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

Background: Up 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. Methods: Pigs 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. Results: Four 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. Conclusions: These animal studies demonstrate the feasibility of transgastric mapping of the diaphragm and implantation of a percutaneous electrode for therapeutic diaphragmatic stimulation.