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Numerical study of temperature-controlled airflow in comparison with turbulent mixing and laminar airflow for operating room ventilation
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.ORCID iD: 0000-0003-1882-3833
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.ORCID iD: 0000-0002-9361-1796
2018 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 144, p. 45-56Article in journal (Refereed) Published
Abstract [en]

Operating room (OR) ventilation is crucial for reducing airborne bacteria-carrying particles (BCPs) concentration and thus preventing post-operative infections. A variety of ventilation schemes have been introduced to ORs. This study explores the effectiveness of a newly developed ventilation scheme, temperature-controlled airflow (TAF), with respect to reducing BCPs distribution and sedimentation in an OR. Comparisons are made with the conventional turbulent mixing and laminar airflow (LAF) ventilation. The study is conducted using Computational Fluid Dynamics (CFD) and Lagrangian particle tracking (LPT), with numerical models validated against literature data. The results reveal that TAF represents reliable and effective ventilation and can serve as an energy-efficient alternative to the LAF systems. The results also show that increasing ventilation rates alone will not always result in better control of BCPs distribution. Airflow patterns play an important role in removing and diluting airborne BCPs, so a specific analysis is necessary to each design of OR ventilation.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD , 2018. Vol. 144, p. 45-56
Keywords [en]
Operating room ventilation, Bacteria-carrying particles, Temperature-controlled airflow, Laminar airflow, Turbulent mixing ventilation
National Category
Construction Management
Identifiers
URN: urn:nbn:se:kth:diva-238119DOI: 10.1016/j.buildenv.2018.08.010ISI: 000447484300005Scopus ID: 2-s2.0-85051404343OAI: oai:DiVA.org:kth-238119DiVA, id: diva2:1268314
Note

QC 20181205

Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2019-11-05Bibliographically approved
In thesis
1. Ventilation Performance in Operating Rooms: A Numerical Assessment
Open this publication in new window or tab >>Ventilation Performance in Operating Rooms: A Numerical Assessment
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Surgical site infections (SSIs) remain one of the most challenging postoperative complicationsof healthcare and threaten the lives of millions of patients each year. Current evidence hasshown a positive relationship between the airborne concentration of bacteria-carryingparticles (BCPs) in the operating room (OR) and the rate of infections. The OR ventilation iscrucial for mitigating the dispersion of airborne bacterial contaminants and thus controllingthe risk of SSIs. A variety of ventilation schemes have been developed for OR use. Each haspros and cons and may be better suited than another for operations under certain conditions.The proper functioning of OR ventilation is also affected by external and internal disruptions.By applying Computational Fluid Dynamics (CFD), the present study investigates the airflowand contaminant distribution in ORs under different conditions.The airflow distribution is of critical importance in removing or diluting airbornecontaminants. The conventional mixing ventilation is not able to reliably create an ultracleanenvironment. The usage of mixing ventilation in infection-prone surgery should be limited,especially when a large surgical team is involved. Laminar airflow (LAF) ventilation demandsa sufficient airflow rate to achieve desired performance. Temperature-controlled airflow(TAF) ventilation represents an effective ventilation scheme that can serve as an energyefficientalternative to LAF.Door openings have a detrimental impact on the microbiological cleanliness of the OR. Thetemperature in the OR and adjacent space should be well controlled to minimize the interzonalcontaminant transfer. Temporarily reducing the OR exhaust flow during door operationforms a directional airflow towards the adjacent space, which is found to be an effectivesolution to ensure the isolation.Surgical lamps serve as physical obstructions in the airflow path and significantly deterioratethe performance of LAF ventilation. It is highly recommended to improve the shape anddesign of the lamps in the LAF ventilation. TAF is found to be less sensitive to the presenceof surgical lamps in the airflow path. The buoyancy-driven airflow used by TAF is morecapable of circumventing obstacles than the inertia-driven flow used by LAF. Thermal plumesdeveloped from the surgical equipment in the OR have the potential to distort the buoyancydrivenairflow in TAF.The thesis conducts a comprehensive literature review of important topics in OR ventilation.The present study enhances the understanding of the strengths and limitations of differentventilation schemes and increases the knowledge of the design and usage of OR ventilation.

Abstract [sv]

Postoperativa infektioner tillhör idag de mest utmanande komplikationerna inom sjukvården. De utsätter årligen miljontals patienter för allvarlig hälsofara. Bevis finns för ett samband mellan luftburen koncentration av bakteriebärande partiklar i operationssalen och infektionsfrekvensen. Ventilationen i operationssalen är avgörande för att minimera spridningen av luftburna bakteriella föroreningar och därmed kontrollera risken för postoperativ infektion. För ventilation i operationsrum har olika luftföringsprinciper utvecklats. Dessa har för- och nackdelar och vissa kan vara bättre lämpade än andra under givna förhållanden. Ventilationens funktion påverkas också av yttre och inre störningar. Med numeriska beräkningsmetoder (CFD) undersöks i denna avhandling luftflöden och föroreningsspridning i operationsrum.

Såväl luftflödets fördelning i rummet som luftflödets volym är av avgörande betydelse för eliminering och utspädning av luftburna föroreningar. Konventionell omblandande ventilation har såväl teoretiska som praktiska begränsningar i detta sammanhang och dess användning bör därför begränsas vid infektionsbenägen operation. Detta gäller särskilt vid stora operationsteam. Ventilation med så kallat laminärt luftflöde (LAF) kräver tillräckligt luftflöde för att uppnå önskat resultat. Ventilation med temperaturstyrt luftflöde (TAF) har befunnits vara ett (energi)effektivt alternativ till LAF.

Dörröppningar till operationssalen har negativ inverkan på den mikrobiologiska renheten i rummet. Temperaturen i operationsrummet och angränsande utrymme bör kontrolleras väl för att minimera överföring av föroreningar mellan zonerna. Genom att tillfälligt reducera frånluftflödet i operationsrummet under dörrdrift bildas ett riktat luftflöde mot intilliggande utrymmen som effektiv visat sig säkerställa isoleringen.

Vissa kirurgiska lampor fungerar som fysiska hinder i luftflödesvägen och försämrar avsevärt funktionen vid LAF-ventilation. Därför rekommenderas starkt att inte förbise lampans form och placering. TAF-ventilation har visat sig vara mindre känslig för kirurgiska lampor i luftflödesvägen. Det termiskt drivna luftflödet vid TAF syns mera kapabelt att klara hinder än tröghetsdrivet flöde vid LAF. Värmeplymer som den kirurgiska utrustningen genererar i operationsrummet kan påverka det termiskt drivna luftflödet vid TAF.

Avhandlingen innehåller en omfattande litteraturstudie inom området. Avhandlingen ökar förståelsen för olika ventilationsprincipers funktion och kunskapen om hur ventilation skall användas i sjukhusmiljöer.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. 79
Series
TRITA-ABE-DLT ; 1939
Keywords
operating room ventilation, bacteria-carrying particles, laminar airflow, mixing ventilation, temperature-controlled airflow, computation fluid dynamics, Lagrangian particle tracking
National Category
Civil Engineering
Research subject
Civil and Architectural Engineering; Civil and Architectural Engineering, Fluid and Climate Theory
Identifiers
urn:nbn:se:kth:diva-263301 (URN)978-91-7873-338-5 (ISBN)
Public defence
2019-11-27, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20191105

Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2019-11-05Bibliographically approved

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