Per-Ola Park

Experimental studies of transgastric gallbladder surgery: cholecystectomy and cholecystogastric anastomosis (videos)

BACKGROUND Transgastric flexible endoscopic surgery might offer advantages over open and laparoscopic surgery. The aim of this study was to develop methods for performing transgastric biliary endosurgery. METHODS Cholecystectomies and biliary anastomoses were performed in 8 anesthetized pigs (27-30 kg) in nonsurvival studies. Two endoscopes passed perorally were inserted through the stomach wall after needle-knife incision. Endoscope-induced pneumoperitoneum allowed viewing and manipulation of the gallbladder with both endoscopes independently. The cystic duct was dissected, clipped, and transected. Cholecystectomy was performed with one of two methods: either by using two endoscopes, or a single endoscope and a 5-mm-diameter grasping instrument inserted transabdominally. Clips and sutures were used to attach the gallbladder to the stomach wall, and an incision was made to form a cholecystogastrostomy. In survival experiments in 8 pigs, transgastric incisions were closed with endoscopic sutures. RESULTS The gallbladder was successfully removed in 8 pigs (nonsurvival experiments). The time for the procedure ranged from 2.5 hours to 40 minutes and decreased with experience. At postmortem examination, clips placed on the cystic duct and the artery were secure. An anastomosis was successfully formed between gallbladder and stomach in 3 pigs. In 8 pigs, full-thickness incisions in the stomach wall were closed with two to 4 stitches. All 8 pigs survived (median follow-up, 22 days; range 14-28 days). CONCLUSIONS Transgastric gallbladder surgery, including cholecystectomy and biliary anastomosis, is feasible. Full-thickness gastric incisions were safely closed in survival studies. The efficacy and the safety of transgastric surgery merits further study.

Transgastric gastropexy and hiatal hernia repair for GERD under EUS control: a porcine model

BACKGROUND Endoluminal operations for gastroesophageal reflux currently are limited by the inability to visualize and manipulate structures outside the wall of the gut. This may be possible by using EUS. The aims of this study were the following: to define the EUS anatomy of structures outside the gut that influence reflux, to place stitches in the median arcuate ligament, to perform posterior gastropexy, and to test the feasibility of crural repair under EUS control in pigs. METHODS In survival experiments in 22 pigs, by using a linear-array echoendoscope, the median arcuate ligament and part of the right crus were identified and punctured with a needle, which served as a carrier for a tag and thread. These were anchored into the muscle. An endoscopic sewing device was used, allowing stitches to be placed through a 2.8-mm accessory channel to any predetermined depth. New methods allowed knot tying and thread cutting through the 2.8-mm channel of the echoendoscope. RESULTS Stitches were placed through the gastric wall into the median arcuate ligament, and one stitch was placed just beyond the wall of the lower esophageal sphincter. The stitches were tied together and locked against the gastric wall. Median lower esophageal sphincter pressure, determined manometrically, was 11 mm Hg before surgery and 21 mm Hg after stitch placement (p=0.0002). The length of the lower esophageal sphincter increased from a median of 2.8 cm before the procedure to 3.5 cm after the procedure. At the postmortem, the median force required to pull the tags out of the median arcuate ligament was 2.8 kg. CONCLUSIONS This study demonstrates that transgastric gastroesophageal reflux surgery, by using stitching under EUS control, can significantly increase lower esophageal sphincter pressure in pigs.

Bard EndoCinch: the device, the technique, and pre-clinical studies.

There is, of course, room for improvement. More work is needed to make endoscopic suturing easier, quicker and more reliable. The single most important next goal is to construct a device, which can place multiple stitches without the need to remove the endoscope between each stitch. Devices, which can place two stitches in one go, would be a start. The development of double stitch and multiple stitch devices has been described earlier. The authors are pleased to see two alternative commercial endoscopic sewing devices appear at the last DDW which place two stitches without needing to withdraw the endoscopes--they use a double needle method.

