Michael F. McGee

A Primer on Natural Orifice Transluminal Endoscopic Surgery: Building a New Paradigm

Access to the abdominal cavity is required for diagnostic and therapeutic endeavors for a variety of medical and surgical diseases. Historically, abdominal access has required a formal laparotomy to provide adequate exposure. Natural orifice transluminal endoscopic surgery (NOTES) is an emerging experimental alternative to conventional surgery that eliminates abdominal incisions and incision-related complications by combining endoscopic and laparoscopic techniques to diagnose and treat abdominal pathology. During NOTES, commercially available flexible video endoscopes are used to create a controlled transvisceral incision via natural orifice access to enter the peritoneal cavity. Common incision-related complications such as wound infections, incisional hernias, postoperative pain, aesthetic disdain, and adhesions could be minimized or eliminated by NOTES. NOTES has evolved from more than 2 centuries of technological innovations and continued growth in the field of surgical endoscopy. Innovative surgical endoscopists have slowly developed means to surpass the constraints of the gastrointestinal lumen by using a flexible endoscope. The future of surgical endoscopy may be the shared entity of NOTES, which further integrates endoscopy, gastroenterology, and minimally invasive and general surgery. Although the promise of NOTES is electrifying to surgeons and endoscopists, several key issues need to be characterized prior to the incorporation of NOTES into routine practice. This article reviews the status, contemporary body of literature, limitations, and potential future implications accompanying the development of NOTES.

Creating electrical contacts between metal particles using directed electrochemical growth

Electrical connections in microelectronics are usually established by means of photolithography to define the conducting channels. But methods that do not involve lithography have been explored, such as the use of electrodeposition or electropolymerization to grow random structures of conducting material between two electrodes. This approach has been used to make diodes, transistors and signal amplifiers based on conducting polymers. Template-based and thermal plating strategies have also been used to direct the growth of electrically conducting media. One advantage of these approaches over photolithography is the possibility of forming contacts in three dimensions and so achieving enhanced data-processing densities. Previous electrochemical approaches have required that the electrodes to be connected are physically linked to the external voltage source. Here we show that electrodissolution and electrodeposition processes in an applied electric field can be exploited to create directional growth of copper deposits between copper particles that are not connected to an external circuit. Moreover, the particles distort the electric field in such a way as to focus the diffusion of copper ions and consequently the direction of ‘wire’ growth, enabling the particles to be connected to one another in a directional and controllable manner. This suggests that appropriately directed electric fields may be used to connect an array of such particles into an arbitrary circuit pattern.

PEG Rescue : a practical NOTES technique

Dislodged percutaneous endoscopic gastrostomy (PEG) tubes occur commonly and may require urgent surgical intervention in a susceptible patient population. Natural orifice translumenal endoscopic surgery (NOTES) may facilitate PEG rescue and avoid the morbidity associated with contemporary surgical techniques. We report a case of a dislodged PEG tube in the early post-operative period with evidence of incomplete gastrocutaneous tract formation and intra-abdominal leakage. Bedside transgastric NOTES exploration facilitated peritoneoscopy, evacuation of intra-abdominal fluid, and re-establishment of the PEG tube through the original gastrotomy tract. Tube feeds were resumed and postoperative contrast fluoroscopy demonstrated no intra-abdominal leakage from the replaced PEG tube. No postoperative complications related to the NOTES procedure were noted at 30 days of follow-up. PEG rescue represents a unique, practical, and empowering application of the burgeoning experience of NOTES.

Pure natural orifice transluminal endoscopic surgery (NOTES) nephrectomy using standard laparoscopic instruments in the porcine model.

