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156 Chapter 7 A. HAPS: Consistent with previous studies 13,17 , these propagatingmotor patterns consisted of an array of pressure events with the majority having a trough-to-peak amplitude of >116 mmHg and always progressed in an antegrade direction. B. Cyclic motor patterns: Repetitive propagating pressure events with cyclic frequency of 2–6 cycles per minute (cpm) occurred in all healthy adults. These motor patterns propagated in either retrograde or antegrade direction. C. Short-single motor patterns: This pattern occurred in isolation separated from other propagating motor patterns by intervals of more than 1 min. They could propagate in a retrograde or anterograde direction. D. Long-single motor patterns: These occurred as single pressure events which propagated over long distances. These motor patterns were always separated by intervals of more than 1 min, when they occurred repetitively. In all instances, these motor patterns comprised pressure events recorded in every pressure sensor (i.e. they spanned the entire recording region). Spectral analysis of colonic pressure wave data Welch’s method was used to calculate a periodogram on the raw data from the pediatric patients. This analysis determines the dominant frequencies of pressure events. 13 For each subject, the root mean square (RMS) amplitude of frequencies of pressure time series (range, 0.15–8 cpm; increasing at increments of 0.15 cpm) was averaged over each individual channel in each of the colonic regions, in this instance the descending and sigmoid colon. Statistical analysis All data are expressed as mean ± SD. The average number, velocity (speed of propagation), extent (distance of propagation), and amplitude of each type of propagating motor patterns were all calculated in PlotHRM. For the pediatric data, the non-parametricWilcoxon signed rank test was used to compare these propagation characteristics between the basal and postprandial periods. The analysis of the adult data has been published previously. 13 Comparisons between the number of propagating motor patterns in the pediatric data and both adult groups were performed with Kruskal–Wallis test of one-way anova, with Dunn’s correction for multiple comparisons. As the data in children and adults were recorded with two different catheters (water-perfused and fiber-optic), no attempt was made to calculate differences in amplitude between children and adults. All statistics were calculated using Prism 5 (GraphPad Software, Inc., La Jolla, CA, USA). A P < .05 was considered statistically significant.