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Gastroduodenal physiology is traditionally understood in terms of motor-secretory functions and their electrical, neural and hormonal controls. In contrast, the fluid-mechanical functions that retain and disperse particles, expose substrate to enzymes, or replenish the epithelial boundary with nutrients are little studied. Current ultrasound and magnetic resonance imaging allows to visualize processes critical to digestion like mixing, dilution, swelling, dispersion and elution. Methodological advances in fluid mechanics allow to numerically analyse the forces promoting digestion. Pressure and flow fields, the shear stresses dispersing particles or the effectiveness of bolus mixing can be computed using information on boundary movements and on the luminal contents. These technological advances promise many additional insights into the mechanical processes that promote digestion and absorption.

Objectives Although biofeedback therapy is effective in the short term management of dyssynergic defecation, its long term efficacy is unknown. Our aim was to compare the one year outcome of biofeedback (manometric- assisted pelvic relaxation, and simulated defecation training), with standard therapy (diet, exercise, laxatives) in patients who completed 3 months of either therapy. Methods Stool diaries, visual analog scales (VAS), colonic transit, anorectal manometry, and balloon expulsion time were assessed at baseline, and at one year after each treatment. All subjects were seen at 3 month intervals and received reinforcement. Primary outcome measure (ITT analysis) was a change in the number of complete spontaneous bowel movements (CSBM) per week. Secondary outcome measures included bowel symptoms, changes in dyssynergia and anorectal function. Results Of 44 eligible patients with dyssynergic defecation, 26 agreed to participate in the long term study. All 13 subjects who received biofeedback, and 7 of 13 who received standard therapy completed one year; 6 failed standard therapy. The number of CSBMs/week increased significantly (p<0.001) in the biofeedback but not in the standard group. Dyssynergia pattern normalized (p<0.001), balloon expulsion time improved (p=0.0009), defecation index increased (p<0.001) and colonic transit time normalized (p=0.01) only in the biofeedback group. Conclusions Biofeedback therapy provided sustained improvement of bowel symptoms and anorectal function in constipated subjects with dyssynergic defecation while standard therapy was largely ineffective.

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BackgroundPills (tablets and capsules) are widely used to administer prescription drugs or to take supplements such as vitamins. Unfortunately, little is known about how much effort it takes Americans to swallow these various pills. More specifically, it is not known to what extent hard-to-swallow pills might affect treatment outcomes (eg, interfering with adherence to prescribed medications or causing clinical complications). It is also unclear which properties (eg, size, shape, or surface texture) Americans prefer or reject for their pills. To learn more about these issues, we interviewed a small group of individuals.MethodsWe invited individuals in waiting rooms of our tertiary health care center to participate in structured interviews about their pill-taking habits and any problems they have swallowing pills. We inquired which pill properties they believed caused swallowing problems. Participants scored capsules and pills of representative size, shape, and texture for swallowing effort and reported their personal preferences.ResultsOf 100 successive individuals, 99 participants completed the interview (65% women, mean age = 41 years, range = 23-77 years). Eighty-three percent took pills daily (mean 4 pills/d; 56% of those pills were prescribed by providers). Fifty-four percent of participants replied yes to the question, "Did you ever have to swallow a solid medication that was too difficult?" Four percent recounted serious complications: 1% pill esophagitis, 1% pill impaction, and 2% stopped treatments (antibiotic and prenatal supplement) because they could not swallow the prescribed pills. Half of all participants routinely resorted to special techniques (eg, plenty of liquids or repeated or forceful swallows). Sixty-one percent of those having difficulties cited specific pill properties: 27% blamed size (20% of problems were caused by pills that were too large whereas 7% complained about pills that were too small to sense); 12% faulted rough surface texture; others cited sharp edges, odd shapes, or bad taste/smell. Extra-large pills were widely loathed, with 4 out of 5 participants preferring to take 3 or more medium-sized pills instead of a single jumbo pill.ConclusionsOur survey results suggest that 4 out of 5 adult Americans take several pills daily, and do so without undue effort. It also suggests that half of today’s Americans encounter pills that are hard to swallow. Up to 4% of our participants gave up on treatments because they could not swallow the prescribed pills. Up to 7% categorically rejected taking pills that are hard to swallow. Specific material properties are widely blamed for making pills hard to swallow; extra-large capsules and tablets are universally feared, whereas medium-sized pills with a smooth coating are widely preferred. Our findings suggest that health care providers could minimize treatment failures and complications by prescribing and dispensing pills that are easy to swallow. Industry and regulatory bodies may facilitate this by making swallowability an essential criterion ...