Duodenal Pressure Research Articles

A continuous manometric study of the human pylorus

Previous manometric studies of the pylorus in humans have yielded conflicting data. These interstudy variations may be the result of differences in technique. It is also possible that pyloric pressure shows cyclic variations with the interdigestive motility complex. PyJoric pressure was monitored continuously for 300 min in 6 healthy men by means of a Dent sleeve. Gastroduodenal activity was measured simultaneously by using a perfused catheter system with two antral and two duodenal ports. With this method the pylorus was shown to have no elevation in basal pressure above baseline duodenal pressure during phase III. Basal pyloric pressure varied between subjects in phases I and II, being elevated in some but not in others. Subjects restudied on a separate day often showed a different pattern of activity. Pyloric pressure increased gradually in response to duodenal acidification. This response was blocked by pretreatment with naloxone. The pylorus also showed phasic activity, which was maximal in phase III. This phasic activity could not be distinguished from that of the adjacent antrum and duodenum. In conclusion, pyloric pressure patterns showed marked variation within and between subjects. These variations may explain some of the differences between previous studies.

Continuous recording of pyloric sphincter pressure in dogs. Relationship to migratory motor complex.

Antral, pyloric, and small bowel intraluminal pressures were continuously recorded in dogs with gastric and duodenal cannulae. A cyclic phasic activity related to fasting motility in the antrum and small bowel was observed at the level of the pylorus. During phase I of the interdigestive motility complex, manometry was characterized by pressure variations of 31 +/- 2 cm H2O. During phase II, two type of waves were observed: small waves similar to those seen during phase I, with superimposed waves of higher amplitude (89 +/- 1.9 cm H2O). Pyloric pressure during phase III, showed a predominance of waves of even greater amplitude: 103 +/- 3.9 cm H2O. A basal tone of 65.6 +/- 3.2 cm H2O above the duodenal pressure was recorded throughout the period of study; but during phase III, frequent decreases in basal pressure were also observed. This relaxation of the pylorus during phase III of the IDMC may be related to the mechanism for size discrimination of particles leaving the stomach at the gastroduodenal junction.

Effects of cimetidine and ranitidine on interdigestive and postprandial lower esophageal sphincter pressures and plasma gastrin levels in normal subjects

The purpose of this study was to investigate the effects of cimetidine and ranitidine on human lower esophageal sphincter pressure (LESP) and plasma levels of gastrin in all phases of the interdigestive motor complex and after a test meal. In a random, double-blind manner, placebo, cimetidine (1.0 mg/kg · h), and ranitidine (0.16 mg/kg · h) were administered by intravenous infusion to nine healthy volunteers. By using a sleeve catheter assembly, LESP was constantly monitored, as were esophageal, fundic, antral, and duodenal pressures. Considerable minute-to-minute and interdigestive motor phase-related LESP variations were observed. Cimetidine and ranitidine decreased the interdigestive LESP, but did not abolish the gradual increase in LESP from phase I to phase III. During the first 2 h after the meal, cimetidine and ranitidine had no significant effect on LESP. Plasma gastrin levels were increased by cimetidine and ranitidine, both in the interdigestive and in the postprandial state. The results indicate that the effect of H2-blockers on LESP is not gastrin-mediated. The results further indicate that, in studies on the effects of drugs on LESP, prolonged recording of LESP in all motor states is a prerequisite.

Bile flow through drainage catheters: an in vitro study.

An in vitro model was developed to measure bile flow at varied pressures through several commonly used transhepatic drainage catheters. As expected, larger catheters conduct more bile flow at a given pressure. All catheters studied conduct adequate amounts of bile at normal physiologic pressure gradients. The clinical observation that large catheters (10-12 French) are necessary for adequate antegrade drainage in some patients must be explained by an abnormal bile viscosity, increased duodenal pressures, or reduced biliary secretory pressure.

