# Study Shows That $250 Million Could Be Saved In Laparoscopic Surgery By Improving Gas Flow A new study estimates that$250 million could be saved annually on laparoscopic surgery in the United States alone by improving gas flow into the patient's abdominal cavity. Carbon dioxide gas is pumped into the patient during surgery to expand the abdomen and provide the surgeon with sufficient working space. Frequently during this procedure the abdomen collapses during instrument insertion or suturing, causing expensive delays while it is reinflated and the surgeon reestablishes his or her orientation. Research by Dr. Volker R. Jacobs and colleagues at Christian-Albrechts-University, Kiel, Germany shows that these collapses can be easily prevented by improvements in the insufflation system, the components that make up the supply line by which gas is pumped into the body.

 Figure 1:Measurement scheme for determination of specific resistance of different insufflation components.

A key component in the insufflation system is the trocar, the device that punctures the abdominal wall, serves as an entry point for gas as well as the surgeon's instruments and seals the cavity to minimize pressure loss. The veress needle is the device used to establish pneumoperitoneum before trocar insertion. Jacobs evaluated a wide range of American and German brand name needles, trocars and other laparoscopic surgical instruments in common use among surgeons today and found that in the majority of cases insufficient annular clearance was available within the trocar to provide the needed gas flow into the abdominal cavity. Dr. Jacobs has compiled the results of his and is disseminating this information to surgeons and equipment manufacturers in order to promote improved surgical methods.

 Figure 2: Gas flow regression curves for Veress needles: 1. Dexide, 2. Ethicon, 3. Storz, 4. Origin, 5. Volzer, 6. Auto Suture, 7. Wiest and 8. HiTec.

Flow Resistance

Jacobs says that up to now surgeons have had to rely on their experience and intuition when selecting equipment for laparoscopic surgery because of the lack of understanding of the importance of the flow resistance through the insufflation system. In order to shed light on this subject, he developed a computer-based data acquisition system that simulates the insufflation process.

Proving the statistical validity of the work and presenting it in a clear, graphical manner was vital to Jacobs' goal of convincing surgeons and equipment manufacturers of the need for a change. In the past, Jacobs used a popular spreadsheet for regression analysis and preparation of technical graphics but found it difficult to achieve results that he found acceptable. Several years ago he switched to a program specially designed for the analysis and presentation of scientific data, Origin from Microcal Software, Inc., Northampton, Massachusetts. Jacobs said that Origin has greatly increased the ease of producing regression curves that prove the statistical validity of his results. It has made it possible for him to produce more compelling and convincing graphics by giving him control over every aspect of the chart with the click of a mouse.