scholarly journals Modeling of aerosol transmission of airborne pathogens in ICU rooms of COVID-19 patients with acute respiratory failure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cyril Crawford ◽  
Emmanuel Vanoli ◽  
Baptiste Decorde ◽  
Maxime Lancelot ◽  
Camille Duprat ◽  
...  
Keyword(s):  
Ventilation System ◽  
Medical Personnel ◽  
Airborne Particles ◽  
Proof Of Concept ◽  
Dynamics Model ◽  
Treatment Unit ◽  
Normal Breathing ◽  
Air Flows ◽  
Boltzmann Method ◽  
Number Of Particles

AbstractThe COVID-19 pandemic has generated many concerns about cross-contamination risks, particularly in hospital settings and Intensive Care Units (ICU). Virus-laden aerosols produced by infected patients can propagate throughout ventilated rooms and put medical personnel entering them at risk. Experimental results found with a schlieren optical method have shown that the air flows generated by a cough and normal breathing were modified by the oxygenation technique used, especially when using High Flow Nasal Canulae, increasing the shedding of potentially infectious airborne particles. This study also uses a 3D Computational Fluid Dynamics model based on a Lattice Boltzmann Method to simulate the air flows as well as the movement of numerous airborne particles produced by a patient’s cough within an ICU room under negative pressure. The effects of different mitigation scenarii on the amount of aerosols potentially containing SARS-CoV-2 that are extracted through the ventilation system are investigated. Numerical results indicate that adequate bed orientation and additional air treatment unit positioning can increase by 40% the number of particles extracted and decrease by 25% the amount of particles deposited on surfaces 45s after shedding. This approach could help lay the grounds for a more comprehensive way to tackle contamination risks in hospitals, as the model can be seen as a proof of concept and be adapted to any room configuration.

scholarly journals Modeling of aerosol transmission of airborne pathogens in ICU rooms of COVID-19 patients with acute respiratory failure

2020 ◽  
Author(s):  
Cyril Crawford ◽  
Emmanuel Vanoli ◽  
Baptiste Decorde ◽  
Maxime Lancelot ◽  
Camille Duprat ◽  
...  
Keyword(s):  
Ventilation System ◽  
Medical Personnel ◽  
Airborne Particles ◽  
Proof Of Concept ◽  
Dynamics Model ◽  
Treatment Unit ◽  
Computer Fluid Dynamics ◽  
Air Flows ◽  
Boltzmann Method ◽  
Number Of Particles

ABSTRACTThe COVID-19 pandemic has generated many concerns about cross-contamination risks, particularly in hospital settings and Intensive Care Units (ICU). Virus-laden aerosols produced by infected patients can propagate throughout ventilated rooms and put medical personnel entering them at risk. Experimental results found with a schlieren optical method have shown that the air flows generated by a cough and normal breathing were modified by the oxygenation technique used, especially when using High Flow Nasal Canulae, increasing the shedding of potentially infectious airborne particles. This study also uses a 3D Computer Fluid Dynamics model based on a Lattice Boltzmann Method to simulate the air flows as well as the movement of numerous airborne particles produced by a patient’s cough within an ICU room under negative pressure. The effects of different mitigation scenarii on the amount of aerosols potentially containing SARS-CoV-2 that are extracted through the ventilation system are investigated. Numerical results indicate that adequate bed orientation and additional air treatment unit positioning can increase by 40% the number of particles extracted and decrease by 25% the amount of particles deposited on surfaces 45s after shedding. This approach could help lay the grounds for a more comprehensive way to tackle contamination risks in hospitals, as the model can be seen as a proof of concept and be adapted to any room configuration.

