Benjamin Krevsky

Role of opiate receptors in the regulation of colonic transit

The effects of morphine and the opiate antagonist naloxone on human colonic transit were investigated. In a crossover, double-blind fashion, two groups of 6 normal volunteers were studied using colonic transit scintigraphy during the administration of a test drug or control. The test drugs were morphine (0.1 mg/kg every 6 h s.c.) or naloxone (0.8 mg every 6 h s.c.); control was saline (1 ml every 6 h s.c.). Morphine significantly delayed transit in the cecum and ascending colon (p less than 0.05), slowed the progression of the geometric center (p less than 0.01), and decreased the number of bowel movements per 48 h (p less than 0.005). Naloxone accelerated transit in the transverse colon and rectosigmoid colon (p less than 0.05) and accelerated the progression of the geometric center (p less than 0.05), but had no effect on the number of bowel movements per 48 h (p greater than 0.05). These results suggest that narcotic analgesics may cause constipation in part by slowing colonic transit in the proximal colon and by inhibiting defecation. Acceleration of transit by naloxone suggests that endogenous opiate peptides may play an inhibitory role in the regulation of human colonic transit.

Colonic Transit Scintigraphy: A Physiologic Approach to the Quantitative Measurement of Colonic Transit in Humans

Colonic transit scintigraphy was developed to quantitatively evaluate colonic transit. Using this technique the progression of a radiolabeled marker from cecal instillation to defecation was studied in 7 normal male volunteers. An 8-ml bolus containing 50 mu Ci of indium 111-diethylene triamine pentaacetic acid was instilled into the cecum via a 2-mm tube, which was passed orally, and serial scintigrams were obtained over 48 h. By 48 h, 70.7% +/- 9.1% (mean +/- SEM) of the instilled activity had been defecated. The cecum and ascending colon emptied rapidly, with a half-emptying time of 87.6 +/- 27.0 min. Geometric center analysis showed an initial logarithmic progression of activity in the proximal colon and a linear progression distally. This study suggests that the transverse colon, not the cecum and ascending colon, may be the primary site for fecal storage. Colonic transit scintigraphy is a safe, physiologic, and quantitative method for evaluating the colonic transit of fecal material and may provide a useful tool for evaluating normal and abnormal large intestinal physiology.

Whole gut transit scintigraphy in the clinical evaluation of patients with upper and lower gastrointestinal symptoms

OBJECTIVE:In a single noninvasive, quantitative test, whole gut transit scintigraphy (WGTS) measures gastric emptying (GE), small bowel transit (SBT), and colonic transit (CT). The aim of this study was to investigate the clinical utility of WGTS in patients with functional gastrointestinal (GI) symptoms.METHODS:A total of 108 patients with either dyspeptic upper GI symptoms (n = 35) or constipation (n = 73) underwent WGTS. Patients consumed a meal of 99 m-Tc egg sandwich with 111-In DTPA in water. They were imaged every 30 min for 6 h to measure GE and SBT, and at 24, 48, and 72 h to measure CT.RESULTS:Of 108 studies, 104 were analyzable. In patients with upper GI symptoms, 14/35 (40%) had delayed GE of solids, 4/35 (11%) delayed SBT, and 11/35 (31%) delayed CT. Of those with constipation, 13/69 (19%) had delayed GE, 5/69 (7%) delayed SBT, and 43/69 (65%) delayed CT. WGTS changed the initial clinical diagnosis in 47/104 (45%) and altered patient management in 70/104 (67%) of the patients.CONCLUSIONS:Transit abnormalities of the upper GI tract and colon are common in patients with functional GI symptoms. Patients with upper GI symptoms frequently have delayed GE, whereas those with constipation tend to have predominantly delayed CT. In many patients with functional GI symptoms, there was evidence of a diffuse GI motility disorder. Whole gut transit scintigraphy is a simple, clinically useful test, as it frequently leads to a change in diagnosis and, therefore, patient management.

