Successful Diaphragm Pacing in a Porcine Model with Natural Orifice Transvisceral Endoscopic Surgery (NOTES): Increasing the Options for Intensive Care Unit(ICU) Patients
Raymond Onders1,2, Michael McGee1,2, Jeffrey Marks1,2, Anthony Ignagni1,2, Michael Rosen1,2, Amitabh Chak1,2, Ashley Faulx1,2, Robert Schilz1,2, Steve Schomisch1,2, MaryJo Elmo1,2, Jeffrey Ponsky1,2; 1University Hospitals of Cleveland, Cleveland, OH; 2Case Western Reserve University, Cleveland, OH
Background: Patients requiring prolonged mechanical ventilation in ICUs spend up to 40% of the time weaning from the ventilator. Failure to wean from mechanical ventilation is attributed to rapid onset of diaphragm atrophy, barotrauma, posterior lobe atelectasis, and impaired hemodynamics; all of which may benefit from a physiologically negative chest pressure with diaphragm pacing. We have shown that laparoscopic implantation of a diaphragm pacing stimulation (DPS) system provides adequate ventilation in spinal cord injured patients and decreases respiratory decline in patients with amyotrophic lateral sclerosis (ALS. We propose that acute ventilator assistance with interventional diaphragmatic neurostimulation is feasible and could facilitate weaning from mechanical ventilation. Bedside placement, like a gastrostomy tube, of the DPS system will expand the benefits of DPS to a new population of critically ill patients. This study expands our previous feasibility evaluations in a porcine model. Methods: Pigs were anesthetized and peritoneal access with the flexible endoscope was obtained using a guidewire, needle knife cautery and balloon dilatation. The diaphragm was mapped to locate the motor point (where stimulation yields maximal muscle contraction) with a novel endoscopic electrostimulation catheter. Intramuscular electrodes were placed at the motor point with a percutaneous needle into each hemidiaphragm. The electrodes were attached to the DPS system for pacing. The gastrotomy was sealed with a gastrostomy tube. Results: Three pigs were studied; the motor point was located in all animals with the endoscopic mapping instrument. Under trans-gastric endoscopic visualization bilateral percutaneous pacing electrodes were placed in all animals in less than 15 minutes. With the DPS system, ventilation was performed and tidal volumes recorded with Wright Spirometer. The animals were sacrificed and examined. There were no trans-diaphragmatic injuries from percutaneous needle placement, the gastrostomy tube adequately closed the gastric opening and the pacing wires could be completely removed with less tensile force than standard temporary cardiac pacing wires. Conclusions: These animal studies confirm that trans-gastric mapping of the diaphragm and implantation of a percutaneous electrode for therapeutic diaphragmatic stimulation is feasible. This NOTES method of implanting temporary pacing wires will be assessed as a continuation of an IRB approved trial of laparoscopic implantation of temporary pacing wires for patients on prolonged mechanical ventilation requiring feeding tube placement.
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