Cystic adventitial degeneration of the femoral artery: is evacuation and cyst excision worthwhile as a definitive therapy?

A case of cystic adventitial degeneration of the left common femoral artery in a patient with localized left groin pain, normal distal pulses, and normal arteriographic findings is reported. This patient was first treated with evacuation and cyst excision. Recurrence was noted after 20 months, and an excision of the cyst and a segment of the common femoral artery with graft interposition was required. At gross examination, the cyst was unilocular and contained gelatinous material. The cyst appeared to be situated in the tunica adventitia and did not communicate with the vascular lumen. No synovial lining was present. Histologically, it was similar to a ganglion cyst with contents rich in hyaluronic acid. A review of the literature was undertaken to determine the results of treating this lesion. The disease is rare. All senior authors of case reports were contacted to construct follow-up information. A high incidence of recurrence was noted in patients treated by evacuation and cyst excision. We believe that total cyst excision with the involved artery and graft interposition at the femoral site can be done easily, safely, and with virtually no chance for recurrence.

Direct proabsorptive effect of octreotide on ionic transport in the small intestine.

Somatostatin is widely distributed within the nervous system and the gastrointestinal tract. Gastrointestinal actions of somatostatin include inhibition of hormone release, reduction of pancreatic secretion, inhibition of motility, and reduction of blood flow. The purpose of this study was to investigate the role of somatostatin and its analogue octreotide on water and electrolyte transport in the small intestine. Rabbit ileal segments (n = 17) were harvested and arterially perfused ex vivo with a nonrecirculating oxygenated sanguineous solution. The lumen was perfused with an isotonic solution containing carbon 14-labeled polyethylene glycol. Net fluxes of water, Na+, and Cl- were calculated for three 20-minute periods designated basal, drug infusion, and recovery. Three groups were studied: somatostatin at 10(-6) mol/L (n = 5), somatostatin at 10(-5) mol/L (n = 5), and octreotide at 10(-5) mol/L (n = 7). Somatostatin at 10(-5) mol/L yielded a proabsorptive effect on the flux of water and electrolytes. Octreotide at 10(-5) mol/L caused a significant (p less than 0.05) proabsorptive response in the fluxes of water, sodium, and chloride during the period of drug infusion, which returned to basal secretory levels during the recovery period. This proabsorptive effect occurred without alterations in vascular resistance and necessarily was independent of systemic hormone interaction, supporting a direct effect of octreotide on intestinal ionic transport.

Neuropeptide Y-induced intestinal absorption: mediation by alpha 2-adrenergic receptors.

In the intestine neuropeptide Y (NPY) is contained in sympathetic nerves, in neuroendocrine cells of the mucosa, and in neurons of the enteric plexuses. After a meal is ingested the concentration of NPY in the blood rises, and intestinal absorption of water and ions increases. We have recently demonstrated a proabsorptive effect of NPY on water and ion transport in the small intestine. The current experiments tested the hypothesis that the alpha 2-adrenergic receptor mediates NPY-induced intestinal absorption. Rabbit ileal segments (n = 35) were harvested and arterially perfused ex vivo. The intestinal lumen was perfused with an isotonic solution containing carbon 14-labeled polyethylene glycol. Net fluxes of H2O, Na+, and Cl- were calculated for three 20-minute periods: basal, drug infusion, and recovery. Five groups were randomly studied: (1) NPY (500 pmol/min); (2) terazosin (1 microgram/min, alpha 1-adrenergic receptor antagonist); (3) NPY + terazosin; (4) yohimbine (1 microgram/min, alpha 2-adrenergic receptor antagonist); and (5) NPY + yohimbine. The infusion of NPY alone caused a significant (p less than 0.05) proabsorptive response for H2O, Na+, and Cl-. Neither terazosin nor yohimbine alone had a significant effect on the transport state of the intestine. Yohimbine, but not terazosin, completely prevented the NPY-induced proabsorptive response. These data support the hypothesis that the proabsorptive effect of NPY is mediated by the alpha 2-adrenergic receptor system.

Surgical experience with pancreatic islet-cell tumors.

