Raymond P. Onders

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.

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.

Amyotrophic lateral sclerosis: the Midwestern surgical experience with the diaphragm pacing stimulation system shows that general anesthesia can be safely performed

BACKGROUND There is a paucity of literature concerning general anesthesia and surgery in patients with amyotrophic lateral sclerosis (ALS or Lou Gehrigs disease). This report summarizes the largest series of surgical cases in ALS during multicenter prospective trials of the laparoscopic diaphragm pacing system (DPS) to delay respiratory failure. METHOD The overall strategy outlined includes the use of rapidly reversible short-acting analgesic and amnestic agents with no neuromuscular relaxants. RESULTS Fifty-one patients were implanted from March 2005 to March 2008 at 2 sites. Age at implantation ranged from 42 to 73 years and the percent predicted forced vital capacity (FVC) ranged from 20% to 87%. On preoperative blood gases, Pco(2) was as high as 60. Using this protocol, there were no failures to extubate or 30-day mortalities. The DPS system increases the respiratory system compliance by decreasing posterior lobe atelectasis and can stimulate respirations at the end of each case. CONCLUSIONS Laparoscopic surgery with general anesthesia can be safely performed in patients with ALS undergoing DPS.

Diaphragm pacing stimulation system for tetraplegia in individuals injured during childhood or adolescence.

Abstract Background: Children with cervical spinal cord injury and chronic respiratory insufficiency face the risks and stigma associated with mechanical ventilators. The Diaphragm Pacing Stimulation (DPS) System for electrical activation of the diaphragm is a minimally invasive alternative to mechanical ventilation. Methods: Review of patients in a prospective Food and Drug Administration trial of the DPS System in individuals who were injured at age 18 years or younger. The procedure involved laparoscopic mapping to locate the diaphragm motor points with electrode implantation. Two weeks after surgery, stimulus/output characteristics of each electrode were determined to obtain an adequate tidal volume for ventilation. A home-based weaning protocol from the ventilator was used. Results: Of 28 patients implanted with the DPS System, 10 had sustained cervical SCI as children or adolescents. Average age at injury was 13 years (range 1.5 to 17 y). Age at implantation ranged from 18 to 34 years. Length of time from injury to implantation averaged 9.7 years (0.8 to 19y). All patients tolerated the implantation procedure. Four patients utilize DPS continuously (24/7), 4 patients pace daytime only, and 2 patients are still actively conditioning their diaphragms. Two patients required surgical correction of scoliosis prior to implantation. All patients prefer breathing with the DPS and would recommend it to others; 4 patients specifically identified that attending college or church without a ventilator eases their integration into society. Conclusions: The results show that the laparoscopic DPS system can be safely implanted in tetraplegics injured as children and used in a home-based environment to wean them off of mechanical ventilation.

Inspiratory Muscle Pacing in Spinal Cord Injury: Case Report and Clinical Commentary

Abstract Background/Objective: A significant fraction of patients with cervical spinal cord injury suffer from respiratory muscle paralysis and dependence on chronic mechanical ventilation. In selected patients, diaphragm pacing (DP) through electrical stimulation of the phrenic nerves provides an alternative to mechanical ventilation with significant advantages in life quality. Methods: A case report of an individual who successfully underwent DP using intramuscular diaphragm electrodes. A brief review of the state of the art of DP including the clinical benefits of DP, patient selection and evaluation, description of equipment, methods of transition from mechanical ventilation to DP, potential complications and side effects, long-term outcome, and potential future developments in this field is included. Results: Several available DP systems are available, including conventional ones in which electrodes are positioned directly on the phrenic nerves through thoracotomy and less invasive systems in which electrodes are placed within the diaphragm through laparoscopy. For patients with only unilateral phrenic nerve function, a combined intercostal and unilateral diaphragm pacing system is under development. Conclusions: In patients with ventilator-dependent tetraplegia, there are alternative methods of ventilatory support, which offer substantial benefits compared to mechanical ventilation.

Multicenter analysis of diaphragm pacing in tetraplegics with cardiac pacemakers: positive implications for ventilator weaning in intensive care units.

BACKGROUND Diaphragm pacing (DP) can replace mechanical ventilation in tetraplegics and in trials has assisted respiration in amyotrophic lateral sclerosis patients. This report describes results of DP in patients with cardiac pacemakers. METHODS Prospective, single-center and multicenter, nonrandomized, controlled, interventional protocols under U.S. Food and Drug Administration and/or institutional review board approval were evaluated. Patients underwent laparoscopic diaphragm motor point mapping to identify optimal electrode site for implantation. With diaphragm conditioning, patients were weaned from their ventilator. Perioperative and long-term assessments between the cardiac pacemakers and DP were analyzed for any device-to-device interactions. RESULTS Over 300 subjects were implanted from 2000 to 2010. Twenty tetraplegics with cardiac pacemakers and DP were analyzed from 6 sites. Subjects ranged from 19 to 61 years old with DP implantation 6 months to 24 years postinjury. There were no immediate or long-term device to device interactions. All patients achieved diaphragm-paced tidal volumes exceeding their basal requirements and, after conditioning, all patients could go >4 hours without mechanical ventilators; 71% could go 24 hours continuously. CONCLUSION DP can be safely implanted in tetraplegics having cardiac pacemakers. Applications for temporary use of DP to maintain diaphragm type 1 muscle fiber and improve posterior lobe ventilation may benefit complex critical care patients.

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.

Diaphragm pacing improves sleep in patients with amyotrophic lateral sclerosis

Abstract In amyotrophic lateral sclerosis (ALS) patients, respiratory insufficiency is a major burden. Diaphragm conditioning by electrical stimulation could interfere with lung function decline by promoting the development of type 1 muscle fibres. We describe an ancillary study to a prospective, non-randomized trial (NCT00420719) assessing the effects of diaphragm pacing on forced vital capacity (FVC). Sleep-related disturbances being early clues to diaphragmatic dysfunction, we postulated that they would provide a sensitive marker. Stimulators were implanted laparoscopically in the diaphragm close to the phrenic motor point in 18 ALS patients for daily conditioning. ALS functioning score (ALSFRS), FVC, sniff nasal inspiratory pressure (SNIP), and polysomnographic recordings (PSG, performed with the stimulator turned off) were assessed before implantation and after four months of conditioning (n = 14). Sleep efficiency improved (69 ± 15% to 75 ± 11%, p = 0.0394) with fewer arousals and micro-arousals. This occurred against a background of deterioration as ALSFRS-R, FVC, and SNIP declined. There was, however, no change in NIV status or the ALSFRS respiratory subscore, and the FVC decline was mostly due to impaired expiration. Supporting a better diaphragm function, apnoeas and hypopnoeas during REM sleep decreased. In conclusion, in these severe patients not expected to experience spontaneous improvements, diaphragm conditioning improved sleep and there were hints at diaphragm function changes.