Factors affecting emission collection by surgical smoke evacuators

Abstract

Gaseous and particulate emissions from laser surgery are often controlled by the use of smoke evacuators. Thus it is important that factors affecting the performance of these evacuators be understood. In this study, a tracer gas technique was used to examine a number of factors affecting the performance of smoke evacuators, including evacuator flow rate, distance from the evacuator nozzle to the surgical site, and direction and speed of external air flow in relation to nozzle flow. The tracer gas technique allowed the release of emissions to be visualized with infrared imaging and also allowed the collection efficiency to be assessed quantitatively. The results were demonstrated with the use of a surgical laser system. It was found that the collection efficiency of the smoke evacuator was affected by all the factors studied. Increasing the evacuator flow rate allowed the collection of emissions under conditions in which lower evacuator flow rates had less efficient collection. The speed and direction of external air flow affected collection of emissions greatly. If the air flow was in the same direction as the nozzle flow, efficient collection of emissions at a distance from the emission release point was observed. However, at other angles relative to nozzle flow, the efficiency degraded rapidly with distance from the emission release site. With the use of the surgical laser system, at laser powers of 30 W, the tracer system predicted the collection of emissions. At 60 and 100 W of laser power, higher external air flows and greater attention to nozzle positioning were necessary. Based on the results of this study, conclusions are drawn on how to improve the collection efficiency of smoke evacuators used in laser surgery.