Measurement of electrical activity of the human small intestine using surface electrodes

Electrical activity of the human small intestine is usually measured by implanted or intraluminal electrodes. The application of these invasive techniques is, however, very limited. In this paper, a noninvasive technique is introduced to measure electrical activity of the small intestine by placing electrodes on the abdominal skin over the small intestine. Surface recordings were obtained in ten healthy volunteers, three patients with total gastrectomy and five patients with gastroparesis (a slight degree of paralysis of the mucosal coat of the stomach) with implanted electrodes on the serosa of the duodenum. An omnipresent 9-12 cpm electrical activity was observed in all surface recordings. Our findings from the surface electrodes were consistent with those reported in the literature via implanted or intubated electrodes. It is concluded that the technique described in this paper provides a noninvasive way to measure electrical activity of the small intestine. It may have potential application in medical research and clinical diagnosis.

Gastroparesis and the current use of prokinetic drugs

Gastroparesis is a chronic gastric motility disorder in which there is delayed gastric emptying of solids plus or minus liquids. Symptoms of gastroparesis may range from early satiety and nausea in mild cases to chronic vomiting, dehydration, and nutritional compromise in severe cases. Diagnosis of gastroparesis is based on demonstration of delayed gastric emptying of a radiolabeled solid meal in the absence of mechanical obstruction. A number of gastrointestinal and systemic disorders may impair gastric motility with resultant gastroparesis. Approximately one third of patients with gastroparesis have no identifiable underlying cause (so called idiopathic gastroparesis). Management of gastroparesis involves four areas: (1) nutritional support, (2) antiemetic drugs, (3) prokinetic drugs, and (4) surgical therapy (in a very small subset of patients). Gastroparesis is often a chronic, relapsing condition; 80% of patients require maintenance antiemetic and prokinetic therapy and 20% require long-term nutritional supplementation. In the near future, the most promising advances in the treatment of patients with gastroparesis will most likely come from the area of combination pharmacological therapy. In the long term, developments in the area of intestinal pacing and intestinal transplantation may offer further treatment options in this difficult disorder.

Objective and subjective results of a randomized, double-blind, placebo-controlled trial using cisapride to treat gastroparesis

Cisapride, a relatively new gastrointestinal prokinetic agent, has been reported to increase gastric emptying and improve symptoms of gastroparesis. We investigated these effects of cisapride in patients with severe idiopathic and diabetic gastroparesis during an eight-week trial. The study design was a two-week single-blind placebo run in period to exclude placebo responders, followed by a six-week randomized, double-blind, placebo-controlled treatment phase. Delayed gastric emptying of solids on radionuclide scan and a minimum symptom intensity score were inclusion criteria. Forty-three patients were entered: four placebo responders and one other patient were excluded, leaving 19 patients randomized to cisapride (20 mg per os three times a day before meals), and 19 patients to placebo. Seven individual symptoms of gastroparesis were scored in a daily diary and reviewed at two-week visits. Sixteen patients in the cisapride group were able to complete the trial compared to 12 on placebo. The gastric emptying study was repeated at the end of treatment or at the time of withdrawal for those who dropped out. Cisapride significantly increased solid gastric emptying relative to baseline (P = 0.005) whereas placebo did not (P > 0.10). Cisapride did not significantly improve any symptom of gastroparesis relative to baseline or to placebo. We conclude that in a population of severe, refractory gastroparetic patients cisapride significantly accelerates gastric emptying of a solid meal without significantly reducing symptoms during a short-term treatment trial compared to placebo. Further trials of cisapride in less advanced and "end-stage" gastroparetics than studied here or combining cisapride with other prokinetic agents or antiemetics, are warranted.

Erythromycin: a motilin agonist and gastrointestinal prokinetic agent

Erythromycin, a commonly used antibiotic, has recently emerged as a potential gastrointestinal prokinetic agent. This follows a decade of research into the mechanism of well-recognized gastrointestinal side effects of erythromycin. Early investigations demonstrated that erythromycin increased gastrointestinal motility, and more recent studies suggest that it fortuitously binds to and stimulates the receptor for the gastrointestinal peptide motilin. From this work it appears that a new and powerful class of gastrointestinal prokinetic agents will evolve from erythromycin and its derivatives. The role of motilin in the genesis of the fasting and fed patterns of gastrointestinal motility is emerging through the study of these motilin agonists.

