Can we meet the requirement for ultra-clean operation room (10CFU/m³) with dilution ventilation?

¹ Department of Energy and Process Engineering, Norwegian University of Science and Technology, Kolbjørn Hejes vei 1b, 7491, Trondheim, Norway
² Sykehusbygg HF Klæbuveien 118, Trondheim, Norway 3Operating rooms of the future, St.Olavs hospital, Prinsesse Kristinas gate 3, 7030, Trondheim, Norway
³ Operating rooms of the future, St.Olavs hospital, Prinsesse Kristinas gate 3, 7030 Trondheim, Norway

Abstract

The objective of this study is to analyse what conditions may, and may not take place during surgery in a dilution ventilated operating room (OR), to fulfil an ultra-clean requirement (10 CFU/m3). To achieve the objective, literature review and a mock surgery with air sampling was performed. Colony forming unit (CFU) measurements were conducted to estimate the bacterial concentration in the air. During the mock surgery, the following conditions was present: a clean air suit, surgical gowns, double-tie-on masks and surgical hoods was used by all surgical members, except for the non-sterile members whom did not wear surgical gowns. 5 surgical members + 1 patient were present, 0 door openings occurred and a predefined movement and action plan set the activity level. The average CFU/m3 for the mock surgery was 15,4(SD:5,4). The CFU/m3 during a high activity period was about 21,5% higher than in low activity periods. With the conditions simulated in the mock surgery, and the clothing used, the OR were not able to fulfil the ultra-clean requirement. To reduce the CFU/m3 the activity level needs to be reduced. The literature shows that to meet the ultra-clean requirement all staff members should wear single-use clean air suits made of non-woven fabric, surgical masks, and a surgical hood. Traffic level needs to be minimized and a calm intraoperative behaviour needs to be maintained by the surgical staff. The amount of people present seems less important compared to the activity level taking place during surgery.