BACKGROUND: The mechanism of prevention of gastric reflux into the esophagus is not exactly known. The lower esophagus has a barrier function provided by the lower esophageal sphincter. We investigated the hypothesis that the crural diaphragm shares in the barrier function not only mechanically but also actively through a crural-esophageal-gastric reflex action. METHODS: The study was performed during repair of abdominal ventral and incisional hernias in 20 subjects (11 men, 9 women; age 38.6+/-4.8 years). The electromyographic response of the crural diaphragm to individual balloon distension of esophagus and stomach was recorded by means of a needle electrode inserted into the crural diaphragm and connected to an electromyographic apparatus. The recordings were repeated after separate crural, esophageal, and gastric anesthetization. RESULTS: The crural diaphragm exhibited basal motor unit action potentials, which decreased on esophageal distension (P<0.001) after a mean latency of 17.3+/-2.8 SD ms. The crural diaphragm response to esophageal distension did not occur after the crural diaphragm or esophagus was anesthetized. Gastric distension effected an increase of crural diaphragm electromyographic activity with a mean latency of 18.4+/-4.6 ms; this effect could not be achieved after the crural diaphragm or stomach was anesthetized. CONCLUSIONS: The crural diaphragm has a resting tone that relaxes after esophageal distension and contracts after gastric distension. This sphincter-like action of the crural diaphragm appears to be a reflex and is mediated through the esophagocrural inhibitory and gastrocrural excitatory reflexes. The crural diaphragm seems to share actively in the gastroesophageal competence mechanism.
BACKGROUND: The mechanism of prevention of gastric reflux into the esophagus is not exactly known. The lower esophagus has a barrier function provided by the lower esophageal sphincter. We investigated the hypothesis that the crural diaphragm shares in the barrier function not only mechanically but also actively through a crural-esophageal-gastric reflex action. METHODS: The study was performed during repair of abdominal ventral and incisional hernias in 20 subjects (11 men, 9 women; age 38.6+/-4.8 years). The electromyographic response of the crural diaphragm to individual balloon distension of esophagus and stomach was recorded by means of a needle electrode inserted into the crural diaphragm and connected to an electromyographic apparatus. The recordings were repeated after separate crural, esophageal, and gastric anesthetization. RESULTS: The crural diaphragm exhibited basal motor unit action potentials, which decreased on esophageal distension (P<0.001) after a mean latency of 17.3+/-2.8 SD ms. The crural diaphragm response to esophageal distension did not occur after the crural diaphragm or esophagus was anesthetized. Gastric distension effected an increase of crural diaphragm electromyographic activity with a mean latency of 18.4+/-4.6 ms; this effect could not be achieved after the crural diaphragm or stomach was anesthetized. CONCLUSIONS: The crural diaphragm has a resting tone that relaxes after esophageal distension and contracts after gastric distension. This sphincter-like action of the crural diaphragm appears to be a reflex and is mediated through the esophagocrural inhibitory and gastrocrural excitatory reflexes. The crural diaphragm seems to share actively in the gastroesophageal competence mechanism.
Authors: James M Tatum; Evan Alicuben; Nikolai Bildzukewicz; Kamran Samakar; Caitlin C Houghton; John C Lipham Journal: Surg Endosc Date: 2018-07-13 Impact factor: 4.584