Biomedical subjects

Fernando Azpiroz

Publications and source records attributed to Fernando Azpiroz.

10 recordsLinked to original sources

PubMed2003

Reflex control of intestinal gas dynamics and tolerance in humans.

Intestinal transit of gas is normally adapted to the luminal gas load, but in some patients impaired transit may lead to gas retention and symptoms. We hypothesized that intestinal gas transit is regulated by reflex mechanisms released by segmental distension at various gut levels. In 24 healthy subjects, we measured gas evacuation and perception of jejunal gas infusion (12 ml/min) during simultaneous infusion of duodenal lipids mimicking the postprandial caloric load (Intralipid, 1 kcal/min). We evaluated the effects of proximal (duodenal) distension (n = 8), distal (rectal) distension (n = 8), and sham distension, as control (n = 8). Duodenal lipid infusion produced gas retention (366 +/- 106 ml) with low abdominal perception (1.5 +/- 0.8 score). Distension of either the duodenum or rectum during lipid infusion expedited gas transit and prevented retention (-120 +/- 164 and -124 +/- 162 ml retention, respectively; P < 0.05 vs. control). However, the tolerance to the intestinal gas load differed markedly, depending on the site of distension; perception remained low during rectal distension (2.6 +/- 0.7 score; not significant vs. control) but increased during duodenal distension (4.4 +/- 0.7 score; P < 0.05 vs. control). We conclude that focal gut distension, either at proximal or distal sites, accelerates gas transit, but the symptomatic response depends on the site of stimulation.

Abdomen↗

PubMed2003

Predictors of response to biofeedback treatment in anal incontinence.

PURPOSE: Biofeedback is considered an effective treatment for anal incontinence, but a substantial proportion of patients fails to improve. The purpose of this study was to identify the key predictors of outcome. METHODS: We retrospectively analyzed the clinical and physiologic data of 145 patients consecutively treated in our unit for anal incontinence by biofeedback. Clinical evaluation was performed by means of a structured questionnaire that included previous history, symptoms of incontinence, and bowel habit. Anorectal evaluation measured anal pressure profiles, neural reflexes, defecatory dynamics, rectal compliance, and rectal sensitivity. Biofeedback treatment was performed by a manometric technique with reinforcement sessions scheduled every three months and daily exercising at home. Six months after the onset of biofeedback treatment the clinical response was evaluated as good (improvement of incontinence) or poor (no improvement or worsening). RESULTS: Of 126 patients (104 female; age range, 17-82 years) with at least six-month follow-up, 84 percent had a good response to treatment. By univariate analysis, several factors, such as age, history of constipation, abnormal defecatory maneuver, and rectal compliance, were significantly related to treatment response, but by multivariate logistic regression only age and defecatory maneuver were independent predictors of the response. The association of both factors provided the best sensitivity and specificity; 48 percent of patients younger than age 55 years and with abnormal defecatory maneuver had negative response to treatment, whereas 96 percent of patients age 55 years or older with normal defecatory maneuver had a positive response. CONCLUSION: In patients with anal incontinence scheduled for biofeedback treatment, potential alterations of defecation should be first searched for and corrected, particularly in younger patients.

Adolescent↗

PubMed2003

Antro-fundic dysfunctions in functional dyspepsia.

BACKGROUND & AIMS: Symptoms in functional dyspepsia have been related to impaired accommodation and hypersensitivity of the proximal stomach. We hypothesized that identification of putative antral dysfunctions provides a more comprehensive pathophysiological interpretation. METHODS: In 30 patients with functional dyspepsia and 22 healthy subjects, 2 consecutive studies were performed. In study I, with the subjects in the upright position, the proximal and distal stomach were selectively distended by bags containing air and water, respectively, while perception and fundic relaxation in response to antral distention were measured. In study II, by using air-filled bags connected to a tensostat, the proximal and the distal stomach were selectively distended by positioning the subjects on the right and left lateral decubitus, respectively, while perception, compliance, and the responses to intestinal nutrient infusion were measured. RESULTS: Patients with dyspepsia showed hypersensitivity of both the proximal stomach (discomfort at 30 +/- 3 g vs. 62 +/- 2 g in controls; P < 0.05) and the antrum (discomfort at 31 +/- 2 g vs. 53 +/- 4 g in controls; P < 0.05). Fundic and antral fasting tone was normal, but reflex fundic relaxation induced either by antral distention (3 +/- 16 mL at 80 mL of distention vs. 38 +/- 10 mL in controls; P < 0.05) or by intestinal nutrients (35 +/- 7 mL vs. 107 +/- 8 mL in controls; P < 0.05) was markedly impaired. CONCLUSIONS: Antral and fundic dysfunctions interact to produce the symptoms of functional dyspepsia, and impaired control of fundic accommodation may lead to overload of a hypersensitive antrum.

Adult↗

PubMed2002

Gastrointestinal perception: pathophysiological implications.

