Search Results (177)

Under deep, high-intensity mining conditions, a high mineral pressure develops at the working face, which can easily cause floor heave deformation of the roadway. In this paper, with the geological conditions of Buertai coal mine as the background, through on-site monitoring and numerical simulation, the mechanism of strong dynamic pressure roadway floor heave is clarified and a cooperative control method for roadway floor heave deformation is proposed. The main conclusions are as follows: (1) The overall strength of the floor of this strong dynamic pressure roadway is low, which can easily cause roadway floor heave, and on-site multivariate monitoring of the mine pressure is carried out, which clarifies the evolution law of the mine pressure of the mining roadway and along-the-airway roadway. (2) Combined with FLAC3D numerical simulation software, we analyze the influence of coal seam depth and floor lithology on the stability of the roadway floor and find that both have a significant influence on the stability of the roadway. Under the condition of high-intensity mining, the floor will deteriorate gradually, forming a wide range of floor heave areas. (3) Based on the deformation and damage mechanism of the roadway floor, a synergistic control method of “roof cutting and pressure relief + floor anchor injection” is proposed and various technical parameters are designed. An optimized design scheme is designed for the control of floor heave in Buertai coal mine. Full article

Stenosis geometries are constrictions of a biological tube that can be found in many forms in the human body. Capturing the flow field in such geometries is important. For this purpose, simulations were performed using the generalised k-$\omega$ (GEKO) turbulence model to study flow through stenosis geometries with throat constrictions of 75, 50 and 25% area reduction. Laminar flow conditions of Re = 2000 and 1000 were applied and the results were compared with experimental data. The effect of four GEKO parameters ($C_{SEP}$, $C_{NW}$, $C_{JET}$ and $C_{MIX}$) on flow in the post-stenotic region was investigated by simulating a wide range of parameter values. Results showed that the $C_{MIX}$ parameter, combined with a modified GEKO blending function, had the greatest effect on axial velocity, velocity fluctuations and the location of the jet breakdown region. A $C_{MIX}$ value of 0.4 closely matched the experimental results for a 75% area reduction stenosis at $Re=2000$ and showed significant improvements over existing Reynolds-averaged Navier–Stokes models. The GEKO model was also able to closely match the axial velocity results predicted by previously published large-eddy simulation models under the same flow conditions. Furthermore, the GEKO model was applied to a realistic oral-to-tracheal airway model for a Reynolds number of 2000 and produced results consistent with the idealised stenotic tube. Full article

Introduction: Supraglottic airway devices play an important role in airway management in both pre-hospital as well as in-hospital settings. They are a well-recognised alternative to definitive airways in current medical practice. However, despite their wide use in clinical practice, little is known about their performance in patients with restricted access. This study aims to evaluate the time required to insert a supraglottic airway device and achieve a successful ventilation of four different devices in a simulated condition of an entrapped trauma patient with simultaneous cervical spine immobilisation. The ease-of-use and first-attempt success rate were also assessed. Methods: Fully qualified paramedics participated in this randomised, controlled manikin trial. A manikin with the cervical collar on was placed on the driver’s seat of a passenger car. Access to the manikin was only allowed from the front. The I-gel, the SLIPA, the LMA Supreme, and the Ambu AuraGain were evaluated. The time required to insert the device and achieve successful ventilation was recorded. The first-attempt success rate and the ease-of-use by the operator were also assessed. Results: The LMA Supreme required the shortest mean time to insert and ventilate the manikin, 10.5 s (±1.7) vs. 16.4 s (±8.4), p < 0.001. The use of the LMA Supreme was associated with the highest first-attempt success rate—88%. The SLIPA device outperformed all other studied devices with regard to ease-of-use and user-friendliness. Its mean score was 8.3 out of 10. Conclusions: The LMA Supreme was superior in terms of both the insertion-to-ventilation time as well as the first-attempt success rate. The SLIPA device was found to be easier to use and more user-friendly. Full article