PURPOSE Natural Orifice Transluminal Endoscopic Surgery (NOTES) is an emerging technology that uses endoscopic instruments passed into the peritoneal cavity through hollow viscera to perform surgical procedures without the use of abdominal incisions. There are, however, limitations regarding the equipment available to simulate traditional surgery. The aim of this study was to determine the feasibility of a pure NOTES nephrectomy by using standard laparoscopic instruments through a modified transvaginal trocar. MATERIALS AND METHODS One 40-kg female swine underwent transgastric peritoneoscopy. Transgastric endoscopic visualization guided the introduction of a second transvaginal endoscope through a novel laparoscopic trocar/endoscopic overtube device. The retroflexed transgastric endoscope provided triangulated visualization as standard endoscopic instruments provided retraction, which allowed dissection of the kidney with standard laparoscopic instruments through our modified transvaginal trocar device. Each renal hilum, artery, vein, and ureter was dissected and divided with a transvaginal laparoscopic stapler. RESULTS Transgastric and transvaginal NOTES accesses were easily achieved, and bilateral nephrectomies were performed. Completion of peritoneoscopy revealed complete hemostasis and identification of ligated ureters and hilar vessels. Total operative time was 40 and 20 minutes for the right and left kidney, respectively. One kidney was captured with a laparoscopic retrieval sac and removed intact through the vaginal defect. CONCLUSIONS Pure NOTES nephrectomies are technically feasible in the porcine model by using standard laparoscopic instruments. Survival studies are necessary to determine the long-term complications and physiologic implications of NOTES nephrectomy. The development of innovative NOTES access trocars may allow for an increased armamentarium of NOTES instruments.

Natural orifice transluminal endoscopic surgery (NOTES) as a diagnostic tool in the intensive care unit

BackgroundAutopsy studies confirm that many intensive care unit (ICU) patients die from unrecognized sources of abdominal sepsis or ischemia. Computed tomography (CT) scans can be of limited use for these diagnoses and difficult to obtain in critically ill patients who require significant support for transport. Bedside laparoscopy has been described but still is cumbersome to perform. Bedside flexible endoscopy as a diagnostic tool or for placement of gastrostomy tubes is a standard ICU procedure. Natural orifice transluminal endoscopic surgery (NOTES) can provide access to the peritoneal cavity as a bedside procedure and may decrease the number of patients with unrecognized intra-abdominal catastrophic events.MethodsPigs were anesthetized and peritoneal access with the flexible endoscope was obtained using a guidewire, needle knife cautery, and balloon dilatation. The transgastric endoscope was used to explore all quadrants of the abdominal cavity. The small bowel was visualized to complete the exploration. The transgastric access location was then managed with the use of a gastrostomy tube. The animals were euthanized and analyzed.ResultsEight pigs were studied and complete abdominal exploration, including diaphragm visualization, was possible in all cases. Endoscopy-guided biopsies were performed, adhesions lysed, and the gallbladder successfully drained percutaneously. The small bowel was run successfully with percutaneous needlescopic suture graspers.ConclusionsThese animal studies support the concept that NOTES, with management of the gastric opening with a gastrostomy tube, may be another approach for finding unrecognized sources of abdominal sepsis or mesenteric ischemia in difficult ICU patients. These encouraging results warrant a prospective human trial to assess safety and efficacy.

Diaphragm pacing with natural orifice transluminal endoscopic surgery: potential for difficult-to-wean intensive care unit patients.

BackgroundUp to 50% of the patients in the intensive care unit (ICU) require mechanical ventilation, with 20% requiring the use of a ventilator for more than 7 days. More than 40% of this time is spent weaning the patient from mechanical ventilation. Failure to wean from mechanical ventilation can in part be attributable to rapid onset of diaphragm atrophy, barotrauma, posterior lobe atelectasis, and impaired hemodynamics, which are normally improved by maintaining a more natural negative chest pressure. The authors have previously shown that laparoscopic implantation of a diaphragm pacing system benefits selected patients. They now propose that an acute ventilator assist with interventional neurostimulation of the diaphragm in the ICU is feasible and could facilitate the weaning of ICU patients from mechanical ventilation. Natural orifice transluminal endoscopic surgery (NOTES) has the potential to expand the benefits of the diaphragm pacing system to this acute patient population by allowing it to be performed at the bedside similarly to insertion of the common gastrostomy tube. This study evaluates the feasibility of this approach in a porcine model.MethodsPigs were anesthetized, and peritoneal access with the flexible endoscope was obtained using a guidewire, needle knife cautery, and balloon dilation. The diaphragm was mapped using a novel endoscopic electrostimulation catheter to locate the motor point (where stimulation provides complete contraction of the diaphragm). An intramuscular electrode then was placed at the motor point with a percutaneous needle. The gastrotomy was managed with a gastrostomy tube.ResultsFour pigs were studied, and the endoscopic mapping instrument was able to map the diaphragm to identify the motor point. In one animal, a percutaneous electrode was placed into the motor point under transgastric endoscopic visualization, and the diaphragm could be paced in conjunction with mechanical ventilation.ConclusionsThese animal studies demonstrate the feasibility of transgastric mapping of the diaphragm and implantation of a percutaneous electrode for therapeutic diaphragmatic stimulation.