Bile duct dyskinesia: Clinical and manometric study

Unexplained right upper quadrant symptoms have often been attributed to bile duct dyskinesia. In this study we evaluated the pressure profile of the sphincter of Oddi in 10 patients with recurrent episodes of right upper quadrant pain, intermittent mild transaminasemia, and a normal pancreatobiliary tract. Nine healthy volunteers served as control. A triple-lumen catheter with an external diameter of 1.7 mm and recording sites at 2-mm intervals was introduced into the papilla through the endoscope. Ductal pressure, basal sphincter of Oddi pressure, and the amplitude and propagation direction of the phasic contractions of the sphincter were determined in patients and subjects. All measurements were performed relative to duodenal pressure, which was taken as zero. There was no significant difference between patients and subjects in the amplitude and frequency of phasic contractions of sphincter of Oddi. In contrast, the patients demonstrated a higher sphincter of Oddi pressure (p < 0.005) and increased proportion of retrograde propagation direction of phasic contractions (p < 0.01). It is concluded that a subpopulation of patients with unexplained abdominal pain demonstrated abnormal pressure profile of the sphincter of Oddi.

Endoscopic sphincterotomy: Follow-up evaluation of effects on the sphincter of Oddi

Endoscopic sphincterotomy (ES) alters the structure and motor function of the sphincter of Oddi (SO). The magnitude and duration of these changes, however, have not been critically examined. Before ES, 22 patients with common bile duct stones were evaluated by endoscopic retrograde cholangiography. The pressure gradient between the common bile duct and the duodenum, the SO basal pressure, and the SO peak phasic pressures were obtained. After ES, the electrosurgical incision length was determined using the extended papillotome and an inflated Fogarty balloon as reference. A high correlation existed between the endoscopist's estimate of ES incision size using this technique and the actual length of simulated incisions fashioned in cardboard mounts. These studies were repeated in all 22 patients at 1-yr follow-up and in 8 of these patients at 2-yr follow-up. At 12 mo and 24 mo after ES, the common bile duct (CBD) to duodenal pressure gradient and the sphincter of Oddi basal pressure were virtually eliminated. The amplitude of SO phasic contractions was significantly diminished 12 mo after ES (124 ± 16 mmHg to 37 ± 10 mmHg; p < 0.001), but 24 mo after ES, SO phasic contraction amplitude was not significantly different from the values before ES. Incision length at 1-yr follow-up was reduced in the group of 22 patients from 11.6 ± 0.8 mm to 8.3 ± 0.5 mm (p < 0.001), and in the group of 8 patients from 11.0 ± 1.5 mm to 7.5 ± 0.7 mm (p < 0.025). After an additional 12 mo, however, i.e., 24 mo after ES, the incision length was 6.5 ± 0.7 mm. There was no significant difference in incision length between the 12-mo and 24-mo examinations. We conclude that after ES, incision length decreases during the first year. There appears to be no further significant reduction in incision length at 2 yr. In addition, the reduction of the CBD to duodenal pressure gradient and the SO basal pressure remain unchanged for at least 2 yr. These manometric findings support the observation that after ES the enlarged opening of the CBD into the duodenum remains open for at least 2 yr.

Endoscopic Manometry of the Sphincter of Oddi in Patients with and without Juxtapapillary Duodenal Diverticula

The motor activity of the sphincter of Oddi (SO) has been evaluated, by endoscopic manometry, in 48 subjects, 8 with and 40 without duodenal juxtapapillary diverticula. All values were expressed in mm Hg, taking duodenal pressure as zero reference. In subjects with diverticula the SO basal pressure was 14.1 +/- 4.3 mm Hg, peak pressure was 52.3 +/- 17.2 mm Hg, and wave height was 39.75 +/- 14.19 mm Hg; in subjects without diverticula these values were 31.2 +/- 8.9 mm Hg, 93.2 +/- 21.3 mm Hg, and 68.17 +/- 25.86, respectively. The difference was statistically significant (P less than 0.001 for basal and peak pressure; P less than 0.002 for wave height). Wave frequency was not significantly different in controls (4.99 +/- 1.17/min) and in subjects with diverticula (4.98 +/- 1.13/min). These findings seem to indicate that in patients with diverticula the SO is insufficient or dysfunctioning . The insufficiency of the SO and a reflux of bacteria from the duodenum into the bile duct could play a major role in the formation of stones in patients with diverticula. The same mechanism could be responsible for duodenopancreatic reflux and possible pancreatic lesion.

