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180 Chapter 8 Colonic manometry protocol Colonic manometry commenced within 2-4 hours after the catheter placement to ensure children were fully awake. First, recordings were performed for two hours before and two hours after a meal; the meal consisted of whatever the patient ordered and patients were encouraged to eat as much as they were able to. After the initial four hours of recording, bisacodyl was infused into the colon and the recording lasted for another hour to identify any HAPCs. With retrograde placement of catheters the bisacodyl was infused into the proximal colon through the central lumen of the catheter. For catheters placed through a cecostomy/appendicostomy, bisacodyl was introduced into the proximal colon via a small diameter tube introduced through the stoma. The dosage of bisacodyl was 0.2 mg kg -1 (max 10 mg). If administration of bisacodyl did not induce HAPCs within 30 to 45 minutes, an additional dose of bisacodyl was administered via the same route (max 20 mg). Recordings were registered with Solar GI colonic manometry software (MMS, Enschede, the Netherlands, stationary manometry version 9.3K). Analysis of manometry recordings Themanual identification of features withinmanometric datawas performed using software (PlotHRM) developed by one of the authors (LW). PlotHRM was written in JavaTM (Oracle, Redwood City, California, USA). Each manometric recording was manually examined for the presence of long single motor patterns, HAPCs and pan-colonic pressurizations, defined as follows: • Long singlemotor patterns: These occurred as single pressure events which propagated over long distances (the majority of recording sites, >40cm). These events had a clear time lag between the onset of the most proximal pressure wave in the sequence and the onset of the most distal pressure wave. • HAPCs: HAPCs were defined as pressure sequences with a peak amplitude of ≥75 mmHg that migrate in an antegrade direction over ≥15 cm. 20 • Pancolonic pressurizations: In a recent publication a novel motor pattern defined as a pan-colonic pressurization was described in adults. 15 We attempted to identify this motor pattern in our data: these patterns were defined as pressure sequences with a peak amplitude <50mmHg, occurring simultaneously across all intracolonic sensors. Subsequently, characteristics of these contractions were analyzed using PlotHRM. Due to the intersensor spacing (>2 cm) on the solid state catheter used, we were unable to accurately identify propagating cyclic events. 21 Instead, we determined the dominant frequencies of pressure events in each channel (excluding respiratory artifacts).