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Published at the AAGL listserv. : Date: Fri, 17 Dec 2010 08:42:22 -0500 From: “Philippe R. Koninckx, Carlo De Cicco, Jasper Verguts, Roberta Corona and Anastasia Ussia” Subject: Loss of pneumoperitoneum through trocar

Reading the comments regarding loss of pneumoperitoneum I do have the impression that many try to reinvent the wheel, or simply do not know that this issue was solved long time ago with the Thermoflator (Storz AG).

In 1990, I patented through Leuven Research and Development and subsequently developed together with Storz AG the thermoflator based on a simple principle : as long as the internal diameter of the tubing and connexions is at least 7mm flow rates of 60 l/min are obtained with an insufflation pressure of 20 cm of water of 15mm of Hg. In contrast with all other insufflators based upon the Semm patent of the 80-ies, (intermittent insufflation with measurement of the intraperitoneal pressure during the pauses of insufflation ) this insufflator / the thermofaltor, has a series of advantages
- It is safer since insufflation can be done at low pressure eg 15 mm of Hg. Thus abdominal overpression becomes impossible. With all other insufflators -to the best of my knowlege, unless patent infringement- insufflating intermittently at higher pressure, overpression in the abdomen is theoretically possible when a valve mechanism would occur permitting insufflation but preventing gas and pressure to flow back. With a minimal leak the measured pressure indeed will remain low.
- It permits a continuous flow which is important for smoke evacuation (especially during CO2 laser surgery) : otherwise smoke is blown away intermittently.
- A high flow is important to work safely in all circumstances. Since continuous aspiration takes between 10 and 20 l of gas/minute, with often some additional leak, this will cause loss of pneumoperitoneum. Thus when a major bleeding occurs, eg a lesion of the external ileac artery or vein, aspiration will cause loss of pneumoperitoneum and a laparotomy becomes necessary. Today 20 years and more than 2500 deep endometriosis excisons later (and many other interventions) I can say that I never had to do a conversion to laparotomy because of a bleeding. It even permits to remove the valve of a 5 mm trocar (sometimes better to put minimal traction on a bowel). Also during total laparoscopic hysterectomy it might be important.

The thermoflator requires a diameter of 7 mm in order to insufflate at high flow , thus requiring either a trocar or an operative laparoscope with a side opening of 7 mm. Besides Storz I am not aware of any other trocar with another side opening than a luer lock, which physically limits flow rates to 7-9 l/min for insufflation pressures of 15 mm Hg.

Till today I kept being surprised, that all this although published and repeated at congresses, never became mainstream. I must admit that I refrained from advertising this too explicitly because of the obvious conflict of interest.

Philippe R. Koninckx* **, Carlo De Cicco**, Jasper Verguts*, Roberta Corona* and Anastasia Ussia**
*University of leuven Belgium and ** Gruppo Italo Belga, Rome Italy

Conflict of interest : patent holder underlying the Thermoflator

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