Interdigestive phasic contractions of the human lower esophageal sphincter

The results of this study show that lower esophageal sphincter contractions occur during phases 2 and 3 of the gastric interdigestive migratory motor complex in humans. In one series of studies, esophageal, gastric, and duodenal pressures were monitored overnight for 12 h in 7 healthy, fasting subjects. A second group of 10 volunteers was studied for 12 h on two consecutive nights. Periods of gastric contraction that reached a maximum frequency of about 3/min were shown to be part of the migratory motor complex cycle because they occurred immediately before phase 3 migratory motor complex activity in the duodenum. In all subjects, gastric interdigestive contractions were accompanied by lower esophageal sphincter contractions that maintained a pressure barrier between the stomach and esophageal body. During Jate phase 2 and phase 3 gastric migratory motor complex activity, the lower esophageal sphincter contractions were especially vigorous. Mean basal lower esophageal sphincter pressure varied significantly during the interdigestive cycle. Lower esophageal sphincter pressure values were maximal during phase 3 of gastric migratory motor complex activity and minimal values occurred during phase 1. No episodes of gastroesphageal reflux occurred as a result of increase of intragastric pressure caused by interdigestive gastric contractions. The coupling of lower esophageal sphincter contractions to interdigestive gastric contractions appears to be an important physiological mechanism for preventing gastroesophageal reflux during forceful gastric contractions.

Duodenogastric reflux in humans: Its relationship to fasting antroduodenal motility and gastric, pancreatic, and biliary secretion

Duodenogastric reflux may have pathophysiologic importance, but its mechanism is poorly understood. We propose that duodenogastric reflux and periodic changes in motor and secretory activity of the upper gut during fasting may be related. Therefore we determined the relationships between duodenogastric reflux and interdigestive motor-secretory cycles in a group of 6 healthy individuals, on each of whom we performed three 7-h studies in random order on separate days. In all studies gastric intubation and antral pressure recordings were performed. However, in design 1 we used a slow duodenal perfusion rate of [14C]PEG in saline (0.25 ml/min) while in design 3 we used a fast perfusion rate (3.0 ml/min). Duodenal pressures were also recorded during these designs. In design 2 no transpyloric tubes were present. Our study shows that, in humans, fasting duodenogastric reflux of bile and pancreatic juice is cyclic and closely related to the interdigestive migrating motor complex. Reflux is highest during late phase II (when secretory activity is also on the rise) and lowest after phase III. One of the important functions of the migrating motor complex in humans may be to clear the stomach of refluxed duodenal secretions.

Interdigestive canine pancreatic juice composition and pancreatic reflux and pancreatic sphincter anatomy.

Canine and human exocrine pancreatic secretion into the duodenum during fasting is cyclical and related to intestinal motility. To characterize the composition of pure pancreatic juice during the cyclically recurring sequence of propagated motor events (interdigestive motor complex) and to establish whether pancreatic reflux occurs, dogs were prepared with three permanent indwelling duodenal catheters and a pancreatodochal cutaneous catheter. The duodenal catheters were used to record duodenal pressures and measure pancreatic secretion of trypsin, lipase, and bicarbonate, based on the recovery of a constantly perfused marker, [14C]PEG. Pancreatic duct pressures or pancreatic juice concentrations of [14C]PEG, trypsin, lipase, or bicarbonate (done separately in each of five dogs throughout one interdigestive cycle on 4 different days) were related to duodenal motor activity. Finally, the pancreatic duct orifice of freshly sacrificed dogs was examined by light and electron microscopy. During fasting, (1) pancreatic volume secretion increased 10-fold during phases II, III, and IV (P less than 0.001), and bicarbonate concentration increased during phases III and IV (P less than 0.05) compared with phase I, while trypsin and lipase concentrations did not change; (2) reflux of duodenally perfused [14C]PEG into the pancreatic duct occurred in two of five dogs and was minimal (less than 0.1%); and (3) a positive mean pressure gradient from duodenum to pancreatic duct occurred only during phase III (7.4 +/- 4.1 cm H2O). Anatomic studies of the pancreatic duct opening showed a specialized papillary mucosa and an independent crescentic sphincter muscle. We conclude that during fasting, pancreatic juice composition is intimately linked to the different phases of interdigestive intestinal motor activity and that an efficient antireflux mechanism exists.

Manometric characteristics of the extrahepatic biliary tract in dogs.

Pressure measurements of the whole extrahepatic biliary tract were performed in dogs using constant perfusion techniques. Studies were done during general anesthesia and in conscious trained dogs. Gallbladder intraluminal fasting pressure was significantly lower than common bile duct pressure. No motor activity was demonstrated in the common bile duct. At the cysticocholedochal junction a static high-pressure zone was observed, probably due to mechanical factors. At the level of the choledochoduodenal junction, a high-pressure zone with a sphincter behavior was demonstrated, with a resting pressure of 38 cm H2O above intraduodenal pressure and with rhythmic contractions with a mean amplitude of 88 cm H2O above duodenal pressure. Duodenal motility was completely different from sphincter dynamics. No differences in pressure values were seen during general anesthesia or in conscious state.

