The impact of age on outcome after surgery for colorectal adenocarcinoma

INTRODUCTION

The incidence of colorectal cancer (CRC) increases with age. The aim of this study was to investigate the impact of age and age-related factors on post-operative mortality and survival following CRC resections.

METHODS

A prospectively collected database of 459 CRC resections was analysed.

RESULTS

The mean age of the patients was 70 years (range: 25-95 years) and 54% were male. The relative proportion of female patients increased with age so that for patients aged over 77 more women were treated than men. The probability of undergoing an emergency resection (25%) did not change with age. In older patients the proportion of rectal cancers resected decreased and the proportion of hemicolectomies and Hartmann's operations performed increased. The 30-day mortality rate was 4% after elective and 11% after emergency resections. Most deaths were caused by medical complications, reflecting increased co-morbidity in the elderly. Post-operative mortality was 1% in patients under the age of 59. This increased by 3 percentage points every 10 years after elective resections and by 8 percentage points every 10 years after emergency resections. CRC-specific survival was independent of age whereas overall survival decreased so the likelihood of dying from CRC decreased with age: at age 50 half the deaths were from CRC, at age 70 a third and at age 80 a quarter.

CONCLUSIONS

CRC stage and the probability of presenting as an emergency did not change with age but older patients were more likely to be female and have colon cancer. Post-operative mortality progressively increased with age. Most deaths were caused by medical complications, reflecting increased co-morbidity. Older patients were less likely to die from CRC.

How accurate are doctors, nurses and medical students at predicting life expectancy?

BACKGROUND

Predicted patient life expectancy, based on a patient's medical history, is an important component of medical decision making. This study therefore aimed to determine the consistency, accuracy and precision with which doctors, nurses and medical students predict life expectancy (LE).

METHODS

20 doctors, 20 nurses and 20 medical students (4th and 5th year) independently examined 70 hypothetical patient case scenarios containing age, sex and comorbidity; this included 13 duplicate scenarios. Accuracy and consistency of prediction was assessed by comparison with statistical LE estimates generated using evidence-based actuarial and life insurance industry methods in collaboration with a team of professional actuaries.

RESULTS

Doctors, nurses and medical students underestimated LE by a mean (95% confidence interval) of -1.46 (-0.31 to -2.61), -1.79 (-0.52 to -3.06) and -2.24 (-1.16 to -3.32) years with an equivalent root mean squared error (RMSE) of 4.74, 5.49 and 5.08 years respectively. LE predictions were equal to actuarial LE in less than 10% of cases and accurate to within 25% of actuarial LE in less than 45% of cases. Intra-observer reliability was 91%, 85% and 87% for doctors, nurses and medical students respectively. Inter-observer reliability was 66%, 57% and 57% for the three groups.

CONCLUSION

Doctors, nurses and medical students were inconsistent, inaccurate and imprecise in their prediction of LE with a tendency toward underestimation. This may lead to patients being managed inappropriately. There is a need for improved training and objective outcome prediction models.

An audit of cystic duct closure in laparoscopic cholecystectomies

BACKGROUND

Cystic duct leak is an infrequent but potentially serious complication of laparoscopic cholecystectomy. The aims of this audit were to assess the efficacy of locking absorbable clips for closing the cystic duct and to compare the results with those for simple clips used previously.

METHODS

The records for all laparoscopic cholecystectomies performed in one hospital over a 5-year period were reviewed. The results were compared using Fisher's exact test.

RESULTS

Of 518 laparoscopic cholecystectomies attempted, 24 were excluded. There was no difference in age or sex ratio between the two groups. Cystic duct leaks were identified either on endoscopic retrograde choloangio pancreatography or at laparotomy. No cystic duct leak occurred in any of the 344 locking clip cases, as compared with 3 leaks in the 146 (2%) simple clip cases (p < 0.03).

CONCLUSION

Locking clips are a safe and effective method for cystic duct closure. They are associated with a reduced cystic duct leak rate, as compared with that for simple clips.

Left subcostal closed (Veress needle) approach is a safe method for creating a pneumoperitoneum

BACKGROUND

The left subcostal closed approach utilizing the Veress needle has been the preferred method at one surgical practice for the past 5 years. The aims of this study were to determine whether this was a safe method for creating a pneumoperitoneum and its success rate.

METHODS

The medical records for all laparoscopic procedures performed at one practice from 1996 through 2001 were reviewed.

RESULTS

A total of 352 laparoscopic cases were reviewed. The median age of the patients was 55 years (range, 14-72), with a sex ratio of 1 male to 3.5 females. The left subcostal closed approach was not attempted in 8 patients (2%) due to left subcostal surgical scars. The left subcostal approach was successful in 342 of 344 attempts (99%). In 2 patients the method failed because the Veress needle hole could not be placed in the peritoneal cavity. An omental hematoma in one patient was the only complication.

CONCLUSION

The left subcostal closed approach is a safe and effective method for creating a pneumoperitoneum.

