W. M. Sun

A retrospective study of the effects of pelvic irradiation for gynecological cancer on anorectal function

PURPOSE To evaluate the prevalence of anorectal dysfunction following therapeutic pelvic irradiation. METHODS AND MATERIALS Anorectal function was evaluated in 15 randomly selected patients (aged 47-84 years) who had received pelvic irradiation for treatment of carcinoma of the uterine body and cervix 5 and 10 years earlier. The following parameters were assessed in each patient: (a) anorectal symptoms (questionnaire), (b) anorectal pressures at rest and in response to rectal distension, voluntary squeeze, and increases in intraabdominal pressure (multiport anorectal manometry with concurrent electromyography of the anal sphincters), (c) rectal sensation (rectal balloon distension) and, (d) anal sphincteric morphology (ultrasound). Results were compared with those obtained in nine female control subjects. RESULTS Ten of the 15 patients had urgency of defecation and 4 also suffered fecal incontinence. Basal anorectal pressures measured just proximal to the anal canal (p = 0.05) and anorectal pressures generated in response to voluntary squeeze measured at the anal canal were less (p < 0.01) in the patients. The fall in anal pressures in response to rectal distension was greater in the patients (p < 0.05) and the desire to defecate occurred at lower rectal volumes (p < 0.05). The slope of the pressure/volume relationship in response to rectal distension was greater (p < 0.05) in the patients, suggestive of a reduction in rectal compliance. In 14 of the 15 patients at least one parameter of anorectal motor function was outside the control range. There was no difference in the thickness of the anal sphincters between the two groups. CONCLUSION Abnormal anorectal function occurs frequently following pelvic irradiation for gynecological malignant diseases and is characterized by multiple dysfunctions including weakness of the external anal sphincter, stiffness of the rectal wall, and a consequent increase in rectal sensitivity.

Acute effects of therapeutic irradiation for prostatic carcinoma on anorectal function

Aim—The incidence of anorectal symptoms after radiotherapy (RTH) for localised pelvic malignant disease is unclear. In addition, the effects of pelvic irradiation on both anorectal motility and sensory function are poorly defined. A prospective study was therefore performed on 35 patients (55–82 years of age) with localised prostatic carcinoma before and four to six weeks after RTH to assess its effects on anorectal function. Methods—Anorectal symptoms were assessed by questionnaire. Anorectal pressures at rest and in response to voluntary squeeze, rectal distension, and increases in intra-abdominal pressure were evaluated with perfused sleeve side hole manometry. Rectal sensation was tested during graded balloon distension. Rectal compliance was calculated by the pressure-volume relation obtained during the testing of rectal sensation. Ultrasound was used to determine anal sphincter structure and integrity. Results—RTH had no effect on anal sphincter morphology. The frequency of defecation increased after RTH (7 (3–21) v 10 (3–56) bowel actions a week; p<0.01). After RTH, 16 patients had faecal urgency and eight faecal incontinence, compared with five and one respectively before RTH (p<0.01 for each). Basal and squeeze sleeve recorded pressures were reduced after RTH (54 (3)v 49 (3) mm Hg (p<0.05) and 111 (8)v 102 (8) mm Hg (p<0.01), before and after RTH respectively; means (SEM)). Rectal compliance was reduced after RTH (1.2 v 1.4 mm Hg/ml, p<0.05). After RTH, threshold volumes for perception of rectal distension were lower in the 16 patients who either experienced faecal urgency for the first time (13 patients) or reported worsening of this symptom (three patients) compared with the remaining patients (34 (4)v 48 (5) ml respectively, p<0.05). Conclusion—Faecal incontinence (23%) is a common problem four to six weeks after RTH for prostatic carcinoma and is associated with minor reductions in anal sphincter pressures. The high prevalence of faecal urgency in patients after RTH may be related to alterations in rectal perception of stool.

Effects of nitroglycerin on liquid gastric emptying and antropyloroduodenal motility.