275 DEVELOPMENT OF SMALL BOWEL MOTILITY IN BEAGLE PUPPIES

To investigate the neonatal development of upper small bowel (SB) peristalsis and the effect of pentagastrin (PG) on motility, we monitored duodenal intraluminal pressure manometrically in 11 beagle puppies from birth until weaning at 5 wk. The response rate of the system employed was 150 mm Hg/sec. Electrodes were implanted on the SB serosal surface for subsequent monitoring of myoelectric activity during the first 2 mo. in 3 add'l puppies. During the first 3 wk there was an increase in duodenal contraction rate immediately after a liquid meal from 11±0.4/min to 16±1/min (p <0.001) followed by a slight decrease during weaning. Peak duodenal pressure increased from 17 to 38 mm Hg (p < 0.002), and subsequently decreased to 25 mm Hg with weaning. The duration of each contraction shortened during the first 3 wk from 3.4 to 2.4 sec (p <0.001). Myoelectric monitoring revealed a gradual increase in slow wave activity from 14 to 20 cycles/min in both fasting and fed states, corresponding with the increased contractions observed in the manometric studies. These developmental changes are similar to those which occur in the beagle lower esophageal sphincter (LES) and stomach during suckling and weaning. However, in contrast to the lack of sensitivity to PG by the beagle LES and stomach during the first week, SB contractions were inhibited on day 1 with 0.03-8 ug/kg PG s.c. We speculate that the differential PG sensitivity of LES, stomach, and SB during the first week of life in the beagle is due to differential gastrin receptor number and/or affinity.

On the question of choosing a method of surgery for chronic calculous cholecystitis

In patients who have undergone surgery for chronic calculous cholecystitis and its complications, an increase in duodenal pressure and tone occurs secondarily, in response to biliary and pancreatic hypertension caused by choledocholithiasis, papillary stenosis, and other complications of the disease. Operations that remove mechanical obstacles to the outflow of bile and pancreatic juice help to reduce duodenal hypertension or normalize pressure in the duodenum. In functional duodenal hypertension, papillosphincterotomy and choledochoduodenostomy are not contraindicated.

Effect of secretin on pancreatic duct pressure, resistance to pancreatic flow, and duodenal motor activity in the dog.

To determine the effect of graded doses of intravenously administered secretin on the relationships among pancreatic duct and duodenal pressures and duodenal motor activity, three dogs were surgically provided with three indwelling duodenal catheters and a permanent pancreaticodochocutaneous catheter. The proximal duodenal catheter was located within the first portion of the duodenum and was used to infuse a nonabsorbable marker. The middle catheter was positioned 5 cm distally so that its open tip was at the level of the pancreatic duct orifice, was water filled and utilized to measure duodenal pressures. Samples of duodenal contents were recovered from the third catheter which was 10 cm distal to the pancreatic ductal orifice. Dogs were studied for 8 hr. Saline was given intravenously for 1 hr at the beginning and end of the study and for 2 hr between two 2-hr periods of secretin administration. Secretin was administered at doses of 0.75, 1.5, 3.0 units/kg/hr. Only two doses of secretin, given in random order, were tested each day. Secretin significantly (P<0.05) reduced pancreatic duct pressure, duodenal pressure, and frequency of duodenal phase-III motor activity and increased duodenal volume flow. All of the responses were dose-related. The highest amounts of constantly infused secretin decreased pressures and increased duodenal volume flow compared with the lowest amount (P<0.05),. Moreover, calculations of resistance to pancreatic flow, the diameter of the pancreatic ductal opening, and the area of the opening indicated that secretin dilated the opening of the pancreatic duct and decreased the resistance of the flow of pancreatic juice into the duodenum as the dose of secretin was increased. Thus, it appears that a pancreatic ductal sphincter mechanism responsive to secretin is present in the dog.

Endoscopic manometry of pancreatic and biliary sphincter zones in man. Basal results in healthy volunteers.