OBJECTIVE: To review the surgical management of pancreatic islet-cell tumors, with attention to preoperative localization, surgical therapy, and postoperative survival. DESIGN: Consecutive case series of patients treated surgically for pancreatic islet-cell tumor. SETTING: The Johns Hopkins Hospital, a large teaching hospital in Baltimore, Md, serving both as a primary and tertiary care center. PATIENTS: Thirty-seven patients with pancreatic islet-cell tumors treated surgically between 1979 and 1990. MAIN OUTCOME MEASURES: Success of preoperative localization studies, types of operations performed, and postoperative survival. RESULTS: Preoperative computed tomography correctly localized the tumor in 20 of 34 patients (59%); angiography in 21 of 28 patients (75%), and the combination of computed tomography and angiography in 23 of 28 patients (82%). Benign islet-cell tumors were found in 19 patients, and malignant tumors in 18 patients. Twenty-four patients (65%) had functional tumors. The proportion of patients with nonfunctioning tumors increased from 0% before 1984, to 43% from 1985 to 1990. Surgical therapy was curative in 27 patients and palliative in 10. The most commonly performed operative procedures were tumor enucleation (11 patients [30%]), distal pancreatectomy (10 patients [27%]). There was no operative mortality. The actuarial survival at 40 months was 100% in patients with benign tumors and significantly lower (66%) in patients with malignant tumors. CONCLUSIONS: This experience from a single institution underscores the role of preoperative localization studies and appropriate surgical management of these rare tumors.

Laparoscopy and colon cancer. Is the port site at risk? A preliminary report.

PURPOSE: To quantify the magnitude of the risk for port/extraction site recurrence of laparoscopically resected colon cancer in a defined study population. METHODS: The data from a prospective laparoscopic bowel surgery registry was used to identify cases of colon cancer that were resected laparoscopically, with a minimum follow-up of 1 year. A questionnaire was sent to the surgeons who performed the procedures. RESULTS: A total of 252 cases were identified from the registry. Questionnaires were returned in 208 of those cases, a response rate of 82.5%. Three cases of port or extraction site recurrence were noted, two of them associated with diffuse peritoneal carcinomatosis. All the patients had a Dukes' stage C tumor at the time of initial surgery. CONCLUSIONS: The incidence of port/extraction site recurrence following laparoscopic colon cancer surgery is low. All the recurrences were in patients with Dukes' stage C tumors, and there was diffuse peritoneal carcinomatosis in two of the three cases, suggesting that port/extraction site recurrence may be attributable to the advanced nature of the disease rather than the laparoscopic technique. Longer follow-up and more cases are required to confirm these findings.

Intra-abdominal abscesses following laparoscopic and open appendectomies.

Recent findings in a small number of studies have suggested a trend toward increased infectious complications following laparoscopic appendectomy. The purpose of the present review was to evaluate the incidence of postappendectomy intra-abdominal abscess formation following laparoscopic and open appendectomies. Using the surgical database of the Los Angeles County-University of Southern California Medical Center, we reviewed the records of all appendectomies performed at the center between March 1993 and September 1995. Incidental appendectomies as well as appendectomies in pediatric patients under the age of 18 years were excluded. A total of 2497 appendectomies were identified; indications for these procedures included acute appendicitis in 1422 cases (57%), gangrenous appendicitis in 289 (12%), and perforated appendicitis in 786 (31%). The intraoperative diagnosis made by the surgeon was used for classification. A two-tailed P value of <0.05 was considered significant. There was no significant difference in the rate of abscess formation between the groups undergoing open and laparoscopic appendectomies for acute and gangrenous appendicitis. In patients with perforated appendicitis, a total of 26 postappendectomy intra-abdominal abscesses occurred following 786 appendectomies for an overall abscess formation rate of 3.3%. Eighteen abscesses occurred following 683 open appendectomies (2.6%), six abscesses occurred following 67 laparoscopic appendectomies (9.0%), and the remaining two abscesses occurred following 36 converted cases (5.6%). For perforated appendicitis, however, there was a statistically significant increase in the rate of abscess formation following laparoscopic appendectomy compared to conventional open appendectomy (9.0% vs. 2.6%, P = 0.015). There was no significant difference in the rate of abscess formation between open vs. converted cases or between laparoscopic vs. converted cases. A comparison of the length of the postoperative hospital stay showed no significant difference between open and laparoscopic appendectomy for perforated appendicitis (6.1 days vs. 5.9 days). Laparoscopic appendectomy for perforated appendicitis is associated with a higher rate of postoperative intra-abdominal abscess formation without the benefit of a shortened hospital stay. Given these findings, laparoscopic appendectomy is not recommended in patients with perforated appendicitis.