Human sphincter of Oddi motility and cholecystokinin response following liver transplantation

The reported incidence of sphincter of Oddi dysfunction following orthotopic liver transplantation has ranged from 3% to 7%. If sphincteric dysfunction is unrecognized, therapy may be inappropriate; when recognized, extensive surgery may be required. To prospectively identify patients with sphincteric dysfunction, we performed sphincter of Oddi motility studies through the t-tube tract three months after transplantation. Baseline sphincter motility and response to intravenous cholecystokinin were evaluated. The results of 10 subjects are reported; nine had normal basal sphincter pressure (16 +/- 5.8 mm Hg), and all had normal frequency (3.6 +/- 1/min), amplitude (86 +/- 31 mm Hg), and duration (4.5 +/- 1 sec) of phasic contractions. One subject had an elevated basal pressure (47 mm Hg). All, including the subject with elevated basal pressure, demonstrated a normal response to intravenous cholecystokinin with significant inhibition of phasic contraction frequency and amplitude. We demonstrate that simultaneous studies of the sphincter and duodenum can be obtained via the t-tube tract, providing the opportunity for prospective evaluation of sphincteric function. We conclude that sphincter of Oddi function usually remains normal following liver transplantation with choledochocholedochostomy.

Spectral analysis of episodic rhythmic variations in the cutaneous electrogastrogram

Electrical activity of the stomach can be measured using surface electrodes. The cutaneous recording of gastric electrical activity is called the electrogastrogram (EGG). Gastric electrical dysrhythmic events associated with abnormal conditions of the stomach may be detected from the EGG. An adaptive spectral analysis method which is based on autoregressive moving average modeling has previously been developed. The aim of this paper is to demonstrate the ability of the previous method in detecting gastric dysrhythmic events from the EGG. A series of bench tests stimulating typical problems with the analysis of nonstationary electric potentials was conducted. The application of the adaptive spectral analysis method to dysrhythmic events and rhythmic variations of the gastric slow wave is presented in this paper. The adaptive spectral analysis approach provides several advantages: narrow frequency peaks permitting more precise frequency identification, determination of changes in frequency components at any time point, and enhanced interpretation of cutaneous EGG recordings.

The treatment of idiopathic and diabetic gastroparesis with acute intravenous and chronic oral erythromycin

The objective of this study was to investigate the effects of intravenous erythromycin and chronic oral dosing of erythromycin on gastric emptying in patients with idiopathic or diabetic gastroparesis. Symptoms were assessed on oral dosing and during long-term follow-up in an ambulatory setting at a University referral center. Fourteen patients (10 idiopathic and four diabetic gastroparesis) were studied. Four patients left during the 4-wk study; two due to rash, one with cramps and vomiting on erythromycin, and one due to other medical problems. Ten patients completed the 4-wk study and commenced long-term therapy. Five of these patients experienced enough symptomatic relief to continue oral erythromycin long-term, being followed for an average period of 8.4 months. After initial documentation of delayed gastric emptying, patients received 6 mg/kg intravenous erythromycin lactobionate before a second gastric emptying study. Erythromycin base was then given orally at a dose of 500 mg tid-ac and qhs, with a final gastric emptying study performed after 4 wk. During long-term follow-up, erythromycin dosage was adjusted to minimize symptoms. Radionuclide-labeled gastric emptying of a solid meal was studied at baseline, following intravenous erythromycin, and after 4 wk of oral treatment with erythromycin. Symptom scores were assessed at baseline, at 4 wk, and then at 8-wk intervals. The percentage of the solid meal retained in the stomach at 2 h decreased from 85% +/- 11% (SD) at baseline to 20% +/- 29% following intravenous erythromycin (p < 0.001), and to 48% +/- 21% after 4 wk of oral therapy (p < 0.01 vs. baseline). There was a reduction in total symptom scores and a significant reduction in global assessment scores (p = 0.03). We conclude that erythromycin has a strong gastric prokinetic effect in both idiopathic and diabetic gastroparesis, and may represent a useful new therapeutic approach to this problem.

