Effect of Face Masking on Transmission of SARS-CoV-2.

The efficacy of face masking for the public is not convincing to prevent the transmission of respiratory tract viruses such as SARS-CoV-2 when the criteria of evidence-based medicine are applied. This finding is mainly explained by the results from randomized-controlled trials (RCTs) when a high prevalence of the infection and a high compliance in mask wearing was assured. Throughout these studies no significant protective effect was observed. Observational studies with surgical masks describe a significant protective effect, but are prone to confounders such as physical distance. Respirators do not provide an additional health benefit compared to surgical or medical masks (RCTs). Community masks can even increase the risk of infection (RCTs). Based on the categories of evidence-based medicine, the efficacy results can best be categorized as conflicting evidence. Many relevant adverse events are described when masks are worn for hours such as dyspnea (12.2-52.8%), headache (3.9-73.4%), pruritus (0.0-60.0%), and skin reactions (0.0-85.0%). Their frequency is often higher with respirators. In future pandemics, masks should only be recommended or mandated for settings in which a clinically relevant health benefit can be expected, defined as the prevention of severe, critical or fatal disease, that clearly outweighs the expectable associated adverse reactions.

Using the Discharge Decision-Making System to Improve the Pressure on Family Members of Ventilator-Dependent Patients.

The relevant regulations for preparing ventilator-dependent patients for discharge to institutions or home care are cumbersome and there are numerous health and education materials, which make family members confused and make the decision to discharge very difficult. The purpose of this study is to explore the use of ventilator-dependent family members in critical care units. Discussion on the pressure before and after "Discharge Decision Assistance System web APP".

Effect of surgical mask and N95 respirator mask use on cerebrovascular reactivity.

Background and purpose:

Face masks are crucial parts of personal protective equipment (PPE) to reduce the risk of respiratory infections. The COVID-19 outbreak has increased healthcare workers’ use of face masks. This study aimed to evaluate changes in cerebrovascular response among healthcare workers using surgical and N95 respirator masks. 

90 healthcare workers: 30 wearing surgical masks, 30 wearing N95 respirators, and 30 without masks were included. After two-hour of face mask use, the baseline mean flow velocity (MFV) and the mean breath-holding index (BHI) of the bilateral middle cerebral arteries (MCAs) were evaluated with transcranial Doppler ultrasound. The presence of de-novo headache was recorded. BHI values ​​below 0.69 were evaluated as a sign of impaired cerebrovascular reactivity (CVR). 

The rate of de-novo headache was significantly higher in the N95 respirator mask group (p = 0.004). Compared to the control and surgical mask groups, the N95 respirator mask group had significantly lower values of the baseline MFV of the right MCA (p = 0.003 and p = 0.021, respectively) and mean BHI (p = 0.003 and p = 0.012, respectively). Still, only one N95 respirator mask user had a mean BHI value below 0.69.

Surgical masks did not signi­fi­cantly affect cerebral hemodynamics. Although N95 respirator mask use significantly decreased BHI values, the CVR is still within normal limits, and the development of de-novo headache is not directly associated with low CVR. 

Measurement of inward leakage of full-face masks in EN and ISO standards: comparison of gas and aerosol test agents.

In Europe, respiratory protective devices must be certified before they can be marketed. Among the parameters of interest, inward leakage (IL) characterizes the tightness between the face seal and the face, to verify that the device is well-designed. European standard EN 13274-1 (2001) and International Organization for Standardization (ISO) standard ISO 16900-1 (2019) specify that IL should be measured using sodium chloride (NaCl) aerosol or sulfur hexafluoride (SF6) gas. For reusable masks made of nonporous materials, both test agents are considered equally acceptable. However, the few studies that have compared IL values measured with various aerosols and gases have come to divergent conclusions. This work then aimed to measure IL with the test agents recommended by the standards to determine whether they are really equivalent. Since krypton (Kr) is an interesting candidate for replacing SF6 in standard tests, IL was assessed with SF6 and Kr simultaneously, and with NaCl aerosol using various calculation methods. Tests were carried out on 5 models of full-face masks donned on a headform connected to a breathing machine simulating 3 sinusoidal breathing rates of various intensities. The respirator fit on the headform was evaluated using a controlled negative pressure method to determine a manikin fit factor. Four scenarios were then tested to represent very poor, bad, good, and excellent fit. Gas concentration was measured using a mass spectrometer, and IL was calculated for SF6 and Kr. A combination of 3 devices allowed the determination of the number-based concentration of particles with diameters between 20 nm and 2 µm, and IL was calculated for each of the 33 channels, as well as using a cumulative number concentration. In addition, to comply with standards, a conversion was carried out to calculate IL using a cumulative mass concentration. The results of this work evidenced that the IL values measured with NaCl were systematically lower than those determined with gases. IL was also shown to vary with particle size, with a maximum value exceeding that calculated with cumulative concentrations (in number or mass). As part of the revision of the standards, protocols for measuring inward leakage should be redefined. On the one hand, acceptability thresholds should be re-evaluated according to the nature of the test agent (gas or aerosol), as it is clear that the 2 options do not give the same results for a given configuration. On the other hand, the aerosol leakage measurement protocol needs to be reworked to enable the measurement of a well-defined, robust, and reproducible inward leakage value.

