Importance of displacement ventilation for operations and small surgical procedures from the infection preventive point of view

Surgical teams need to breathe air that is conducive to their health. An adequate exchange of air ensures oxygen supply, the ventilation of humid-ity, smells, toxic substances, especially narcotic gases and surgical smoke, pathogens and particles. With regard to the infection risk, DIN 1946 / 4 -differentiates between operation theaters with the highest demand for clean air (operation room class I a), operation theatres with a high demand (operation room class I b) and rooms within the operation theatres without special requirements, meaning that the microbial load in the air is close to or equal to that of normal in-room air quality (room class II). For an operation room class I a, ventilation that displaces the used air is neces-sary, while a regular ventilation is sufficient for operation room class I b. Because of ambiguous -results in previous studies, the necessity to define a -class I a for operation rooms is being questioned. Therefore, this review focuses on the analysis of the existing publications with respect to this -question. The result of this analysis indicates that so far there is only one surgical procedure, the -implantation of hip endoprosthetics, for which a preventive effect on SSI of a class I a ventila-tion (displacement of the used air) is docu-mented. One recent study, reviewed critically here, -showed opposite results, but lacks meth-od-ological clarity. Thus, it is concluded that evidence for the requirement of operation room classes can only be derived from risk assessment (infection risk by surgical intervention, extent of possible damages), but not from epidemiological studies. Risk assessment must be based on the following criteria: size and depth of the operation field, -duration of the procedure, vascular perfusion of the wound, implantation of alloplastic material and general risk of the patient for an infection. From an infection preventive point of view, no class I a “displacement ventilation” is necessary for small surgical procedures for which the RKI recommends only a procedure room, and for surgical procedures for which a risk evalua-tion indicates that the air in the operation theater can be equal to normal air.