An alternative ventilation system for operating theatres: A full-scale experimental study on the performance of a local ventilation system

Surgical side infections occurred in 2.9% of the operations in conventionally ventilated operating theaters in The Netherlands. New performance-based Dutch guidelines offer the opportunity to apply alternative systems. Therefore, a local ventilation system was studied where only the wound area and the instrument tables are ventilated. The clean air supply around the wound area was combined with a blanket which lies over the patient during the operation. Two configurations were studied: HEPA-filtered air supply around and parallel to the wound area (configuration 1) and from the top surface of the blanket, perpendicular to the wound area (configuration 2). Similar approaches were applied to the instrument tables. The performance was tested in a detailed full-scale mock-up of an operating theatre. Relative particle concentrations were determined according to Dutch guidelines. In the centre of the wound area, relative particle concentrations varied between 1% and 10% for both configurations. The variances were probably caused due to irregular contamination in the periphery and imperfections of the prototypes. The results of the instrument tables were more uniform and resulted in relative particle concentrations of approximately 1% (configuration 1) and 0% (configuration 2) at the center of the tabletop. Although both configurations gave a reduced particle concentration in the wound area and on the instrument table compared to the contaminated periphery, only configuration 2 of the instrument table performed conform the VCCN guideline.