How accurate are endoscopic estimates of size

The accuracy of polyp size estimations in clinical studies is not known. This study was designed to evaluate how well endoscopists can estimate the size of objects at endoscopy. Observations were made by six attending gastroenterologists, six gastroenterology fellows, and seven untrained medical residents. Ball bearings ranging in size from 3 mm to 19 mm were randomly inserted into a latex colon model, and size was estimated while being viewed with a video colonoscope with and without the aid of an open biopsy forceps. Estimated size correlated well to actual size (R ranged from 0.78 to 0.93), although the mean estimates were consistently lower (13% to 29%) than the actual size for all groups, with and without forceps. The use of forceps did not improve the estimates. Exactly correct estimates occurred in 8%; errors of as much as 110% were recorded. The 12 mm bearing was estimated to be less than 10 mm half of the time. We conclude that endoscopists frequently underestimate the size of objects viewed at the time of endoscopy. There was no difference in the performance of experienced gastroenterologists, fellows in training, or untrained residents. This study indicates that better methods of training and for determining size are needed. Research that depends on endoscopic estimates of polyp size may be biased.

The effect of oral cisapride on colonic transit

A prospective double‐blind cross‐over trial of oral cisapride 10 mg and placebo was performed to determine the effects of cisapride on the transit of colonic contents in normal humans. Six male volunteers were studied twice using Colonic transit scintigraphy. After passing a tube to the caecum, 50 μCi of 111Indium diethylene triamine pentaacetic acid were instilled into the bowel lumen. The movement of radiolabelled material was followed using a gamma camera interfaced to a digital computer. Cisapride decreased the half‐emptying of the caecum and ascending colon from 1.68 ± 0±4 hours to 0.72 ± 0.15 hours (P < 0.05). The total colon half‐emptying time was reduced from 38.5 ± 7.2 hours to 11.1 ± 2.9 hours on cisapride (P < 0.05). Cisapride accelerated transit through the transverse colon, but not the descending colon. The progression of the geometric centre was faster during cisapride administration than with placebo (P < 0.05). The number of bowel movements 48‐hours−1 increased after cisapride from 2.5 ± 0.8 to 5.0 ± 0.4 (P < 0.05). This study demonstrates that cisapride has a marked prokinetic effect on Colonic transit in normal subjects. Cisapride may be a useful agent in the treatment of constipation.

Effect of verapamil on human intestinal transit.

Although constipation is a well-known side effect of calcium channel blockers such as verapamil, this side effect has not been evaluated in a quantitative manner. In a double-blind, randomized, crossover trial, the effect of verapamil (240 mg/day) was compared to placebo in 15 normal male volunteers. Subjects recorded their bowel movements and any side effects. Scintigraphy was used to quantitate gastric emptying, small intestinal transit, and colonic transit. In the study period of four days, verapamil did not change the frequency, consistency, or passage of bowel movements. A significantly increased number of side effects was noted during verapamil treatment—notably abdominal pain and dry mouth. The slope of gastric emptying was not significantly different for verapamil (0.012±0.02) than for placebo (0.013±0.001). Distal ileum filling was also not different for verapamil (0.41±0.13%/min) than placebo (0.33±0.05%/min). Progression of the colonic geometric center was significantly delayed at 48 hr by verapamil (5.2±0.4 vs 6.2±0.23;P<0.01). This study suggests that the constipating effect of verapamil is due to a delay of colonic transit and not due to an effect on upper gastrointestinal transit.

Optimal evaluation of patients with nonobstructive esophageal dysphagia : Manometry, scintigraphy, or videoesophagography ?

The aims of this study were to compare diagnostic accuracy, cost, and patient tolerance of videoesophagography and esophageal transit scintigraphy to esophageal manometry in the evaluation of nonobstructive esophageal dysphagia. Eighty-nine consecutive patients underwent videoesophagography, scintigraphy, and manometry. The sensitivities for diagnosing specific esophageal motility disorders, using esophageal manometry as the standard, were 75% and 68% for videoesophagography and scintigraphy, respectively, with positive predictive accuracies of 96% and 95% for achalasia, 100% and 67% for diffuse esophageal spasm, 100% and 75% for scleroderma, 50% and 67% for isolated LES dysfunction, 57% and 48% for nonspecific esophageal motility disorders, and 70% and 68% for normal esophageal motility. The cost for videoesophagography is less than that for either manometry or scintigraphy. Both videoesophagography and scintigraphy were better tolerated than manometry. It is concluded that videoesophagography and scintigraphy accurately diagnose primary esophageal motility disorders, achalasia, scleroderma, and diffuse esophageal spasm, but are less accurate in distinguishing nonspecific esophageal motility disorders from normal. When considering accuracy, cost, and patient acceptance, these findings suggest that videoesophagography is a useful initial diagnostic study for the evaluation of nonobstructive esophageal dysphagia.