An endoscopic manometric technique was applied to the study of intraductal biliary and pancreatic pressures and sphincter activity in normal subjects. A perfused system using a modified endoscopic retrograde cholangiopancreatography catheter was tested and found to provide reliable ductal and phasic recordings. Twenty-five healthy volunteers, aged 19-37, underwent endoscopic manometry under diazepam sedation. Distinct zones of high-pressure phasic activity were identified on pull-through from the pancreatic duct and common bile duct at mean distances of 4.5 and 5.0 mm, respectively, from the papillary orifice with frequencies of 7.0 +/- 1.8 (mean +/- SD) and 5.6 +/- 2.4 waves/min, respectively. These were considered to represent separate pancreatic duct and bile duct sphincters. Peak pancreatic duct sphincter pressure (47.6 +/- 8.2 mm Hg) and bile duct sphincter pressure (57.2 +/- 10.7 mm Hg) were similar. Pancreatic duct pressure was 11.4 +/- 3.0 mm Hg and common bile duct pressure was 3.0 +/- 2.5 mm Hg. Values were adjusted to duodenal pressure as zero reference. The ductal and sphincteric pressures reported in this study provide a basis for the assessment of physiological, pharmacological, pathophysiological, and surgical effects on this area.

Relationships among canine interdigestive exocrine pancreatic and biliary flow, duodenal motor activity, plasma pancreatic polypeptide, and motilin

To evaluate the cyclic patterns of interdigestive pancreatic and biliary flows into the duodenum and to correlate these and the plasma levels of pancreatic polypeptide and motilin with duodenal interdigestive motor activity, five dogs were surgically prepared with three indwelling duodenal catheters. Through the first catheter, located just distal to the pylorus, a nonabsorbable marker was perfused at 3 ml/min. The second catheter, opposite the main pancreatic duct orifice, was water-filled and was used to continuously record duodenal pressures and also to deliver pulses of a second nonabsorbable marker in order to measure transit time through the duodenum and sampling catheter. From the third catheter, 10 cm distal to the second, duodenal samples were continuously collected by siphonage. Twominute aliquots were analyzed for trypsin, bile acids, bicarbonate, and markers. At the beginning and end of each phase of motor activity, blood samples were analyzed for pancreatic polypeptide and motilin. Four phases of duodenal interdigestive motor activity were defined. During phase I, outputs of trypsin, bile acids, and bicarbonate were absent or minimal. During phase II, maximal outputs of trypsin and bile acids occurred. During phase III, there was a trend toward maximal bicarbonate output, but this was not significantly greater than the output during phase II. Low plasma levels of pancreatic polypeptide and motilin were present during phase I. Peak levels of pancreatic polypeptide occurred during phases II and III, and peak levels of motilin occurred during phases III and IV. In summary, pancreatic and biliary flows into the duodenum are cyclic and associated with interdigestive motor activity. Cyclic changes of plasma motilin and pancreatic polypeptide also were associated with changes in pancreatic and biliary flows into the duodenum and intestinal motor activity, but whether these events are modulated by motilin or pancreatic polypeptide is uncertain.

Pressure measurements in the biliary and pancreatic duct systems in controls and in patients with gallstones, previous cholecystectomy, or common bile duct stones

Resting common bile duct, main pancreatic duct, and resting Oddi sphincter pressures were measured in controls and in patients with gallstones, previous cholecystectomy, common bile duct stones, hepatic duct cancer, and chronic pancreatitis. No significant differences in resting common bile duct pressures were observed in controls compared with the other groups. No significant differences in resting intrapancreatic duct pressure were observed in controls compared with patients with various biliary diseases. Resting intrapancreatic duct pressure was two to three times greater than the common bile duct pressure in all patients. No motor activity was found in either of the ducts. Only passive transmission of changes in intraabdominal pressures was demonstrated. No correlation between diameter of the ducts and intraluminal pressure was observed. The injection of a known volume of normal saline or contrast medium was associated with abrupt increase in intraluminal pressure, and in some patients typically biliary cholics were produced. Oddi sphincter pressure caused a phasic activity composed of contractions and relaxations in all patients. Peak Oddi sphincter pressure was approximately 100 mm Hg above the duodenal pressure, and no significant differences were seen in controls compared with any other group (P > 0.4). The results of this study show that a unique high pressure zone with sphincter characteristics exists at the level of the choledochoduodenal and pancreaticoduodenal junction, and that it is independent of duodenal dynamics. This sphincter creates a gradient between the bile or pancreatic ducts and the duodenum, and probably prevents reflux of duodenal content into these ducts.

Relationships among canine fasting pancreatic and biliary secretions, pancreatic duct pressure, and duodenal phase III motor activity--Boldyreff revisited.

