Figure 6 - Physiologic record of a spontaneous, transient relaxation of the LES.

Manometric recordings were made with an electrode sleeve sensor (inset) at pressure recording ports at various locations (from the pharynx to the stomach). The vertical arrow indicates the onset of relaxation, which occurs in the absence of a swallow as shown by the absence of a pressure wave or contraction in the pharynx. There is complete LES relaxation for more than 20 seconds (horizontal line at the bottom of the tracing for the LES). Relaxation is associated with inhibition of the crural diaphragm, as indicated by the loss of inspiratory pressure oscillations at the level of the sphincter and loss of inspiratory DEMG. The contribution of the LES is shown in pink, and that of the crural diaphragm in brown. Reflux (indicated by a decrease in esophageal pH) occurs after complete relaxation of the sphincter and crural diaphragm and is associated with an increase in intraesophageal pressure. (Source: Adapted from Mittal et al¹⁵⁹, with permission from American Gastroenterological Association.)