Figure 7 - Two examples from the same patient, showing different patterns of regurgitation.

In the top tracing, there is an abrupt fall in esophageal pH, which is followed, virtually immediately, by an abrupt fall in pharyngeal pH. Both of the events in this situation occurred in the upright posture, presumably as an "explosive" phenomenon in which the acidic content travel directly from stomach to the pharynx. The bottom tracing, during sleep, shows a very different picture where one sees a fall in pharyngeal pH only following a prolonged period of esophageal acidification.