Biomedical subjects

A K Morimoto

Publications and source records attributed to A K Morimoto.

4 recordsLinked to original sources

PubMed1997

Laparoscopic Roux-en-Y choledochojejunostomy.

OBJECTIVE: Although surgical biliary bypass for nonresectable periampullary tumors is superior to endoscopic stent placement, the latter has become popular because of the "minimally invasive" approach. Laparoscopic biliary bypass would appear to offer the advantages of both. However, this technique remains technically difficult using existing instrumentation. This study investigates the efficacy of a new endoscopic device designed for rapidly completing a small-diameter intestinal anastomosis under laparoscopic guidance. METHODS: Eighteen female pigs (mean weight 35 kg, range 31 to 44) were randomly divided into three groups: animals undergoing handsewn (group H) or instrumental transient endoluminally stented anastomosis (TESA; groups P and D) laparoscopic Roux-en-Y choledochojejunostomy. For TESA two different reabsorbable stents were used, polyglycolic acid (PGA; group P) and polyurethane ester (Degrapol; group D). Blood chemistry, weight gain, and abdominal X-rays were taken weekly to document any possible migration or reabsorption of the radio-opaque stents. After 3 months, necropsy was performed. Patency of the biliary bypass and choledochojejunostomy were examined using fluoroscopy and measured by introducing graduated dilators into the anastomosis. RESULTS: Fluoroscopy revealed immediate passage of contrast through the anastomosis in all animals. Weight gain, bilirubin, and alkaline phosphatase were within normal range in all groups. Diameter of the bile duct (group H 10.7 +/- 2.9 mm/group P 9.5 +/- 3.6 mm/group D 11.0 +/- 4.6 mm) and choledochojejunostomy (group H 4.5 +/- 1.1 mm/group P 4.7 +/- 1.8 mm/group D 3.6 +/- 1.9 mm) did not differ. The time required to complete the biliary bypass was significantly decreased when TESA was applied (group H 152 +/- 13 min/group P 86 +/- 14 min, P <0.001/group D 110 +/- 20 min, P <0.002). CONCLUSIONS: Applying TESA, laparoscopic choledochojejunostomy can be performed rapidly and safely, revealing good bypass function over a period of 3 months. With regard to treatment for nonresectable periampullary tumors, TESA may offer a new therapeutic approach combining the benefits of minimally invasive endoscopic stent placement with the functional results and lower readmission of conventional Roux-en-Y choledochojejunostomy.

Anastomosis, Surgical↗

PubMed1997

Micro-telerobotic surgical system for microsurgery.

Modern surgical methods which utilize microscopes have allowed medical professionals to visualize the surgical field on the order of microns. This new found visual capacity has created a performance gap between a surgeon's visual skills and manipulative skills that surgical robotics have the capability to remedy. Robotics can be used as an aid to the surgeon to help correct natural human dexterity problems such as tremor and resolution of motion. Devices that would benefit surgical dexterity at the micron scale are in development at Sandia National Laboratories. A six degree-of-freedom (DOF) force reflecting telerobotic manipulator has been designed and developed for use in microsurgical applications. The system utilizes a unique mechanical platform, actuation schemes, and controller that provides high positional precision while maintaining high frequency response for implementation of force feedback. Thus, the same device is used to form a master-slave telerobotic arrangement to assist the surgeon. This makes the system very intuitive to the surgeon and easier to implement for the engineer. The system utilizes high performance Digital Signal Processors (DSP) for control of both the master and slave platforms. Six dimensional force information is obtained from transducers located at the end effectors of both the master and slave. Two distinctly different types of motors are currently being evaluated, as well as several types of control algorithms. Position scaling, force scaling, and tremor filtering are being implemented in the DSP control software. Control parameters are based upon system frequency response testing. Results from our system identification and performance testing will be discussed.

Computers↗

PubMed1997

High definition 3D ultrasound imaging.

We have demonstrated high definition and improved resolution using a novel scanning system integrated with a commercial ultrasound machine. The result is a volumetric 3D ultrasound data set that can be visualized using standard techniques. Unlike other 3D ultrasound images, image quality is improved from standard 2D data. Image definition and bandwidth is improved using patent pending techniques. The system can be used to image patients or wounded soldiers for general imaging of anatomy such as abdominal organs, extremities, and the neck. Although the risks associated with x-ray carcinogenesis are relatively low at diagnostic dose levels, concerns remain for individuals in high risk categories. In addition, cost and portability of CT and MRI machines can be prohibitive. In comparison, ultrasound can provide portable, low-cost, non-ionizing imaging. Previous clinical trials comparing ultrasound to CT were used to demonstrate qualitative and quantitative improvements of ultrasound using the Sandia technologies. Transverse leg images demonstrated much higher clarity and lower noise than is seen in traditional ultrasound images. An x-ray CT scan was provided of the same cross-section for comparison. The results of our most recent trials demonstrate the advantages of 3D ultrasound and motion compensation compared with 2D ultrasound. Metal objects can also be observed within the anatomy.

Computer Simulation↗

PubMed1997

Force sensor for laparoscopic Babcock.

UNLABELLED: GENERAL: A force sensor has been designed and fabricated that will fit to existing laparoscopic grasping forceps (Babcocks) from Ethicon Endosurgery Inc. The goal of the sensor development is to provide tool-tissue force information to the surgeons so that surgeons can regain the sense of touch that has been lost through laparoscopy. Eventually, force sensing will provide feedback for robotic laparoscopic surgical platforms. OBJECTIVE: We have developed a prototype force sensor system with ATI Industrial Automation. This tool is provided as an in-line transducer with six degrees of freedom that can retrofit current Babcocks. The sensor is currently being used in clinical trials with animals to determine the benefits. The sensor system utilizes industry proven technology in combination with a custom transducer and user interface. A GUI is part of the system and provides resolved force magnitude data in a graphical format for case of interpretation. Sterilization, size, and ease of use are addressed by the current design. Operating room reliability and safety are currently being investigated. CLINICAL TRIAL: A three phase experimental trial using a porcine model is being completed that will test the hypothesis that force information can be used to minimize tissue trauma during laparoscopic surgery. RESULTS: Based on our research, there is strong evidence that surgeons would benefit from information regarding the levels of force applied to tissues. In the future, robotic surgery will require force sensing. Surgical simulators could provide force feedback during simulated surgical procedures by using a sensor platform such as this. In addition, tool tip design in the future will benefit from the application of this technology and data base.

Animals↗