Complete endoscopic closure of gastrotomy after natural orifice translumenal endoscopic surgery using the NDO Plicator.

BackgroundThe NDO Plicator is a device developed for endoscopic treatment of gastroesophageal reflux disease (GERD) by approximation of tissues together with a double-pledgeted U-stitch. It was theorized that this device may facilitate transgastric natural orifice translumenal endoscopic surgery (NOTES) because closure of the transgastric defect remains a key component for advancement of this new technology.MethodsA standardized 12-mm gastrotomy was created endoscopically in four pigs using a combination of needle-knife cautery and balloon dilation. As the endoscope was removed, a Savary soft-tipped wire was introduced into the stomach, and the NDO Plicator was subsequently advanced over the wire. Each defect was identified, and the device was positioned. If necessary, the Plicator’s tissue grasper was used to hold the superior aspect of the gastrotomy and bring the opposed borders of the defect within the jaws of the device. The device was fired three times, leaving three pledgeted suture bundles to close the gastric defect. After closure, each animal was explored, and the integrity of the closure was assessed. The animals underwent in vivo contrast fluoroscopy and ex vivo burst pressure testing studies for assessment of leakage at the closure site.ResultsThe first animal was used to test feasibility, refine techniques, and develop a standard procedure. All of the next three animals studied showed complete sealing of the gastrotomy site without evidence of contrast extravasation on multiplanar fluoroscopic imaging. Each stomach was excised, submerged in water, and subjected to a pressurized air leak test. No leaks were noted until pressures exceeded 55 mmHg.ConclusionThis study supports the use of the NDO Plicator for closure of standardized gastric defects in a porcine model. In addition to closing NOTES gastrotomies, the NDO Plicator may be a particularly useful tool for obtaining complete closure of gastric perforations and anastomotic leaks, and for performing stomal reduction after gastric bypass procedures. The mechanical properties of a closure are not the only factor determining whether a leak will develop. Tissue opposition, ischemia, and tension are important factors that are not easily or reliably measured. The physiologic relevance of gastric bursting pressure is not known. Therefore, corollary animal studies with longer-term evaluation are necessary before research proceeds to clinical trials.

Tract length predicts successful closure with anal fistula plug in cryptoglandular fistulas

PURPOSE: Collagen anal fistula plug treatment of transsphincteric fistulas produces variable results. The purpose of our study was to determine whether long-tract fistulas (>4 cm) correlated with successful closure. METHODS: All patients undergoing transsphincteric cryptoglandular fistula repair with anal fistula plugs were enrolled in a prospective database. Patients with Crohns disease were excluded. Fistula tract length was measured intraoperatively by subtracting the remaining plug length from the original plug size. All procedures used standardized techniques and postoperative care pathways. The primary outcome was complete fistula closure assessed through both postoperative outpatient visits and a follow-up telephone questionnaire. RESULTS: Forty-one patients with 42 fistula tracks were enrolled over a 39-month period. Complete closure was achieved in 18 of 42 (43%) fistulas at a mean follow-up of 25 months. Closure was not associated with gender, age, tract location, duration of seton, or length of follow-up. Successful closure was significantly associated with increased tract length, because fistulas longer than 4 cm were nearly 3 times more likely to heal compared with shorter fistulas ((14/23, 61%) vs (4/19, 21%), P = .004; relative risk = 2.8; 95% CI 1.14-7.03). CONCLUSIONS: Anal fistula plug repair of cryptoglandular anorectal fistulas is more successful for long-tract fistulas. Although the overall success is modest, limiting surgical indications to fistulas exceeding 4 cm may maximize benefits of the plug technique.

