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1.
PLoS One ; 16(11): e0260237, 2021.
Article in English | MEDLINE | ID: covidwho-1528725

ABSTRACT

Present day risk assessment on the spreading of airborne viruses is often based on the classical Wells-Riley model assuming immediate mixing of the aerosol into the studied environment. Here, we improve on this approach and the underlying assumptions by modeling the space-time dependency of the aerosol concentration via a transport equation with a dynamic source term introduced by the infected individual(s). In the present agent-based methodology, we study the viral aerosol inhalation exposure risk in two scenarios including a low/high risk scenario of a "supermarket"/"bar". The model takes into account typical behavioral patterns for determining the rules of motion for the agents. We solve a diffusion model for aerosol concentration in the prescribed environments in order to account for local exposure to aerosol inhalation. We assess the infection risk using the Wells-Riley model formula using a space-time dependent aerosol concentration. The results are compared against the classical Wells-Riley model. The results indicate features that explain individual cases of high risk with repeated sampling of a heterogeneous environment occupied by non-equilibrium concentration clouds. An example is the relative frequency of cases that might be called superspreading events depending on the model parameters. A simple interpretation is that averages of infection risk are often misleading. They also point out and explain the qualitative and quantitative difference between the two cases-shopping is typically safer for a single individual person.


Subject(s)
Basic Reproduction Number , COVID-19/transmission , Social Behavior , Aerosols , Diffusion , Humans , Inhalation , Models, Statistical , Monte Carlo Method , Restaurants/statistics & numerical data
3.
PLoS One ; 16(8): e0256609, 2021.
Article in English | MEDLINE | ID: covidwho-1376628

ABSTRACT

OBJECTIVES: Although, pre-operative inspiratory muscle training has been investigated and reported to be an effective strategy to reduce postoperative pulmonary complications, the efficacy of postoperative inspiratory muscle training as well as the proper load, frequency, and duration necessary to reduce the postoperative pulmonary complications has not been fully investigated. This study was designed to investigate the effect of postoperative high-load long-duration inspiratory muscle training on pulmonary function, inspiratory muscle strength, and functional capacity after mitral valve replacement surgeries. DESIGN: Prospective randomized controlled trial. METHODS: A total of one hundred patients (mean age 38.3±3.29years) underwent mitral valve replacement surgery were randomized into experimental (n = 50) and control (n = 50) groups. The control group received conventional physiotherapy care, while experimental group received conventional care in addition to inspiratory muscle training, with 40% of the baseline maximal inspiratory pressure targeting a load of 80% by the end of the 8 weeks intervention protocol. Inspiratory muscle training started on the patient's first day in the inpatient ward. Lung functions, inspiratory muscle strength, and functional capacity were evaluated using a computer-based spirometry system, maximal inspiratory pressure measurement and 6MWT respectively at 5 time points and a follow-up assessment was performed 6 months after surgery. Repeated measure ANOVA and post-hoc analyses were used (p <0.05). RESULTS: Group-time interactions were detected for all the studied variables (p<0.001). Between-group analysis revealed statistically significant postoperative improvements in all studied variables in the experimental group compared to the control group (p <0.001) with large effect size of η2 ˃0.14. Within-group analysis indicated substantial improvements in lung function, inspiratory pressure and functional capacity in the experimental group (p <0.05) over time, and these improvements were maintained at follow-up. CONCLUSION: High intensity, long-duration postoperative inspiratory muscle training is highly effective in improving lung function, inspiratory muscle strength, and functional capacity after mitral valve replacement surgeries.