Effect of erythromycin on gastric myoelectrical activity in normal human subjects

While a great deal of attention has been paid to the effect of erythromycin (Ery) on gastric contractility, its effect on gastric myoelectrical activity, which controls gastric motility, remains unknown. In this study, Ery (6 mg/kg) was infused intravenously in 14 normal human subjects (placebo controlled). Gastric myoelectrical activity was recorded using the surface electrogastrographic method. The electrogastrogram (EGG) recordings were analyzed using spectral analysis methods. It was found that the presence of the 2-4 cycles/min activity (normal slow wave frequency range) in the EGG was 51 +/- 19% in the first hour of the intravenous Ery infusion, which was significantly smaller (P less than 0.001, t test) than that (72 +/- 20%) during the corresponding control period (intravenous saline). This difference was, however, not quite significant (P = 0.067, t test) in the second hour after the infusions. The average score for nausea during Ery was 4.5 (0 for no nausea, 10 for the most severe nausea). We conclude that 1) intravenous Ery induces irregularities in the cutaneous EGG in normal human subjects; and 2) the noninvasive cutaneous EGG is an attractive method both for the investigation of the effects of pharmacological and prokinetic agents such as Ery on gastric myoelectrical activity in humans and for correlating clinical responses to changes in the EGG.

Acceleration of gastric emptying with electrical stimulation in a canine model of gastroparesis

We investigated the effects of electrical stimulation of the stomach on gastric emptying and the electrical activity of the stomach in 10 dogs. A model of gastroparesis was developed in five dogs using truncal vagotomy combined with injections of glucagon. Glucagon also induced electrical dysrhythmias. Bipolar electrodes were implanted in the stomach and the duodenum for electrical stimulation and for recording electrogastrograms. Gastric emptying of an isotope-labeled solid meal was assessed for 2 h. External electrical stimulation was delivered to the corpus of the stomach at its own physiological frequency to investigate whether it could restore normal gastric emptying. Such stimulation had no significant effect on gastric emptying in intact animals (45 vs. 43%: retention of isotope after 2 h) or when only vagotomy was performed (78 vs. 66%), but it significantly accelerated gastric emptying in animals with vagotomy and glucagon (from 86 to 68%). From this model of delayed gastric emptying, we suggest that electrical stimulation of the stomach at its own intrinsic frequency may recoordinate uncoupled slow wave activity induced by glucagon after vagotomy thus improving the rate of gastric emptying.

Gastric slow wave abnormalities in patients with gastroparesis

The aim of this study was to determine whether cutaneous electrogastrograms (EGGs) could be used to differentiate gastroparetic patients from asymptomatic healthy controls. Pre- and postprandial cutaneous EGGs were obtained from 24 asymptomatic healthy volunteers and 27 patients with gastroparesis documented by a delayed gastric emptying of a solid test meal. A definition of slow wave abnormality was introduced. For the fasted condition, all 24 controls showed highly regular, predominant peaks in the 2-4 cycles/min (cpm) range, in contrast to the patient group in which 11 subjects showed an absence of normal slow wave activity (p less than 0.001). For the postprandial condition, again, all 24 controls showed slow wave normality consisting of increased amplitude and regularity of the 2-4 cpm frequency component. This was in sharp contrast to the patient group in which 13 subjects showed abnormalities (p less than 0.0001). Approximately 75% of the patients had an abnormal pre- or postprandial EGG: four patients had abnormal EGGs both during fasting and after eating, seven patients had abnormal EGGs during fasting but normal EGGs after eating, and nine patients had normal EGGs during fasting but abnormal EGGs after eating. We conclude that the cutaneous EGG may be used to differentiate gastroparetic patients from asymptomatic normals.

What has the surgeon to know about pathophysiology of reflux disease?

Much has been learned about the pathophysiology of gastro-esophageal reflux (GER) since it was initially described by Asher Winkelstein in 1935. With the development and refinement of esophageal function tests in the past decades, the diagnostic modalities have become available for a deliberate and systematic evaluation of antireflux mechanisms. Some of the newer concepts of the pathogenesis of reflux esophagitis are reviewed in this article.