Peritoneal and systemic pH during pneumoperitoneum with CO2 and helium in a pig model

BackgroundLocal peritoneal effects of laparoscopic gases might be important in peritoneal biology during and after laparoscopic surgery. The most commonly used gas, CO2, is known to be well tolerated, but also causes changes in acid-base balance. Helium is an alternative gas for laparoscopy. Although safe, it is not widely used. In this study a method for monitoring peritoneal pH during laparoscopy was evaluated and peritoneal pH during CO2 and helium pneumoperitoneum was studied as well as its systemic reflection in arterial pH.MethodsFor these experiments 20 pigs were used, with ten exposed to pneumoperitoneum with CO2, and ten to helium. Peritoneal and sub-peritoneal pH were continuously measured before and during gas insufflation, during a 30-minute period with a pneumoperitoneum and during a 30-minute recovery period. Arterial blood-gases were collected immediately before gas insufflation, at its completion, at 30 minutes of pneumoperitoneum and after the recovery period.ResultsPeritoneal pH before gas insufflation was in all animals 7.4. An immediate local drop in pH (6.6) occurred in the peritoneum with CO2 insufflation. During pneumoperitoneum pH declined further, stabilising at 6.4, but was restored after the recovery period (7.3). With helium, tissue pH increased slightly (7.5) during insufflation, followed by a continuous decrease during pneumoperitoneum and recovery, reaching 7.2. Systemic pH decreased significantly with CO2 insufflation, and increased slightly during helium insufflation. Systemic pH showed co-variation with intra-peritoneal pH at the the end of insufflation and after 30 minutes of pneumoperitoneum.ConclusionsInsufflation of CO2 into the peritoneal cavity seemed to result in an immediate decrease in peritoneal pH, a response that might influence biological events. This peritoneal effect also seems to influence systemic acid-base balance, probably due to trans-peritoneal absorption.

A randomized trial comparing rates of abdominal contamination and postoperative infection among natural orifice transluminal endoscopic surgery, laparoscopic surgery, and open surgery in pigs

BACKGROUND Bacterial contamination of the abdominal cavity and infectious complications have been debated concerning transgastric natural orifice transluminal endoscopic surgery (NOTES) procedures. OBJECTIVE The aim of this study was to compare bacterial contamination of the abdominal cavity and clinically relevant infections after open, laparoscopic, and transgastric NOTES procedures. DESIGN Randomized survival study in a porcine model. SETTING Animal laboratory at a university hospital. INTERVENTION Thirty pigs were randomized to open, laparoscopic, or transgastric NOTES uterine horn resection under sterile conditions. Bacterial cultures were obtained from the pelvic area immediately at entry of the abdominal cavity and just before closure. The left uterine horn was dissected and ligated. The animals survived for 4 weeks. At necropsy, bacterial culture was obtained from the pelvic area. MAIN OUTCOME MEASUREMENTS Perioperative: operation time and incision length, bacterial growth in abdominal samples. Postoperative: infections or complications, weight gain. Necropsy: signs of peritonitis or infection, abdominal bacterial growth. RESULTS Procedure time was significantly longer for transgastric NOTES. At the start of the procedure, 4 of the NOTES animals showed positive cultures, but only 1 showed positive cultures at the end. No open surgery or laparoscopic surgery animals showed positive cultures at these time points. At necropsy, none of the animals in the NOTES group showed bacterial growth, whereas 4 open surgery animals and 3 laparoscopic surgery animals had positive cultures. Four of these animals (2 from each group) had concurrent wound infections. LIMITATIONS Small sample size and lack of power calculation. CONCLUSION This study indicates that clinically relevant infections are rare after transgastric NOTES procedures despite evidence of bacterial contamination and longer operating times.

Self-expandable metal stents as a new treatment option for perforated duodenal ulcer.

Primary stenting and drainage has been shown to be an effective and safe way to treat esophageal perforations and anastomotic leaks after gastric bypass surgery. We present a case series of eight patients with perforated duodenal ulcers treated with covered self-expandable metal stents (SEMS). The first two patients received their stents because of postoperative leakage after initial traditional surgical closure. The following six patients had SEMS placed as primary treatment due to co-morbidities or technical surgical difficulties. Endoscopy and stent treatment in these six patients was performed at a median of 3 days (range, 0 - 7 days) after initial symptoms. Six patients had percutaneous abdominal drainage. Early oral intake, 0 - 7 days after stent placement, was possible. All patients except one recovered without complications and were discharged 9 - 36 days after stent placement. This series indicates that primary treatment with SEMS and drainage might be an alternative to surgery in patients with perforated ulcer disease.

