ZONED VERTICAL ULTRACLEAN OPERATING-ROOM VENTILATION - A NOVEL CONCEPT MAKING LONG SIDE WALLS UNNECESSARY

We evaluated a novel concept of High Efficiency Particulate Air (HEPA) -filtered vertical Laminar Air Flow (LAF) for operating room ventilati on, designed to be used without side-walls. The LAF-unit has a central zone with an airflow of 0.4 m/s and a peripheral zone with an airflow of 0.2 m/s. The design provides an exponential downflow of air resemb ling an upside-down trumpet mouth and it was claimed to prevent entrai nment of peripheral contaminated air. The unit was evaluated with rega rd to elimination of particles with focus on bacteria-carrying particl es (colony-forming units = cfu) during rigidly standardized sham opera tions. Three different lengths of walls/enclosures (short-ending 2.0 m , medium 1.0 m and long 0.2 m above the floor) were tested. It provide d a high degree of bacteriological cleanliness (0.05-4 cfu/m(3) of air and 7-64 cfu/m(2)/h surface contamination) and its efficiency was pro ved to be independent of the length of the enclosures. We conclude tha t the novel zoned ultraclean vertical LAF unit is versatile, as it all ows for omitting long side-walls, without compromising bacteriological safety.