International assessment results on non-NIOSH approved respirators by the national personal protective technology laboratory (NPPTL): a data note.

OBJECTIVES: Due to the COVID-19 pandemic and the shortage of the National Institute for Occupational Safety & Health (NIOSH)-approved N95 respirators, the Food and Drug Administration granted an Emergency Use Authorization to allow the use of non-NIOSH approved respirators provided that these respirators must undergo tests by a protocol of TEB-APR-STP-0059, similar methods of NIOSH standard testing procedure. This initiative safeguards the quality of respirators and the effectiveness of occupational protection. The dataset of all the testing results could benefit further analysis of COVID-19 infection rates in relation to different types of N95 respirators used and identify potential correlations of various test parameters in the testing system for validation. The analysis enhances understanding of the quality, effectiveness, and performance of N95 respirators in the prevention of respiratory infectious transmission and develops improved occupational safety measures. DATA DESCRIPTION: The dataset was transformed, transcribed, and compiled from the official testing data of non-NIOSH-approved N95 respirators reported in the NIOSH website under the Centers for the Disease Control and Prevention in the United States. The dataset included details of 7,413 testing results of N95 respirators (manufacturer, model, and maximum and minimum filtration efficiency) and test parameters (flow rate, initial filter resistance, and initial percent leakage). Supplementary items were added to increase the availability of data analysis and enhance the interpretability of the assessments of the quality of N95 respirators.

An Engineering Alternative to Lockdown During COVID-19 and Other Airborne Infectious Disease Pandemics: Feasibility Study.

BACKGROUND: Now and in the future, airborne diseases such as COVID-19 could become uncontrollable and lead the world into lockdowns. Finding alternatives to lockdowns, which limit individual freedoms and cause enormous economic losses, is critical. OBJECTIVE: The purpose of this study was to assess the feasibility of achieving a society or a nation that does not require lockdown during a pandemic due to airborne infectious diseases through the mass production and distribution of high-performance, low-cost, and comfortable powered air purifying respirators (PAPRs). METHODS: The feasibility of a social system using PAPR as an alternative to lockdown was examined from the following perspectives: first, what PAPRs can do as an alternative to lockdown; second, how to operate a social system utilizing PAPR; third, directions of improvement of PAPR as an alternative to lockdown; and finally, balancing between efficiency of infection control and personal freedom through the use of Internet of Things (IoT). RESULTS: PAPR was shown to be a possible alternative to lockdown through the reduction of airborne and droplet transmissions and through a temporary reduction of infection probability per contact. A social system in which individual constraints imposed by lockdown are replaced by PAPRs was proposed, and an example of its operation is presented in this paper. For example, the government determines the type and intensity of the lockdown and activates it. At that time, the government will also indicate how PAPR can be substituted for the different activity and movement restrictions imposed during a lockdown, for example, a curfew order may be replaced with the permission to go outside if wearing a PAPR. The following 7 points were raised as directions for improvement of PAPR as an alternative method to lockdown: flow optimization, precise differential pressure control, design improvement, maintenance method, variation development such as booth type, information terminal function, and performance evaluation method. In order to achieve the effectiveness and efficiency in controlling the spread of infection and the individual freedom at a high level in a social system that uses PAPRs as an alternative to lockdown, it was considered effective to develop a PAPR wearing rate network management system utilizing IoT. CONCLUSIONS: This study shows that using PAPR with infection control ability and with less economic and social damage as an alternative to nationwide lockdown is possible during a pandemic due to airborne infectious diseases. Further, the efficiency of the government's infection control and each citizen's freedom can be balanced by using the PAPR wearing rate network management system utilizing an IoT system.