Subject(s)
Cardiac Surgical Procedures/rehabilitation , Lung/physiopathology , Mitral Valve/surgery , Respiratory Muscles/physiology , Rheumatic Heart Disease/rehabilitation , Adult , Breathing Exercises , Female , Humans , Inhalation , Male , Middle Aged , Mitral Valve/physiopathology , Muscle Strength/physiology , Myocardium/pathology , Respiratory Muscles/surgery , Respiratory Physiological Phenomena , Rheumatic Heart Disease/physiopathology , Rheumatic Heart Disease/surgery , Spirometry , Young Adult
4.
Rev Sci Instrum ; 92(7): 074101, 2021 Jul 01.
Article in English | MEDLINE | ID: covidwho-1338585

ABSTRACT

A fluid mechanics model of inhaled air gases, nitrogen (N2) and oxygen (O2) gases, and exhaled gas components (CO2 and water vapor particles) through a facial mask (membrane) to shield the COVID-19 virus is established. The model was developed based on several gas flux contributions that normally take place through membranes. Semiempirical solutions of the mathematical model were predicted for the N95 facial mask accounting on several parameters, such as a range of porosity size (i.e., 1-30 nm), void fraction (i.e., 10-3%-0.3%), and thickness of the membrane (i.e., 10-40 µm) in comparison to the size of the COVID-19 virus. A unitless number (Nr) was introduced for the first time to describe semiempirical solutions of O2, N2, and CO2 gases through the porous membrane. An optimum Nr of expressing the flow of the inhaled air gases, O2 and N2, through the porous membrane was determined (NO2 = NN2 = -4.4) when an N95 facial mask of specifications of a = 20 nm, l = 30 µm, and ε = 30% was used as a personal protection equipment (PPE). The concept of the optimum number Nr can be standardized not only for testing commercially available facial masks as PPEs but also for designing new masks for protecting humans from the COVID-19 virus.


Subject(s)
COVID-19/prevention & control , Masks , SARS-CoV-2 , Biomechanical Phenomena , Carbon Dioxide , Equipment Design , Exhalation , Gases , Humans , Hydrodynamics , Inhalation , Mathematical Concepts , Membranes, Artificial , Models, Theoretical , N95 Respirators , Nitrogen , Oxygen , Personal Protective Equipment , Porosity , Steam
5.
Int J Mol Sci ; 22(15)2021 Jul 24.
Article in English | MEDLINE | ID: covidwho-1325682

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as with the influenza virus, has been shown to spread more rapidly during winter. Severe coronavirus disease 2019 (COVID-19), which can follow SARS-CoV-2 infection, disproportionately affects older persons and males as well as people living in temperate zone countries with a tropical ancestry. Recent evidence on the importance of adequately warming and humidifying (conditioning) inhaled air in the nasal cavity for reducing SARS-CoV-2 infectivity in the upper respiratory tract (URT) is discussed, with particular reference to: (i) the relevance of air-borne SARS-CoV-2 transmission, (ii) the nasal epithelium as the initial site of SARS-CoV-2 infection, (iii) the roles of type 1 and 3 interferons for preventing viral infection of URT epithelial cells, (iv) weaker innate immune responses to respiratory viral infections in URT epithelial cells at suboptimal temperature and humidity, and (v) early innate immune responses in the URT for limiting and eliminating SARS-CoV-2 infections. The available data are consistent with optimal nasal air conditioning reducing SARS-CoV-2 infectivity of the URT and, as a consequence, severe COVID-19. Further studies on SARS-CoV-2 infection rates and viral loads in the nasal cavity and nasopharynx in relation to inhaled air temperature, humidity, age, gender, and genetic background are needed in this context. Face masks used for reducing air-borne virus transmission can also promote better nasal air conditioning in cold weather. Masks can, thereby, minimise SARS-CoV-2 infectivity and are particularly relevant for protecting more vulnerable persons from severe COVID-19.