Despite the old observations of Boldyreff that pancreatic and biliary secretions occur during periods of intestinal contraction, quantification of these secretions and their relationships to duodenal motor activity and pancreatic ductal pressures have not been reported. By utilizing a recently developed canine model, we simultaneously measured these events. Each of nine dogs was provided with a permanent indwelling pancreatodochal cutaneous catheter (to monitor pancreatic pressure) and three duodenal cutaneous catheters. [14C]PEG was infused through the proximal catheter located in the first part of the duodenum and intraluminal duodenal pressures were monitored through the middle catheter, located at the level of the pancreatic duct orifice. From a third catheter located 15 cm distal to the middle catheter duodenal samples were siphoned, pooled over ice every 15 min, and analyzed for concentration of marker, lipase, and bilirubin. Duodenal volume flows and outputs of lipase and bilirubin were calculated relative to the recovery of the marker. All studies were done in fasting, conscious, upright dogs. Lipase and bilirubin outputs, duodenal volume flow, and mean pancreatic duct pressures increased (P<0.05) during phase III duodenal motor activity, compared with values 15 and 30 min before the onset and after the cessation of phase III motor activity. It is concluded that the inter-digestive housekeeper (phase III motor activity) is comprised of electric, motor, and digestive components. The amount of pancreatic enzymes secreted during phase III activity is 50% of that secreted during a similar time postprandially and is theoretically in sufficient quantity to hydrolyze food remnants and cellular debris. Thus it is likely that the association of increased pancreatic and biliary secretion with intense motor activity of the duodenum render the housekeeping action of the complex more effective.

The effects of sphincteroplasty on manometric profile of common bile duct and the duodenum (author's transl)

A simultaneous manometric monitoring of the common bile duct (CBD) and the duodenum were performed 2 weeks after choledocholithotomy on 15 patients whose common bile ducts were explored without sphincteroplasty and 30 patients with sphincteroplasty. These manometric studies were carried out by open-tip catheters intubated into the CBD and duodenum through the T-tube at the operation. In patients without sphincteroplasty, no effects of the duodenal pressure on a CBD pressure profile were recognized, while a synchronized pressure profile of the CBD and the duodenum was obtained in patients with sphincteroplasty. By stimulation with morphine (Morphine sulfate; 0.17 mg/Kg iv bolus), waxing and waning of the pressured in the CBD without sphincteroplasty were observed with 20 cmH2O in maximum at about 13 minutes after injection. However, in the CBD with sphincteroplasty, scale-over increase of the pressure curve was seen immediately after duodenal contraction caused by morphine stimulation. A direct infusion of 5 ml of 0.1 N hydrochloride to the duodenum causes hyperperistalsis of the duodenum, which made a synchronized pressure profile in the CBD with sphincteroplasty but made no remarkable change in a pressure profile of the CBD without sphincteroplasty. These findings conclude that the sphincter of Oddi plays an important role as a "pressure barrier" between the CBD and the duodenum, and that with the destruction of this sphincter by sphincteroplasty, a pressure profile of the CBD becomes close to that of the duodenum. This simultaneous manometric study of the CBD and the duodenum might be one of most valuable methods for evaluation of completeness of the sphincteroplasty.

Relationships Between Fasting and Postprandial Pancreaticoduodenal Pressures, Pancreatic Secretion, and Duodenal Volume flow in the Dog

We have developed a canine model which allows simultaneous quantification of pancreatic enzyme outputs, duodenal volume flow, and pancreatic and duodenal pressures under physiological circumstances. Twelve studies on 4 conscious healthy dogs demonstrated that mean fasting pancreatic pressure was 5 to 10 cm H2O higher than mean fasting duodenal pressure. Furthermore, 8 min after ingestion of a meal, both the pancreatic and the duodenal pressure increased. Surprisingly, the mean duodenal pressure was higher than the mean pancreatic pressure 20 min after feeding. This relationship lasted for 30 min. Lastly, elevation of postprandial pancreatic pressure occurred concomitantly with increased pancreatic enzyme output, and duodenal pressure increased with increased duodenal volume flow. The observed large postprandial duodenal volume flows associated with duodenal pressures greater than pancreatic duct pressures may favor reflux of duodenal contents into the pancreatic duct. These relationships may be important in the pathogenesis of postprandial pancreatitis and in the induction of pancreatic cancer.