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170 Chapter 7 also observed in adults with constipation; therefore, either both manometric systems are incapable of recording the motor patterns in the patients or the differences were caused by the underlining pathology. Finally, a previous study has shown that motor patterns detected by water-perfused and solid-state manometry are comparable. 43 While that study used a very different protocol to ours, recording motor patterns simultaneously with both catheters in the same subject at the same time, these data indicate that water-perfused manometry is capable of detecting both low- and high-amplitude contractile activity. It could also be argued that the water perfusion in the studies performed in children resulted in the increase in the long-single motor pattern. However, this seems unlikely because the increase in this motor pattern was only observed in around half the children (See Figure 4E), and we have now seen the same significant increase in this motor pattern in children with severe constipation in which the motility was recorded with a solid-state catheter (data unpublished). It is also possible that the different sensor spacing (1.5 cm in water perfused vs 1 cm in fiber optic) resulted in fewer propagating motor patterns being detected with the water- perfused catheter. Although we have previously shown that the number of propagating motor patterns identified is dependent on the catheter sensor spacing 20 , the apparent chaotic nature of pressure events recorded in adjacent channels in the colon of these children (see Figure 3A) indicates that a slight decrease in the sensor spacing would be unlikely to transform these into organized motor patterns. Another difference between adult and pediatric protocols involved the meal that study subjects received. Adult patients received a set meal, whereas children were given a meal of free choice, which had an age-dependent calorie load. The decision of a free choice meal for the children was made to ensure that they ate a meal. While there have been a number of studies that demonstrate the effects of different meals upon the colon 44,45 , it is important to note that in all instances the colon responds to a meal. Indeed, a study by Price et al. 46 demonstrated that meal containing 70% fat or carbohydrate or protein all resulted in a gastrocolonic response and none of the different compositions had any effect upon ileocolonic transit. In our own data, the meal response in healthy adults occurred within a minute of starting the meal (see Figure 2 in Ref. 13 ). Thus, it is clear that it is not required for adults to finish the entire 700 kcal meal for this response to start. Therefore, the absence of the meal response in the constipated children cannot be explained by the difference in meals.