Achieving room air quality of room class Ib in the aseptic area using a mobile sterile ventilation unit in a room class II surgical unit.

Abstract

Introduction: Room air class (RC) Ib may be necessary for surgical procedures in aseptic working areas. The aim of the study was to examine whether a mobile, three-stage sterile ventilation unit (MSVU) can replace a room ventilation system (RVS) with turbulent mixed flow (TMF) in the area of the operating field and on the instrument table from hygienic-microbiological point of view.

Method: During 26 surgeries (varicose vein stripping or treatment of umbilical and inguinal hernias), the microbial load was recorded at 4 measuring points (M1-M4) during regular operations by setting up sedimentation plates and measuring the particle concentration. Measuring points M1 and M2 were located at the beginning and the end of the instrument table, measuring point M3 next to the operating field and measuring point M4 outside the sterilely ventilated area approx. 135 cm from the operating field. The measured values were compared with results with simulated, incorrect positioning and with MSVU not switched on.

Results: The number of people and the duration of the operation did not differ between the 3 measurement situations.The MSVU achieved a significant reduction in the number of sedimented colony-forming units (CFU) at M1 by 88.4%, at M2 by 91.5% and at M3 by 65.2%. At measuring point M4, the values did not differ between MSVU switched on or off. Even with an unacceptably increased distance between the MSVU and the instrument table, the difference at measuring points M1, M2 and M3 was still significant in comparison with MSVU switched off. Coagulase-negative staphylococci were predominantly detected, followed by Micrococcus luteus and apathogenic spore-forming bacteria, but Gram-negative bacteria were not detected in any cases. The number of CFU detected fulfils the criteria for conventionally turbulent non-directionally ventilated surgical units with TMF of RC Ib.The particle count was reduced by an average of 66%. As comparable particle counts were found in the aseptic working area in a separately conducted study in an RC Ib surgical unit, it can be assumed that the results obtained with the MSVU are hygienically safe.

Conclusion: With the MSVU, a reduction of the microbial load and the particle count in the room air was achieved in the area of the operating field and on the instrument table during operation in an RC II surgical unit, which can be categorised as sufficient for operations in RC Ib. With the aid of an MSVU, operations with a high risk of surgical sire infections can also be carried out in surgical units of RC II from hygienic-microbiological point of view. The MSVU is an organisationally flexible and economically interesting, safe and sustainable option in terms of the microbiological load and particle count in the operating field and instrument table instead of an RVS that ventilates the entire room. In times of increasing outpatientisation of surgical services, MSVU is a promising option for outpatient surgical units in particular.