Wound Ventilation With Ultraclean Air for Prevention of Direct Airborne Contamination During Surgery

2004 ◽  
Vol 25 (4) ◽  
pp. 297-301 ◽  
Author(s):  
Mikael Persson ◽  
Jan van der Linden
Keyword(s):  
Operating Room ◽  
Median Number ◽  
Airborne Particles ◽  
University Hospital ◽  
Surgical Wound ◽  
Wound Model ◽  
Wound Contamination ◽  
Room Ventilation ◽  
Airborne Contamination ◽  
Number Of Particles

AbstractBackground and Objective:Despite the novelties in operating room ventilation, airborne bacteria remain an important source of surgical wound contamination. An ultraclean airflow from the ceiling downward may convey airborne particles from the surgical team into the wound, thus increasing the risk of infection. Therefore, similar ventilation from the wound upward should be considered. We investigated the effect of wound ventilation on the concentration of airborne particles in a wound model during simulated surgery.Design:Randomized experimental study simulating surgery with a wound cavity model.Setting:An operating room of a university hospital ventilated with ultraclean air directed downward.Interventions:Particles 5 um and larger were counted with and without a 5-cm deep cavity and with and with-out the insufflation of ultraclean air.Results:With the surgeon standing upright, no airborne particles could be detected in the wound model. In contrast, during simulated operations, the median number of particles per 0.1 cu ft reached 18 (25th and 75th percentiles, 12 and 22.25) in the model with a cavity and 15.5 (25th and 75th percentiles, 14 and 21.5) without. With a cavity, wound ventilation markedly reduced the median number of particles to 1 (range, 0 to 1.25;P< .001).Conclusions:To protect a surgical wound against direct airborne contamination, air should be directed away from the wound rather than toward it. This study provides supportive evidence to earlier studies that operating room ventilation with ultraclean air is imperfect during surgical activity and that wound ventilation may be a simple complement. Further clinical trials are needed.

scholarly journals Innovative HVAC System Using an Integrated Greenhouse for a Virtual Low Energy Office Building

2019 ◽  
Vol 111 ◽  
pp. 04011
Author(s):  
Catalin Lungu ◽  
Florin Baltaretu
Keyword(s):  
Natural Ventilation ◽  
Energy Use ◽  
Ventilation System ◽  
Office Building ◽  
Treatment Unit ◽  
Heating And Cooling ◽  
Venturi Effect ◽  
Innovative System ◽  
Air Intake ◽  
Air Humidification

In this paper the authors describe a HVAC innovative system using an integrated greenhouse for heating and cooling an office building. The ventilation system allows natural (night) or mechanical ventilation and the passive cooling during the summer, including cold storage in the building structure and the PCM plywood and the refrigeration energy use during the day. Natural ventilation occurs when the wind or the Venturi effect, created by the « hat » that supports the photovoltaic panels, is strong enough; otherwise, a variable speed exhaust fan mounted on top of the building is used. The plants inside the greenhouse can produce O2 under certain conditions necessary for refreshing the ventilation air. The environment of the greenhouse allows air humidification naturally, without the use of humidifiers. If the greenhouse is sufficiently insulated in winter, it can be used in the ventilation process: the air intake from offices through the greenhouse, humidified and enriched in O2 (premixed, if necessary, with fresh air) reaches the general air treatment unit, and then sent back. The process is similar in the summer, but without recirculation, due to the humidity of the air extracted from offices. Stale air humidification enhances the thermal transfer process from the desiccant collector.

scholarly journals Performance Analysis of the Ventilation System for a Surgical Operating Room in Egypt: A Case Study of Mataria Teaching Hospital in Cairo

2021 ◽  
Author(s):  
Philip Maxemos ◽  
abouelmagd abdelsamie ◽  
Hatem Sadek
Keyword(s):  
Laminar Flow ◽  
Operating Room ◽  
Teaching Hospital ◽  
Ventilation System ◽  
Experimental Studies ◽  
Airborne Particles ◽  
Airflow Distribution ◽  
Proposed Modification ◽  
High Level

Abstract The Design of the ventilation system in a hospital operating room plays a very important role, not only in providing thermal comfort and hygienic environment for the patients or staff, but also to ensure the scavenging of any contaminants or airborne particles in the operating room theatre that might leak from outside to the operating room or emitting from patients’ infections. The present study focuses at airflow distribution, temperature, humidity and velocity profiles in a surgical operating room. An operating room inside the Mataria teaching hospital in Cairo (Egypt) has been chosen for the study. Numerical and experimental studies were carried out, where the room was ventilated through laminar flow diffuser system and 100% fresh air. The air was released by four outlet grills: two grills at a low level of the floor and two grills at a high level of the floor. In this work, two cases are investigated. In case I, the air outlets have been installed on one side of the room (which already exists in the hospital); and in Case II, the air outlets have been installed on two opposite sides (the suggested case). The results showed that the proposed modification (Case II) performed better distribution of ventilation than Case I. Therefore, it is recommended to install air outlets in two different side areas inside the room in order to avoid the accumulation of contaminants.