The effects of the nitric oxide donor nitroglycerin on gastric emptying and antropyloroduodenal motility were evaluated in nine healthy male subjects (ages 19-36 yr). Antropyloroduodenal pressures were recorded with a manometric assembly that had nine side holes spanning the antrum and proximal duodenum and a pyloric sleeve sensor; gastric emptying was quantified scintigraphically. In each subject, the emptying of 300 ml of 25% glucose labeled with 99mTc was assessed on two separate days during intravenous infusion of either nitroglycerin (5 micrograms/min in 5% dextrose) or 5% dextrose (control). Studies were performed with the subject in the supine position; blood pressure and heart rate were monitored. Nitroglycerin had no significant effect on blood pressure or heart rate. Nitroglycerin slowed gastric emptying (P < 0.02), and this was associated with greater retention of the drink in the proximal stomach (P < 0.05). In both nitroglycerin and control studies, ingestion of the drink was associated with an increase in the number of isolated pyloric pressure waves (P < 0.05) and antral pressure wave sequences (P < 0.05). Nitroglycerin reduced the number of isolated pyloric pressure waves (P < 0.05), basal pyloric pressure (P < 0.05), and the number of antral pressure wave sequences (P < 0. 05), but not the total number of antral pressure waves. The rate of gastric emptying and the number of isolated pyloric pressure waves were inversely related during control (P = 0.03) and nitroglycerin (P < 0.05) infusions. We conclude that in normal subjects, 1) gastric emptying of 300 ml of 25% glucose is inversely related to the frequency of phasic pyloric pressure waves, and 2) nitroglycerin in a dose of 5 micrograms/min inhibits pyloric motility, alters the organization but not the number of antral pressure waves, and slows gastric emptying and intragastric distribution of 25% glucose.The effects of the nitric oxide donor nitroglycerin on gastric emptying and antropyloroduodenal motility were evaluated in nine healthy male subjects (ages 19-36 yr). Antropyloroduodenal pressures were recorded with a manometric assembly that had nine side holes spanning the antrum and proximal duodenum and a pyloric sleeve sensor; gastric emptying was quantified scintigraphically. In each subject, the emptying of 300 ml of 25% glucose labeled with99mTc was assessed on two separate days during intravenous infusion of either nitroglycerin (5 μg/min in 5% dextrose) or 5% dextrose (control). Studies were performed with the subject in the supine position; blood pressure and heart rate were monitored. Nitroglycerin had no significant effect on blood pressure or heart rate. Nitroglycerin slowed gastric emptying ( P < 0.02), and this was associated with greater retention of the drink in the proximal stomach ( P < 0.05). In both nitroglycerin and control studies, ingestion of the drink was associated with an increase in the number of isolated pyloric pressure waves ( P < 0.05) and antral pressure wave sequences ( P < 0.05). Nitroglycerin reduced the number of isolated pyloric pressure waves ( P < 0.05), basal pyloric pressure ( P < 0.05), and the number of antral pressure wave sequences ( P < 0.05), but not the total number of antral pressure waves. The rate of gastric emptying and the number of isolated pyloric pressure waves were inversely related during control ( P = 0.03) and nitroglycerin ( P < 0.05) infusions. We conclude that in normal subjects, 1) gastric emptying of 300 ml of 25% glucose is inversely related to the frequency of phasic pyloric pressure waves, and 2) nitroglycerin in a dose of 5 μg/min inhibits pyloric motility, alters the organization but not the number of antral pressure waves, and slows gastric emptying and intragastric distribution of 25% glucose.

Effects of duodenal distension on antropyloroduodenal pressures and perception are modified by hyperglycemia

Marked hyperglycemia (blood glucose approximately 15 mmol/l) affects gastrointestinal motor function and modulates the perception of gastrointestinal sensations. The aims of this study were to evaluate the effects of mild hyperglycemia on the perception of, and motor responses to, duodenal distension. Paired studies were done in nine healthy volunteers, during euglycemia ( approximately 4 mmol/l) and mild hyperglycemia ( approximately 10 mmol/l), in randomized order, using a crossover design. Antropyloroduodenal pressures were recorded with a manometric, sleeve-side hole assembly, and proximal duodenal distensions were performed with a flaccid bag. Intrabag volumes were increased at 4-ml increments from 12 to 48 ml, each distension lasting for 2.5 min and separated by 10 min. Perception of the distensions and sensations of fullness, nausea, and hunger were evaluated. Perceptions of distension (P < 0.001) and fullness (P < 0.05) were greater and hunger less (P < 0.001) during hyperglycemia compared with euglycemia. Proximal duodenal distension stimulated pyloric tone (P < 0.01), isolated pyloric pressure waves (P < 0.01), and duodenal pressure waves (P < 0.01). Compared with euglycemia, hyperglycemia was associated with increases in pyloric tone (P < 0.001), the frequency (P < 0.05) and amplitude (P < 0.01) of isolated pyloric pressure waves, and the frequency of duodenal pressure waves (P < 0.001) in response to duodenal distension. Duodenal compliance was less (P < 0.05) during hyperglycemia compared with euglycemia, but this did not account for the effects of hyperglycemia on perception. We conclude that both the perception of, and stimulation of pyloric and duodenal pressures by, duodenal distension are increased by mild hyperglycemia. These observations are consistent with the concept that the blood glucose concentration plays a role in the regulation of gastrointestinal motility and sensation.Marked hyperglycemia (blood glucose ∼15 mmol/l) affects gastrointestinal motor function and modulates the perception of gastrointestinal sensations. The aims of this study were to evaluate the effects of mild hyperglycemia on the perception of, and motor responses to, duodenal distension. Paired studies were done in nine healthy volunteers, during euglycemia (∼4 mmol/l) and mild hyperglycemia (∼10 mmol/l), in randomized order, using a crossover design. Antropyloroduodenal pressures were recorded with a manometric, sleeve-side hole assembly, and proximal duodenal distensions were performed with a flaccid bag. Intrabag volumes were increased at 4-ml increments from 12 to 48 ml, each distension lasting for 2.5 min and separated by 10 min. Perception of the distensions and sensations of fullness, nausea, and hunger were evaluated. Perceptions of distension ( P < 0.001) and fullness ( P < 0.05) were greater and hunger less ( P < 0.001) during hyperglycemia compared with euglycemia. Proximal duodenal distension stimulated pyloric tone ( P < 0.01), isolated pyloric pressure waves ( P < 0.01), and duodenal pressure waves ( P< 0.01). Compared with euglycemia, hyperglycemia was associated with increases in pyloric tone ( P < 0.001), the frequency ( P < 0.05) and amplitude ( P < 0.01) of isolated pyloric pressure waves, and the frequency of duodenal pressure waves ( P < 0.001) in response to duodenal distension. Duodenal compliance was less ( P < 0.05) during hyperglycemia compared with euglycemia, but this did not account for the effects of hyperglycemia on perception. We conclude that both the perception of, and stimulation of pyloric and duodenal pressures by, duodenal distension are increased by mild hyperglycemia. These observations are consistent with the concept that the blood glucose concentration plays a role in the regulation of gastrointestinal motility and sensation.

