Colonoscopic injection for murine solid cecal cancer model.

BACKGROUND: The validity of current animal colon cancer models is questionable. This study was performed to evaluate whether colonoscopic injection of a murine colon cancer cell line into the cecal wall of immunocompetent rats leads to a solid tumor. METHODS: A bolus of bowel prep was given to BD-IX rats. Anesthesia was injected intraperitoneally. Video fiberscope allowed for irrigation and suction. Failure was inability to reach/inject cecum. Procedure was performed by four surgeons; 100 µl of colon tumor cell suspension (DHD/K12TRb; 10 million cells in 0.1 ml) was injected into cecal wall with 23-gauge needle placed on 3 mm wire resulting in a blister. Rats were allowed to recover. Solid tumor growth was measured at scheduled necropsy at 4 weeks. Sample size (107 rats: type I error 0.05; power 80%) was based on a pilot study. Data were presented as median (range). RESULTS: A total of 107 male BD-IX retired breeders weighing 356 g (range 256-432 g) underwent colonoscopy with submucosal injection of cecal wall. A single solid cecal cancer was identified in 98 (91.5%) rats at scheduled necropsy. Histology confirmed adenocarcinoma with tumor size of 4 mm (range 2.6-8.4 mm). Peritoneal carcinomatosis was found in ten (9.3%) rats. Distant metastases were found in three (2.8%) rats. Complications occurred in four (3.8%) rats: two aspirations and two colon perforations. CONCLUSIONS: A solid cecal tumor without carcinomatosis or metastasis has been developed by colonoscopic injection of a rat colon cancer cell line in 79% of immunocompetent rats.

Endoscopic retrograde cholangiopancreatography after laparoscopic Roux-en-Y gastric bypass: a case series and review of the literature.

Endoscopic retrograde cholangiopancreatography (ERCP) has become an important tool in the diagnosis and treatment of pancreaticobiliary pathology. ERCP in patients that have undergone Roux-en-Y gastric bypass (RYGB) is particularly challenging because traditional transoral endoscopy may be limited. We present our experience with ERCP after RYGB and review the literature. In 2007 eight patients underwent ERCP after RYGB using open or laparoscopic transgastric access. After introduction of pneumoperitoneum, a total of four ports were placed. A purse-string was placed around a gastrotomy 4 to 6cm proximal to the pylorus. The endoscope was introduced through a 15 mm left-upper-quadrant port and the gastrotomy. Endoscopy was then performed. Laparoscopic gastrotomy was used in all patients that underwent a previous laparoscopic Roux-en-Y gastric bypass (LRYGB) (n = 6) and open gastrotomy was used for patients with a previous open RYGB (n = 2). Cannulation and interventions in the pancreaticobiliary tree were successful in all cases. There were no postoperative complications. Laparoscopic transgastric ERCP after LRYGB is feasible, highly successful, may be performed expeditiously, and does not seem to add significant morbidity to the procedure. The ability to perform ERCP in this patient population is critical due to their tendency to have preexisting biliary disease and to develop gallstones and the associated complications.

Do hybrid simulator-generated metrics correlate with content-valid outcome measures?

BACKGROUND: Hybrid simulators provide objective metrics for laparoscopic task performance. This study aimed to evaluate the correlation between hybrid simulator-generated metrics and content-valid outcome measures. METHODS: Residents underwent training with a previously validated 5-task simulation model (5-TSM). The resident tasks included vessel clipping and dividing, lesion excision, loop appendectomy, mesh placement with tacks, and suture perforation with intracorporeal knot tying. After training, the residents were tested using the open module of a hybrid simulator (ProMIS) with previously validated passing scores. Content validity was defined as the extent to which outcome measures departed from clinical reality. Content-valid outcome measures (accuracy error, knot slippage, leak, operating time, tissue damage) were evaluated by two blinded raters. The hybrid simulator-generated metrics were path length and smoothness of movements. Values are given as means (standard deviation is not shown). RESULTS: Over 23 months, 20 residents underwent training with 5-TSM. Respectively, for tasks 1 to 5, the path length was 3,895, 3,472, 4,620, 2,408, and 9,089 mm; the smoothness (jerk) was 346, 455, 549, 264, and 910 cm/sec3; the accuracy error was 0.45, 2.20, 0.55, 0.87, and 0.20 mm; and the knot slippage was 5%. There were no leaks. The operating time, respectively, was 54, 61, 135, 43, and 130 s, and the tissue damage was 0, 0.28, 0, 0.8, and 0 mm. The interrater reliability was more than 0.80 for all the outcome measures except accuracy error (k=0.52). There was correlation between path length and operating time (Spearman rho, 0.537-0.709; p<0.05) for all the tasks. There was no correlation between path length and accuracy error, knot slippage, leak, and tissue damage. No correlation was found between smoothness and any of the outcome measures for any of the tasks except operating time (Spearman rho, 0.762-0.958; p<0.05). CONCLUSIONS: Although an expected strong correlation was observed between hybrid simulator-generated metrics and operating time, this study showed no correlation between simulator-generated metrics and other content-valid outcome measures.

The impact of sleep deprivation on product quality and procedure effectiveness in a laparoscopic physical simulator: a randomized controlled trial.

BACKGROUND: To compare the impact of sleep deprivation after 24-hour duty (post-call) with that of 8-hour work (post-work) on product quality (PQ) and procedure effectiveness (PE) in a laparoscopic physical simulator. METHODS: Voluntary surgeons and nurses were pretested with the Epworth Sleepiness Scale (ESS) and Minimally Invasive Surgical Trainer-Virtual Reality (MIST-VR). Surgical task was suturing perforated ulcer on a foam stomach in a physical simulator. PQ and PE were measured by accuracy error (AE), tissue damage (TD) leak rate (LR), goal- (GDA) non-goal-directed actions (NGDA), and operating time (OT), respectively. Construct validity was assessed comparing measures when surgeons and nurses performed the surgical task. Inter-rater reliability (IRR) was assessed by Kendall's tau b coefficient. An 80% power parallel block randomization design at alpha = .05 required 60 subjects. RESULTS: Thirty-two post-call surgeons and 32 post-work surgeons were well matched for age, gender, practice duration, and ESS and MIST-VR scores. The amount of time slept in the previous 24 hours was 1.5 versus 6.5 hours (P < .05). AE (1.0 mm vs. .5 mm), TD (2.18 mm vs. 2.18 mm), LR (56.2% vs. 65.6%), GDA (33.5 vs. 32.5), NGDA (.56 vs. .31), and OT (381.0 seconds vs. 364.5 seconds) were not significantly different when 32 surgeons in the post-call arm were compared with their 32 counterparts in the post-work arm, respectively. Construct validity was shown by significant improvement in 4 outcome measures (AE 1.0 mm vs. 2.0 mm, P = .00001; GDA 32.5 vs. 39.0, P = .07, NGDA .43 vs. .96, P = .045; and OT 377.5 vs. 557.0, P = .0005) when 64 surgeons performed the task as compared to 64 nurses. Tau b for IRR was 1.0 (P < .0001) for AE, TD, LR, and OT, .75 (P = .325) for GDA, and .77 (P = .305) for NGDA. CONCLUSIONS: Sleep deprivation had no impact on the studied outcome measures of a surgical task performed in a laparoscopic simulator.