Physiological gut stimuli during the digestive process are not normally perceived. However, gut stimuli activate a variety of afferent pathways and in some circumstances may induce conscious sensations. Experimental evidence gathered during the past decade suggests that patients with functional gut disorders and unexplained abdominal symptoms may have a sensory dysfunction of the gut, so that physiological stimuli would induce symptoms. Assessment of visceral sensitivity is still poorly developed, but in analogy to somatosensory testing, differential stimulation of visceral afferents may be achieved by a combination of stimulation techniques, which may help to characterize sensory dysfunctions. Visceral afferent input is modulated by a series of mechanisms at different levels of the brain gut axis, and conceivably, a dysfunction of these regulatory mechanisms could cause hyperalgesia. The sensory dysfunction in functional patients seems associated to altered reflex activity, and both mechanisms may interact to produce the symptoms. Evidence of a gut sensory-reflex dysfunction as a common pathophysiological mechanism in different functional gastrointestinal disorders, would suggest that they are different forms of the same process, and that the clinical manifestations depend on the specific pathways affected.

Digestive System↗

PubMed2002

Prokinetic effects in patients with intestinal gas retention.

BACKGROUND & AIMS: We have previously shown that patients with irritable bowel syndrome (IBS) have impaired transit of intestinal gas loads. Because abnormal gas retention can be experimentally reproduced in healthy subjects by pharmacological inhibition of gut motility, we hypothesized that impaired gas transit and retention can be reciprocally corrected by pharmacologically stimulating intestinal propulsion. METHODS: In 28 patients with abdominal bloating (14 IBS, 14 functional bloating) and in 14 healthy subjects, gas evacuation and perception of jejunal gas infusion (12 mL/min) were measured. After 2 hours, in 20 patients we tested the effect of intravenous neostigmine (0.5 mg) vs. intravenous saline administered blindly and randomly at a 1-hour interval. RESULTS: After 2 hours of gas infusion, patients with IBS and functional bloating alike exhibited significant gas retention (418 +/- 86 mL), abdominal symptoms (2.7 +/- 0.5 score), and objective distention (8 +/- 2 mm girth increment), in contrast to healthy controls, who experienced none (46 +/- 102 mL retention, 0.4 +/- 0.3 symptom score, and 3 +/- 1 mm distention; P < 0.05 for all). Neostigmine produced immediate clearance of gas retained within the gut (603 +/- 53 mL/30 minutes vs. 273 +/- 59 mL/30 minutes after saline; P < 0.05) and by 1 hour reduced gas retention (by 373 +/- 57 mL), abdominal symptoms (by 1.1 +/- 0.5 score), and distention (by 6 +/- 1 mm; P < 0.05 for all), whereas intravenous saline produced no effects. CONCLUSIONS: In patients with intestinal gas retention, pharmacological stimulation of intestinal propulsion improves gas transit, abdominal symptoms, and distention.

Abdomen↗

PubMed2002

Lipid-induced intestinal gas retention in irritable bowel syndrome.

BACKGROUND & AIMS: We hypothesized that lipids, which induce various motor and sensory effects on the gut, modulate intestinal gas dynamics and that alteration of this regulatory mechanism may result in impaired gas transit in patients with irritable bowel syndrome (IBS). METHODS: In 45 healthy subjects and 30 patients with IBS, evacuation of gas infused into the jejunum (at 12 mL/min) was measured for 2 hours. The effect of simultaneous duodenal perfusion of lipids at 0 kcal/min (saline), 0.5 kcal/min, and 1 kcal/min was tested in groups of 15 subjects each. RESULTS: In healthy subjects, duodenal lipids at 1 kcal/min but not at 0 kcal/min or 0.5 kcal/min produced significant gas retention (281 +/- 53 mL vs. 22 +/- 64 mL at 0 kcal/min and -65 +/- 72 mL at 0.5 kcal/min; P < 0.05 for both). Patients with IBS exhibited gas retention during saline perfusion (259 +/- 85 mL at 0 kcal/min; P < 0.05 vs. healthy subjects) and were hypersensitive to duodenal lipids (505 +/- 61 mL retention at 0.5 kcal/min; P < 0.05 vs. saline and vs. healthy subjects). The "gas plus lipids" challenge test discriminated patients with 100% sensitivity and 93% specificity. CONCLUSIONS: Physiologic concentrations of intestinal lipids exert an inhibitory control on intestinal gas transit, and this mechanism is up-regulated in patients with IBS. Hence, impaired gas propulsion, shown by the gas challenge test, may be useful as a diagnostic test if replicated in a larger series of patients.

Adult↗

PubMed2002

Significance of pelvic floor muscles in anal incontinence.

