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July 2006 – Potential Role for Transluminal Endoscopic Surgery in ICU

By: Mary B. Nierengarten

Dallas—Natural orifice transluminal endoscopic surgery may play both a therapeutic and a diagnostic role in the intensive care unit, according to research presented at the 2006 annual meeting of the Society of American Gastrointestinal and Endoscopic Surgeons.

Two studies presented by Raymond Onders, MD, director of minimally invasive surgery, University Hospitals of Cleveland, offered a glimpse into some of the potential ways that natural orifice transluminal endoscopic surgery (NOTES) may be used to solve frequent and challenging problems facing patients in the intensive care unit (ICU).

In an attempt to help wean patients from mechanical ventilation while in the ICU, Dr. Onders and his colleagues from the Case Advanced Surgical Endoscopic Team (CASE-T) at Case Western Reserve University investigated the feasibility of an intervention that could stimulate the diaphragm in ICU patients at the bedside. Previous work from these investigators showed that neurostimulation of the diaphragm using a laparoscopically implanted diaphragm pacing stimulation (DPS) system helped patients with spinal cord injuries wean off mechanical ventilation and to breathe on their own.

According to Dr. Onders, the purpose of the new study was to evaluate the feasibility of bringing this technology to the bedside in the ICU with the help of NOTES.

"If we can place the system at the bedside with NOTES, instead of laparoscopic surgery, which is still usually done in the [operating room]," he said, "it will simplify the procedure and decrease the cost."

The researchers used a flexible endoscope to access the peritoneum of four anesthestized pigs and to locate the motor point in the diaphragm where neurostimulation provided complete contraction of the diaphragm. After this point was mapped, an intramuscular electrode was placed at the point with a percutaneous needle that was then attached to a diaphragm pacing system. A percutaneous endoscopic gastrostomy (PEG) tube was used to manage the gastrotomy.

The authors found that this NOTES technique allowed for successful visualization and stimulation of the diaphragms in all of the pigs, and therefore showed the feasibility of using a transgastric mapping technique to stimulate the diaphragm.

Among the main advantages of using NOTES techniques in this setting, according to Nathaniel Soper, MD, professor of surgery and director of the Institute for Minimally Invasive Surgery at Washington University School of Medicine, St. Louis, is avoiding the difficulty of moving patients to the operating room to perform a laparoscopic procedure. In addition, he said, "the PEG procedure is already done on a regular basis in the ICU and the NOTES procedure would be combined with a PEG, which would assure secure closure of the gastric hole."

Among the challenges of NOTES is "convincing internists that diaphragm pacing in the usual ICU patients makes sense," he said.

For Dr. Onders, "the challenges will be to show that diaphragm pacing will not only increase the strength of the diaphragm but also decrease pneumonias and subsequently increase patients' survival."

In another study based on a porcine model, Dr. Onders and his colleagues showed the feasibility of using the NOTES technique to explore the abdomens of eight pigs to diagnose abdominal sepsis or ischemia. According to researchers, the ability to evaluate and diagnose infections at the bedside of ICU patients may help to reduce the substantial number of ICU patients who die of unrecognized causes of abdominal infection.

Whether NOTES will emerge as a viable approach in the ICU or for other uses in humans is still unknown. Dr. Soper said it is too soon to tell whether NOTES is the future of minimally invasive surgery.

"[There is] lots of smoke but few flames, so far, and a long way before the instrumentation is adequate," he said. "However, [there is] lots of excitement and ongoing research."

Dr. Onders agreed that better instrumentation is needed and believes that the use of NOTES for diaphragm pacing "may become the initial procedure that drives industry to develop better instrumentation for NOTES."