Subject(s)
Air , COVID-19/immunology , COVID-19/virology , Nasopharynx/immunology , Nasopharynx/virology , SARS-CoV-2/pathogenicity , Age Factors , COVID-19/genetics , Humans , Humidity , Inhalation , Sex Factors , Temperature
6.
Can Respir J ; 2021: 6638048, 2021.
Article in English | MEDLINE | ID: covidwho-1301736

ABSTRACT

Background: High-flow nasal cannula (HFNC) oxygen therapy has been recommended for use in coronavirus disease 2019 (COVID-19) patients with acute respiratory failure and many other clinical conditions. HFNC devices produced by different manufacturers may have varied performance. Whether there is a difference in these devices and the extent of the differences in performance remain unknown. Methods: Four HFNC devices (AIRVO 2, TNI softFlow 50, HUMID-BH, and OH-70C) and a ventilator with an HFNC module (bellavista 1000) were evaluated. The flow was set at 20, 25, 30, 35, 40, 45, 50, 60, 70, and 80 L/min, and the FiO2 was set at 21%, 26%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, and 90%. Then, one side of the cannulas was clipped to simulate the compression, bending, or blocking of the nasal cannulas. The flow and FiO2 of the delivered gas were recorded and compared among settings and devices. Results: The actual-flow and actual-FiO2 delivered by different settings and devices varied. AIRVO 2 had superior performance in flow and FiO2 accuracy. bellavista 1000 and OH-70C had good performance in the accuracy of actual-flows and actual-FiO2, respectively. bellavista 1000 and HUMID-BH had a larger flow range from 10 to 80 L/min, but only bellavista 1000 could provide a stable flow with an excessive resistance up to 60 L/min. TNI softFlow 50 had the best flow compensation and could provide sufficient flow with excessive resistance at 20-50 L/min. Conclusions: The variation in flow, FiO2 settings, and devices could influence the actual-flow and actual-FiO2 delivered. AIRVO 2 and OH-70C showed better FiO2 accuracy. TNI softFlow 50, bellavista 1000, and HUMID-BH could lower the risk of insufficient flow support due to accidental compression or blocking of the cannulas. In addition, ventilators with HFNC modules provided comparable flow and FiO2 and could be an alternative to standalone HFNC devices.


Subject(s)
Acute Kidney Injury/therapy , COVID-19 , Cannula , Inhalation/physiology , Oxygen Inhalation Therapy , Acute Kidney Injury/etiology , Analysis of Variance , COVID-19/complications , COVID-19/therapy , Cannula/classification , Cannula/standards , Comparative Effectiveness Research , Humans , Materials Testing/methods , Maximal Respiratory Pressures , Oxygen Inhalation Therapy/instrumentation , Oxygen Inhalation Therapy/methods , SARS-CoV-2 , Tidal Volume/physiology
8.
Biomech Model Mechanobiol ; 20(3): 1087-1100, 2021 Jun.
Article in English | MEDLINE | ID: covidwho-1107829

ABSTRACT

It is essential to study the viral droplet's uptake in the human respiratory system to better control, prevent, and treat diseases. Micro-droplets can easily pass through ordinary respiratory masks. Therefore, the SARS-COV-2 transmit easily in conversation with a regular mask with 'silent spreaders' in the most physiological way of breathing through the nose, indoor and at rest condition. The results showed that the amount of deposited micro-droplets in the olfactory epithelium area is low. Also, due to receptors and long droplet residence time in this region, the possibility of absorption increases in the cribriform plate. This phenomenon eventually could lead to brain lesion damage and, in some cases, leads to stroke. In all inlet flow rates lower than 30 L/min inlet boundary conditions, the average percentage of viral contamination for upper respiratory tract is always less than 50% and more than 50% for the lungs. At 6L/min and 15L/min flow rates, the average percentage of lung contamination increases to more than 87%, which due to the presence of the Coronavirus receptor in the lungs, the involvement of the lungs increases significantly. This study's other achievements include the inverse relationship between droplets deposition efficiency in some parts of the upper airway, which have the most deformation in the tract. Also, the increased deformities per minute applied to the trachea and nasal cavity, which is 1.5 times more than usual, could lead to chest and head bothers.


