Working Space Establishment For Miccoli's Approach

ObjectiveTo comprehend the magnitude and change characteristics of the lifting force produced by a working space marker in process of it's cavity-forming.Methods37 patients were successively operated with the surgical mode of minimally invasive video-assisted thyroidectomy(22/37 cases received a lobectomy, others a partial thyroidectomy) from January to August,2010. Instead of hand-retraction, a mechanical arm—working space marker typeⅠ(WSM-I (?), MIEO Medinstr Co. Ltd, China) was applied to establish a working space. After the pathway making, an interlayer-cavity above the lobe was created by the space maker and endoscopic view was properly built. After all these steps, a simulated space making procedure was interposally performed in a way of stepwise hook-lifting (5mm raising per time). Lifting force (LF) was measured during the process with a modified force-measure device(FB-50, DESIK company, Germen).Then Recorded data were assessed and analyzed statistically.Results①Ascending scope of LF in the process of entire space-forming was 0～27.5 Newton(N).②long with hook raising the LF ascended correspondingly, but two specific values emerged:One was 11.2±3.5 N, as the lifting height approached 1.5cm(also a approximate position of essential space-forming, at which the musculo-cutaneous tissue just became tight); the other was 17.5±4.3 N, as the lifting height approached 1.75 cm(also a approximate position of maximal space-forming, at which the musculo-cutaneous tissue appeared real tight, but not in a status of extreme tightness).③Two types of LF ascending were found when the values transferred to a curve diagram:A palliative linearity increasing while lifting height varied from 0 to 1.5 cm (PO to Pe) and a rapid exponent-like increasing while lifting height varied from 1.5 to 1.75cm(Pe to Pmax).④Dependability analyses yielded a diverse statistical outcome:Negative significance of the comparison between incision length and LF value (P>0.05), and positive significance of the comparison between skin thickness and LF value (P<0.01).Conclusion①LF produced by WSM-I while it establish a working space is proper and relatively small, since the maximal value is merely 27.5N, far less than the stress produced by ordinary cosmetic skin expansion.②The whole space-forming process can be divided into two stages according to characteristic of LF ascending which correspond also separately to the essential cavity-forming and the maximum cavity-forming in the real establishing of a working space.③Attention should be given on the later stage since in which a rapid LF increasing occurs while the appearance of musculo-cutaneous tissue changes from "just become tight" to " real appears tight".④The LF controlling,specially the fine readjusting at or about Pmax should be of necessity in Individual space-forming, and then, ideal working space establishment can be archived at a precisely balanced LF point:maximum cavity volume acquired and minimal tissue expansion stress produced.