Late phase TNF-alpha depression in natural orifice translumenal endoscopic surgery (NOTES) peritoneoscopy

BACKGROUND Natural orifice translumenal endoscopic surgery (NOTES) allows access to the peritoneal cavity without skin incisions. Contamination of the peritoneal cavity by enteric contents may render NOTES more physiologically and immunologically invasive than previously thought. Measurement of interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) is a validated method to quantify surgical stress. The physiologic and immunologic impact of NOTES is unknown. METHODS A total of 37 swine underwent abdominal exploration via transgastric NOTES peritoneoscopy, laparoscopy (LX), laparotomy (OPEN), or sham surgery (CONTROL) and were allowed to survive. TNF-alpha, IL-1beta, and IL-6 plasma levels were determined at the start and completion of surgery, and at 1 hour, 2 days, and 14 days postoperatively. RESULTS At surgical completion, OPEN animals demonstrated higher TNF-alpha levels than all groups. TNF-alpha levels were similar for all groups at 1 hour and 2 days. NOTES animals had significantly reduced plasma levels of TNF-alpha than all other groups on postoperative days 7 and 14. Controlling for baseline cytokine variability, analysis was repeated using normalized data, which confirmed significantly reduced TNF-alpha levels for NOTES compared with all groups at 14 days. Subset analysis excluding LX and OPEN complications revealed lower NOTES TNF-alpha levels at 7 and 14 days compared with all groups. IL-1beta and IL-6 levels were undetectable in 66.8% and 70.5% of samples, respectively, without significant trends. CONCLUSIONS Diagnostic NOTES peritoneoscopy demonstrated similar levels of systemic proinflammatory cytokine TNF-alpha compared with diagnostic laparoscopy and exploratory laparotomy in the immediate postoperative period despite gross intraperitoneal contamination. None of the surgical groups, however, produced a measurable, consistent trend in IL-1beta or IL-6. Consistently reduced levels of TNF-alpha in NOTES animals in the late postoperative period indicates an immunomodulatory effect of the NOTES surgical technique not present in laparoscopy or laparotomy.

Infectious implications in the porcine model of natural orifice transluminal endoscopic surgery (NOTES) with PEG-tube closure: a quantitative bacteriologic study

BACKGROUND Obtaining reliable closure of transvisceral defects currently limits natural orifice transluminal endoscopic surgery (NOTES). PEG tubes are potential means of managing NOTES gastrotomies. OBJECTIVE To determine the efficacy of PEG closure after NOTES. DESIGN An experimental animal study. SETTING A laboratory. INTERVENTIONS The pigs received gastric lavage with saline solution, chloramphenicol, or no lavage, and then underwent transgastric NOTES peritoneoscopy. Cultures were obtained by endoscopy during the surgery. A sterile foreign body was left in the peritoneal cavity. The gastrotomy was closed with a 20F PEG tube. The animals were observed for 14 days and underwent sterile laparotomy. Cultures of the foreign body and the peritoneal cavity were obtained. MAIN OUTCOME MEASUREMENTS Abscess rate, peritoneal quantitative cultures. RESULTS After 1 exclusion for anesthetic complications, 19 animals underwent NOTES; 18 (94.7%) survived the entire postoperative period. One animal died on postoperative day 2 after the PEG tube dislodged. At 14 days, 5 animals (27.8%) had intra-abdominal abscesses, 8 (44.4%) had positive peritoneal cultures, and 9 (50%) foreign bodies were contaminated on culture. Infectious complications were not altered by the type of gastric lavage or peritoneal bacterial inoculum introduced at the time of surgery. LIMITATION An animal model. CONCLUSIONS PEG closure of a NOTES gastrotomy is associated with subclinical intra-abdominal abscess formation and can result in death when the tube is dislodged during the early postoperative period. Preprocedural gastric lavage does not alter the intra-abdominal bacterial burden introduced at the time of surgery or subsequent infectious outcomes in the porcine model. These concerning findings necessitate additional studies to determine if porcine models are appropriate and applicable to human subjects in the NOTES setting.