Typical Misconceptions Pertaining to Facepiece Masks against Viral Aerosols.

Since the early stages of the COVID-19 pandemic, there have been debates regarding the transmission modes of contagious viruses, including the influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), along with its variants [...].

Bioprotective Respirator Assembled by Defective Carbon Nitride for Long-Term Light Triggered Health Protection.

Wearing face masks is the best way to stop the spread of respiratory infections. However, if masks are not sterilized, changing them too frequently can actually increase the risk of cross-contamination. Herein, the construction of an antipathogen photocatalytic mask with carbon vacancy-modified carbon nitride nanosheets (g-C3N4-VC Ns) coated on the non-woven fabrics of the out layer of the mask, offering effective and long-term protection against damaging pathogens when exposed to light is reported. The introduced carbon vacancies are found capable of creating energy-disordered sites and inducing energetic electric force to overcome the Coulomb interactions between electron-hole pairs, thus promoting the electron-hole separation to achieve a high generation of reactive oxygen species (ROS). Thanks to its high activity in generating ROS upon exposure to light, the as-prepared photocatalytic mask shows high pathogen sterilization performance. This, in turn, prolongs the mask's protective lifetime, decreases the need for regular replacement, and decreases medical waste production. The work demonstrated here opens new viewpoints in designing pathogens biocidal protective devices for health protection, offering significant promise in specific environment self-protection.

Infra-Red Imaging to Detect Respirator Leak in Healthcare Workers During Fit-Testing Clinic.

OBJECTIVE: This study addressed the problem of objectively detecting leaks in P2 respirators at point of use, an essential component for healthcare workers' protection. To achieve this, we explored the use of infra-red (IR) imaging combined with machine learning algorithms on the thermal gradient across the respirator during inhalation. RESULTS: The study achieved high accuracy in predicting pass or fail outcomes of quantitative fit tests for flat-fold P2 FFRs. The IR imaging methods surpassed the limitations of self fit-checking. CONCLUSIONS: The integration of machine learning and IR imaging on the respirator itself demonstrates promise as a more reliable alternative for ensuring the proper fit of P2 respirators. This innovative approach opens new avenues for technology application in occupational hygiene and emphasizes the need for further validation across diverse respirator styles. SIGNIFICANCE STATEMENT: Our novel approach leveraging infra-red imaging and machine learning to detect P2 respirator leaks represents a critical advancement in occupational safety and healthcare workers' protection.

Reliability analysis of respirators based on the analytic hierarchy process and multicriteria decision-making.

This study examined the reliability of respirators using hierarchical analysis and multicriteria decision-making. The hierarchical structure, which consists of three assessment criteria and six product assemblies as decision possibilities, reveals that the priority of evaluation criteria follows the trend of cost, complexity and technology. Face-piece, triple-piece and visor assemblies have the highest failure rate, according to an analysis of product reliability at the assembly level. However, according to the analysis at the parts level, the most likely failures are found in the face-piece, upper and lower visor frames, visor, head-harness, exhalation valve disc and exhalation valve seat. In addition, the Weibull distribution function (with a shape parameter >1) can be utilized to predict product reliability. Among the six defined product assemblies, according to the sensitivity analysis, the overall weight of the triple-piece assembly and the visor assembly has the most sensitivity to changes in the priority of evaluation criteria.

Reducing airborne transmissible diseases in perioperative environments.

