Victor Plourde

Canadian Association of Gastroenterology position statement on screening individuals at average risk for developing colorectal cancer: 2010

The Canadian Association of Gastroenterology and the Canadian Digestive Health Foundation published guidelines on colon cancer screening in 2004. Subsequent to the publication of these guidelines, many advances have occurred, thereby necessitating a review of the existing guidelines in the context of new technologies and clinical knowledge. The assembled guideline panel recognized three recent American sets of guidelines and identified seven issues that required comment from a Canadian perspective. These issues included, among others, the role of program-based screening, flexible sigmoidoscopy, computed tomography colonography, barium enema and quality improvement. The panel also provided context for the selection of the fecal immunochemical test as the fecal occult blood test of choice, and the relative role of colonoscopy as a primary screening tool. Recommendations were also provided for an upper age limit for colon cancer screening, whether upper endoscopy should be performed following a negative colonoscopy for a positive fecal occult blood test and when colon cancer screening should resume following negative colonoscopy.

Evolution of Visceral Sensitivity in Patients with Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) has been associated with visceral hypersensitivity. Here we examined the evolution of rectal sensitivity and of gastrointestinal symptomatology in IBS patients over time, to verify if the clinical and biological parameters showed parallel behavior. Patients complaining of IBS, identified by Rome 1 criteria, were included in this study. The severity of the gastrointestinal (Gastrointestinal) symptoms was assessed by a gastrointestinal index. The pain threshold to rectal distension was measured by a barostat programmed for phasic ascending distensions. Both measures were obtained before and after treatment. Thirty-nine patients were followed while on a 10-week group psychotherapy (psy) program. Twelve patients were controlled after pharmacological treatment with amitriptyline (Ami) 10 mg hours for two weeks and then 25 mg hours for the following 4 weeks. Clinical improvement with symptom reduction was achieved in both patients groups. With psy, the Gastrointestinal index declined from an initial value of 78.4 ± 4.8 to 65.5 ± 4.5 at the end of treatment (P < 0.05). With Ami, the gastrointestinal index decreased from 91.6 ± 5.6 to 61.8 ± 9.1 (p < 0.01). The pain threshold to rectal distension increased from 27.7 ± 1.0 to 33.7 ± 1.9 mmHg (P < 0.01) after drug treatment, but remained unchanged (30.6 ± 1.0 vs 30.6 ± 1.1 mm Hg) with psy. Evolution of the gastrointestinal index and rectal sensitivity were directly correlated (r = −0.71; P < 0.01) in Ami patients, but not in those treated with Psy (r = −0.001). In conclusion, visceral hypersensitivity appeared as a stable biological defect over a 10- to 12-week period during clinically-effective treatment with psychotherapy. Rectal pain threshold, however, seemed to be pharmacologically manipulatable in patients treated with Ami.

Intolerance to visceral distension in functional dyspepsia or irritable bowel syndrome: an organ specific defect or a pan intestinal dysregulation?

Abstract  Functional gastrointestinal disorders (FGID) are characterized by visceral hypersensitivity that could be specific to a region of the gut or reflect a diffuse pan‐intestinal disorder. Sensory thresholds to distension at two visceral sites in patients with different FGIDs were determined. According to Rome II criteria, 30 patients from three groups were studied: patients with (i) functional dyspepsia (FD) or (ii) irritable bowel syndrome (IBS), and (iii) patients with concomitant symptoms of FD and IBS. Pain thresholds to balloon distension were determined in stomach and rectum. In FD patients, gastric intolerance to balloon distension was found in 91% patients; rectal hypersensitivity was documented in 18% patients. In IBS patients, rectal hypersensitivity was seen in 75% patients; while gastric hypersensitivity was never found. In patients with concomitant symptoms of FD + IBS, gastric and rectal intolerance to distension were present respectively in 82 and 91% patients. In the whole group, visceral intolerance to distension was documented at one site in 90% patients and at both sites, i.e. stomach and rectum, in 33% patients. Visceral intolerance to distension can be pan‐intestinal in patients with multiple sites of symptoms, but appears organ‐specific in patients exhibiting a specific site of symptoms.

