Robotic Assisted Laparoscopy Versus Open Gastroesophageal Resection; Effects on the Mesenteric Traction Reflex and PGI2 Levels

Background:

Gastroesophageal resection because of gastroesophageal junction (GEJ) adenocarcinoma is a massive surgical intervention. Nevertheless, surgery is the only treatment with significant long-term survival. Currently, gastroesophageal cancer surgery is performed with upper laparotomy followed by thoracotomy at the Department of Surgical Gastroenterology, Rigshospitalet, Denmark. However, minimal invasive techniques (MIT), e.g. robotic assisted laparoscopy, is in the progress of being implemented in this field as they are hypothesized to be more beneficial for the patients, and in some aspects better than conventional laparoscopic surgery [1]. The benefits of MIT are believed to be due to several factors, a smaller surgical stress response [2] and less pain [3] resulting in earlier mobilization, to mention a few.

When reconstructing the gastrointestinal continuity, a gastric tube is prepared from the upper part of the remaining stomach. It is challenging to visualize, if the remaining stomach has adequate blood supply. Earlier studies have shown an up to 70 % reduction in blood flow, to the upper part of the remnant stomach [4-6], and ischemia is one of the most significant causes of anastomotic leakage [7, 8]. Anastomotic leakage occurs in up to 10 % of the patients and is fatal in up to 50 %. Furthermore, a recent study originated from the investigators department demonstrated, that patients experiencing anastomotic leakage after gastroesophageal cancer resection, have a significantly reduced long-term survival, even when early death and other postoperative complications were accounted for [9]. The overall 5-year survival rates in patients with and without anastomotic leakage were 20 and 35 %, respectively. Therefore, sufficient blood flow to the area of anastomosis is of paramount concern. Different techniques have been used in the attempt to assess the microcirculation during gastroesophageal resection [5, 10-13]. However, none of these techniques has proven to be practical, reliable, and time-efficient, and therefore not being routinely implemented in the clinical settings.

During open gastroesophageal resection, hypotension is common (systolic blood pressure less than 90 mm Hg is experienced in more than 30 % of the patients) and is probably accompanied by a reduced gastric microcirculatory flow. The hypotension may be due to several factors;

• Sympathic nerve system blockage due to thoracic epidural neuraxial anesthesia: Several studies have found reduced splanchnic flow after epidural anesthesia, which was associated with a decrease in systemic resistance and mean arterial pressure [14, 15]. The impact of the time-point for activation of epidural analgesia, on complications in the postoperative period is unknown. An unpublished study (Nielsen T: "Increased cardiac output after Whipple's procedure for pancreatic cancer") suggests that early activation during operation leads to significantly longer stay in the recovery ward after the surgery.
• The initial manipulation of viscera, results in a mesenteric traction reflex (also called eventration syndrome) with vasodilatation and secondary hypotension [16, 17]. The reason for mesenteric traction reflex is unknown, but is believed to be elicited by traction on the mesenterial blood vessels, resulting in a local release of prostacyclin (PGI2) from the endothelium. This reflex has mainly been shown to occur during pancreatic, gastric and aortic surgery, where manipulation of the mesenteric root is inevitable [18-21]. PGI2 is a potent vasodilatator, with inhibitory effect on platelet aggression and on vascular smooth cell proliferation [22-24].