Whole-gut transit scintigraphy in the evaluation of small-bowel and colon transit disorders

Scintigraphic methods for performing gastric emptying and colon transit studies are now well standardized. Although not as well established, several methods have been proposed for measuring small-bowel transit. The measurement of orocecal transit time appears to be a practical scintigraphic measurement of small-bowel transit. When combined into a single test of gastric emptying, small-bowel, and colon transit, whole-gut transit scintigraphy is an important, noninvasive tool for documenting dysmotility of any segment of the gastrointestinal tract. Despite attempts to simplify the study, whole-gut transit scintigraphy still requires a significant commitment of time and equipment. As with other gastrointestinal studies, each laboratory must determine which protocol best fits its clinical needs, equipment, and staffing. Attention must be paid to adhere to established protocols, or normal values will need to be determined for each laboratory. Despite these difficulties, whole-gut transit scintigraphy now represents an important clinical tool for the evaluation of patients with a wide range of abdominal complaints.

Role of flexible endoscopy in the evaluation of possible esophageal trauma after penetrating injuries

OBJECTIVE:In urban medical centers, penetrating injuries of the chest, neck, and head are frequently encountered due to the use of firearms and sharp weapons. Successful management of esophageal injury requires a high index of suspicion and prompt diagnosis. The role of flexible endoscopy, a readily available modality, has not been studied extensively in the management of potential esophageal injuries due to trauma.METHODS:A retrospective chart review of 55 patients who underwent emergent flexible endoscopy for the evaluation of suspected penetrating esophageal injuries was performed to determine if endoscopy was safe and if it yielded information that altered patient management.RESULTS:Flexible endoscopy was performed safely in all patients. It yielded a sensitivity of 100%, specificity of 92.4%, a negative predictive value of 100%, and a positive predictive value of 33.3% for detecting an esophageal injury. Although positive findings (prevalence, 3.6%) are infrequent, no esophageal injuries were missed. Endoscopy altered patient management in 38 (69.1%) patients.CONCLUSIONS:Emergent flexible endoscopic examination of the esophagus is a safe and useful diagnostic tool in the early evaluation of penetrating injuries. Flexible endoscopy resulted in four negative surgical explorations, which was deemed acceptable by the Trauma Service, as the consequences of a missed esophageal injury is likely to be devastating.

Prolonged survival and effective palliation in patients with squamous cell carcinoma of the esophagus following endoscopic laser therapy

Endoscopic laser therapy provides effective symptomatic palliation for patients with squamous cell carcinoma of the esophagus. To investigate whether this treatment also prolongs survival, a retrospective case‐control study was performed. Ten patients with squamous cell carcinoma of the esophagus, diagnosed between 1983 and 1985, were treated with the neodymium: yttrium aluminum garnet laser (Cooper Lasersonics, Model 8000, Santa Clara, CA). Twenty patients with the same diagnosis observed between 1979 and 1984 served as age‐matched controls. There was no significant difference in sex, race, location of the cancer, prior treatment, or dysphagia scores for the two groups. Laser therapy produced a significant improvement in the mean dysphagia score. Life table analysis demonstrated a median survival of 17.5 months for the patients treated with endoscopic laser therapy compared with 5.7 months for the control subjects (P < 0.05). One‐year survival after laser treatment was 75%, compared with 20% in the control group (P < 0.05). These results suggest that endoscopic laser therapy is effective for prolonging survival and improving the quality of life in patients with squamous cell carcinoma of the esophagus.