scholarly journals Simulated operating room aerodynamics to improve air quality and prevent surgical site infections

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
G Messina ◽  
G Spataro ◽  
M Tarroni ◽  
G Cevenini
Keyword(s):  
Air Quality ◽  
Operating Room ◽  
Ventilation System ◽  
Surgical Site Infections ◽  
Simulation Software ◽  
University Hospital ◽  
Operating Table ◽  
Air Filtration ◽  
Air System ◽  
Air Flows

Abstract Background Proper operating room (OR) ventilation and air filtration are important measures to prevent infection of the surgical site and consequently reduce hospital stay and healthcare costs. In order to identify how changes in the air system can affect air quality, tailor-made researches need to be conducted in ORs. The aim of the study is to verify how a mobile air filtration system can affect the air quality of ORs when placed in different positions. Methods This is a descriptive study conducted during April and May 2018 in the University Hospital of Siena, Italy. We measured air flows through the vents of both the OR air system and a mobile novel air system unit, which includes a patented crystalline ultraviolet C reactor and an HEPA filter. Using a CAD 3D simulation software (SolidWorks 2017) the air flows interactions were simulated in the replicated OR. Results The device influenced the original airflows generated by the integrated OR ventilation system. Simulations have shown that when the device is positioned close to the wall with its intake beside the entrance and its outlet towards the operating table, air from outside can enter the room because the air intake from the device prevails over the internal pressure of the OR, increasing contamination. If the device is placed near the OR centre with its suction towards the operating table and its outlet towards the OR entrance, if the door is opened, airflows towards the outside of the room prevail, improving ability to retain outgoing contaminants. Conclusions The different positioning of mobile devices that generate clean air flows within ORs can have a significant impact on aerodynamics, which can turn can affect critical aspects of the surgical outcome. In order to achieve an effective device placement and orientation, OR-specific environmental measurements should be carried out. Key messages Movable devices may help boosting the performance of air systems in operating rooms. Every operating room needs a specific study in order to obtain the best profit.

scholarly journals Enhancement of Airborne Particles Removal in a Hospital Operating Room

2019 ◽  
Vol 16 (4) ◽  
pp. 7447-7463
Author(s):  
K. Y. Wong ◽  
H. M. Kamar ◽  
N. Kamsah
Keyword(s):  
Operating Room ◽  
Numerical Study ◽  
Ventilation System ◽  
Airborne Particles ◽  
Operating Table ◽  
Particle Removal ◽  
Discrete Phase Model ◽  
Air Velocity ◽  
Air Supply ◽  
Discrete Phase

This article presents the results of a numerical study to examine the transport of particles in an operating room equipped with an Econoclean ventilation system. Its aims are to reduce the number of particles falling onto the operating table. A simplified CFD model of the operating room was developed and validated based on the measured air velocity distribution. An SST k-ω turbulent flow model was used to simulate the airflow, while a discrete phase model was used to simulate the movement of the airborne particles. The effects of the standing posture of the surgical staff on the settlement of the particles on the operating table were examined. Results show that under the present ventilation system, when the surgical staff bend forward at an angle of 45°,  the number of airborne particles that tend to fall onto the operating table increased by 1.4-fold. Adding an exhaust grille to the operating room does not have any significant effects on the distribution of the airborne particles. However, when a larger air supply diffuser is also used, the number of airborne particles that settled on the operating table was reduced 4-fold. More airborne particles are transported towards the exhaust grilles, and more airborne particles accumulate below the operating table. The present study shows that the usage of large air supply diffuser in the operating room is capable of reducing the number of airborne particles fall onto the operating table. Also, it enhances the efficiency of airborne particle removal.

