Silvana Perretta, MD1, John O’Dea, PhD2, Lee L Swanstrom, MD3, Ricardo Soare, MD3, Andras Legner, MD3, Bernard Dallemagne, MD1. 1IRCAD, Strasbourg, France, 2Crospon, Galway, Ireland, 3IHU Strasbourg
Current insufflators used for flexible endoscopy are inadequate as they lack pressure limitation and depend on the endoscopist to manually inflate and deflate the field. This increases the risk of either poor visualization (over-deflation) or patient comfort/safety (over-inflation). Alternatives such as the use of insufflators used for laparoscopy are not viable due to their pulsatile flow/pressure reading nature which, in the confined endolumenal space, leads to alternating collapsing and inflating movements that are distracting to the surgeon. These drawbacks are increasingly problematic as interventional endoscopy becomes more surgical in nature: lasting longer, demanding more critical precision and frequently crossing the gut wall. For advanced endoscopic surgery, the ideal insufflator would: provide constant pressure controlled insufflation, adjust automatically to loss of endolumenal pressure from suction or leaks, evacuate smoke, and prevent over-inflation of the abdomen or chest in the advent of an inadvertent or intended leak. We present a new C02 endoscopic insufflator that accomplishes these goals and document its effectiveness in live animal models of complex endoscopic procedures.
The EVA (Enhanced Ventilatory Assistance) insufflation technology (Crospon, Ireland) consists of a pressure controller which delivers a targeted pressure into the lumen of interest, in this example the rectum, during an ESD procedure. Compared with a constant flow insufflator where a leak leads to a reduction in insufflation pressure within the rectum, the EVA system automatically compensates by injecting additional flow when it sees a pressure drop, regardless of whether such a pressure drop arises from a leak or from suctioning. This targeted pressure is achieved based on feedback from a 1mm diameter pressure sensor attached to the tip of the endoscope. A second part of the EVA system comprises a vacuum system attached to a veress needle which may be inserted into the peritoneum during partial or full thickness resection in the rectum or stomach. A pressure sensor attached to the needle allows activation and deactivation of suctioning from the peritoneal cavity if the pressure exceeds or falls below pressure levels set by the surgeon. This ensures that gas leakage into the peritoneum (via leak or diffusion) does not cause an undesirable pressure rise.
The EVA insufflation performance has been compared with that of commercially available insufflator for flexible endoscopy in a pig model, the rectum being instrumented with a custom pressure gauge, to allow pressure traces at various stages during the procedure to be observed. Significant improvement in maintenance of the surgical field within the rectum was observed. Furthermore, by virtue of the pressure targeted nature of the insufflation, the presence of leaks beneficially assisted in removal of smoke in a more rapid fashion.
As expected, during suction, the standard insufflator pressure was seen to drop, in this case by 2.5mmHg and only restored pressure after suction was removed. The EVA insufflator responded to suction by a 4mmHg pressure increase of short duration followed by an underdamped pressure response.
Work continues on control algorithms to smooth pressure waveform response during insufflation.