Figure 1.

Examples of UES contractile response to slow 1ml/s (1a) and ultra-slow 0.05ml/s (1b) acid and saline intra-esophageal infusions in young and elderly. As seen in figure 1a, in both age groups and for both types of infusions, UES contraction occurred shortly after the start of infusions and continued during the entire period of infusion. In addition, UES contraction was sustained after the active infusion ceased through the passive dwell time in which acid and saline residue remained in the esophagus as evidenced by the impedance signature. In contrast, as seen in Figure 1b, in both acid and saline infusions, significant increase in UES pressure was only observed in the young group and at the late stage of infusion which was sustained into dwell interval (also see figure 2 and 3). As seen there was no significant UES response noted in the elderly either during active infusion or passive dwell interval.