The COVID-19 pandemic has transformed our understanding of aerosol transmissible disease and the measures required to minimise transmission. Anaesthesia providers are often in close proximity to patients and other hospital staff for prolonged periods while working in operating and procedure rooms. Although enhanced ventilation provides some protection from aerosol transmissible disease in these work areas, close proximity and long duration of exposure have the opposite effect. Surgical masks provide only minimal additional protection. Surgical patients are also at risk from viral and bacterial aerosols. Despite having recently experienced the most significant pandemic in 100 yr, we continue to lack adequate understanding of the true risks encountered from aerosol transmissible diseases in the operating room, and the best course of action to protect patients and healthcare workers from them in the future. Nevertheless, hospitals can take specific actions now by providing respirators for routine use, encouraging staff to utilise respirators routinely, establishing triggers for situations that require respirator use, educating staff concerning the prevention of aerosol transmissible diseases, and providing portable air purifiers for perioperative spaces with low levels of ventilation.

A critique of Occupational Safety and Health Administration's halfmask respirator assigned protection factor.

Halfmask air-purifying respirators are used by millions of workers to reduce inhaling air contaminants, both chemical (e.g., asbestos, styrene) and biological (e.g., SARS-CoV-2, Mycobacterium tuberculosis). In 2006, the federal Occupational Safety and Health Administration (OSHA) promulgated a standard that gave halfmask respirators an assigned protection factor (APF) of 10. This signified that OSHA assumes a fit-tested and trained wearer will experience a 10% maximum total inward leakage of contaminated air into the facepiece. To derive APF = 10, OSHA analyzed data from 16 workplace studies of the efficacy of halfmask respirators worn against particulate contaminants. In this commentary, I contend that, in considering the data, OSHA made several errors that overstated halfmask respirator efficacy. The errors were (i) failing to properly account for within-wearer and between-wearer variability in respirator efficacy; (ii) ignoring the effect of particle deposition in the respiratory tract; (iii) aggregating unbalanced data within and between studies, and effectively double-counting the data in some studies; and (iv) ignoring the effect that particle size exerts in penetrating respirator facepiece leak paths. The net result is that OSHA's APF = 10 can lead to excessive toxicant exposure for many workers.

Development of a rapid, multi-organisational, multi-modal assessment of a newly available disposable respirator.

BACKGROUND: A rapid large-scale evaluation of a newly available duckbill style P2/N95 respirator, the Care Essentials (CE) MSK-003, was required to determine its suitability for deployment into the Victorian healthcare service. The aims of this study were to assess the feasibility of establishing a rapid, multi-organisational and multi-modal evaluation of the respirator, and to investigate whether this respirator would meet the needs of healthcare workers. METHODS: The evaluation was a collaboration among three healthcare organisations - two tertiary hospitals in metropolitan Melbourne and a rural-based hospital. Participants were healthcare workers undertaking their routine fit tests. They were required to complete quantitative fit testing and a usability assessment survey on the CE MSK-003 respirator. The a priori performance criteria were set as fit test pass rate of >70%, plus satisfactory subjective overall comfort and performance assessments, defined as a rating of adequate, good, or very good in >90% of the cohort. RESULTS: A total of 1070 participants completed the multi-modal assessment within a month. Seventy-eight percent of participants passed their quantitative fit test. Over 90% of survey respondents reported that the CE MSK-003 was adequate, good or very good in terms of its overall comfort and performance assessments. CONCLUSION: We demonstrated that a multi-modal evaluation of a new respirator can be rapidly conducted with a high level of participation in a controlled, consistent manner across multiple organisations. The evaluation results of the CE MSK-003 respirator exceeded our predetermined (a priori) minimal criteria, making it suitable for broad distribution to healthcare organisations.

The Impact of the COVID-19 Pandemic on the Quality of Examination in Eye Clinics in the Czech Republic - Questionnaire Study.