Site specificity and meal stimulation of the intestinal absorption of water, electrolytes, and bile acids.

Ileal water and electrolyte absorption exceed jejunal absorption in both the basal and meal-stimulated states. The purposes of these experiments were to determine: (1) if luminal bile acids alter basal or meal-stimulated intestinal absorption, and (2) if there is site specificity or meal stimulation of intestinal bile acid absorption. Twenty-five centimeters of canine proximal jejunal and distal ileal Thiry-Vella fistulas were constructed. Simultaneous jejunal and ileal absorption studies (n = 88) were performed with a luminal perfusate containing polyethylene glycol labeled with radioactive carbon-14 to calculate the absorption of water, electrolytes, and the bile acid taurocholate (TC). In group 1, there was no TC in the luminal perfusate, whereas in group 2, 10 mM of TC was present in the luminal perfusate. Half of the observations were performed after a meal stimulus, which consisted of an orally ingested, 480-kcal mixed nutrient meal. Intraluminal TC did not affect basal or meal-stimulated water or electrolyte absorption. In both the basal and meal-stimulated states, ileal absorption of water, electrolytes, and TC significantly exceeded jejunal absorption (p < 0.05). A meal significantly stimulated water and electrolyte absorption in both the jejunum and ileum, but it stimulated absorption of TC in the ileum only (p < 0.05). Intraluminal TC does not alter basal or meal-stimulated intestinal water and electrolyte absorption. A meal stimulates increased water and electrolyte absorption in both the jejunum and the ileum, but it stimulates bile acid absorption in the ileum only. Bile acid absorption is site specific and responsive to a meal stimulus.

Meal-induced jejunal absorption requires intact neural pathways.

A signal for meal-induced absorption originates from the small intestine and is transmitted to a luminally excluded segment of the proximal jejunum (Thiry-Vella [TV] fistula). Using intraluminal topical anesthesia with oxethazaine, this study assessed the role of intestinal neural pathways in basal and postprandial jejunal water and electrolyte absorption. Studies (n = 45) were performed on dogs with 25-cm proximal jejunal TV fistulae and feeding jejunostomies, using luminal perfusion with 14C-polyethylene glycol. The animals were randomized into five study groups: (1) jejunostomy oxethazaine alone, (2) jejunostomy water and jejunal meal, (3) jejunostomy oxethazaine and jejunal meal, (4) TV fistula water and jejunal meal, and (5) TV fistula oxethazaine and jejunal meal. The jejunal meal significantly increased TV fistula absorption, whereas oxethazaine significantly reduced basal absorption when administered via the TV fistula and postprandial absorption when administered via the jejunostomy (p less than 0.05). TV fistula oxethazaine did not diminish the magnitude of postprandial absorption. We conclude that intact intestinal neurotransmission is necessary for maintenance of the normal basal absorptive state of the proximal jejunum and for the generation of a normal meal-stimulated proabsorptive signal from the small intestine. A nonneural mechanism appears to be of predominant importance in transmitting the proabsorptive signal from the intact gastrointestinal tract to the TV fistula.

Reasons for conversion from laparoscopic to open cholecystectomy in an urban teaching hospital.