The clinical efficacy of inhalation therapy in chronic respiratory diseases is fundamentally constrained by particle deposition patterns. This study employs computational fluid dynamics (CFD) and response surface methodology (RSM) to elucidate the mechanistic interplay of deposition determinants through multifactorial sensitivity mapping. The study comprises two key components: (i) the development of an accurate three-dimensional respiratory airway model spanning from the oral cavity to the fifth-generation bronchi and (ii) the integration of a Box–Behnken Design (BBD) experimental framework with computational fluid dynamics simulations. Furthermore, we developed a multifactorial regression model to analyze the synergistic interactions among deposition determinants. The study demonstrated a positive correlation between breath-holding time and drug deposition efficiency, revealing a hierarchical order of critical parameters: peak flow rate > breath-holding time > particle diameter. These findings have important implications for optimizing respiratory drug delivery strategies in clinical settings. Full article

Background/Objectives: Neonatal intubation is a complex procedure, often associated with low first-pass success rates and a high incidence of complications. Video laryngoscopes provide several advantages, including higher success rates, especially for novice clinicians, a magnified airway view that can be shared with supervisors, and the ability to record still or video images for debriefing and education. However, video laryngoscope devices vary, raising the possibility of differences in usability. Methods: The study used mixed methodology, including observations, semi-structured interviews, think-aloud techniques, high-fidelity simulations, function tests, and questionnaires to assess usability, defined by the clinician satisfaction, efficacy, and efficiency of six video laryngoscope devices; (1) C-MAC^® with Miller blade, (2) GlideScope^® Core^TM with Miller blade, (3) GlideScope^® Core^TM with hyperangle LoPro blade, (4) Koala^® Vision Ultra with Miller blade, (5) Koala^® Handheld with Miller blade, and (6) Parker Neonatal with Miller blade. Clinician satisfaction was determined by the System Usability Scale (SUS), National Aeronautics and Space Administration Task Load Index (NASA-TLX), and clinician preference. Device efficacy was determined by first-pass success, number of attempts, and overall success. Efficiency was assessed by time to successful intubation and function test completion rates. Results: Neonatal video laryngoscopes varied considerably in design, impacting usability. All devices were deemed suitable for neonatal intubation, with the Koala^® Handheld, C-MAC^®, and GlideScope^® Core ^TM Miller demonstrating the highest usability. Conclusions: This simulation-based study highlights substantial variability in neonatal video laryngoscope usability, indicating the need for further research into usability in the clinical setting. Full article

This literature review explores factors influencing neonatal ICU intubation success, compares outcomes across settings, and identifies strategies to improve outcomes in this vulnerable population. A PubMed search was conducted using relevant keywords related to neonatal tracheal intubation. Studies published in English from 2000 to 2024 were included, with additional sources identified through manual bibliography reviews. Extracted findings were qualitatively synthesized by themes such as procedural outcomes, intubation setting, and provider training level. Nearly half of all neonatal tracheal intubations (TIs) are unsuccessful, with the rate of tracheal intubation adverse events (TIAEs) increasing with each additional attempt. First-pass success rates (FPSRs) correlate with provider experience, with attending physicians achieving the highest rates across all settings. Video laryngoscopy is associated with improved outcomes, particularly in neonates with difficult airways; however, direct laryngoscopy (DL) remains more commonly used. Premedication has been shown to reduce TIAEs and enhance FPSR, yet it remains underutilized in clinical practice. Standardized protocols, improved simulation-based training, and multidisciplinary strategies are essential to reduce complications. Future research should prioritize optimizing airway management and evaluating the impact of otorhinolaryngologist involvement, especially in difficult airway cases. Full article

