A technique for laparoscopic extraperitoneal colostomy with an intact posterior sheath of rectus.

Regardless of the advances in surgical techniques, parastomal hernia is still an inevitable complication for many patients with low rectal cancer undergoing abdominal perineal resection (APR). Extraperitoneal colostomy (EPC) seems to be a effective method to reduce the risk of parastomal hernia. We propose a new approach to simplify and standardize laparoscopic EPC to make this operation easy to perform. We used the technique of laparoscopic TEP groin hernia repair to produce an extraperitoneal tunnel, which can not only facilitate precise visualization of the extraperitoneal tunnel but also utilize the intact posterior rectus abdominis sheath as biologic materials to maintain soft-tissue augmentation, with a satisfactory result. With laparoscopy, we can create adequate space without insufficient dissection of the extraperitoneal tunnel while avoiding damage to the retrorectus sheath. At the time of writing, we had performed this method in four patients, without any complications. This technique is effective at preventing parastomal hernia without extra costs.

Critical phenomenon of granular flow on a conveyor belt.

The relationship between the granular wafer movement on a two-dimensional conveyor belt and the size of the exit together with the velocity of the conveyor belt has been studied in the experiment. The result shows that there is a critical speed v(c) for the granular flow when the exit width d is fixed (where d=R/D, D being the diameter of a granular wafers). When vv(c), the flow rate Q is described as Q=Crho(v)(beta)(d-k)(3/2). These are the effects of the interaction among the granular wafers and the change of the states of the granular flow due to the changing of the speed or the exit width d.