BACKGROUND: Although laparoscopic cholecystectomy has replaced open cholecystectomy for the majority of patients, it is clear that a substantial minority will require laparotomy for safe and successful removal of the gallbladder. PATIENTS AND METHODS: Seven hundred forty-six laparoscopic cholecystectomies performed at LAC+USC Medical Center for January 1991 to May 1993 were retrospectively reviewed. Hospital stay, laboratory values, and complications, as well as the need for and reason for conversion to open cholecystectomy were recorded. There were 661 females and 85 males, with a mean age of 38 years (range 15 to 92). RESULTS: One hundred one (14%) of the 746 patients were converted to open cholecystectomy. Difficult dissection secondary to inflammation or adhesions and the need to treat common-bile-duct stones were the most common reasons for conversion. Patients requiring conversion to open cholecystectomy were more likely to have been admitted through the emergency department (72% versus 46%, P < 0.0001), have had prolonged hospital stays prior to surgery (mean time from admission to surgery 4.4 days versus 2.8 days, P < 0.0001), and to have had a thickened gallbladder wall on preoperative ultrasound (54% versus 20%, P < 0.001). CONCLUSIONS: The most common reasons for conversion to open cholecystectomy are inflammation and adhesions secondary to severe acute and chronic disease and/or the need for clearance of the common bile duct. Patients who were admitted to the emergency department, particularly if they were managed nonoperatively for a period of time and had a preoperative diagnosis of acute cholecystitis, were more likely to require conversion to open cholecystectomy.

IV chenodeoxycholate prevents calcium bilirubinate gallstones during total parenteral nutrition in the prairie dog.

BACKGROUND: The purpose of this study was to determine whether IV chenodeoxycholate (CDC) could prevent total parenteral nutrition (TPN)-associated pigmented gallstones in the prairie dog. METHODS: Twelve prairie dogs were divided into two equal groups, each receiving an identical TPN regimen. Each animal received 92 kcal/d with 61% of the calories from carbohydrate. The total volume of infusate delivered to each animal was 59 mL/d. Animals in one group, termed the TPN + CDC group, received a daily bolus injection of CDC at a dose of 15 mg/kg. Prairie dogs in the second group, termed the TPN group, received water (vehicle carrier) 1 mL/kg/d. The TPN and TPN + CDC groups received TPN for 40.3 +/- 1.3 and 42.5 +/- 0.6 days, respectively. RESULTS: There was no statistical difference in the initial and final weights between the two groups. None of the TPN + CDC-treated animals had gallstones or calcium bilirubinate crystals. In contrast, all of the TPN-treated animals had calcium bilirubinate crystals (p = .002), and five of six had macroscopic black pigmented gallstones (p = .015). Cholesterol crystals were not observed in either group of animals. The amount of biliary bilirubin and ionized calcium was significantly greater in the TPN group (both p < .001); however, both groups had a similar total biliary calcium concentration. CONCLUSION: IV CDC is effective in preventing TPN-associated gallstones in the prairie dog.

Small bowel origin and calorie dependence of a signal for meal-induced jejunal absorption.

The ingestion of a meal stimulates the absorption of water and electrolytes from the small intestine independent of the cephalic or gastric phases of digestion. This study tested two hypotheses: (1) the jejunum is the origin of a postmeal proabsorptive signal and (2) the magnitude of the proabsorptive response is dependent on the caloric content of the meal stimulus. Twenty-five-centimeter proximal canine jejunal Thiry-Vella fistulas and feeding jejunostomies were constructed under general anesthesia. Jejunal absorption studies (n = 50) were performed by luminal perfusion of the Thiry-Vella fistula with 14C-polyethylene glycol (PEG) to calculate fluxes of water and electrolytes. Five groups were studied: (1) CONTROL: no meal, (2) 240 kcal oral meal, (3) 480 kcal oral meal, (4) 240 kcal jejunal meal, and (5) 480 kcal jejunal meal. Independent of the route of delivery (i.e., oral vs. jejunal), each meal stimulus significantly increased jejunal water and electrolyte absorption (p < 0.05). The magnitude of the proabsorptive response increased significantly as the calories delivered increased (p < 0.05). These data support the hypothesis that a proabsorptive signal responsible for meal-induced jejunal absorption originates from, or distal to the jejunum and suggest that intestinal chemoreceptors or osmoreceptors participate in the generation of the proabsorptive signal.

Site-specific variations in basal and meal-stimulated intestinal absorption.