Subject(s)
COVID-19/transmission , COVID-19/virology , Models, Biological , Respiratory System/virology , SARS-CoV-2 , Adult , Air Microbiology , Algorithms , Biomechanical Phenomena , Brain/diagnostic imaging , COVID-19/diagnostic imaging , Computer Simulation , Disease Transmission, Infectious/statistics & numerical data , Humans , Hydrodynamics , Imaging, Three-Dimensional , Inhalation , Male , Models, Anatomic , Nose/virology , Pandemics , Particle Size , Respiratory Rate , Respiratory System/anatomy & histology , Respiratory System/diagnostic imaging , SARS-CoV-2/isolation & purification , SARS-CoV-2/pathogenicity , Stroke/diagnostic imaging , Stroke/etiology , Tomography, X-Ray Computed
9.
Pan Afr Med J ; 35(Suppl 2): 138, 2020.
Article in English | MEDLINE | ID: covidwho-1106484

ABSTRACT

Ground-glass opacity is a CT sign that is currently experiencing renewed interest since it is very common in patients with COVID-19. However, this sign is not specific to any disease. Besides, the possibility of false positive ground-glass opacity related to insufficient inspiration during the acquisition of the chest CT should be known. We report the case of a 36-year-old patient suspected of COVID-19 and in whom a second acquisition of chest CT was necessary to remove false ground-glass opacities that erroneously supported the diagnosis of COVID-19.


Subject(s)
Artifacts , Betacoronavirus , Clinical Laboratory Techniques , Coronavirus Infections/diagnostic imaging , Lung/diagnostic imaging , Pneumonia, Viral/diagnostic imaging , Tomography, X-Ray Computed/methods , Adult , COVID-19 , COVID-19 Testing , Coronavirus Infections/diagnosis , False Positive Reactions , Female , Humans , Inhalation , Pandemics , SARS-CoV-2
11.
Comput Methods Programs Biomed ; 200: 105843, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-921868

ABSTRACT

BACKGROUND AND OBJECTIVE: It is crucial to study the uptake of viral droplets in the human respiratory system to control, prevent, and treat diseases. METHODS: In this study, a well-verified real anatomical model was used; the passage of air in the human upper respiratory system computed using high-quality Computer Tomography (CT) images. Then, the airflow field, along with the coronavirus micro-droplets injection, was examined in this realistic model using the Fluid-Structure Interaction (FSI) method. The Discrete Phase Model (DPM) was used to solve the field, and with the help of it, the accurate assessment of the temporal and spatial motion of the deposition in the virus-impregnated droplets was obtained in vitro in the upper respiratory system. RESULTS: The results show that the amount of deposited micro-droplets in the nasal cavity area is meager at the inhalation only through the oral. However, it has the most residence time in this area. The most and least droplet absorption occurred in the oral cavity and larynx-trachea, respectively. Deposition efficiency is about 100% in 30 L/min flow rate and 10 µm diameter; in other words, no droplet enters the lungs. This study's other achievements include the relatively inverse relationship between droplets deposition efficiency in some parts of the upper airway, which have the most deformation in the tract. CONCLUSIONS: Utilization of a realistic model with accurate and precise computational analysis can end speculation about the deposition zone, accumulation, and the effects of the COVID-19 virus on the upper respiratory tract. On the other hand, recognizing the virus-containing droplet location can ease understanding the areas where the virus can first infect in the upper respiratory tract.


Subject(s)
COVID-19/transmission , Disease Transmission, Infectious , Inhalation , Mouth , Respiratory System/microbiology , SARS-CoV-2/pathogenicity , Humans , Models, Biological
12.
Math Biosci Eng ; 17(6): 6909-6927, 2020 10 12.
Article in English | MEDLINE | ID: covidwho-907612

ABSTRACT

A mathematical model is proposed that incorporates the key routes of COVID-19 resurgence: human-to-human transmission and indirect transmission by inhaling infectious aerosols or contacting public facilities with the virus. The threshold condition for the disease invasion is established, and the relationships among the basic reproduction number, peak value and final size are formulated. The model is validated by matching the model with the data on cases of COVID-19 resurgence in April of 2020 from Heilongjiang province in China, which indicates that the predictive values from the mathematical model fit the real data very well. Based upon the computations from the model and analytical formulae, we reveal how the indirect transmission from environmental pathogens contribute to the disease outbreak and how the input of asymptomatic individuals affect the disease spread. These findings highlight the importance of mass detection and environmental disinfection in the control of COVID resurgence.