Acute hyperglycaemia affects anorectal motor and sensory function in normal subjects

Background—The pathogenesis of anorectal dysfunction, which occurs frequently in patients with diabetes mellitus, is poorly defined. Recent studies indicate that changes in the blood glucose concentration have a major reversible effect on gastrointestinal motor function. Aims—To determine the effects of physiological changes in blood glucose and hyperglycaemia on anorectal motor and sensory function in normal subjects. Subjects—In eight normal subjects measurements of anorectal motility and sensation were performed on separate days while blood glucose concentrations were stabilised at 4, 8, and 12 mmol/l. Methods—Anorectal motor and sensory function was measured using a sleeve/sidehole catheter incorporating a balloon, and electromyography. Results—The number of spontaneous anal relaxations was greater at 12 mmol/l than at 8 and 4 mmol/l glucose (p<0.05 for both). Anal squeeze pressures were less at a blood glucose of 12 mmol/l when compared with 8 and 4 mmol/l (p<0.05 for both). During rectal distension, residual anal pressures were not significantly different between the three blood glucose concentrations. Rectal compliance was greater (p<0.05) at a blood glucose of 12 mmol/l when compared with 4 mmol/l. The threshold volume for initial perception of rectal distension was less at 12 mmol/l when compared with 4 mmol/l (40 (20–100) ml versus 10 (10–150) ml, p<0.05). Conclusions—An acute elevation of blood glucose to 12 mmol/l inhibits internal and external anal sphincter function and increases rectal sensitivity in normal subjects. In contrast, physiological changes in blood glucose do not have a significant effect on anorectal motor and sensory function.

Effects of Hyperglycemia on Cortical Response to Esophageal Distension in Normal Subjects

Acute changes in the blood glucose concentrationaffect the intensity of gastrointestinal sensations. Theaim of this study was to examine the effects ofhyperglycemia on cortical potentials evoked byesophageal distension. In 16 healthy volunteers, a balloonwas positioned in the lower esophagus. A series of 50distensions was performed at both a lower volume(producing definite sensation) and a higher volume (producing unpleasant sensation), at bloodglucose concentrations of 5 and 13 mmol/liter. Triphasiccortical potentials were recorded from a midline scalpelectrode (Cz). During euglycemia, interpeak amplitudes were greater at the higher than the lowerballoon volume (P < 0.005). At the lower balloonvolume, the interpeak amplitudes were greater duringhyperglycemia than euglycemia (P < 0.05). There was no effect of the blood glucose concentration onamplitude at the higher balloon volume. We conclude thatin healthy subjects, the amplitude of the corticalresponse to moderate, but not unpleasant, esophageal distension is greater during hyperglycemia whencompared to euglycemia. These observations areconsistent with the concept of increased intensity ofgut sensation during hyperglycemia.

