Working Space Establishment For Miccoli's Approach

Objective:To comprehend spatial characteristics of the cavity created by a working space marker.Methods 40 patients were successively operated according to the surgical mode of minimally invasive video-assisted thyroidectomy from January to August,2010. Instead of hand-retraction, a mechanical arm—working space marker type I(WSM-I (?), MIEO Medinstr Co. Ltd,, China), was applied to establish a working space. After the pathway making, a cavity above the gland was created and adjusted properly by the space maker, and then, endoscopic view were built and manipulation in the cavity was progressed throughout the later process. Geometric measurement of the cavity were performed at a "basic space position" just after the initial cavitation, and parameters such as length, width and height of the cavity were measured with a specifically scale-marked puncture needle (MCI 820, Bard(?) Max·Core(?) Instrument) through mini-holes lay in the lifting hook(Φ4mm, middle point and distant point).Results 13/40 cases received a lobectomy and others a partial thyroidectomy. Dimensional parameters were calculated as below.①The basic length of cavity button was 4.35±0.39cm; The basic width of cavity button (distance at central point) was 4.66±0.53cm; The basic central height of cavity was 1.36±0.34cm; The maximal central height archived by readjusting was 1.66±0.32cm(height increase 0.3cm<22.1%>);② The basic peripheral height was 0.98±0.29cm; The maximal peripheral height archived by readjusting directionally was 1.33+0.14cm(height increase 0.35cm< 35.7%>).③Statistic analysis yielded a negative correlation between the cavity volume and the size of thyroid lobe and/or the nodule, but a positive correlation between the cavity volume and the incision length.Conclusions The working space created by WSM-I appears to be an laigh and irregular trapezoid stock with oblique roof formed by lifting hook. Although vertical height, especially the peripheral height, is a major restrictive dimension, Cavity can still be usable and enough for factual observation and manipulation, due to "compensating effect" of endoscope, finite space requirement of Harmonica and "directional volume shifting" of WSM.