Subject(s)
COVID-19/epidemiology , COVID-19/prevention & control , COVID-19/transmission , Disinfection/methods , Algorithms , Basic Reproduction Number , China/epidemiology , Computer Simulation , Disease Outbreaks , Disinfectants , Environmental Exposure/statistics & numerical data , Epidemiological Monitoring , Humans , Infection Control , Inhalation , Models, Theoretical , Risk Assessment/methods
13.
Spinal Cord Ser Cases ; 6(1): 87, 2020 09 17.
Article in English | MEDLINE | ID: covidwho-779971

ABSTRACT

INTRODUCTION: Respiratory complications (RC) are a leading cause of death after spinal cord injury (SCI) due to compromised immune function and respiratory muscle weakness. Thus, individuals with SCI are at high risk of developing COVID-19 related RC. Results of a SCI clinical trial showed a supervised respiratory muscle training (RMT) program decreased risk of developing RC. The feasibility of conducting unsupervised RMT is not well documented. Four publications (n = 117) were identified in which unsupervised RMT was performed. Significant improvements in respiratory outcomes were reported in two studies: Maximal Inspiratory and Expiratory Pressure (MIP40% and MEP25%, respectively), Peak Expiratory Flow (PEF9%), seated and supine Forced Vital Capacity (FVC23% and 26%, respectively), and Peak Cough Flow (28%). This review and case report will attempt to show that an inspiratory muscle training (IMT) home exercise program (HEP) is feasible and may prepare the respiratory system for RC associated with COVID-19 in patients with SCI. CASE PRESENTATION: A 23-year-old with tetraplegia (P1), history of mechanical ventilation, and hospitalization for RC, completed 27 IMT HEP sessions in one month. MIP and sustained MIP (SMIP) increased from baseline by 28% and 26.5%, respectively. Expiratory volumes and rates also improved (FVC, FEV1, and PEF: 11.7%, 8.3%, and 14.2%, respectively). DISCUSSION: The effects of COVID-19 on patients with SCI remains inconclusive, but recent literature and the results of this case suggest that unsupervised IMT is feasible and may limit the severity of RC in patients with SCI who contract COVID-19.


Subject(s)
Betacoronavirus , Breathing Exercises/methods , Coronavirus Infections/prevention & control , Inhalation/physiology , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Respiratory Tract Infections/prevention & control , Spinal Cord Injuries/therapy , COVID-19 , Coronavirus Infections/physiopathology , Humans , Male , Pneumonia, Viral/physiopathology , Quadriplegia/complications , Quadriplegia/physiopathology , Quadriplegia/therapy , Respiratory Tract Infections/physiopathology , SARS-CoV-2 , Spinal Cord Injuries/complications , Spinal Cord Injuries/physiopathology , Young Adult
14.
Int Forum Allergy Rhinol ; 10(10): 1173-1179, 2020 10.
Article in English | MEDLINE | ID: covidwho-640185