The COVID-19 pandemic raised global concerns about the shortage of ventilators and revealed the challenges of rapidly scaling up production to meet emergency needs. In response, numerous teams worldwide attempted to develop emergency and simple mechanical ventilators. Among these, the CoroVent ventilator was developed to meet the urgent need for ventilatory support in the Czech Republic. The aim of this study was to describe the innovative and simple design of the CoroVent emergency ventilator, evaluate its compliance with international safety and performance standards, verify its reliability under simulated clinical conditions, and demonstrate its suitability for use in crisis scenarios. CoroVent was designed with a focus on the clinical needs of patients with COVID-19 respiratory failure and to ensure safe ventilation while maintaining a simplified design. It features volume-controlled, pressure-limited mandatory ventilation and supports key adjustable parameters such as tidal volume, respiratory rate, inspiratory-to-expiratory time ratio, inspired oxygen fraction, and positive end-expiratory pressure (PEEP). The ventilator incorporates robust safety mechanisms, including alarms and a safety relief valve, to protect against excessive airway pressures. Results confirmed the ability to maintain consistent tidal volumes, stable PEEP, and precise pressure limitation over extended periods of use. The results showed that CoroVent met the essential international standards for accuracy, including those set by the UK Medicines and Healthcare products Regulatory Agency, U.S. Food and Drug Administration, and ISO 80601-2-12. Although production of these ventilators was stopped in 2021 as the Czech Republic managed the crisis and shortage of ventilators, the results validate their reliability as emergency ventilators and indicate their potential to support critical care needs in crisis situations. Full article

Background/Objectives: This retrospective study used computer fluid dynamics (CFD) to evaluate the medium-term changes in the upper airways (UA) airflow after rapid maxillary expansion (RME) in three age-matched groups with different degrees of adenoidal obstruction. Methods: The sample included Cone-Beam Computed Tomography (CBCT) of 67 adolescents taken before (T0) and 12 months after RME (T1) and divided into three cohorts: Control Group (CG, <25% obstruction: 24 subjects, mean age = 11.8 ± 1.3), Adenoids Group 1 (AG1, >25% <75% obstruction: = 22 subjects, mean age = 10.9 ± 1.5), Adenoids Group 2 (AG2, >75% obstruction: = 21 subjects, mean age = 11.2 ± 1.6). The airflow pressure, velocity and obstruction were simulated using computer fluid dynamics (CFD). Results: The pressure significantly improved in CG and AG1 groups while the velocity improved in AG1 as well as the prevalence of obstruction improvement. The airflow pressure and velocity changes could be attributed to the reduction of the resistances in the adenotonsillar region, which was remarkably more marked in the AG1. Conclusions: Alterations in the adenotonsillar region likely represent the most substantial factors influencing airflow changes after RME. The integration of anatomical and functional data, along with the identification of baseline patient characteristics, may facilitate the characterization of phenotypes most appropriate for initial management through either Rapid Maxillary Expansion (RME) or otolaryngologic (ENT) interventions. Full article

The COVID-19 pandemic highlighted the importance of mathematical modeling for understanding viral infection dynamics and accelerated its application into immunological research. Collaborative efforts among international research groups yielded a wealth of experimental data, which facilitated model development and validation. This study focuses on developing a modular mathematical model of the immune response, capturing the interactions between innate and adaptive immunity, with an application to SARS-CoV-2 infection. The model was validated using experimental data from middle-aged individuals with moderate COVID-19 progression, including measurements of viral load in the upper and lower airways, serum antibodies, CD4+ and CD8+ T cells, and interleukin-6 levels. Parameter optimization and sensitivity analysis were performed to improve the model accuracy. Additionally, identifiability analysis was conducted to assess whether the data were sufficient for reliable parameter estimation. The verified model simulates the dynamics of moderate, severe, and critical COVID-19 progressions using measured data on lung epithelium damage, viral load, and IL-6 levels as key indicators of disease severity. We also performed a series of validation scenarios to assess whether the model correctly reproduces biologically relevant behaviors under various conditions, such as immunity hyperactivation, co-infection with HIV, and interferon administration as a therapeutic strategy. The model was developed as a component of the Digital Twin project and represents a general immune module that integrates both innate and adaptive immunity. It can be utilized for further COVID-19 research or serve as a foundation for studying other infectious diseases, provided sufficient data are available. Full article

