A comparative study of point-of-care protection from N95 filtering face-piece respirators in a Residential Aged Care Facility and a Tertiary Hospital-Respiratory protection challenges remain amidst long-term impacts of COVID-19.

This study compared the effectiveness of N95 FFRs in providing respiratory protection for healthcare staff in a residential aged care facility (RACF) and tertiary teaching hospital (TTH) who had previously passed their occupational respiratory protection program fit test. A total of 126 healthcare workers who were regularly using N95 FFRs and who had previously passed a fit test participated in this comparative study. In this study, participants were again fit tested with the PortaCount machine, and their self-assessed tolerability of wearing an N95 FFR was assessed using a standardized questionnaire. The main outcome measures included the pass rate of the fit test and the assessment of tolerability and comfort of the N95 FFR. Across all participants, the fit test pass rate was low (27%), indicating persistent gaps in respiratory protection programs for healthcare workers during the ongoing COVID-19 pandemic. Hospital workers were 3.7 times more likely to pass the test compared to their counterparts in RACFs (p < 0.001). It was also found that workers in RACFs reported higher levels of discomfort and overall dissatisfaction with N95 FFRs compared to hospital staff. These findings highlight the need for targeted interventions and improvements in respiratory protection practices beyond annual fit testing, particularly in RACFs, to ensure the safety of healthcare workers and the vulnerable population they serve.

Observable Atrial and Ventricular Fibrillation Episode Durations Are Conformant With a Power Law Based on System Size and Spatial Synchronization.

BACKGROUND: Atrial fibrillation (AF) and ventricular fibrillation (VF) episodes exhibit varying durations, with some spontaneously ending quickly while others persist. A quantitative framework to explain episode durations remains elusive. We hypothesized that observable self-terminating AF and VF episode lengths, whereby durations are known, would conform with a power law based on the ratio of system size and correlation length ([Formula: see text]. METHODS: Using data from computer simulations (2-dimensional sheet and 3-dimensional left-atrial), human ischemic VF recordings (256-electrode sock, n=12 patients), and human AF recordings (64-electrode basket-catheter, n=9 patients; 16-electrode HD-grid catheter, n=42 patients), conformance with a power law was assessed using the Akaike information criterion, Bayesian information criterion, coefficient of determination (R2, significance=P<0.05) and maximum likelihood estimation. We analyzed fibrillatory episode durations and [Formula: see text], computed by taking the ratio between system size ([Formula: see text], chamber/simulation size) and correlation length ([Formula: see text], measured from pairwise correlation coefficients over electrode/node distance). RESULTS: In all computer models, the relationship between episode durations and [Formula: see text] was conformant with a power law (Aliev-Panfilov R2: 0.90, P<0.001; Courtemanche R2: 0.91, P<0.001; Luo-Rudy R2: 0.61, P<0.001). Observable clinical AF/VF durations were also conformant with a power law relationship (VF R2: 0.86, P<0.001; AF basket R2: 0.91, P<0.001; AF grid R2: 0.92, P<0.001). [Formula: see text] also differentiated between self-terminating and sustained episodes of AF and VF (P<0.001; all systems), as well as paroxysmal versus persistent AF (P<0.001). In comparison, other electrogram metrics showed no statistically significant differences (dominant frequency, Shannon Entropy, mean voltage, peak-peak voltage; P>0.05). CONCLUSIONS: Observable fibrillation episode durations are conformant with a power law based on system size and correlation length.

A real-time signal processing software package for the electrophysiology laboratory.

