A new motor-driven surgical probe and its in vitro comparison with the cavitron ultrasonic surgical aspirator

The Cavitron Ultrasonic Surgical Aspirator (CUSA) has been applied in neurosurgery for several years, but its mode of action is not yet clear and its efficiency at removing soft tissue has not been quantified. We describe here how we have measured the rate of removing soft tissue per unit time, taking ox-liver tissue as the test material. A motor-driven vibrator/aspirator has been developed in our laboratory. It has permitted us to examine the effect of varying independently frequency, amplitude of the vibration, and suction pressure on the removal rate. The results of this investigation show that beyond a certain tip acceleration amplitude (about 100 g) the removal rate does not increase significantly. Also the removal rate is more or less independent of vibration amplitude within the range between 300 μm and 1 mm. Our in vitro experiments with the new probe show that a tip acceleration of about 100 g is enough to remove ox-liver tissue and then the rate of removal is comparable to that obtained with the CUSA operating at maximum vibration amplitude. Analysis of the particle size of the debris collected from CUSA and from our motor-driven device shows that the particle size distribution is similar over the range of 0.5 μm < d < 250 μm.