Upper Openings Ventilation System Study of the Building by the Lattice Boltzmann Model

2021 ◽  
Vol 406 ◽  
pp. 164-169
Author(s):  
Zine Elabidine Bouayed ◽  
Samir Houat
Keyword(s):  
Lattice Boltzmann ◽  
Numerical Study ◽  
Ventilation System ◽  
Lattice Boltzmann Model ◽  
Heat Temperature ◽  
Double Population ◽  
Boltzmann Method ◽  
Thermal Lattice Boltzmann ◽  
Boltzmann Model ◽  
Floor Heating

We present in this work a numerical study of a ventilation system in a room with two openings in the ceiling and a floor heating indicated by constant heat temperature. The double population thermal lattice Boltzmann method is used, with nine velocities model D2Q9 for the dynamic field and a five velocities model D2Q5 for the temperature field. The results are presented in the form of streamlines, temperature contour and velocity profile, and analysed as a function of the Richardson number.

Decreasing Airborne Contamination Levels in High-Risk Hospital Areas Using a Novel Mobile Air-Treatment Unit

2007 ◽  
Vol 28 (10) ◽  
pp. 1181-1186 ◽  
Author(s):  
V. Bergeron ◽  
G. Reboux ◽  
J. L. Poirot ◽  
N. Laudinet
Keyword(s):  
High Risk ◽  
Operating Room ◽  
High Efficiency ◽  
Nonthermal Plasma ◽  
Fungal Species ◽  
Airborne Particles ◽  
Treatment Unit ◽  
Air Treatment ◽  
Hospital Environments ◽  
Airborne Contamination

Objective.To evaluate the performance of a new mobile air-treatment unit that uses nonthermal-plasma reactors for lowering the airborne bioburden in critical hospital environments and reducing the risk of nosocomial infection due to opportunistic airborne pathogens, such asAspergillus fumigatus.Methods.Tests were conducted in 2 different high-risk hospital areas: an operating room under simulated conditions and rooms hosting patients in a pediatric hematology ward. Operating room testing provided performance evaluations of removal rates for airborne contamination (ie, particles larger than 0.5μm) and overall lowering of the airborne bioburden (ie, colony-forming units of total mesophilic flora and fungal flora per cubic meter of air). In the hematology service, opportunistic and nonpathogenic airborne fungal levels in a patient's room equipped with an air-treatment unit were compared to those in a control room.Results.In an operating room with a volume of 118 m3, the time required to lower the concentration of airborne particles larger than 0.5μm by 90% was decreased from 12 minutes with the existing high-efficiency particulate air filtration system to less than 2 minutes with the units tested, with a 2-log decrease in the steady-state levels of such particles (P<.01). Concurrently, total airborne mesophilic flora concentrations dropped by a factor of 2, and the concentrations of fungal species were reduced to undetectable levels (P<.01). The 12-day test period in the hematology ward revealed a significant reduction in airborne fungus levels (P<.01), with average reductions of 75% for opportunistic species and 82% for nonpathogenic species.Conclusion.Our data indicate that the mobile, nonthermal-plasma air treatment unit tested in this study can rapidly reduce the levels of airborne particles and significantly lower the airborne bioburden in high-risk hospital environments.

LATTICE BOLTZMANN SIMULATION OF A SINGLE CHARGED ELLIPTIC CYLINDER IN A NEWTONIAN FLUID

2004 ◽  
Vol 18 (17n19) ◽  
pp. 2757-2761 ◽  
Author(s):  
CAOYING ZHANG ◽  
HUILI TAN ◽  
MUREN LIU ◽  
LINGJIANG KONG ◽  
HAIPING FANG
Keyword(s):  
Newtonian Fluid ◽  
Lattice Boltzmann ◽  
Present Model ◽  
Elliptic Cylinder ◽  
Coulomb Force ◽  
Initial Condition ◽  
Two Dimensional ◽  
Dynamics Model ◽  
Lattice Boltzmann Simulation ◽  
Boltzmann Method

A two-dimensional dynamics model of an elliptic cylinder is derived by using the lattice Boltzmann method. With the present model, we have simulated the sedimentation of a single charged elliptic cylinder in a two-dimensional tube in a Newtonian fluid. Due to the polarizing effects and non-axial symmetry shape, there are the Coulomb force and the Coulomb torque on the elliptic cylinder during the sedimentation, which change its ordinary motion significantly. Comparing with the sedimentation of an un-charged elliptic cylinder under the same initial condition, we have further discussed the dynamics characteristics of the charged elliptic cylinder, and obtained some interesting results.

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