Could Abdominal Surgery Be Performed Without General Anesthesia?

A new study suggests regional pain relief could be used during abdominal surgery by employing Natural Orifice Transluminal Endoscopic Surgery (NOTES), in which the organs are reached through a natural opening in the body, such as the mouth or the vagina.

According to a study by Michael Schaefer, M.D., of Charité University Berlin (Germany), NOTES has the potential to further improve the advantages of laparoscopy over open surgery. This becomes most obvious in the first reports of patients who underwent a NOTES procedure, who recovered promptly after surgery, had no or only minimal pain, required no narcotic medications, and were discharged the day after surgery. According to Dr. Schaefer, the enthusiasm about these promising results makes some doctors believe that, in the future, NOTES procedures can be done only by local anesthesia at the access site. However, he claims, this is unrealistic since the results from the first clinical reports about NOTES suggest differences between visceral and somatic pain, and recent evidence from experimental studies sees major differences in the innervation of the gut compared with the skin. The ability to identify the source of pain is excellent in the skin, generally good in muscles and deeper tissues, but poor, and diffuse in the viscera.

In contrast to the dense and somatotopically-oriented innervation of the skin, the viscera are only sparsely innervated. Fewer than 7% of afferent nerves entering the spinal cord project to the viscera, and only a small fraction of these transmit sensory input to the central nervous system (CNS). Further studies need to show whether the sparse innervation of the viscera is contributing to the lack of severe pain following abdominal NOTES procedures. The study was published on October 29, 2009, in Faculty of 1000 Medicine Reports.

"Innervation of the vaginal wall, for example, spreads via the pelvic and hypogastric nerves over several spinal segments (L2-S2), and innervation of the gastric wall expands over even more spinal segments (T1-L4),” concluded Dr. Schaefer. "This will preclude the possibility that some enthusiastic proponents of NOTES already envision, namely that entire NOTES procedures can be done by local anesthesia at the access site.”

NOTES procedures, like laparoscopy, require the establishment of a pneumoperitoneum, which influences several physiologic functions. Carbon dioxide (CO2) insufflation accumulates in the circulation via absorption through the peritoneum, resulting in elevated arterial partial pressure of carbon dioxide (pCO2) and decreased arterial pH; increasing pressure in the abdominal cavity compromises movement of the diaphragm and diminishes pulmonary function parameters, which could lead to the formation of alveolar atelectases and resultant ventilation/perfusion mismatch. Finally, hemodynamic parameters are affected via direct and indirect effects on the cardiovascular system.

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Charité University Berlin