PURPOSE: The aim of the study was to map the behavior of ophthalmologists regarding protective equipment during the COVID-19 pandemic (coronavirus disease 2019), both during the time of the mandatory restrictive measures and after their relaxation. Another aim was to evaluate the awareness of ophthalmologists in the Czech Republic about the possible impact of nose and mouth protective measures (masks, respirators) on the quality of eye examinations, especially on the results of standard automated perimetry (SAP) and intraocular pressure (IOP) measurement. MATERIALS AND METHODS: As part of two professional ophthalmological events in the Czech Republic, which took place in 2022, we obtained and evaluated data from the ophthalmologists in attendance using a questionnaire. We evaluated demographic parameters, frequency of use and type of nose and mouth protective equipment and their influence on the quality of ophthalmological examination as well as the awareness of ophthalmologists about their possible influence on the outcome of SAP and IOP measurements. RESULTS: We obtained data from a total of 212 respondents (148 women, 44 men, in 20 cases gender was not stated). In 91.5% of cases, ophthalmologists agreed that the use of respirators and masks makes ophthalmological examination more difficult. The most common problems were eyepiece fogging (85.8%), examination lens fogging (85.8%), and lens fogging when spectacles correction was prescribed (79.2%). The respondents most often combated these problems either by completely removing the respirator (24.1%) or at least by pulling it under the nose (39.2%). At the time when the measures were relaxed, significantly more men did not use any nose and mouth protection at all during ophthalmological examinations (15.8% of men vs. 4.2% of women; p = 0.032). An alarming finding was the fact that 35.6% of respondents did not know whatsoever whether the nurse was performing a perimetry examination on a patient with a respirator/mask or without protective equipment, i.e. they were not aware whatsoever of the possible formation of artifacts. Only 21.2% of respondents were aware of the possible difficulties of measuring IOP while wearing a respirator, while 59.9% of respondents were not aware of this risk (39.6% had never considered this problem, 20.3% of respondents were convinced that a respirator could not have an effect on the measurement of IOP). CONCLUSION: The use of nose and mouth protective equipment clearly affects the ophthalmological examination and makes it more difficult. Although ophthalmologists belong to a group at high risk for the possible transmission of infection in the performance of their profession, they often removed nose and mouth protection in an effort to eliminate fogging of eyepieces and examination lenses. The awareness of ophthalmologists regarding the possible influence on the results of SAP and IOP measurement by wearing a respirator was low in our questionnaire survey. It is therefore advisable to discuss this issue more widely and warn doctors about these risks.

Development of Korean Representative Headforms for the Total Inward Leakage Testing on Filtering Facepiece Respirators.

Background: The lack of headforms that accurately reflect the head characteristics of Koreans and the demographic composition of the Korean population can lead to inadequate FFR testing and reduced effectiveness of FFRs. Method: Direct measurements of 5,110 individuals and 3D measurements of 2,044 individuals, aged between 9 and 69 years, were sampled from the data pool of Size Korea surveys based on the age and gender ratios of the Korean resident demographics. Seven head dimensions were selected based on the ISO 16976-2, availability of Size Korea measurements, and their relevance to the fit performance of FFRs. A principal component analysis (PCA) was performed using the direct measurements to extract the main factors explaining the head characteristics and then the main factors were standardized and remapped to 3D measurements, creating five size categories representing Korean head shapes. Lastly, representative 3D headforms were constructed by averaging five head shapes for each size category. Results: The study identified two main factors explaining Korean head characteristics by the PCA procedure specified in ISO 16976-2 and developed five representative headforms reflecting the anthropometric features of Korean heads: medium, small, large, short & wide, and long & narrow. Conclusion: This study developed representative headforms tailored to the Korean population for conducting total inward leakage (TIL) tests on filtering facepiece respirators (FFRs). The representative headforms can be used for TIL testing by employing robotic headforms to enhance the performance of FFRs for the Korean target population.

Respiratory fit test panel representing population of Malaysia.

BACKGROUND: The existing respiratory fit test panels (RFTPs) are based on Bivariate and Principal Component Analysis (PCA) which utilise American and Chinese head and facial dimensions. As RFTPs based on local facial anthropometric data for Malaysia are not available, this study was conducted with the aim to develop new RFTPs using Malaysian data. METHODOLOGY: A cross-sectional study was conducted across Malaysia among 3,324 participants of the study of National Health and Morbidity Survey 2020 aged 18 and above. Ten head and facial dimensions were measured. Face length and face width were used to construct bivariate facial panel, whereas the scores from the first two PCA were used to develop the PCA panel. RESULTS: This study showed that Malaysians have the widest upper limit for facial width. It also found that three factors could be reduced from the PCA analysis. However only 2 factors were selected with PCA 1 representing head and facial size and PCA 2 representing facial shape. Our bivariate panel could accommodate 95.0% of population, while our PCA panel accommodated 95.6%. CONCLUSION: This was the first study to use Malaysian head and facial anthropometry data to create bivariate and PCA panels. Respirators constructed using these panels are likely to fit ≥ 95.0% of Malaysia's population.

