Model to determine resistance and leakage-dependent flow on flow performance of laparoscopic insufflators to predict gas flow rate of cannulas

Study Objective. To characterize insufflator CO2 gas flow performance to pr edict gas flow rate with standard cannulas. Design, Prospective, observational study (Canadian Task Force classificatio n IL-2). Setting. Laboratory of university clinic. Patients, None. Intervention. Gas flow (L/min) and average pressure (mm Hg) inside an abdom en model were measured at 12 mm Hg nominal pressure during steady state. Measurements and Main Results. An abdomen box model for laboratory measurem ents was designed with different entrance and exit diameters simulated with hole disks from 0.5 to 7.6 mm. With a computer-based data-acquisition mode l, five insufflators (Olympus 9L and 16L, Storz 10L and 30L, HiTec 16L) wer e evaluated with 150 disk combinations. Flow performance in three-dimension al profiles showed different flow, rates for all insufflators depending on resistance and leakage combination, maximum flow rare, and insufflation pri nciple. Maximum flow was reached without resistance only in the insufflatio n system at high leakage rates. Low-pressure principle is more affected by resistance. Cannula flow rates at 12 mm Hg and 15 L/minute leakage ranged f rom 4.8 (Origin) to 6.0 L/minute (Storz HiCap) for Olympus 9-L insufflators and from 5.4 (Origin) to 15.10 L/minute (Storz HiCap) for Storz 30-L Therm oflator. Reusable cannulas have more flow efficacy than disposable ones, es pecially with high-flow insufflators, because of larger diameter at insuffl ation supply. Conclusion. Gas flow depends not only on maximum Now of insufflators but al so on resistance of cannulas and leakage rate. With this model it is possib le to predict the real, available flow of insufflator-cannula combinations for the first time. Improved resistance of all components can save insuffla tion time.