Background: Foreign body airway obstruction is a sudden emergency that can occur unexpectedly in healthy people, leading to severe consequences if immediate first aid is not provided. Unlike the Heimlich maneuver for adults, the first aid for infant choking is less widely known and more complex, making it difficult to explain verbally. This study aimed to assess the efficiency of using an animated graphics interchange format (GIF) to teach first aid for infant choking due to foreign bodies. Methods: Eighty adults who had not received recent training in choking first aid within the last two years were randomly assigned to either the auditory (n = 40) or audiovisual (n = 40) groups. The participants were asked to perform first aid on an infant manikin under the guidance of a researcher using a smartphone in a separate room. The auditory group received verbal instructions only, while the audiovisual group received animated GIFs on their smartphones along with verbal instructions simultaneously. The entire process was recorded with two cameras, and two emergency physicians reviewed the videos to assess the adequacy of the first aid administered. Results: The “infant position”, “supporting arm posture”, and “head tilt” were more adequate in the audiovisual group. The Instruction Performance scores were higher in the audiovisual group. There was no significant difference in the time required to administer first aid between the two groups. Conclusions: Audiovisual guidance using animated GIFs has been shown to effectively enhance the adequacy of first-aid performance for infant airway obstruction caused by foreign bodies. Full article

Airway mucus plays a critical role in respiratory health, with diseases such as cystic fibrosis (CF) being characterized by mucus that exhibits increased viscosity and altered viscoelasticity. In vitro models that emulate these properties are essential for understanding the impact of CF mucus on airway function and for the development of therapeutic strategies. This study characterizes a mucus mimic composed of xanthan gum and locust bean gum, which is designed to exhibit the rheological properties of CF mucus. Mucus concentrations ranging from 0.07% to 0.3% w/v were tested to simulate different states of bacterial infection in CF. Key rheological parameters, including yield stress, storage modulus, loss modulus, and viscosity, were measured using an HR2 rheometer with strain sweep, oscillation frequency, and flow ramp tests. The results show that increasing the concentration enhanced the mimic’s elasticity and yield stress, with values aligning with those reported for CF mucus in pathological states. These findings provide a quantitative framework for tuning the rheological properties of mucus in vitro, allowing for the simulation of CF mucus across a range of concentrations. This mucus mimic is cost-effective, readily cross-linked, and provides a foundation for future studies examining the mechanobiological effects of mucus yield stress on epithelial cell layers, particularly in the context of bacterial infections and airway disease modeling. Full article

Atmospheric turbulence leads to aircraft bumpiness. In current vertical wind-based eddy dissipation rate (EDR) estimation algorithms based on flight data, the inertial subrange is determined empirically. In application, specific aircraft bumpiness can only be described by an EDR indicator. In this study, the objective turbulence severity and aircraft-related bumpiness estimation were explored with an optimized inertial subrange. To obtain the inertial subrange, the minimum series length to estimate EDR was determined under different flight data sampling rate. In addition, the basic series length to estimate the inertial subrange was determined according to Blackman–Tukey spectra estimation theory. In aircraft-dependent bumpiness estimation, the unsteady vortex lattice method (UVLM) was designed to obtain an accurate aircraft acceleration response to turbulence. An in situ aircraft bumpiness estimation and bumpiness prediction method were further proposed. Simulation and experiments on real flight data testified the optimized aircraft-independent EDR estimation and aircraft-dependent bumpiness estimation successively. This study can be further applied to estimate the turbulence severity on a particular airway, while the bumpiness of specific aircraft can be predicted. Full article

