Water-Perfusion
The catheter delivered 0.1 ml/min sterile water via each sensor to a total of 0.57 L per hour. A drainage tube (OD 3.3 mm) was placed in the rectum to allow passive outflow of excess water. The remainder of the water was expelled by colon motor activities or absorbed. Intraluminal pressure in between motor patterns did not change during the recording session (38), hence, the water inflow did not cause passive tonic pressure changes.

Quantification and Statistical analysis of HRCM Data

All data were stored using the software developed by Medical Measurement Systems (MMS; Laborie, Toronto, ON, Canada), and analyzed using programs developed by Sean Parsons by Image J (National Institutes of Health, Bethesda, MD, United States) and MATLAB (Mathworks, Natick, MA, United States). After HAPWs were identified visually in Image J, they were encircled free hand and a Contourer plug-in was used to set a 20 mmHg isobar and accurately outline the HAPW to obtain its amplitude as an average of all measured points within the contour. This method is substantially different from measurements using low-resolution manometry where only a few points along the motor pattern are considered. Other motor patterns such as SPWs were measured through freehand outline using a rectangular selection tool to obtain different characteristics such as amplitude, duration, propagation length and velocity, if applicable. Responses to stimuli were described and compared to baseline activity and activity after meal. Data are given as mean ± SEM. Significance was determined by ANOVA with multiple comparisons as mentioned in the table footnotes using Prism 8 software (GraphPad, United States), P < 0.05 was considered significant. Percentage of anal sphincter relaxation was calculated by comparing the mean amplitude of the anal sphincter in a 3-minute period before relaxation and the whole period of relaxation. Due to the oscillatory nature of the anal sphincter pressure, relaxation was quantified when it reached higher than 25% of the average pressure value recorded in the 3-minute period before the relaxation. The period of relaxation started with the first sign of relaxation and ended with return to its baseline pressure. In the middle of this period, complete anal sphincter relaxation could be achieved. MATLAB was used to generate the 3D images.

Identified Motor Patterns by HRCM

The focus of this case study was on propulsive motor patterns and their coordination with anal sphincter relaxation. Therefore, the following motor patterns were studied:
  1. Simultaneous pressure waves (SPWs) are pressure transients that occur simultaneously at all sensors that record them, as identified by Rao et al., (41) and De Schryver et al., (14), and further defined and characterized by us (9, 10, 38). They have also been called simultaneous contractions (40) or pan-colonic pressurizations (11).
  2. High- amplitude propagating pressure waves (HAPWs) are defined as transient increases in pressure of more than 50 mmHg that propagate almost always in anal direction (37). They are also called high-amplitude propagating contractions or sequences (4).
  3. High- amplitude propagating pressure waves followed by simultaneous pressure waves (HAPW-SPWs). A proximal HAPW can promptly switch to an SPW at the transverse or descending colon (9) (37). The SPW within this motor pattern is not pan-colonic.
  4. The colo-anal reflex: anal sphincter activity and its relaxation associated with the motor patterns described above (37).