Face anthropometry for filtering facepiece respirators: analysis of the association between facial dimensions and respirator fit.

OBJECTIVE: Ensuring proper respirator fit for individuals remains a persistent challenge in occupational environments, yet there is limited knowledge about how respirators interact with the face to "'fit." Previous studies have attempted to understand the association between face dimensions and respirator fit using traditional head/face anthropometry not specifically tailored for respirators. The purpose of this study was to assess and compare the ability of filtering facepiece respirator (FFR)-specific face anthropometry with traditional head/face anthropometry in exploring the relationship between facial dimensions and the fit of FFR. METHODS: The study utilized 3D face scans and quantitative fit factor scores from 56 participants to investigate the relationship between face anthropometry and FFR fit. Both FFR-specific and traditional anthropometric measurements were obtained through 3D anthropometric software. Intra-correlation of anthropometry was analyzed to evaluate the efficiency and effectiveness of FFR-specific and traditional anthropometry respectively. Principal component analysis (PCA) was conducted to test the usefulness of the PCA method for investigating various facial features. Logistic regression was used to develop fit association models by estimating the relationship between each face measurement set and the binary outcome of the fit test result. The prediction accuracy of the developed regression models was tested. RESULTS: FFR-specific face anthropometry consists of a set of measurements that can inform the detailed facial shape associated with the FFRs more effectively than traditional head/face anthropometry. While PCA may have been effective in reducing the variable dimensions for the relatively large parts of the human body such as upper and lower bodies in previous literature, PCA results of FFR-specific and traditional anthropometry were inconsistent and insufficient to describe face dimensions with complex anatomy in a small-detailed area, suggesting that facial shape should be understood through a variety of approaches including statistical methods. Logistic regression analysis results confirmed that the association models of FFR-specific face anthropometry were significant with higher prediction accuracy and had a better model's goodness of fit than those of traditional head/face anthropometry in 3 conditions inputting all measurements, all PC scores, or top 5 measurements from PCA. CONCLUSIONS: The findings showed that the FFR fit association model enables an understanding of the detailed association between face and respirator fit and allows for the development of a system to predict respirator fit success or failure based on facial dimensions. Future research would include testing the validity of the model and FFR-specific measurement set on different respirator types, expanding the population set, and developing an integrated approach using automated and machine learning technologies to inform FFR selection for occupation workers and the general population.

Perfusion Pressure and the Histology of Brain Death: A Unique Case in an Infant Maintained on Life Support.

Brain death is a not uncommon phenomena in the adult and pediatric population. Most cases are removed from life support soon after brain death is declared. Less commonly, systemic perfusion is maintained by life support for some time after neurologic function stops. These cases present uncommon opportunities to explore the histology of necrosis and autolysis in the context of global hypoxic ischemic damage. Here, we describe the unusual case of an infant maintained on life support for 2 weeks after brain death was declared with an emphasis on the resulting gross and histologic findings including a discussion of their underlying physiology.

Using the Number of N95® Filtering Facepiece Respirator Models as an Indicator of Supply Chain Stability in a US Health-Care System.

OBJECTIVES: Personal protective equipment (PPE) supply chain disruptions force US health-care entities to adopt conservation strategies such as procurement from different respirator manufacturers. This research seeks to better understand how the number of respirator models on hand can serve as an indicator of N95 filtering facepiece respirator (FFR) supply chain stability or disruption. METHODS: Researchers looked at differences in the mean number of N95 FFR models, averaged weekly, from 10 hospitals in a health-care system over 15 wk from June 1 to September 10, 2020. Participating hospitals entered near-daily PPE inventory data by manufacturer and model number. RESULTS: A linear mixed effect model was run in SPSS v. 26 using a random intercept for hospitals, with week as a fixed predictor and mean number of respirator models (averaged weekly) on hand as the dependent variable. Each week showed a small but significant effect compared with the past week (P < 0.001), where the average weekly number of respirator models on hand decreased. CONCLUSIONS: The limited data may indicate a resolution of supply chain disruptions and warrant further investigation. Consequently, the number of respirator models may be applicable as an indicator of supply chain stability and be more easily ascertained and tracked by health-care entities.