Background/Objectives: The effect of rapid maxillary expansion (RME) on the nasal and pharyngeal airways in children remains uncertain. This retrospective study utilized computational fluid dynamics (CFD) to assess the changes in ventilation parameters caused by RME in children. Methods: Pre- and post-RME cone beam computed tomography (CBCT) images of 20 patients (4 males, mean age 13 ± 2 years) treated with RME for maxillary transverse insufficiency were evaluated. The RME treatment was conducted using two distinct techniques: tooth-borne and tooth-bone-borne. CFD simulations were used to investigate the airflow conditions (pressure and velocity) in the whole upper airway, nasal airway, and maxillary sinus. Morphological alterations and variations in ventilation parameters before and after RME treatment were statistically compared. The extent of changes in the morphological and ventilatory characteristics of the upper airway, depending on the type of RME, was assessed. Additionally, changes in the ventilation conditions of the upper airway, nasal airway, and maxillary sinus after RME treatment were statistically analyzed. Statistical analyses using IBM SPSS v22 (New York, USA) software included paired t-tests, Mann–Whitney U tests, Wilcoxon matched-pairs signed-rank tests, intraclass correlation coefficients, and coefficients of variation (p < 0.05). Results: The CFD study revealed a notable reduction in both air flow velocity and pressure after the RME treatment (p < 0.05). A statistically significant increase was seen in the parameters used to assess the morphological changes following RME treatment, including nasal width, anterior and posterior nasal cross-sectional area, intermaxillary and intermandibulary molar width, and oropharyngeal airway width (p < 0.05). Regarding the change in airway ventilation, there was no statistically significant difference between tooth-borne and tooth-bone-borne RME treatments (p > 0.05). Conclusions: RME not only treats orthodontic issues in childhood but also increases airflow, which enhances ventilation. CDF is an effective method for the detection of ventilation improvement. Full article

On-chip microfluidics are advanced in vitro models that simulate lung tissue’s native 3D environment more closely than static 2D models to investigate the complex lung architecture and multifactorial processes that lead to pulmonary disease. Current microfluidic systems can be restrictive in the quantities of biological sample that can be retrieved from a single micro-channel, such as RNA, protein, and supernatant. Here, we describe a newly developed large-scale airway-on-chip model that employs a surface area for a cell culture wider than that in currently available systems. This enables the collection of samples comparable in volume to traditional cell culture systems, making the device applicable to any workflow utilizing these static systems (RNA isolation, ELISA, etc.). With our construction method, this larger culture area allows for easier handling, the potential for a wide range of exposures, as well as the collection of low-quantity samples (e.g., volatiles or mitochondrial RNA). The model consists of two large polydimethylsiloxane (PDMS) cell culture chambers under an independent flow of medium or air, separated by a semi-permeable polyethylene (PET) cell culture membrane (23 μm thick, 0.4 μm pore size). Each chamber carries a 5 × 18 mm, 90 mm² (92 mm² with tapered chamber inlets) surface area that can contain up to 1–2 × 10⁴ adherent structural lung cells and can be utilized for close contact co-culture studies of different lung cell types, including airway epithelial cells, fibroblasts, smooth muscle cells, and endothelial cells. The parallel bi-chambered design of the chip allows for epithelial cells to be cultured at the air–liquid interface (ALI) and differentiation into a dense, multi-layered, pseudostratified epithelium under biological flow rates. This millifluidic airway-on-chip advances the field by providing a readily reproducible, easily adjustable, and cost-effective large-scale fluidic 3D airway cell culture platform. Full article

Background/objectives: Point-of-care ultrasound (POCUS) in the intensive care unit (ICU) has gained much attention in the last few years as an alternative to the classic ways of assessing and diagnosing life-threatening conditions in critical patients. During the COVID-19 pandemic, we proposed a POCUS protocol based on the airway, breathing, and circulation (ABC) approach to quickly evaluate and diagnose life-threatening diseases in critical patients with acute respiratory failure and shock, and later, we used it as a curriculum to teach POCUS to anesthesia and intensive care trainees. Methods: We developed an evaluation protocol where evaluators with experience in POCUS in critically ill patients had to assess the trainee’s ultrasound scan; this was based on the ABC protocol taught in the simulation laboratory and applied in a clinical setting at the bedside. Results: Statistically significant differences were observed in some categories evaluated regarding independence and diagnosis. Conclusion: Initial POCUS simulation-based training using an ABC POCUS protocol (that demonstrated good results in the simulation laboratory) is useful when transferring US skills to the bedside and is applicable in daily clinical practice with good results in terms of operator independence. Full article