BACKGROUND: Real-time signal processing has to date been difficult to implement in the clinical electrophysiology laboratory. To date, no open access software solutions are available in electrophysiology (EP) laboratories to facilitate real-time intraprocedural signal analysis. We aimed to develop an open access, scalable Python plug-in to allow real-time signal processing during human EP procedures. METHODS AND RESULTS: A Python-based plug in for the widely available EnsiteX mapping system was developed. This plug-in utilized the LiveSync feature of the system to allow real-time signal analysis. An open access library was developed to allow end-users to implement real-time signal analysis using this platform, implemented in the Python programming language https://github.com/anand9176/WaveWatch5000Public. CONCLUSION: We have developed and demonstrated the feasibility of a readily scalable and open-access Python-based plug in to an electroanatomic mapping system (EnSiteX) to allow real-time processing and display of electrogram (EGM) based information for the procedural electrophysiologist to view intraprocedurally in the electrophysiology laboratory. The availability, to the clinician, of traditional and novel EGM-based metrics at the time of intervention, such as atrial fibrillation ablation, allows for key mechanistic insights into critical unresolved questions regarding arrhythmia mechanism.

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.

Assessing Torque Transfer in Conduction System Pacing: Development and Evaluation of an Ex Vivo Model.

BACKGROUND: Conduction system pacing (CSP) faces challenges in achieving reliable and safe deployments. Complex interactions between tissue and lead tip can result in endocardial entanglement, a drill effect that prevents penetration. No verified ex vivo model exists to quantitatively assess this relationship. OBJECTIVES: The purpose of this study was to quantitatively characterize CSP lead tip to tissue responses for 4 commonly used leads. METHODS: CSP leads (from Medtronic, Biotronik, Boston Scientific, and Abbott) were examined for helix rotation efficiency in ex vivo ovine right ventricular septa. A custom jig was utilized for rotation measurements. Fifteen turns were executed, documenting tissue-interface changes every 90° using high-resolution photography. Response curves (input rotation vs helix rotation) were evaluated using piecewise linear regression, with a focus on output vs input response slopes and torque breakpoint events. RESULTS: We analyzed 3,840 quarter-turn CSP insertions with 4 different lead types. Helix rotations were consistently less than input: Abbott Tendril = 0.21:1, Medtronic 3830 = 0.21:1, Biotronik Solia = 0.47:1, and Boston Scientific Ingevity = 0.56:1. Torque breakpoint events were observed on average 7.22 times per insertion (95% CI: 6.08-8.35; P = NS) across all leads. In 57.8% of insertions (37 of 64), uncontrolled torque breakpoint events occurred, signaling unexpected excess helix rotations. CONCLUSIONS: Using a robust ex vivo model, we revealed a muted helix rotation response compared with input turns on the lead, and frequent torque change events during insertion. This is critical for CSP implanters, emphasizing the potential for unexpected torque breakpoint events, and suggesting the need for novel lead designs or deployment methods to enhance CSP efficiency and safety.

Percolation theory as a conceptual framework to explain spontaneous atrial fibrillation termination: a pilot study.

Atrial fibrillation (AF) strikingly possesses the ability to abruptly transition into more organized electrical activity and spontaneously terminate, even after persisting for long periods. Despite being central to the clinical behavior and treatment of AF, these phenomena remain incompletely understood. In this paper, we hypothesized that the spontaneous termination of AF may represent a type of percolation phase transition, which is more likely to occur when a domain spanning cluster of refractory sites in the atrium are connected (called a 'percolation cluster'). This was assessed in n=50 computational simulations of AF developed using the Aliev-Panfilov (APV) 2-dimensional cell model. In self-terminating simulations of AF, it was found that the average refractory cluster size, χ(p) (median: 647.7), and the largest refractory cluster size, M1 (median: 1702.3), abruptly increased just prior to AF spontaneously terminating, indicating the onset of the formation of a domain spanning percolation cluster. In contrast, simulations of sustained AF did not demonstrate an increase in χ(p) (median: 463.0) and M1 (median: 1448.2). Self-terminating AF simulations also demonstrated hallmark properties characteristic of a percolation phase transition, such as an abrupt increase in χ(p) at the critical occupation probability pc. The cluster size distribution was also shown to obey a power law for various occupation probabilities p, also indicative of a percolation phase transition. Collectively, these properties suggests that the spontaneous termination of AF could be a form of percolation phase transition, which could provide new insights for AF treatment.

