A System for Teaching Advanced Colonoscopic Skills and Endoscopic Submucosal Dissection Based on Nonclinical Models.

Endoscopic submucosal dissection (ESD) requires skills that the vast majority of endoscopists do not possess. ESD be broken down into component skills and at least three of the necessary skill sets can be taught separately. In the United States most trainees initially participate in half- or full-day courses that utilize ex vivo and in vivo animal models and the great majority learn these advanced skills in the clinical setting. We describe a comprehensive training over a well-defined period using ex vivo porcine or bovine large bowel models. There are five components or modules that make up the training program: (1) bowel wall injections in ex vivo tissue, (2) inanimate figure tracing model to teach scope control, (3) ESD in plastic tube with window cutout over which square of ex vivo tissue is placed, (4) ESD in ex vivo porcine or bovine large bowel, and (5) mucosal wound closure. The authors are in the midst of training a group of residents, fellows, and young attendings using this approach. This approach has not been vetted yet; however, the preliminary results are promising.

Compared to preoperative plasma levels post-operative urokinase-type plasminogen activator-1 levels are persistently elevated for 6 weeks after minimally invasive colorectal resection.

Background: Urokinase-type plasminogen activator-1 (uPA) is a serine protease that converts plasminogen to plasmin after binding to uPA receptor (uPAR). Plasmin catalyzes the regeneration of basement membrane, extracellular matrix, and other tissues. uPA alone and with plasmin leads to activation of angiogenic growth factors that impact tumor cell proliferation, adhesion, and migration. uPA over expression has been noted in colorectal cancer (CRC) and high tissue levels have been correlated with prognosis. uPA/uPAR promotes immune cell activation in healing surgical wounds and may alter perioperative uPA plasma levels. Postoperative (postop) plasma levels, if elevated, may impact the early growth of residual metastases. The impact of minimally invasive colorectal resection (MICR) surgery for CRC on plasma uPA levels is unknown. This study's aim was to measure plasma uPA levels during the first postop month. Methods: CRC patients undergoing MICR who enrolled in an Institutional Review Board (IRB) approved data/plasma bank for whom adequate plasma was available were included in the study. Patients who had chemotherapy or radiotherapy within 4 weeks, those who received blood transfusions perioperatively and immunosuppressed patients were excluded. Clinical and pathological data were prospectively collected as were blood samples preoperatively, postop day (POD) 1, 3 and at least 1 late time point between POD 7-41. Plasma was isolated and stored at -80 ℃. Late samples were bundled into 7-day blocks and considered as single time points. Total uPA levels (ng/mL) were analyzed in duplicate via enzyme-linked immunosorbent assay (ELISA) and results reported as mean ± standard deviation (SD). The Wilcoxon paired t-test was used for analysis. Results: Ninety-three patients undergoing MICR for CRC [colonic 68%; rectal 32%; average age 65.6 years, laparoscopic 63%, hand-assisted minimally invasive surgery (MIS) 37%] who met criteria were studied. Cancer stage breakdown was; stage I, 30%, stage II, 29%, stage III, 34%, stage IV, 7%. The median preoperative (preop) uPA plasma level (ng/mL) was 529.8 [95% confidence interval (CI): 462.8, 601.1] (n=93). Significant elevations in median levels vs. preop were present during POD 3 (542.8, 95% CI: 518.8, 597.3, n=86, P=0.003), POD 7-13 (688.1, 95% CI: 591.7, 753.0, n=72, P<0.001), POD 14-20 (764.9, 95% CI: 704.1, 911.6, n=27, P<0.001), POD 21-27 (685.6, 95% CI: 443.8, 835.8, n=15, P<0.001), and on POD 28-41 (800.3, 95% CI: 626.9, 940.6, n=21, P<0.001). The colon cancer subgroup's preop and POD 14-20 median results were significantly higher than the corresponding rectal cancer results; otherwise, at the other 5 postop time points there were no significant differences between the rectal and colon cancer subgroups. In addition, no association was found between cancer stage and preop uPA levels and no significant differences were found in postop uPA levels between the hand-assisted laparoscopic group and the lap assisted subgroup at any of the postop time points. Conclusions: Persistently elevated plasma uPA levels at 5/6 postop time point (P<0.05), in combination with other previously demonstrated long duration proangiogenic plasma protein changes, may render the plasma proangiogenic within the period of the first month post-surgery and may promote angiogenesis within the residual tumor foci. The clinical significance pertaining to these changes, if any, is uncertain and remains to be proven.

A colonoscopic overtube system that creates a 'therapeutic zone' and permits retraction facilitates endoscopic submucosal dissection, was associated with fewer deep bowel wall injuries and instrument exchanges, and required less lifting solution vs classic endoscopic submucosal dissection in an ex vivo bovine model.

INTRODUCTION: Endoscopic submucosal dissection (ESD) is the 'gold standard' for large flat polyps; nevertheless, the rate of adoption in the USA is low. In ESD, the polyp is 'surgically' detached with a needle knife after a submucosal lift; gravity and the dissection cap are used for retraction. ESD would be easier if active retraction were possible. In an ex vivo bovine colon model, this study assessed an overtube system (Boston Scientific ORISE Tissue Retraction System, TRS) that permits retraction and creates 'an operative field' for removal of rectal/sigmoid lesions. METHOD: Classic ESD (C-ESD) was compared to TRS-facilitated ESD (TRS-ESD). Cleaned/preserved bovine large bowel was used, and two 2-cm 'lesions'/colon were branded onto the mucosal surface 25 and 35 cm from the anus. Submucosal saline lifts were made using a thin catheter and a standard needle knife. We tracked case length, number of instrument exchanges (to refresh lift), the volume of lift solution, the fullness of resection, and deep muscle injuries. RESULTS: Fifty ESDs were carried out in 25 colons (25 C-ESD, 25 TRS-ESD). Complete resections were noted in all cases. The TRS method required fewer instrument exchanges (median 5) vs C-ESD (median 9, p < 0.0001) and less lift solution (median 39 ml) than the C-ESD cases (median 55 ml, p = 0.0003). TRS-ESD was associated with fewer deep muscle injuries (median 2) than C-ESD (median 3, p = 0.0191). Finally, the TRS group's median case length (34.5 min) was shorter than that of C-ESD (41 min, p = 0.0543). CONCLUSION: The TRS system provides retraction and facilitates ESD regarding the number of lift injections, the volume of lift solution needed, and avoidance of muscle injuries. Of note, there is an apparent TRS learning curve, and the device mandates a distal-to-proximal approach and initial 360 degree mucosal incision. Further study is warranted.