Optimization of prostatic magnetic resonance imaging technique

With a 1.5-T magnetic resonance imager the authors systematically varied a large number of technical factors to obtain an optimum balance between high image quality and reasonable imaging time for the prostate gland. Each parameter was adjusted relative to benchmark images of very high quality to achieve a reasonable acquisition time with as little loss of the signal-to-noise ratio (SNR) as possible. Image quality was judged subjectively by magnetic resonance radiologists and objectively by measurements of SNR for the prostate. The authors recommend multislice, multiecho spin-echo pulse sequences with dual surface coils, fat suppression, reduced bandwidth, a repetition time of 1500 ms, echo times of 30 and 60 ms, a flip angle of 60 degrees, two excitations, a slice thickness of 5 mm with a 1.5-mm gap and 192 phase-encoding steps. The acquisition time for one such series was 9.6 minutes.

The interrelationship between salivary epidermal growth factor and the functional integrity of the esophageal mucosal barrier in the rat

The role of salivary epidermal growth factor (sEGF) in the maintenance of the esophageal mucosal mucus coat and its permselective properties was investigated for this study. Eighteen Sprague-Dawley male rats underwent sialoadenectomy (SAD), while 18 others with sham operation served as a control. Nine SAD rats in each group received EGF in a dose of 15 micrograms/kg/d for five consecutive days prior to sacrifice. Esophageal mucosa dissected from the muscle layer was placed in the central port of a specially designed permeability chamber filled on both sides with equimolar solutions of NaCl or HCl (0.155 M). The rate of hydrogen ion diffusion from the mucosal to the serosal side was estimated by continuous recording of pH in the NaCl compartment. In addition, the mucosal mucus coat was evaluated by Alcian blue uptake methodology. SAD led to a 108% increase in the rate of permeability of the esophageal mucosa to hydrogen ion. Simultaneously, an 83% decrease in the mucus content on the surface of the esophageal mucosa was observed. A five-day supplementation of EGF substantially improved the permeability of esophageal mucosa (67%) and the mucous layer of esophagus (41%). sEGF seems to play an important physiological role in the maintenance of the functional integrity of the esophageal mucosa.

Sleep and nocturnal acid reflux in normal subjects and patients with reflux oesophagitis

Nocturnal gastro-oesophageal reflux may be important in the pathogenesis of reflux oesophagitis. This study aimed to determine whether: (1) gastro-oesophageal reflux occurs during sleep in patients with reflux oesophagitis and, if so, to explore the mechanism, and (2) the sleep pattern of patients with oesophagitis is different from that of control subjects. After a standard evening meal, simultaneous manometric, oesophageal pH, and polysomnographic recordings were obtained in 11 patients with endoscopic oesophagitis and 11 control subjects. Patients with gastrooesophageal reflux disease had significantly more total reflux episodes throughout the nocturnal monitoring period than control subjects (105 v 6). Ninety two of 105 episodes of gastro-oesophageal reflux in patients occurred during the awake state and 10 during sleep stage II. A number of reflux episodes occurred during brief periods of arousal from the various sleep stages. Of the 105 reflux events recorded in patients, 42 were induced by transient lower oesophageal sphincter relaxation, 20 by stress reflux, 22 by free reflux mechanisms, and in 21 the mechanism was unclear. The sleep pattern and the time spent in each sleep stage was not different between the two groups. It is concluded that the awake state is crucial for the occurrence of nocturnal reflux episodes in normal subjects as well as in patients with reflux oesophagitis and that the difference between the frequency of gastro-oesophageal reflux between normal subjects and patients cannot be explained by different sleep patterns.

Completion gastrectomy for refractory gastroparesis following surgery for peptic ulcer disease. Long-term follow-up with subjective and objective parameters

We recently have shown that 50% of patients with preoperative gastric outlet obstruction go on to develop chronic nonmechanical gastric stasis after surgery and require further operations in attempts to relieve their symptoms. In the present study we report our experience with completion gastrectomy (CG), offered to a subgroup of this population who failed to respond to both available and experimental medical therapy with prokinetic agents. Manometric studies of the small bowel were performed on three of these patients using a semiconductor solid recording probe to assess the motility of efferent jejunal limbs. There were seven females and one male (N = 8) with a mean age of 45 years. All had persistent symptoms of abdominal pain, bloating, nausea, vomiting, early satiety, decreased appetite, and weight loss dating back to the time of surgery. Gastric stasis was documented by delayed gastric emptying of a radionuclide solid meal (chicken liver labeled with technetium-99m sulfur colloid) with a mean retention of 86 +/- 6.2% (less than 60% being normal) in the setting of an upper endoscopy showing stomal patency. The mean duration of symptoms was 31.6 +/- 15.7 months (range 6-60) since the last surgery. The number of previous gastric operations was a mean of 2.3 per patient. Five of eight patients had undergone a Roux-en-Y procedure as the last operation while the other three had a Billroth II. Surgery consisted of a 90% or complete resection of the remaining stomach and a jejunal-esophageal anastomosis. In some cases the Roux-en-Y limb was lengthened to greater than 45 cm if needed.(ABSTRACT TRUNCATED AT 250 WORDS)

