Michael D. Crowell

Effect of prolonged, continuous rectal distention on mouth-to-cecum and colonic transit time in pigs

The effect of prolonged (6 h), continuous rectal distention on mouth-to-cecum and colonic transit time was studied in four unrestrained pigs. Mouth-to-cecum transit time was determined from samples of cecal efflux using the phenol red dye technique. Colonic transit time was assessed with radiopaque markers that were injected into the cecum before each trial. Rectal distention was applied 2-1/2 h before feeding, during feeding, and 3-1/2 h after feeding. No distention was applied during control conditions. Stools were collected for 48 h after marker application. Rectal distention increased mouth-to-cecum transit time (p < 0.05). Colonic transit time was also prolonged by rectal distention as shown by a significant decrease in the number of markers excreted within 36 h (p < 0.05). Rectal distention for 6 h increased colonic transit time up to 30 h following distention and prolonged mouth-to-cecum transit of a high fat liquid meal.

The effect of feeding on defecation behaviour in pigs

The effect of eating on defecation behaviour was investigated in four 20-30 kg pigs. Rectal distention stimulation was performed pre- and postprandially at 10 cm from the anus with a 5 cm latex balloon. Volume was increased in steps of 10 ml up to 200 ml of air or until balloon defecation. Dependent measures were volume, rectal pressure, determined with a solid state pressure transducer inside the balloon probe, rectal compliance, and an index of distention induced contractile activity. The volume and pressure required to elicit defecation was significantly lower after feeding (p less than 0.01). Distention induced contractile activity was significantly increased near defecation threshold, but pre- and postprandial conditions were not different. There was no difference in rectal compliance pre- and postprandially. These results suggest that eating lowers defecation threshold in terms of distention volume and rectal pressure, and that these changes are not dependent on altered rectal compliance or changes in distention induced motor activity.

Effect of rectal distention and feeding on cecal tone in pigs

The effects of eating and rectal distention on cecal tone were evaluated. Cecal tone was measured using a computer-controlled barostat in four female 30 to 40 kg Yucatan Micropigs fitted with cecal fistulas. Each pig underwent two separate trials of pre and postprandial measurements of cecal tone, either with or without continuous rectal distention with a 30 ml water-filled balloon. Cecal tone was measured 10 min prior to, during, and 10 min following a high-fat (60%) liquid meal (473 ml). Cecal tone significantly increased (intrabag volume decreased) after feeding (119.6 +/- 9.1 ml vs. 81.2 +/- 7.9 ml; p = 0.008). Rectal distention tended to reduce the postprandial change in cecal tone (142.8 +/- 11.5 vs. 130.9 +/- 12.6 ml; p = 0.196). There was also a strong tendency for cecal volumes to be higher (decreased tone) with rectal distention preprandially (142.8 +/- 11.5 ml vs. 119.6 +/- 9.1 ml; p = 0.024). Nutrient ingestion significantly increased cecal tone and rectal distention abolished this effect. These findings may indicate a regulatory pathway that allows additional storage of fecal material in the event that the output of the system is disturbed.

Eating lowers defecation threshold in pigs through cholinergic pathways.

The effect of atropine on defecation threshold was compared to placebo pre- and postprandially in four 20- to 30-kg pigs. Stepwise balloon distention was performed 10 cm from the anal verge with a 5-cm latex balloon. Volume was increased in steps of 10 ml up to 200 ml of air or until the balloon was defecated (defecation threshold). Dependent measures were balloon volume, rectal pressure, rectal compliance, and an index of distention-induced contractile activity. Under placebo conditions, the volume and pressure to elicit defecation were significantly lower after feeding (p < 0.05). The distention-induced contractile activity significantly increased near the defecation threshold, but pre- and postprandial conditions were not different. No differences were seen between pre- and postprandial rectal compliance curves. Atropine abolished the postprandial decrease in defecation threshold, but did not affect rectal compliance. The increase in contractile activity at defecation threshold seen with placebo was abolished by atropine. These results show that eating lowers the defecation threshold in terms of distention volume and rectal pressure, and demonstrate that these changes are mediated through cholinergic pathways.

Do patient's complaints of dysphagia predict esophageal manometry findings?

Purpose: Complaints of dysphagia can be measured by location, frequency, duration, and severity. It is not known whether the intensity of symptoms correlate with manometric findings. The aim of this study was to investigate the relationships between a patients rating of dysphagia symptoms and characteristics of esophageal manometry.

Does the combination of solid and liquid swallows improve esophageal manometry in patients with dysphagia

Does the combination of solid and liquid swallows improve esophageal manometry in patients with dysphagia