The issue of surgical site infections has become more critical during the last years. The number of airborne microbes depends on the number released by the staff in the room or supplied from neighbouring rooms. In order to minimize the risk of nosocomial infections during surgical procedures technical developments like ventilation systems were introduced in the operating room (OR). In this study several factors like clothing and types of ventilation systems have been investigated and their impact on the effectiveness for reducing microbial burden in the OR has been assessed. In case of OR-gowns we found a benefit for a disposable Swedish clothing concept regarding microbiological contamination in comparison with the German standard multiuse clothing. Moreover our study shows that there is comparable effectiveness of a fairly novel temperature controlled airflow ventilation system (TAF) compared to standard low turbulent uni-directional airflow (TAV).
According to studies, surgical site infections are the most common nosocomial infections.  The German DIN 1946/4 (2008) demands a low turbulent uni-directional airflow system (TAV) for a class Ia OR used for infection sensitive surgeries . In a room class Ia generally operations with a large wound area take place, e.g. open surgical procedures such as joint replacements. In contrast to this standard system a new temperature controlled airflow ventilation system (Opragon) was developed by the Swedish company Avidicare AB . Opragon supplies the operative zone with slightly cooled, HEPA-filtered air (class H14) from an external air treatment unit equipped with a heating/cooling battery. The supply air is discharged through hemispherical air showers (air volume per shower = approx. 350 m3/h) and falls to the floor, where it is sucked into the side corners. It is crucial that the temperature of the air above the operative zone is cooler than the outer room air in the operating room. The higher density of the cooled air causes it to fall at a speed dictated by this temperature difference. This System was set up in the research OR at the Ostbayerische Technische Hochschule in Weiden for further studies.
The condition of OR clothing is also determined in a German directive, the DIN EN 13795 . This clothing is necessary for the stability of hygiene in the OR and has to protect the medical staff and the patient from microbiological contaminations and infections. In contrast to the German OR scrubs, the Swedish single-use design has obvious differences like tightened cuffs or a closed neck region to avoid unintentional spreading of particles (Figure 1).
2 Material and methods
To examine the impact on the microbiological burden in the OR we performed active air samplings on culture plates (blood agar plates; BD). The samplings were done for 1 h with an interval of six plates for 10 min each. The overall volume was 1 m3 for each sampling. During the measurement a simulated surgical procedure was performed with seven participants according to the Swedish standard for ventilation systems in the OR SIS-TS 39:2012 . Three locations in the OR were defined as measuring points: the OR table, the instrument table and the peripheral region of the OR near to an air exhaust. The plates were incubated for 72 h at 35 ± 1°C. After incubation the colonies were counted and documented as colony forming units/m3 (CFU/m3).
These measurements were repeated up to 144 times to determine the differences between the Swedish and the German OR clothing and also in three ORs with different ventilation systems.
In case of the OR clothing a reduction of the microbial burden could be detected in our experiments by the use of the Swedish in contrast to the German gowns (Table 1).
|Location||German clothing (CFU/m3)||Swedish clothing (CFU/m3)|
During the whole experiment a germ reduction of approx. 3–10 fold could be measured for the Swedish clothing compared with the German clothing.
Our benchmark studies for the different ventilation systems were done in the research OR at the University in Weiden for the temperature controlled ventilation (TAF), as well as in a class Ia OR TAV and a class Ib OR turbulent mixed ventilation (TML) in a collaborating hospital. The measurements were also performed according to the Swedish SIS-TS 39:2012 to obtain comparable results for the different ventilation systems. Again the same three locations were defined as measuring points: the OR table, the instrument board and the peripheral region of the OR near to an air exhaust. As a result the TAF ventilation system reaches similar if not better results than the standard low turbulent uni-directional airflow system for German class Ia OR. The class Ib OR with the TML showed the expected higher CFU counts for the bacterial burden (Table 2). Because of a minor difference and the generally very small values directly under the ventilation system (OR table) the measurements from all three locations (OR Table, Instrument board and Periphery) were combined to one mean value for a better clarity and comparability.
|Ventilation system||Max. value (CFU/m3)||Overall mean value (CFU/m3)|
Although no statistical Tests were performed due to the relatively small amount of measurements, our results indicate an at least similar efficiency of the new developed temperature based ventilation system compared with the hitherto standardly used TAV system for a class Ia OR. It should be discussed if the technologies should be treated equally.
Also we could show an influence of the OR clothing on the bacterial burden in the OR. Here the Swedish clothing concept is more favourable than the German. It should be discussed, if the advantage in hygiene is worth the probably higher costs for the single-use strategy.
These trends will be investigated further with a broader set of experiments to achieve a statistically assessable amount of Data.
The authors want to thank Peter Ekolind for his support with the Swedish documents and material.
Research funding: The author state no funding involved. Conflict of interest: Authors state no conflict of interest. Material and methods: Informed consent: Informed consent is not applicable. Ethical approval: The conducted research is not related to either human or animals use.
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©2016 Clemens Bulitta et al., licensee De Gruyter.
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