An experimental study on the effects of positioning medical equipment on contaminant exposure of a patient in an operating room with unidirectional downflow

Abstract

This study investigated the influence of medical equipment on contaminant levels in the sterile field of an operating room (OR) equipped with unidirectional downflow (UDF). Nitrous oxide (N2O) tracer gas was used to simulate constant emission both inside and outside the operating field. Medical equipment positioned above the sterile field consisted of two surgical lights and one fluoroscopy imaging device. This study compared the effect of different configurations of the equipment layout on the contaminant levels at several points in the proximity of a simulated patient. The air samples in the case without medical equipment had significantly lower (p < 0.01) N2O (ppm) levels than the rest of the cases with medical equipment when the pollution source was located inside the operating field. The normalized outdoor exhaust concentrations were substantially higher when the pollution source was positioned inside the operating field than when the pollution source was positioned outside the operating field. When the pollution source was located inside the operating field at a height of 1.5 m above the floor, the outdoor exhaust removal index was <1 when the sterile field was free of equipment. When obstructed by medical equipment, the unidirectional downflow (UDF) systems did not reduce the outdoor exhaust removal index compared to completely mixed conditions. The value of the outdoor exhaust removal index was lower than 1 regardless of the presence of medical equipment when the pollution source was located outside the operating field at the same height of 1.5 m above the floor.