ABSTRACT
Injectable thermo-sensitive chitosan hydrogels have recently been developed for the use of submucosal fluids in endoscopic submucosal dissections (ESD). This study aimed to investigate the efficacy and safety of chitosan hydrogels during ESD. Submucosal fluids were administered as follows: 0.9% normal saline (NS), 0.4% hyaluronic acid (HA) and chitosan/ß-glycerophosphate (CS/GP) hydrogel. Each solution was administered twice into the stomach and colon of a pig, with a total of 72 ESD procedures performed on 12 pigs. The injected volume and procedure-related parameters were recorded and analyzed. ESDs that created ulcers after 7 days were histologically compared. All ESD specimens were resected en bloc. The total injected volumes during ESD of the stomach (NS, 16.09±3.27 vs. HA, 11.17±2.32 vs. CS/GP, 9.44±2.33; p<0.001) and colon (NS, 9.17±1.80 vs. HA, 6.67±1.50 vs. CS/GP, 6.75±1.57; p = 0.001) were significantly different. Hydrogel showed significant differences from normal saline in terms of fluid power (mm2/vol; NS, 35.70±9.00 vs. CS/GP 57.48±20.77; p = 0.001) and consumption rate (vol/min; NS, 2.59±0.86 vs. CS/GP, 1.62±0.65; p = 0.013) in the stomach. Histological examination revealed preserved muscularis propria, although the chitosan hydrogel resulted in a partial inflammatory response, with a hypertrophied submucosal layer. Chitosan hydrogel was found to be superior to normal saline, with an efficacy similar to that of hyaluronic acid. Nonetheless, long-term histological changes should be evaluated before clinical implementation.
Subject(s)
Chitosan/administration & dosage , Endoscopic Mucosal Resection/veterinary , Glycerophosphates/administration & dosage , Hyaluronic Acid/administration & dosage , Animals , Chitosan/adverse effects , Chitosan/chemistry , Colon/drug effects , Female , Glycerophosphates/adverse effects , Glycerophosphates/chemistry , Hyaluronic Acid/adverse effects , Hyaluronic Acid/chemistry , Hydrogels/chemistry , Injections , Saline Solution/administration & dosage , Saline Solution/adverse effects , Saline Solution/chemistry , Stomach/drug effects , Swine , ThermodynamicsABSTRACT
OBJECTIVE: To evaluate the feasibility of transanal minimally invasive surgery (TAMIS) for submucosal rectal resection in large breed dogs. STUDY DESIGN: Cadaveric study. SAMPLE POPULATION: Canine cadavers (n = 6) weighing between 37.5 and 60 kg. METHODS: Dogs were positioned in sternal recumbency. After rectal cleansing, a transanal access platform was placed in the rectum, and a pneumorectum was established. An area of ventral rectal wall approximately 2 × 2 cm was resected in a submucosal plane by using laparoscopic instruments and submitted for histopathological evaluation. The rectal wall defect was closed with a single-layer continuous suture pattern with barbed suture. Postoperatively, the rectum was removed en bloc and evaluated for suture or surgical penetration of the serosal surface. RESULTS: Submucosal rectal resection was successfully completed by using TAMIS in all dogs. The median length of resected specimens after fixation was 24.5 mm (range 9.8-26.5). In two of six dogs, suture was macroscopically visible on the serosal surface, but no dogs had evidence of iatrogenic full-thickness surgical penetration of the rectum. The median distance from the aborad extent of the suture closure line to the anocutaneous junction was 35 mm (range, 35-105). CONCLUSION: Submucosal resection of the canine rectal wall was feasible in large breed dogs by using TAMIS. No evidence of full-thickness penetration of the rectal wall was seen in these cadaveric specimens. CLINICAL SIGNIFICANCE: Transanal minimally invasive surgery may provide an alternative minimally invasive approach for resection for benign adenomatous rectal polyps in large breed dogs that might otherwise require a rectal pull-through.