Effect of drink temperature on antropyloroduodenal motility and gastric electrical activity in humans

There is little information on the motor mechanisms underlying the effects of meal temperature on gastric emptying. The effects on antropyloric pressures and the surface electrogastrogram of ingesting drinks at 4 degrees C, 37 degrees C, and 50 degrees C (350 ml normal saline and 50 ml low calorie (7 kj) orange cordial) given in randomised order were measured over 60 minutes in 12 normal volunteers (10 men and 2 women, aged 18-55 years). The warm and cold drinks suppressed antral pressure waves (p < 0.05), altered the organisation of antropyloric pressure waves (p < 0.05), stimulated isolated pyloric pressure waves (p < 0.05), and increased electrogastrogram frequency (p < 0.05) when compared with the 37 degrees C drink. These changes were greatest in the first 30 minutes after ingestion and greater (p < 0.05) with the 4 degrees C drink. Temperature has major effects on postprandial antropyloroduodenal motility in normal subjects. Both cold and warm drinks stimulate a pattern of motility associated with retardation of transpyloric flow.

Postural changes in proximal gastric volume and pressure measured using a gastric barostat

A barostat was used to examine the effect of changes in posture on the volume and pressure in a bag positioned in the proximal stomach of 14 normal volunteers. Volumes in the supine position were compared with those in the standing, left lateral and right lateral positions at a constant pressure 2 mmHg above basal intragastric pressure. A separate series of measurements was then used to evaluate the effects of the same postural changes on pressure within the bag whilst its volume was kept constant. Changing from the supine to the left lateral position decreased bag volume by 62% when pressure was controlled; pressure increased by 60% when volume was controlled. In contrast, movement from the supine to the right lateral position resulted in a 68% increase in bag volume and a 31% fall in pressure. Moving from supine to standing had inconsistent effects on bag volume and pressure. There was a negative correlation between the magnitudes of the changes in pressure and volume (r2 = 0.557). The observed effects of posture probably result from changes in the compression of the stomach by abdominal viscera and indicate that subject position must be specified and maintained constant in studies of proximal gastric motor function using a barostat.

Long-term effects of pyloromyotomy on pyloric motility and gastric emptying in humans.

Abstract OBJECTIVE: The aim of this study was to determine the long term effects of pyloromyotomy for infantile hypertrophic pyloric stenosis (IHPS) on gastric emptying and pyloric motility. METHODS: Concurrent measurements of gastric emptying and antropyloroduodenal pressures were performed in six volunteers (aged 24–26 yr) who had had pyloromyotomy performed in infancy because of IHPS, and in six normal subjects. Subjects were studied on 2 days, once sitting and once in the left lateral position. Gastric emptying of 300 ml 25% dextrose labeled with 20 MBq 99mTc sulfur colloid was measured. Antropyloroduodenal motility was evaluated with a sleeve/multiple sidehole manometric assembly, which was also used to deliver an intraduodenal triglyceride infusion at 1.1 kcal/min for 60 min, starting 30 min after ingestion of the dextrose. RESULTS: In both body positions, gastric emptying and intragastric distribution of the drink did not differ between the two groups. In both groups and postures, the amount emptied was less during intraduodenal lipid infusion. The number (p CONCLUSIONS: These results indicate that, in adults who have had pyloromyotomy for IHPS in infancy, patterns of pyloric motility are abnormal; pyloric tone is higher, whereas the number and amplitude of phasic pyloric pressure waves are less. In contrast, the overall rate of gastric emptying of a nutrient liquid meal is normal. These observations are consistent with the concept that the stomach has the capacity to compensate for changes in pyloric motility to minimize effects on gastric emptying.

Stereospecific Effects of Intraduodenal Tryptophan on Pyloric and Duodenal Motility in Humans

BACKGROUND L-Tryptophan delays gastric emptying in animals to a greater extent than D-tryptophan, but none of the possible motor mechanisms responsible for this stereospecific effect have been evaluated. METHODS In 11 healthy volunteers antropyloroduodenal pressures were recorded in the fasted state with a sleeve/sidehole manometric assembly during 20-min intraduodenal infusions (2 ml.min-1) of isotonic L- and D-tryptophan (50 mM, pH 5.7) and normal saline (pH 5.5), given in randomized order. RESULTS Intraduodenal L-tryptophan increased basal pyloric pressure (p < 0.05), whereas D-tryptophan had no effect. In contrast, L- and D-tryptophan both stimulated (p < 0.05) localized phasic pyloric pressure waves, and there was no significant difference in the responses. The number of duodenal pressure waves was greater during infusion of L-tryptophan than during D-tryptophan (p < 0.05). CONCLUSION We conclude that intraduodenal tryptophan has stereospecific effects on pyloric and duodenal motility. Although the precise contribution of these differential effects to gastric emptying remains to be clarified, they may be partially responsible for the differences in gastric emptying of D-tryptophan and L-tryptophan.