Estimation of collagen content of liver specimens. Variation among animals and among hepatic lobes in cirrhotic rats

We undertook a study to evaluate the correlation between morphometric evaluation and colorimetric determination of hepatic collagen content, and to analyze the variation among animals as well as among lobes of the same liver in hepatic collagen content after CCl4-induced micronodular cirrhosis. The results revealed a significant correlation (r = 0.9458; p less than 0.001) between the morphometric and colorimetric methods of collagen evaluation of liver specimens; both methods also significantly distinguished data obtained from controls and from cirrhotic rats (p less than 0.0005). After induction of micronodular cirrhosis by chronic CCl4 administration, a highly significant variation in hepatic collagen content was observed among animals (p less than 0.0001). By contrast, no significant difference in collagen content was observed (p less than 0.05) among hepatic lobes of a given animal. These results indicate that in this animal model of liver cirrhosis, interpretation of biochemical data would benefit by being related to the severity of the hepatic collagen infiltration of each animal. Our data also show that representative values for total hepatic collagen infiltration can be obtained from a single liver specimen; we suggest, however, that the specimen be taken from a major lobe of the liver and that a sufficiently large number of animals be used to avoid occasional sampling errors.

Recommendations on Chronic Constipation (Including Constipation Associated with Irritable Bowel Syndrome) Treatment

While chronic constipation (CC) has a high prevalence in primary care, there are no existing treatment recommendations to guide health care professionals. To address this, a consensus group of 10 gastroenterologists was formed to develop treatment recommendations. Although constipation may occur as a result of organic disease, the present paper addresses only the management of primary CC or constipation associated with irritable bowel syndrome. The final consensus group was assembled and the recommendations were created following the exact process outlined by the Canadian Association of Gastroenterology for the following areas: epidemiology, quality of life and threshold for treatment; definitions and diagnostic criteria; lifestyle changes; bulking agents and stool softeners; osmotic agents; prokinetics; stimulant laxatives; suppositories; enemas; other drugs; biofeedback and behavioural approaches; surgery; and probiotics. A treatment algorithm was developed by the group for CC and constipation associated with irritable bowel syndrome. Where possible, an evidence-based approach and expert opinions were used to develop the statements in areas with insufficient evidence. The nature of the underlying pathophysiology for constipation is often unclear, and it can be tricky for physicians to decide on an appropriate treatment strategy for the individual patient. The myriad of treatment options available to Canadian physicians can be confusing; thus, the main aim of the recommendations and treatment algorithm is to optimize the approach in clinical care based on available evidence.

Involvement of N-methyl-d-aspartate (NMDA) receptors in a rat model of visceral hypersensitivity.

N-Methyl-d-aspartate (NMDA) is known to be involved in the transmission of nociceptive information. In the present study, we investigated the effect of peripheral and central NMDA receptor antagonist MK-801 in visceral hypersensitivity. In an animal model of colorectal distension (CRD), administration of both intrathecal MK-801 (1.5 nmol) and intraperitoneal MK-801 (0.15 mg/kg) completely abolished the CRD-induced visceral hypersensitivity of noxious and innocuous stimuli. Thus, the results from this experiment demonstrate the efficacy of MK-801 in blocking the visceral hypersensitivity mediated by central and peripheral mechanisms.

Role of tachykinin NK1, NK2 and NK3 receptors in the modulation of visceral hypersensitivity in the rat

Tachykinins are known to be involved in the processing of information leading to central sensitization and nociception. Using an animal model of repetitive colorectal distensions (CRD), we investigated the effect of spinal administration of tachykinin receptor antagonists in the mediation of visceral hypersensitivity. Intrathecal administration of the NK(1) receptor antagonist RP-67,580 (6.5 nmol) and the NK(3) receptor antagonist R-820 (6.5 nmol) completely blocked the CRD-induced hyperalgesia for both noxious and innocuous stimuli. The intrathecal administration of SR-48,968, a tachykinin NK(2) receptor antagonist, did not affect the visceral pain threshold of hypersensitive animals. Thus, the results from the present experiment support the concept that tachykinins with actions at spinal NK(1) and NK(3) but not NK(2) receptor sites are involved in visceral hypersensitivity mediated by nociceptive and non-nociceptive afferent inputs.