Personalized 3D-printed frames to reduce leak from N95 filtering facepiece respirators: A prospective crossover trial in health care workers.

Correctly fitting N95 filtering facepiece respirators (FFRs) have become increasingly important in health care throughout the COVID-19 pandemic. We evaluated the hypothesis that personalized 3D-printed frames could improve N95 FFRs quantitative fit test pass rates and test scores in health care workers (HCWs). HCWs were recruited at a tertiary hospital in Adelaide, Australia (ACTRN 12622000388718). A mobile iPhone camera + app was used to produce 3D scans of volunteers' faces, which were then imported into a software program to produce personalized virtual scaffolds suited to each user's face and their unique anatomical features. These virtual scaffolds were printed on a commercially available 3D printer, producing plastic (and then silicone-coated, biocompatible) frames that can be fitted inside existing hospital supply N95 FFR. The primary endpoint was improved pass rates on quantitative fit testing, comparing participants wearing an N95 FFR alone (control 1) with participants wearing the frame + N95 FFR (intervention 1). The secondary endpoint was the fit factor (FF) in these groups, and R-COMFI respirator comfort and tolerability survey scores. N = 66 HCWs were recruited. The use of intervention 1 increased overall fit test pass rates to 62/66 (93.8%), compared to 27/66 (40.9%) for controls. (OR for pFF pass 20.89 (95%CI: 6.77, 64.48, p < 0.001.) Average FF increased, with the use of intervention 1-179.0 (95%CI: 164.3,193.7), compared to 85.2 (95%CI: 70.4,100.0) with control 1. Pass rates and FF were improved with intervention 1 compared to control 1 for all stages of the fit-test: bending, talking, side-to-side, and up-down motion. (p < 0.001 all stages). Tolerability and comfort of the frame were evaluated with the validated R-COMFI respirator comfort score, showing improvement with the frame compared to N95 FFR alone (p = 0.006). Personalized 3D-printed face frames decrease leakage, improve fit testing pass rates and FF, and provide improved comfort compared to the N95 FFR alone. Personalized 3D-printed face frames represent a rapidly scalable new technology to decrease FFR leakage in HCW and potentially the wider population.

Nanoscape, a data-driven 3D real-time interactive virtual cell environment.

Our understanding of cellular and structural biology has reached unprecedented levels of detail, and computer visualisation techniques can be used to create three-dimensional (3D) representations of cells and their environment that are useful in both teaching and research. However, extracting and integrating the relevant scientific data, and then presenting them in an effective way, can pose substantial computational and aesthetic challenges. Here we report how computer artists, experts in computer graphics and cell biologists have collaborated to produce a tool called Nanoscape that allows users to explore and interact with 3D representations of cells and their environment that are both scientifically accurate and visually appealing. We believe that using Nanoscape as an immersive learning application will lead to an improved understanding of the complexities of cellular scales, densities and interactions compared with traditional learning modalities.

Conformational dynamics data bank: a database for conformational dynamics of proteins and supramolecular protein assemblies.

The conformational dynamics data bank (CDDB, http://www.cdyn.org) is a database that aims to provide comprehensive results on the conformational dynamics of high molecular weight proteins and protein assemblies. Analysis is performed using a recently introduced coarse-grained computational approach that is applied to the majority of structures present in the electron microscopy data bank (EMDB). Results include equilibrium thermal fluctuations and elastic strain energy distributions that identify rigid versus flexible protein domains generally, as well as those associated with specific functional transitions, and correlations in molecular motions that identify molecular regions that are highly coupled dynamically, with implications for allosteric mechanisms. A practical web-based search interface enables users to easily collect conformational dynamics data in various formats. The data bank is maintained and updated automatically to include conformational dynamics results for new structural entries as they become available in the EMDB. The CDDB complements static structural information to facilitate the investigation and interpretation of the biological function of proteins and protein assemblies essential to cell function.