Design
This study was an analysis of clinical outcomes data associated with different types of pancreatic stent placement. It is a retrospective review of patient medical records documented in the Department of Biliary Minimally Invasive Surgery affiliated to Zhongshan Hospital of Dalian University in China. The study was approved by the Conduct of Human Ethics Committee of the Affiliated Zhongshan Hospital of Dalian University.
Patients
A single endoscopist performed ERCP in 735 consecutive patients with pancreatobiliary disease from November 2013 to November 2015. Exclusion criteria were, malignant tumor with biliary metal stent insertion, pancreatic duct stone, and cases that did not place nasobiliary drainage tubes at the same time. Two hundred thirty patients who had prophylactic pancreatic stent placed were eligible for inclusion. One hundred fifty received an ordinary pancreatic stent and nasobiliary drainage tubes (ordinary group) from November 2013 to October 2014 and 80 received the modified pancreatic stent (Modified group) from November 2014 to November 2015. The main outcome measures were the difficulty level and complications of pancreatic stent placement and extraction between the two groups.
Endoscopic equipment and accessories
The following equipment and accessories were utilized during endoscopy: JF-260v/TJF-240 electronic duodenoscope (Olympus, Japan), VIO-200 s high frequency generator (mixed currents, cut current of 40-W, coagulation current of 40-W) (ERBE, German), papillary sphincter knife (Endo-Flex, German), balloon dilatation catheter (balloon diameter: 6 to 12 mm, length: 4 cm, pressure: 8 to 18 ATM) (OptiMed, German), inflation device (Boston Scientific, USA), yellow zebra guide wire, pancreatic stent, nasal biliary drainage tube (Boston Scientific, USA), sutures (Wego, China).
Standard and method of pancreatic stent placement
Prophylactic PS should be placed if the patient has more than two factors as following: younger age, female gender, previous pancreatitis, SOD, normal serum bilirubin, difficult cannulation, precut sphincterotomy, EST, EPT, pancreatic duct injection, intraductal ultrasonography, sphincter of Oddi manometry, minor papilla sphincterotomy and trainee involvement in procedure [12]. PS was required be placed if the patient was diagnosed with acute or chronic pancreatitis or in patients in which contrast medium in the pancreatic duct drained slowly.
Therapeutic endoscopy
ERCP was performed using digital subtraction angiography (DSA). EST was performed using a high frequency generator with the following settings: blend 1, cutting of 55, and coagulation of 30. The bile or pancreatic duct was first accessed by insertion of a soft-tipped Teflon tracer (diameter 0.035 in.) guidewire through a 6F, double channel sphincterotome. This was followed by cannulation, injection of contrast solution, EST, and endoscopic papillary balloon dilation (EPBD). Stones were removed by basket or balloon catheter and endoscopic nasal biliary drainage (ENBD) was performed to drain infected bile.
An ordinary PS is pushed into the main pancreatic duct by a PS propeller with guidewire. In modified group (Fig. 1) (Patent number in China: 201,510,238,034.9), the end of the straight PS and the head of the nasobiliary catheter are connected by a line. After the successful placement of PS, nasobiliary catheter will be separated from the PS when the guide wire is pulled back into the lumen of the nasobiliary catheter. Then nasobiliary catheter with guidewire is cannulated into the common bile duct and pushed into the proper position. When the line at end of nasobiliary catheter is stretched two drainage tubes will link together (Fig. 2).
The modified PS system can be removed a week after ERCP (Fig. 3). Cholangiography is performed through nasobiliary catheter to judge whether there is residual stone in common bile duct. To remove the PS the line is tightened and nasobiliary catheter, along with the PS, can be pulled out slowly using X-ray imaging as a guide.
Determination of clinical outcomes from patient records
Patient records were reviewed to confirm pancreatobiliary disease, efficacy of operation and complications. Complications included, the result of preoperative imaging, intraoperative endoscopy and cholangiography, postoperative laboratory results, X-ray results and laboratory results following the removal of PS. Imaging workup included hepatobiliary pancreas spleen ultrasound, computerized tomography (CT), and magnetic resonance cholangiopancreatography (MRCP). Laboratory workup included blood and urine analysis, as well as serum lipase and liver function tests (LFTs). Endoscopy and cholangiography included the type of nasobiliary catheter and PS. X-ray was used to document the location of stents.
Data collection
We searched the entire electronic medical record in the Department of Biliary Minimally Invasive Surgery affiliated to Zhongshan Hospital of Dalian University in China. The data of interest recorded in the electronic medical record were collected and tabulated.
Statistical analysis
Descriptive statistics were used to characterize the quantitative date with means and 95% confidence intervals. The two-tailed student’s t-test was used to assess for differences between continuous means of the two groups. The two-tailed Fisher exact and chisquare tests were used to compare categorical variables. P < 0.05 was considered to be statistically significant. All statistical analyses were performed using SPSS software package, version 21 (Statistical Package for Social Sciences, IBM Corporation, Armonk, NY, USA).