Evaluation of Gastric Emptying Function in Clinical Practice

In this retrospective analysis, we compareddifferent methods to evaluate gastric emptying function,aiming to improve the sensitivity and the clinicalavailability of our diagnostic testing. In the first study, we compared, in 72 patients clinicallysuspected of gastroparesis, the emptying of a mealcontaining two solid nutrients with differentdisintegration rates: 111Inlabeled scrambled eggs and99Tc-labeled liver cubes. Gastric emptying of111In-labeled egg was delayed in 12 of ourpatients and the evacuation of the99Tc-labeled liver was prolonged in 19patients. The choice of the nutrient was not important for the identification of diabeticgastroparesis (43% vs 57%; NS), but it was determinantin the case of patients suspected of idiopathicgastroparesis (12% were positive with the egg and 25%with the liver; P < 0.05). In the second study, wecompared two different diagnostic methods in 46patients: a simple radiological detection of the gastricemptying of radiopaque pellets, and the scintigraphic emptying of a solid meal containing99Tc-labeled liver cubes. Both testscorrelated perfectly in 78% of our patients. In 15% ofthe population (six of these seven patients werediabetics suspected of gastroparesis) the scintigraphic method was normal, while theevacuation of radiopaque pellets was delayed. Forclinical purposes, we therefore propose: (1) thescintigraphic method should use liver rather than egg as a radiolabeled tracer in order to improve thesensitivity of the test for detection of gastroparesis;and (2) the radiological detection of radiopaque markersis a reliable and convenient method for the detection of gastroparesis in clinicalpractice. It is possibly more sensitive thanscintigraphy.

Stress-Induced Changes in the Gastrointestinal Motor System

Several autonomic, hormonal, behavioural and neuropeptidergic bodily responses to stressful stimuli have been described over the past few decades. Both animal models and human paradigms have been explored. It is acknowledged that stress modulates gastrointestinal (GI) motility through central mechanisms including corticotropin-releasing-factor. This process requires the integrity of autonomic neural pathways. It has become evident that the effects of stress on GI motility vary according to the stressful stimulus, its intensity, the animal species under study and the time course of the study. Recent evidence suggests that chronic or possibly permanent changes develop in enteric smooth muscle properties in response to stress. In animals, the most consistent findings include retardation of gastric emptying in response to various stressors; acceleration of gastric emptying upon cold stress, presumably through the secretion of brain thyroglobulin-hormone; acceleration of intestinal transit; and stimulation of colonic transit and fecal output. In humans, the cold water immersion test has been associated with an inhibition of gastric emptying, while labyrinthine stimulation induces the transition from postprandial to fasting motor patterns in the stomach and the small bowel. Psychological stress has been shown to induce a reduction in the number and amplitude of intestinal migrating motor complexes and to neither affect nor stimulate colonic motility. These various responses to stress are presumably attributed to the preferential activation of specific neuronal pathways under the influence of a given stimulus or its intensity. The significance of these findings and the directions of further studies are discussed.

Survey of Access to GastroEnterology in Canada: The SAGE Wait Times Program

BACKGROUND Assessment of current wait times for specialist health services in Canada is a key method that can assist government and health care providers to plan wisely for future health needs. These data are not readily available. A method to capture wait time data at the time of consultation or procedure has been developed, which should be applicable to other specialist groups and also allows for assessment of wait time trends over intervals of years. METHODS In November 2008, gastroenterologists across Canada were asked to complete a questionnaire (online or by fax) that included personal demographics and data from one week on at least five consecutive new consultations and five consecutive procedure patients who had not previously undergone a procedure for the same indication. Wait times were collected for 18 primary indications and results were then compared with similar survey data collected in 2005. RESULTS The longest wait times observed were for screening colonoscopy (201 days) and surveillance of previous colon cancer or polyps (272 days). The shortest wait times were for cancer-likely based on imaging or physical examination (82 days), severe or rapidly progressing dysphagia or odynophagia (83 days), documented iron deficiency anemia (90 days) and dyspepsia with alarm symptoms (99 days). Compared with 2005 data, total wait times in 2008 were lengthened overall (127 days versus 155 days; P<0.05) and for most of the seven individual indications that permitted data comparison. CONCLUSION Median wait times for gastroenterology services continue to exceed consensus conference recommended targets and have significantly worsened since 2005.