacy of using these skin barriers without compromising a sufficient mask–face seal.

Aim

To conduct the largest study to date of various skin barriers and seal integrity with quantitative fit testing (QNFT).

Methods

This pilot study explored whether the placement of a silicone scar sheet (ScarAway®), Cavilon™, or Tegaderm™ affects 3M™ half-face mask respirator barrier integrity when compared to no barrier using QNFT. Data were collected from nine clinicians at an academic level 1 trauma centre in New Jersey.

Findings

The silicone scar sheet resulted in the lowest adequate fit, whereas Cavilon provided the highest fit factor when compared to other interventions (P < 0.05).

Conclusion

These findings help inform clinicians considering barriers for comfort when wearing facemasks during the COVID-19 pandemic and for future pandemics.

In Vitro Evaluation of Facial Pressure and Air Leak with a Newly Designed Cushion for Non-Invasive Ventilation Masks

Background: The aim of this study was to evaluate the effect of a newly designed foam cushion on the air leakage and pressure when applied to the face. Methods: A teaching manikin connected to a bilevel positive airway pressure ventilator attached to four different brands of oronasal masks (Amara, Mirage, Forma, and Wizard) was used. The foam cushions of 5-mm and 10-mm-thickness were attached to the masks, and each mask was tested without a cushion. Six pressure sensors were placed on the manikin’s face, and data were recorded. Inspiratory volume and air leak flow from the ventilator were observed. Results: Air leakage was influenced by both the mask brand and the presence of a cushion. The presence of a cushion did not affect the Wizard mask in terms of leakage (p = 0.317) or inspiratory volume (p = 0.726). The Wizard and Amara masks generated the lowest contact pressure on the frontal forehead (p < 0.001) compared to the other five points. Conclusions: Utilisation of a cushion reduces air leakage and maintains greater inspiratory volume regardless of its thickness. The contact pressure varies depending on the brand of the mask, which would require a difference in the thickness of the cushion for pressure reduction.

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

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.

Mask pressure effects on the nasal bridge during short-term noninvasive ventilation

The aim of this study was to assess the influence of different masks, ventilator settings and body positions on the pressure exerted on the nasal bridge by the mask and subjective comfort during noninvasive ventilation (NIV). We measured the pressure over the nasal bridge in 20 healthy participants receiving NIV via four different NIV masks (three oronasal masks, one nasal mask) at three different ventilator settings and in the seated or supine position. Objective pressure measurements were obtained with an I-Scan pressure-mapping system. Subjective comfort of the mask fit was assessed with a visual analogue scale. The masks exerted mean pressures between 47.6±29 mmHg and 91.9±42.4 mmHg on the nasal bridge. In the supine position, the pressure was lower in all masks (57.1±31.9 mmHg supine, 63.9±37.3 mmHg seated; p<0.001). With oronasal masks, a change of inspiratory positive airway pressure (IPAP) did not influence the objective pressure over the nasal bridge. Subjective discomfort was associated with higher IPAP and positively correlated with the pressure on the skin. Objective measurement of pressure on the skin during mask fitting might be helpful for mask selection. Mask fitting in the supine position should be considered in the clinical routine.

Investigating the effects of strap tension during non-invasive ventilation mask application: a combined biomechanical and biomarker approach

Non-invasive ventilation is commonly used for respiratory support. However, in some cases, mask application can cause pressure ulcers to specific features of the face, resulting in pain and reduced quality of life for the individual. This study investigated the effects of mask strap tension on the biomechanical and biomarker responses at the skin interface. Healthy participants (n = 13) were recruited and assigned two different masks in a random order, which were fitted with three strap conditions representing increments of 5 mm to increase tension. Masks were worn for 10 minutes at each tension followed by a 10-minute refractory period. Assessment at the device–skin interface included measurements of pressures at the nose and cheeks, temperature and humidity, a selection of inflammatory cytokine concentrations collected from sebum and scores of comfort. The results indicated significantly higher interface pressures at the bridge of the nose compared to the cheeks for both masks (p < 0.05), with nasal interface pressures significantly increasing with elevated strap tension (p < 0.05). One inflammatory cytokine, IL-1α, increased following mask application at the highest tension, with median increases from baselines ranging from 21 to 33%. The other cytokines revealed a less consistent trend with strap tension. The participants reported statistically greater discomfort during elevated strap tension. Temperature and humidity values under the mask were elevated from ambient conditions, although no differences were observed between mask type or strap tension. The bony prominence on the bridge of the nose represented a vulnerable area of skin during respiratory mask application. This study has shown that mask strap tension has a significant effect on the pressure exerted on the nose. This can result in discomfort and an inflammatory response at the skin surface. Further studies are required to investigate respiratory mask application for appropriate individuals with comorbidities.

Case Report of a Pressure Ulcer Occurring Over the Nasal Bridge Due to a Non-Invasive Ventilation Facial Mask

Non-invasive ventilation (NIV) is used in patients with respiratory failure, sleep apnoea, and dyspnoea related to pulmonary oedema. NIV is provided through a facial mask. Many complications of NIV facial masks have been reported, including the breakdown of facial skin. We report a case of an elderly male admitted with multiple co-morbidities. The facial mask was applied continuously for NIV, without any relief or formal monitoring of the underlying skin. It resulted in a Grade II pressure ulcer. We discuss the possible mechanism and offer advice for prevention of such device-related pressure ulcers.