The ingestion of a meal increases water and electrolyte absorption in the proximal jejunum. The purpose of these experiments was to elucidate any site-specific variations in intestinal absorption, comparing jejunum to ileum, in both the basal and the meal-stimulated states. Twenty-five-centimeter proximal jejunal and distal ileal Thirty-Vella fistulae were constructed in four dogs. Simultaneous jejunal and ileal absorption studies were performed using [14C]PEG to calculate net absorption of water and electrolytes. Two groups were studied: in Group 1 no meal was ingested, while in Group 2, the animals ingested a mixed meal. Each study consisted of a 1-hr basal period and a 3-hr experimental period. In the basal state ileal absorption significantly exceeded jejunal absorption (P less than 0.0001). The ingestion of mixed meal significantly increased water and electrolyte absorption in both the jejunum and the ileum, (P less than 0.001), with the magnitude of meal-stimulated ileal absorption significantly exceeding the magnitude of meal-stimulated jejunal absorption (P less than 0.001). These studies demonstrate distinct site specific variations in intestinal water and electrolyte absorption in both the basal and the meal-stimulated states.

Water transport in native and transplanted porcine jejunum.

Adequate absorptive function of transplanted small intestine is essential for success of this procedure. This study compared water transport under basal and meal stimulated conditions in the transplanted swine jejunum to native jejunum. Six female adolescent Yorkshire swine were randomized to undergo construction of either a 25-cm native proximal jejunal Thiry-Vella Fistula (TVF), n=3, or a 25-cm proximal jejunal allograft TVF, n=3. Immunosuppression in the transplanted animals was accomplished with intravenous methylprednisolone, azathioprine, and cyclosporin. Jejunal absorption studies, each 4 hr long, were performed utilizing 14C-polyethylene glycol to calculate net water flux. Each animal underwent at least three fasting and three postprandial studies. New water flux was negative, i.e., secretory, in both the native and transplanted proximal swine jejunum. In the basal state, integrated hourly water transport was more secretory in the native bowel vs the transplanted bowel during the 2nd, 3rd, and 4th experimental hr (-4.6 +/- .8 vs -2.1 +/- .7 cc, P = 0.034; -4.4 +/- .7 vs -1.8 +/- .6 cc, P = 0.012; and -4.7 vs 1.3 +/- .5 cc, P < 0.005), respectively. In native jejunum, integrated hourly water transport was less secretory 2 and 3 hr postprandially compared to basal (-1.9 +/- .5 vs -4.4 +/- .7 cc, P = 0.016; and -2.0 +/- .5 vs -4.7 +/- .7 cc, P = 0.021), respectively. This postprandial proabsorptive response did not occur in the transplanted jejunum. Native and transplanted jejunal water flux in the postprandial state did not differ significantly. We conclude that there is higher secretion in native vs transplanted jejunum during fasting. The postprandial proabsorptive response of the proximal porcine jejunum is abolished by transplantation.

Follow-up of colorectal cancer: a meta-analysis.

PURPOSE: The value of intensive follow-up for patients after resection of colorectal cancer remains controversial. This study reviews all randomized and prospective cohort studies to assess the value of aggressive follow-up. METHODS: The literature was searched from the years 1972 to 1996 for studies reporting on the follow-up of patients with colorectal cancer. Randomized and comparative-cohort studies that included history, physical examination, and carcinoembrionic antigen values at least three times a year for at least two years were included in a meta-analysis. Single-cohort studies with intensive follow-up and traditional follow-up were also included in a two-group comparative analysis for each outcome indicator. Outcome indicators were 1) curative resection rates after recurrent cancer, 2) survival rates of curative re-resections, 3) length of survival after recurrence, and 4) cumulative five-year survival. RESULTS: Two randomized and three comparative-cohort studies met these criteria and included 2,005 patients, which were evaluated in the meta-analysis. The cumulative five-year survival was 1.16 times higher in the intensively followed group (P = 0.003). Two and one-half times more curative re-resections were performed for recurrent cancer in those patients undergoing intensive follow-up (P = 0.0001). Those patients in the intensive follow-up group with a recurrence had a 3.62-times higher survival rate than the control (P = 0.0004). Fourteen single-cohort studies were also included in the comparative analysis of 6,641 patients. The findings from these aggregated studies support the results of the meta-analysis. CONCLUSION: Our study concludes that intensive follow-up detects more recurrent cancers at a stage amenable to curative resection, resulting in an improvement in survival of recurrences and an increased overall five-year cumulative rate of survival.