New methods for innovation: the development of a toolbox for natural orifice translumenal endoscopic surgery (NOTES) procedures.

BackgroundDevices used for flexible intralumenal procedures are inadequate when used for intraperitoneal surgical procedures such as cholecystectomy.ObjectiveTo assess/address limitations of flexible endoscopic devices in intraperitoneal surgery.DesignTo describe processes used to invent new devices to facilitate this new surgical genre.SettingEngineering laboratory.PatientsNone.Interventions and inventionsReviews of the limitations of flexible endoscopic instruments and instrumentation/invention needs for a “NOTES cholecystectomy” were completed.Main outcome measuresThe appropriateness of existing methods of device innovation was evaluated against an inventory of new technologies necessary to perform NOTES. The deficiencies in traditional innovation methods led to the creation of a novel process for invention of new medical devices: the “Inventorama.”MethodsCooperation between clinicians and industry to develop device concepts to enable NOTES.ResultsThe devices included: (1) steerable flex trocar, (2) rotary access needle, (3) bipolar hemostasis forceps, (4) Maryland dissectors, (5) articulating hook knife, (6) rotating hook knife, (7) articulating graspers, (8) scissors, (9) ligating clip applier, and (10) tissue apposition system. Six of these ten were built and tested as initial crude prototypes in the Inventorama process; two underwent major modifications. Three were invented via alternate methods, including by independent clinicians.ConclusionsA new method for efficient medical device invention and development was created to address key technology needs for NOTES. The result was a “toolbox” of devices designed to address the key surgical activities necessary for advanced intralumenal and translumenal flexible endoscopic procedures.

A New In Vivo Method for Testing Closures of Gastric NOTES Incisions Using Leak of the Closure or Gastric Yield as Endpoints

BACKGROUND We developed a non-survival in vivo model for testing of gastric natural orifice translumenal endoscopic surgery (NOTES) closures based on the gastric yield pressure. The aim of this study was to test our model comparing different endoscopic closure techniques with surgical closure of a NOTES gastric incision. METHODS Laparotomy was performed in 30 pigs. One tube for air inflation and one manometry tube were inserted into the stomach via the pylorus, which was closed gas-tight, and the abdominal wall was closed. The stomach was inflated with air, and the gastroesophageal yield pressure was measured. A gastroscopy was performed, and a standard NOTES access was created followed by randomization to closure by surgical suturing, T-tags, Padlock-G over-the-scope (OTS)-clips, OVESCO OTS-clips, and traditional clips. All closures were tested twice with air insufflation. Gastric yield pressure or leak pressure of each closure was recorded. RESULTS The mean baseline gastric yield pressure was 80.5 mm Hg. Post-closure yield pressure was 79.9 mm Hg. Leak test results after closure were as follows: surgery, 0/6 leaked; T-tags, 1/6 leaked before reaching yield pressure (56 mm Hg); Padlock-G, 2/5 leaked (71.5 mm Hg); OVESCO OTS-clips, 3/6 leaked (27.2 mm Hg); and traditional clips, 5/6 leaked (27.2 mm Hg). TAS T-tags and surgical closures leaked significantly less than the other groups (P=.01). Traditional clips and OVESCO OTS-clips leaked at significantly lower pressures than the other three groups (P=.007). CONCLUSION This in vivo model using leak of the closure or the gastric yield pressure as endpoints for testing of the closure strength of a NOTES gastric access site seems to be reproducible. Our results support closure with T-tags and Padlock-G-clips over OVESCO OTS-clips and standard endoscopic clips.

Exploring pyloric dynamics in stenting using a distensibility technique

Perforated duodenal ulcers can be treated with a covered stent. Stent migration is a severe complication, sometimes requiring surgery. Pyloric physiology during stent treatment has not been studied and mechanisms for migration are unknown. The aim of this study was to investigate the pyloric response to distention, mimicking stent treatment, using the EndoFLIP.

ERCP in Altered Anatomy

ERCP is the standard technique for dealing with pathology of the common bile duct, such as bile duct stones or strictures due to malignant or benign processes. However, ERCP in patients with surgically altered anatomy, such as Roux-en-Y gastric bypass (RYGBP), total gastrectomy, Billroth II procedure or Whipple procedure (Fig. 10.1), is challenging. Several more or less invasive methods have been described for endoscopic biliary interventions in these patients.