A novel algorithm for determining contact area between a respirator and a headform

The contact area, as well as the contact pressure, is created when a respiratory protection device (a respirator or surgical mask) contacts a human face. A computer-based algorithm for determining the contact area between a headform and N95 filtering facepiece respirator (FFR) was proposed. Six N95 FFRs were applied to five sizes of standard headforms (large, medium, small, long/narrow, and short/wide) to simulate respirator donning. After the contact simulation between a headform and an N95 FFR was conducted, a contact area was determined by extracting the intersection surfaces of the headform and the N95 FFR. Using computer-aided design tools, a superimposed contact area and an average contact area, which are non-uniform rational basis spline (NURBS) surfaces, were developed for each headform. Experiments that directly measured dimensions of the contact areas between headform prototypes and N95 FFRs were used to validate the simulation results. Headform sizes influenced all contact area dimensions (P < 0.0001), and N95 FFR sizing systems influenced all contact area dimensions (P < 0.05) except the left and right chin regions. The medium headform produced the largest contact area, while the large and small headforms produced the smallest.

Nocturnal non-invasive ventilation for cardio-respiratory disorders in adults

Following the classic 'iron lung' non-invasive negative pressure ventilator, non-invasive positive pressure ventilation (NIPPV), particularly used 'nocturnally' has developed a broad role in both the acute hospital setting and domiciliary long-term use for many cardio-respiratory disorders associated with acute and chronic ventilatory failure. This role is based in part upon the perceived relative ease of application and discontinuation of NIPPV, ability to avoid intubation or tracheostomy and their associated morbidities and availability of increasingly portable pressure and volume cycled NIPPV devices. Nevertheless, the many methodologies necessary for optimal NIPPV use are often underappreciated by health care workers and patients alike. This review focuses on the rationale, practice, and future directions for 'nocturnal' use of non-invasive positive pressure ventilation (nNIV) in cardio-respiratory disorders in adults which are commonly associated with sleep-related apnea, hypoventilation and hypoxemia: congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), obesity hypoventilation syndrome (OHS), cystic fibrosis (CF) and neuromuscular disorders.

Randomized controlled trial of noninvasive positive pressure ventilation (NPPV) versus servoventilation in patients with CPAP-induced central sleep apnea (complex sleep apnea)

STUDY OBJECTIVES

To compare the treatment effect of noninvasive positive pressure ventilation (NPPV) and anticyclic servoventilation in patients with continuous positive airway pressure (CPAP)-induced central sleep apnea (complex sleep apnea).

DESIGN

Randomized controlled trial.

SETTING

Sleep center.

PATIENTS

Thirty patients who developed complex sleep apnea syndrome (CompSAS) during CPAP treatment.

INTERVENTIONS

NPPV or servoventilation.

MEASUREMENTS AND RESULTS

Patients were randomized to NPPV or servo-ventilation. Full polysomnography (PSG) was performed after 6 weeks. On CPAP prior to randomization, patients in the NPPV and servoventilator arm had comparable apnea-hypopnea indices (AHI, 28.6 ± 6.5 versus 27.7 ± 9.7 events/h (mean ± standard deviation [SD])), apnea indices (AI,19 ± 5.6 versus 21.1 ± 8.6 events/h), central apnea indices (CAI, 16.7 ± 5.4 versus 18.2 ± 7.1 events/h), oxygen desaturation indices (ODI,17.5 ± 13.1 versus 24.3 ± 11.9 events/h). During initial titration NPPV and servoventilation significantly improved the AHI (9.1 ± 4.3 versus 9 ± 6.4 events/h), AI (2 ± 3.1 versus 3.5 ± 4.5 events/h) CAI (2 ± 3.1 versus 2.5 ± 3.9 events/h) and ODI (10.1 ± 4.5 versus 8.9 ± 8.4 events/h) when compared to CPAP treatment (all P < 0.05). After 6 weeks we observed the following differences: AHI (16.5 ± 8 versus 7.4 ± 4.2 events/h, P = 0.027), AI (10.4 ± 5.9 versus 1.7 ± 1.9 events/h, P = 0.001), CAI (10.2 ± 5.1 versus 1.5 ± 1.7 events/h, P < 0.0001)) and ODI (21.1 ± 9.2 versus 4.8 ± 3.4 events/h, P < 0.0001) for NPPV and servoventilation, respectively. Other sleep parameters were unaffected by any form of treatment.

CONCLUSIONS

After 6 weeks, servoventilation treated respiratory events more effectively than NPPV in patients with complex sleep apnea syndrome.

Complications of non-invasive ventilation techniques: a comprehensive qualitative review of randomized trials

Non-invasive ventilation (NIV) has become a common treatment for acute and chronic respiratory failure. In comparison with conventional invasive mechanical ventilation, NIV has the advantages of reducing patient discomfort, procedural complications, and mortality. However, NIV is associated with frequent uncomfortable or even life-threatening adverse effects, and patients should be thoroughly screened beforehand to reduce potential severe complications. We performed a detailed review of the relevant medical literature for NIV complications. All major NIV complications are potentially life-threatening and can occur in any patient, but are strongly correlated with the degree of pulmonary and cardiovascular involvement. Minor complications can be related to specific structural features of NIV interfaces or to variable airflow patterns. This extensive review of the literature shows that careful selection of patients and interfaces, proper setting of ventilator modalities, and close monitoring of patients from the start can greatly reduce NIV complications.