New technique for mesh repair of paracolostomy hernias.

Paracolostomy hernias are common and require treatment when symptomatic. Traditional methods of repair have high recurrence rates. We describe a new technique using polytetrafluoroethylene mesh, which offers preservation of stoma site, lack of recurrences, ease, and safety.

Intraabdominal abscesses following laparoscopic and open appendectomies.

BACKGROUND: The purpose of this review was to evaluate the incidence of postoperative intraabdominal abscess formation following laparoscopic and open appendectomies. METHODS: The current study retrospectively examines appendectomies performed during the period from January 1993 to July 1994. Excluded were cases which were started laparoscopically but converted to open procedures. There were 1,287 cases identified; 597 were perforated (46%), 114 were gangrenous (9%), and 576 were acute (45%). These diagnoses represent intraoperative diagnoses. RESULTS: Of the 576 appendectomies for acute appendicitis, 64 (11%) were performed laparoscopically. There were four intraabdominal abscesses (0.7%), all occurring after open procedures. Of the 114 appendectomies for gangrenous appendicitis, 16 (14%) were done laparoscopically. There were two postoperative abscesses (1.8%), one following an open and one following a laparoscopic procedure. There was no significant difference in abscess rate between laparoscopic and open appendectomies for either acute or gangrenous appendicitis. Of the 597 appendectomies for perforated appendicitis, 28 (5%) were done laparoscopically. There were 19 postoperative abscesses in the whole group, accounting for a 3.2% abscess rate. Sixteen abscesses occurred after open appendectomies and three occurred after laparoscopic appendectomies (2.9% vs 11%, P = 0.054). The preoperative diagnosis was incorrectly identified as acute appendicitis in 95 cases subsequently found to have perforated appendicitis; there was only 1 postoperative abscess in this group. There was no difference in postoperative stay in the open vs laparoscopic group (6.3 days vs 6.1 days). CONCLUSIONS: We found no significant difference in the rate of postoperative intraabdominal abscess formation between laparoscopic and open appendectomies in cases of acute or gangrenous appendicitis. However, laparoscopic appendectomy for perforated appendicitis was associated with an important trend toward a higher rate of postoperative intraabdominal abscess formation than open appendectomy. This observation calls for closer prospective scrutiny of laparoscopic appendectomy in the setting of perforated appendicitis.

Does peritoneal mobilization increase laparoscopic acidosis?

PURPOSE: It was hypothesized that laparoscopic colon surgery may be associated with increased absorption of CO2 resulting from mobilization of lateral peritoneal reflections. METHODS: Six pigs underwent laparotomy with removal of a measured quadrant of peritoneum before insufflation to 15 mmHg with CO2. Six paired control animals also underwent insufflation with CO2 to 15 mmHg. Measurements of the end-tidal CO2 (PetCO2), arterial blood gas analysis for CO2 (PaCO2), and pH were performed before insufflation, at 5 and 10 minutes following insufflation, then at successive 15-minute intervals for a total of two hours, and 15 minutes following desufflation. No attempt was made to correct the hypercarbia by increasing minute ventilation. RESULTS: PaCO2 reached its maximum level at two hours with values of 70.77 +/- 5.54 mmHg and 64.62 +/- 5.18 mmHg in the peritonectomized and control groups, respectively. PetCO2 also peaked at two hours to 60 +/- 13 mmHg for the study group and 54 +/- 11 mmHg for controls. pH reached its nadir at two hours, falling from a baseline of 7.45 +/- 0.08 to 7.23 +/- 0.09 in the study group, and from 7.42 +/- 0.04 to 7.24 +/- 0.04 in the control group. There were no statistically significant differences between the two groups for any of the parameters measured at each time interval. CONCLUSIONS: The hypothesis that peritonectomy produces greater CO2 absorption during CO2 pneumoperitoneum was disproved under these experimental conditions.

Meal-stimulated canine jejunal ionic absorption. Effect of direct jejunal meal delivery and premeal intravenous hydration.

