Evaluation of mist production and tissue dissection efficiency using different types of ultrasound shears

Ultrasound shears often are applied in minimally invasive surgery because they facilitate fast and secure tissue dissection, thereby reducing operative time. Although the technical principle underlying all the shears is almost identical, considerable differences exist between specific instruments. However, production of disturbing mist should be avoided.

To obtain quantitative measurements regarding mist production, a novel hermetically sealed test system was developed. Tissue dissection efficiency was evaluated by means of a standardized cutting test. The dissection time and the numbers of cuttings were recorded. In this study, four different ultrasound dissectors from three manufacturers were assessed. One manufacturer provided two instruments: a conventional instrument and an improved version, which was designed particularly to reduce mist emission.

The fastest ultrasound dissector emitted the highest quantity of disturbing mist. However, improved dissection efficiency does not linearly correlate with mist production. This clearly could be shown for the improved "less mist production instrument," which turned out to work faster than the comparable standard dissector but produced significantly less mist.

Ultrasonic shears are effective for bloodless tissue dissection but may impede surgical proceeding by mist production. The findings of this study demonstrate that emission of mist can be reduced not only by lowering the dissection power, resulting in a prolonged dissection time, but also by modifying the technical design of an instrument. Further development of ultrasonic cutting devices therefore should account for the desired results.