ABSTRACT

The coronavirus disease-2019 (COVID-19) pandemic has heightened the awareness of aerosol generation by human expiratory events and their potential role in viral respiratory disease transmission. Concerns over high severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) viral burden of mucosal surfaces has raised questions about the aerosol-generating potential and dangers of many otorhinolaryngologic procedures. However, the risks of aerosol generation and associated viral transmission by droplet or airborne routes for many otorhinolaryngology procedures are largely unknown. Indoor aerosol and droplet viral respiratory transmission risk is influenced by 4 factors: (1) aerosol or droplet properties; (2) indoor airflow; (3) virus-specific factors; and (4) host-specific factors. Herein we elaborate on known aerosol vs droplet properties, indoor airflow, and aerosol-generating events to provide context for risks of aerosol infectious transmission. We also provide simple but typically effective measures for mitigating the spread and inhalation of viral aerosols in indoor settings. Understanding principles of infectious transmission, aerosol and droplet generation, as well as concepts of indoor airflow, will assist in the integration of new data on SARS-CoV-2 transmission and activities that can generate aerosol to best inform on the need for escalation or de-escalation from current societal and institutional guidelines for protection during aerosol-generating procedures.


Subject(s)
Aerosols , COVID-19/transmission , Disease Transmission, Infectious/prevention & control , Otolaryngology/methods , SARS-CoV-2/physiology , Air Pollution, Indoor , COVID-19/prevention & control , Humans , Inhalation , Lipid Droplets , Pandemics
15.
Rev Esp Anestesiol Reanim (Engl Ed) ; 67(7): 367-373, 2020.
Article in Spanish | MEDLINE | ID: covidwho-607196

ABSTRACT

COVID-19 pandemic caused not only many deaths around the world but also made evident technical limitations of hospital and intensive care units (ICU). The growing demand of ICU ventilators in a short lapse of time constitutes one of the main community concerns. The main goal of this communication is to give simple solutions to transform a noninvasive ventilator in an invasive one for intubated patients. The proposal can be applied in two well defined strategies for the COVID-19 pandemic: To replace anesthesia workstations, leaving those machines to be used in patients. To apply this option in COVID-19 patients by way of a therapeutic "bridge", waiting for the release of a ventilator in the ICU.


Subject(s)
Betacoronavirus , Coronavirus Infections/therapy , Critical Care , Equipment Design/methods , Noninvasive Ventilation/instrumentation , Pneumonia, Viral/therapy , Ventilators, Mechanical , COVID-19 , Carbon Dioxide/metabolism , Filtration/instrumentation , Humans , Inhalation , Pandemics , Respiration, Artificial/instrumentation , SARS-CoV-2 , Simulation Training , Ventilators, Mechanical/supply & distribution
16.
Respir Physiol Neurobiol ; 280: 103474, 2020 09.
Article in English | MEDLINE | ID: covidwho-592467

ABSTRACT

AIM: To describe the response of breathing pattern and inspiratory effort upon changes in assist level and to assesss if changes in respiratory rate may indicate changes in respiratory muscle effort. METHODS: Prospective study of 82 patients ventilated on proportional assist ventilation (PAV+). At three levels of assist (20 %-50 %-80 %), patients' inspiratory effort and breathing pattern were evaluated using a validated prototype monitor. RESULTS: Independent of the assist level, a wide range of respiratory rates (16-35br/min) was observed when patients' effort was within the accepted range. Changing the assist level resulted in paired changes in inspiratory effort and rate of the same tendency (increase or decrease) in all but four patients. Increasing the level in assist resulted in a 31 % (8-44 %) decrease in inspiratory effort and a 10 % (0-18 %) decrease in respiratory rate. The change in respiratory rate upon the change in assist correlated modestly with the change in the effort (R = 0.5). CONCLUSION: Changing assist level results in changes in both respiratory rate and effort in the same direction, with change in effort being greater than that of respiratory rate. Yet, neither the magnitude of respiratory rate change nor the resulting absolute value may reliably predict the level of effort after a change in assist.


Subject(s)
Inhalation/physiology , Interactive Ventilatory Support/methods , Respiratory Rate/physiology , Work of Breathing/physiology , Aged , Aged, 80 and over , Airway Resistance , Critical Illness/therapy , Female , Humans , Lung Compliance , Male , Maximal Respiratory Pressures , Middle Aged , Tidal Volume
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