High Resolution Manometry (HRM) recording of esophagogastric junction (EGJ) pressure

Panel A: High resolution manometry (HRM) recording of esophagogastric junction (EGJ) pressure in an individual without a hiatal hernia as evident by the crural diaphragm (CD) being completely superimposed on the lower esophageal sphincter (LES) pressure signature, ie, the LES-CD separation is 0. Both during quiet respiration and deep breaths, the LES is only evident between inspirations when the CD signal is minimal. In this example, the pressure inversion point (PIP) tool has been positioned to optimally isolate the respiratory inversion point (RIP) as evident by the PIP tool output shown as an insert. Barely visible on the pressure topography are a horizontal blue dashed line and green dashed line indicating the locations of the proximal and distal pressure (P) recordings shown in the PIP tool output. The red line in the PIP tool output box is the computed average of those signals. In using the tool, the area of interrogation is scrolled up and down to find the location at which the red line in the PIP tool output box is most nearly flat, indicative of the site at which the respiratory increases in pressure are offset by the respiratory decreases in pressure seen on the blue line. The area of interest is during quiet respiration and the RIP is seen to localize toward the upper margin of the CD signal. This positions the majority of the LES signal within the hiatus, being pulled downward during the three deep breaths.
Panel B: HRM recording of EGJ pressure in an individual with a small hiatal hernia as evident by the CD being only partially superimposed on the LES pressure signature, ie, the LES-CD separation is 2 cm. Formatting of the figure is identical to that of Panel A, with the dominant EGJ pressure profile highlighted by the black line (the 15 mmHg isobaric contour) and the PIP tool optimally positioned to isolate the RIP. Note how the LES-CD separation is measured. The center of the LES and CD high pressure zones (white and black horizontal arrows, respectively) are isolated with the help of the isobaric contour tool (set at 15 mmHg in this example), and the separation between the two rounded off to the nearest cm. In this example, the RIP continues to localize toward the upper margin of the CD signal, implying that the CD still exerts sufficient sphincteric effect such that it closes the lumen isolating the stomach below from the hernia and LES above. This is particularly evident during the three deep breaths where the strongly negative intrathoracic pressure (deep blue) is seen to abut directly on the CD-apex signal.
Panel C: HRM recording of EGJ pressure in an individual with a moderate-sized hiatal hernia as evident by the CD being isolated from the LES pressure signature, ie, the LES-CD separation is 4 cm. Formatting of the figure is identical to that of Panels A and B, with the dominant EGJ pressure profile highlighted by the black line (the 25 mmHg isobaric contour in this case) and the PIP tool optimally positioned to isolate the RIP. However, in this example, the RIP no longer localizes the CD signal, instead localizing at the proximal margin of the LES. Even without the aid of the PIP tool, that is evident by the inspiratory bursts of red on the LES recording. Consequently, the CD no longer functions as a competent extrinsic sphincter, and the entire hiatal hernia up to the lower margin of the LES is subject to intra-gastric pressure throughout the respiratory cycle.