Variations in gas flow of laparoscopic insufflators.

Maintenance of an adequate pneumoperitoneum is important in laparoscopy, yet little is known about the functioning of laparoscopic insufflators except for the manufacturer's description of the specifications. Frequent failure to maintain an established pneumoperitoneum with the insufflator switched to its automatic mode prompted evaluation of the volume of gas delivered per unit of time by machines in active use. Limited standardization was found between machines in regard to the gas flow mediated by the automatic flow control. In this mode, the insufflator did not adequately compensate for changes in resistance to flow. Disparity of response among flow control devices and interinstrument variations suggest the need to test and calibrate each unit separately for clinical use.