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(c) Zhijian Liu, Di Yin, Lina Hu, Junzhou He, Guoqing Cao (2022) 

Bacteria-carrying particles diffusion in the operating room due to the interaction between human thermal plume and ventilation systems: An experimental-numerical simulation study

During surgery, the release of bacterial-carrying particles (BCPs) by surgeons is one of the major pollution sources in operating rooms (ORs), which may cause surgical site infection (SSIs) or health problems. The human thermal plume emitted by the human body may affect the airflow in the surgical micro-environment, leading to the further spread of BCPs. The experiments of airspeed measurements and biological particle emission were carried out in a standard vertical laminar ventilation operating room. Computational fluid dynamics (CFD) was used to extend the investigation of the different ventilation systems. The TcAF (called TAF in the article) ventilation system was superior to the other three systems in reducing BCPs levels in the air of the operating room.

(b) Bulitta C., Schlautmann B. (2020)

Relevance and implications of positioning analysis for infection-preventive effectiveness of ventilation systems with low-turbulence dis-placement flow

Ventilation technology in German operating rooms is regulated by DIN 1946-4. Since the release of the latest version in 2018, a positioning analysis (worst-case scenario with the largest space requirement) for determining the required protected area in class 1a operating rooms is mandatory. The aim of this investigation was to use typical workflow scenarios to assess existing installations regarding the match of the required and the built size of the protected area. Positioning analyses were carried out together with the on-site staff for various clinical procedures in 2 hospitals to assess the built versus required protected areas. In all cases, the positioning analysis revealed that required protected areas need to be significantly larger than provided by the existing setup. The size of the protected area that is actually required can only be determined by individual positioning analysis. Most existing installations of low turbulence displacement flow systems (TAV) are likely to be too small. The larger protected areas actually require significantly larger rooms in order to maintain proper thermodynamics. Furthermore, significantly higher volumetric flow rates are required. Finally, the current mismatch between actual and necessary protected area would be a possible explanation for the controversial data situation regarding the infection preventive effects of TAV systems.

(a) Alsved, M., Civilis, A., Ekolind, P., Tammelin, Erichsen-Andersson A., Jakobsson, J., Svensson, T.; Ramstorp, M.; Sadrizadeh, S., Lars- son, P.-A., Bohgard, M. Šantl-Temkiv, T. & Löndahl, J. (2017)

Temperature controlled airflow ventilation in operating rooms compared with laminar airflow and turbulent mixed airflow. Journal of Hospital Infection

CFU concentrations were measured at three locations in an operating room during 45 orthopaedic surgeries close to the wound (<40 cm), at the instrument table, and in the periphery. 15 of these operations corresponding to 250 samples, were performed in operating rooms equipped with TAF-ventilation. The study resulted in a median value of 1 CFU/m3 in the vicinity of the wound for the TAF system. Median values at the instrument table and in the periphery were also well below the limit required for infection-prone surgery 10 CFU/m3.

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An extensive list of all scientific literature – in total 45 pieces – that supports Opragon is available on request using the download button below.

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