Ultrasonic surgery: Power quantification and efficiency optimization

Abstract

Background: Ultrasonic surgery systems present the surgeon with a host of control parameters and design choices that may directly affect clinical outcome. These include amplitude setting, probe/cannula tip design, probe/cannula diameter, vibration frequency, and mode of energy delivery. Currently, no commonly accepted objective means of measurement (or measurements) exists that can be used to assess the impact of these control parameters, to compare different systems/designs, or to provide a common basis for interpreting clinical outcomes. Objectives: The goals of this study were to develop the following as functions of the surgeon's choice of control parameters: (1) a measure of the vibratory power that could potentially be applied to the subcutaneous tissues, and (2) a measure of the effectiveness of the applied vibratory power. Methods: The vibratory power produced by 4 commercially available ultrasonic surgery systems was quantified on the basis of a measured temperature rise in a known volume of water with various combinations of ultrasonic probes/cannulas. The data were normalized to develop a measure of energy efficiency. Results: The data show that ultrasonic surgical probes/cannulas have zones of high and low efficiency, that the vibratory power and energy efficiency that may be applied to tissues varies widely over the range of the possible control parameters, and that zones of optimal efficiency may be developed. Conclusions: Two simple measurements referred to as H2O power and energy efficiency provide a basis for objective comparison of different ultrasonic instrumentation. These measurements will assist in standardizing clinical observations.