A noninvasive scintigraphic assessment of the colonic transit of nondigestible solids in man

A noninvasive, scintigraphic technique for quantifying large intestinal transit time that provides low radiation doses was developed. The scintigraphic large intestinal transit (SLIT) method uses a total of 100 microCi of 111In encapsulated in ten 2-cm nondigestible capsules, which are ingested after a 6-hr fast. Two hundred fifty microcuries of 99mTc-sulfur colloid were given to outline the gastrointestinal tract. Images were acquired at 4-hr intervals until all capsules were excreted. Normal volunteers (n = 10) consumed a standardized diet 2 days prior and during imaging. Segmental transit times were measured in the following: ascending, transverse, descending, recto-sigmoid colons; hepatic and splenic flexures. The radiation absorbed dose to the large intestine for the SLIT technique is less than half of that associated with other radiographic methods of colonic transit time measurement.

Electrogastrography: measurement, analysis and prospective applications

Electrogastrography (EGG), the cutaneous recording of the myoelectrical activity of the stomach using surface electrodes, is attractive due to its noninvasiveness and its correlation with gastric motility. Since the first measurement of the EGG, a great deal of research effort has been expended on investigating its relationship with specific activities of the stomach in question. In this review, we discuss how to measure the EGG, what information is available in the EGG, how to extract useful information from the EGG and the prospective applications of the EGG. After a brief historic evolution of the EGG, we first discuss the measurement of the EGG, the importance of localisation of the stomach and the characteristics of the EGG. The most commonly used EGG data-analysis methods, both power spectral analysis and waveform analysis, are then outlined. Some of prospective applications of the EGG in clinical diagnosis and medical research are described, mainly concerning the correlation between EGG amplitude and gastric motility and that between EGG rhythmic variations and motility disorders. Specifically, we present studies on pre- and postprandial EGGs, observation of the propagation direction of the gastric slow wave and gastric electrical dysrhythmias and their correlation with gastric motility.

Subcutaneous metoclopramide in the treatment of symptomatic gastroparesis: clinical efficacy and pharmacokinetics

We investigated the safety and efficacy of short-term s.c. administration of metoclopramide in the treatment of symptomatic gastric stasis. Ten patients with gastroparesis, documented by abnormal solid phase radionuclide gastric emptying study, were treated with 10 mg (2 ml) of s.c. metoclopramide every 6 hr for 3 days. Patients gave themselves the injections as outpatients. Questionnaires were then completed concerning symptom relief, local side effects and adverse reactions. A repeat gastric emptying study was obtained immediately after the last dose of metoclopramide. Serum metoclopramide concentrations were obtained at trough, 1, 2, 3, 4 and 5 hr postadministration and serum prolactin levels at trough, 1 and 3 hr. Pharmacokinetic analysis showed mean peak metoclopramide concentration at 30 min of 99.7 +/- 47.1 ng/ml with measured levels of 93.9 +/- 106.83 ng/ml at 60 min and return to trough values by 4 hr; trough prolactins remained elevated above normal values. Gastric stasis improved from a base-line retention of 78.7% of radioisotope at 2 hr to 72.5% after 3 days of therapy (P = .65). Eight patients reported significant improvement in symptomology and two patients reported lessening of symptoms such as nausea, vomiting, bloating, abdominal pain, heartburn and vomiting. The side effects were minimal and did not interfere with completion of the protocol. We demonstrated that s.c. administration of metoclopramide was well accepted by patients and resulted in subjective and objective improvement of gastric stasis. In addition, serum metoclopramide concentrations were comparable with other parenteral routes of administration. Furthermore, serum prolactin levels may provide both a bioassay of efficacy and a marker for monitoring compliance.