BACKGROUND & AIMS: The pathophysiology of anal incontinence may be elusive using current parameters. Our aim was to establish the role of the levator ani in anal continence. METHODS: In 53 patients with anal incontinence, 30 with constipation as disease controls, and 15 healthy controls, we evaluated incontinence severity by a 0-12 scale, anorectal function by standard manometric tests, and levator ani contraction by a perineal dynamometer. RESULTS: Patients with incontinence exhibited various physiologic abnormalities (3.2 +/- 0.3 per patient), but multiple regression analysis showed that levator ani contraction was the independent variable with strongest relation to the severity of incontinence (R = -0.84; P < 0.0001), as well as a predictive factor of the response to treatment (R = 0.53; P < 0.01). Furthermore, in contrast to other physiologic parameters, clinical improvement in response to treatment (4.4 +/- 0.5 score vs. 7.9 +/- 0.5 score pre; P < 0.001) was associated with a marked and significant strengthening of levator ani contraction (448 +/- 47 g vs. 351 +/- 35 g pre; P < 0.05). CONCLUSIONS: We have shown the importance of levator ani failure in understanding the etiology of anal incontinence and in predicting response to treatment.

Adult↗

PubMed2002

Anorectal functional testing: review of collective experience.

Anorectal manometry includes a number of specific tests that are helpful in the diagnostic assessment of patients with fecal incontinence and constipation; their purpose is to delineate the pathophysiological mechanism for these symptoms. Some of these tests may also provide helpful information in the assessment of patients with rectal pain or diarrhea, but their sensitivity and specificity are less well established for these symptoms. Tests for which there is consensus regarding their clinical utility include 1) resting anal canal pressure, 2) anal canal squeeze pressure (peak pressure and duration), 3) the rectoanal inhibitory reflex elicited by balloon distension of the rectum, 4) anal canal pressure in response to a cough, 5) anal canal pressure in response to defecatory maneuvers, 6) simulated defecation by means of balloon or radiopaque contrast, 7) compliance of the rectum in response to balloon distension, and 8) sensory thresholds in response to balloon distension. Anal endosonography and pelvic floor electromyography from intra-anal plate electrodes are nonmanometric tests that are also specifically useful in the evaluation of constipation and fecal incontinence. The clinical utility of all anorectal manometric tests is limited by the relative absence of 1) standardization of test protocols and 2) normative data from a large number of healthy individuals. The interpretation of these diagnostic tests is also complicated by the fact that patients are able to compensate for deficits in specific physiological mechanisms maintaining continence and defecation by utilizing other biological and behavioral mechanisms.

Anal Canal↗

PubMed2002

Gastric distension and duodenal lipid infusion modulate intestinal gas transit and tolerance in humans.

OBJECTIVE: Patients with unexplained abdominal complaints often attribute their symptoms to intestinal gas and indicate that symptoms are exacerbated by ingestion of a meal. However, the mechanisms responsible are unknown. Our aim was to analyze the specific influence of two meal-related factors, gastric distension, and intestinal nutrients, on intestinal gas dynamics and tolerance. METHODS: In 35 healthy subjects, gas evacuation and perception of jejunal gas infusion (12 ml/min) were measured for 3 h, during simultaneous duodenal infusion of saline, as control, lipids at 1 Kcal/min, or gastric distension. RESULTS: Infusion of lipids into the duodenum induced gas retention (584 +/- 154 ml, p < 0.05 vs 161 +/- 86 ml after saline infusion) without perception (2.2 +/- 0.5 score), whereas gastric distension induced perception (score 5.6 +/- 0.4, p < 0.05 vs score 1.9 +/- 0.4 after saline) without gas retention (7 +/- 205 ml). CONCLUSIONS: Different meal-related factors exert specific effects on intestinal gas dynamics and tolerance, and these mechanisms may interact to produce postprandial gas symptoms.

Abdominal Pain↗

PubMed2002

Gut perception in humans is modulated by interacting gut stimuli.

Digestive symptoms depend on multiple interacting gut stimuli, but integration of visceral afferent traffic is poorly understood. Our aim was to elucidate the contribution of simultaneous intestinal stimuli to conscious perception. In 17 healthy subjects, we performed stimulus-response trials of jejunal distensions (1-min duration at 5-min intervals in 8-ml increments) either alone or with a background electrical stimulus, and stimulus-response trials of electrical stimuli (1-min duration at 5-min intervals in 6-mA steps) either alone or with a background intestinal distension. The four stimulus-response trials were performed concomitantly applying the different types of stimuli in random order. Perception was measured on a scale of 0 to 6. Background stimulation markedly increased perception of test stimuli, reducing tolerance from 44 +/- 3 to 32 +/- 3 ml and from 67 +/- 6 to 33 +/- 4 mA (P < 0.05 for both). However, whereas jejunal distensions below the perception threshold did not modify perception of the background stimulus (4 +/- 1% change; not significant), unperceived electrical stimuli exerted a sensitizing effect and increased perception of the background distension up to uncomfortable levels (111 +/- 40% increment; P < 0.05). In conclusion, activation of different pools of jejunal afferents produces summative effects on perception, and this sensitizing effect can be exerted by unperceived stimulation of mechanoinsensitive jejunal afferents.

Adult↗