The ingestion of a meal stimulates water and ion absorption from the small intestine. The administration of nutrient substances directly to the small bowel can cause dumping symptoms, with intraluminal fluid accumulation and relative systemic hypovolemia. This study compared the effect of oral versus direct jejunal meal delivery on jejunal water and ion absorption, with and without premeal intravenous saline infusion. Jejunal absorption studies (N = 40) were performed on dogs with 25 cm proximal jejunal Thiry-Vella fistulas and feeding jejunostomies. Luminal perfusion with [14C]PEG was used to calculate fluxes of water and electrolytes. Five groups were randomly studied: (1) intravenous 0.9% saline alone, (2) oral meal alone, (3) intravenous 0.9% saline plus oral meal, (4) jejunal meal alone, and (5) intravenous 0.9% saline plus jejunal meal. Hydration status was assessed hourly by measurement of hematocrit. Water and electrolyte absorption was significantly stimulated by both oral and jejunal meal delivery (P less than 0.01). Intravenous saline hydration significantly reduced the hematocrit (P less than 0.05) but did not alter the proabsorptive response to an oral or jejunal meal. In conclusion, a postprandial signal for proximal jejunal water and electrolyte absorption was stimulated equally by orally or jejunally administered nutrients and was not affected by premeal hydration. These data support the hypothesis that the proabsorptive signal that stimulates water and ion absorption is an enteroenteric phenomenon originating from the small intestine, without implicating pathophysiologic events such as hypovolemia or dumping.

Basal and meal-stimulated colonic absorption.

PURPOSE: Few quantitative experiments evaluating colonic absorption of water and electrolytes have been performed using an awake, conscious animal model. The purpose of these experiments was to develop this type of model and evaluate both basal and meal-stimulated colonic absorption of water and electrolytes. METHODS: Canine Thiry-Vella fistulas were created using a 20 cm segment of distal colon under general anesthesia. Colonic absorption studies were performed using infusion of the Thirty-Vella fistulas with a buffer solution containing [14C]polyethylene glycol. Electrolyte analysis and concentration of radioactivity in the effluent were obtained and used to calculate the net flux of water, sodium, and chloride. Each study consisted of an one-hour basal period and a three-hour experimental period divided into two groups. Group 1 received no meal. Group 2 orally ingested a mixed meal at the completion of the basal hour. RESULTS: In the basal state, water and electrolytes are absorbed from the distal colon at a steady and constant rate. An orally ingested meal produces a statistically significant increase in the rate of absorption, independent of direct colonic luminal contact with the nutrients of the meal given. CONCLUSIONS: These studies demonstrate an in vivo quantitative and qualitative measure of mammalian colonic water and electrolyte absorption. An increase in absorption rate occurs in response to a meal that is probably the result of an unidentified neural or humoral signal.

Meal-stimulated canine jejunal ionic absorption. Influence of mucosal neural blockade.

The oral ingestion of a meal or the delivery of nutrients directly to the stomach or duodenum stimulates water and ion absorption from the proximal jejunal lumen. To further investigate this phenomenon, this study tested two hypotheses: (1) direct jejunal nutrient delivery stimulates jejunal absorption, and (2) the signal for jejunal absorption requires intact enteric neurotransmission and will therefore be altered by mucosal neural blockade with the local anesthetic bupivacaine. Intestinal absorption studies (N = 52) were performed on eight dogs with 25-cm jejunal Thiry-Vella fistulas (TVF) and feeding jejunostomies. Luminal perfusion with [14C]PEG was used to calculate TVF absorption of H2O, Na+, and Cl-. Six groups were randomly studied over 4 hr. Each group incorporated a basal hour, a TVF or jejunostomy treatment hour, and an oral (groups 1 and 3) or a jejunal (groups 4 and 6) meal stimulus. The oral and jejunal meals were isocaloric and of identical composition. Groups 1-3 had saline (as a control) or 0.75% bupivacaine applied to the lumen of the TVF. Groups 5 and 6 had 0.75% bupivacaine application to the feeding jejunostomy. Both the oral and the jejunal meal stimuli resulted in a significant proabsorptive response in the TVF. TVF bupivacaine reduced basal absorption but did not diminish the meal-induced proabsorptive response. Treatment of the jejunostomy with bupivacaine caused no change in basal or postmeal absorption in the TVF.(ABSTRACT TRUNCATED AT 250 WORDS)