Pathogenesis of pancreatic infection

John Hunter studied comparative anatomy of the pancreas but was unaware of pancreatic infection which is now the leading cause of mortality in pancreatitis. This was investigated using a feline model of pancreatitis. Pathogens spread to the healthy and inflamed gland from many sources including colon, gallbladder, or a septic focus and by various routes including the circulation, reflux into the pancreatic duct or by transmural migration from the colon. Colonisation risk was proportional to necrosis and inflammation, confirming clinical observations. These studies showed that pathogens frequently colonised the pancreas, but infection developed only in animals with pancreatitis. In cats with pancreatitis, phagocytic function was reduced by 28%. This was probably owing to phagocytic capacity being overwhelmed by protease-antiprotease complexes because, in humans, granulocyte and lymphocyte function was normal. These experiments suggested that it would be difficult to prevent pancreatic colonisation, but indicated some types of therapy may have potential. These were investigated using this animal model of pancreatic infection. Treatment with either cefotaxime or levamisole (an immunostimulant) were effective. However, the anti-inflammatory drug dopamine, which reduced inflammation, did not eradicate all pathogens.

Immune function early in acute pancreatitis

Circulating lymphocyte numbers and activation together with granulocyte function were measured in 20 patients in the early stages of an attack of acute pancreatitis and in 20 healthy controls. Circulating lymphocytes, T lymphocytes, and CD4 and CD8 T lymphocyte subsets were decreased in both mild pancreatitis (67-80 per cent of controls) and severe pancreatitis (22-40 per cent of controls). CD4:CD8 ratios were unchanged and median (interquartile range) interleukin 2 receptor expression was increased from less than 1 per cent in controls to 14(6) per cent in severe pancreatitis, suggesting lymphocyte activation. Median granulocyte chemiluminescence was increased to 293 per cent of controls in severe pancreatitis and random motility was reduced to 77 per cent of controls, indicating increased metabolic activity. Complement-mediated antibody-independent opsonization and chemotaxis toward endotoxin were normal. Immune function is not reduced early in acute pancreatitis. Granulocyte hyperactivity may be important in the development of multiple organ failure.

Can we predict when an operating list will finish?

Mean anaesthetic, surgical and turnover times were used to predict finishing times for elective general surgical operating lists. A predicted early finish was correct in 70 per cent, a predicted on-time finish in 19 per cent, and a predicted late finish in 56 per cent. Overall, predictions of an early or late finish had a low sensitivity (62 per cent and 65 per cent) and high false positive rate (30 per cent and 44 per cent). Over-runs, caused by too many cases, and early finishes, owing to insufficient cases were reliably predicted. It is suggested that mean procedure times can be used to identify under or over utilisation caused by under or over-booking but indiscriminate use will not improve list utilisation.

Open cholecystectomy in the age of the laparoscope

We reviewed our experience with open cholecystectomy since laparoscopic cholecystectomy became the treatment of choice for symptomatic gallstones. Over a 3 year period 35 open (6%) and 578 laparoscopic cholecystectomies (94%) were performed. Fourteen trainee surgeons performed only 16 open cholecystectomies and assisted at 19. The proportion of open cholecystectomies declined through the study period. Ten emergency cholecystectomies were performed for empyema, gallbladder perforation, severe acute cholecystitis, liver abscess, and cholangitis. In 12 patients, laparoscopic surgery was converted to an open procedure because of severe inflammation, empyema, dense adhesions, carcinoma of the gallbladder, cholecystoduodenal fistula, and perforated small bowel. Ten patients underwent open cholecystectomy and bile duct exploration after failure to clear duct stones endoscopically, and three patients had Mirizzi's syndrome. Open cholecystectomy is infrequently performed giving trainee surgeons little experience. However, such cases are occasionally inevitable and laparoscopic surgeons need to have the appropriate skills.

Pancreatic vascular regulation in chronic pancreatitis in cats

In experimental obstructive chronic pancreatitis the normal hyperaemic response to secretory stimulation is lost, suggesting abnormal vascular regulation. Vascular regulatory mechanisms were investigated by observing the effect of increments in portal pressure on pancreatic blood flow in normal cats and cats with chronic pancreatitis. Normal cats maintained pancreatic blood flow until portal pressure was > 15 mm Hg, after which it decreased. Total vascular resistance decreased until the portal pressure was 15 mm Hg and increased thereafter. These observations suggested that metabolic regulatory mechanisms prevailed while portal pressure was in the physiological range but myogenic mechanisms became dominant during portal hypertension. In chronic pancreatitis the basal pancreatic blood flow was reduced and was inversely proportional to portal pressure. Total vascular resistance increased as portal pressure increased. In chronic pancreatitis myogenic regulatory responses prevailed at all levels of portal pressure. In conclusion, intrinsic regulation of pancreatic blood flow was abnormal in cats with chronic pancreatitis. The loss of the predominance of metabolic regulation over the normal range of portal pressure may partly explain the reduction of pancreatic blood flow in response to secretory stimulation.

Routes of spread of pathogens into the pancreas in a feline model of acute pancreatitis

The routes of spread of pathogens into the pancreas in acute pancreatitis were investigated. Four experiments were performed: (1) cats with and without acute pancreatitis were given 10(7) Escherichia coli (E coli) intravenously, (2) in cats with acute pancreatitis 10(8) E coli was placed in the colon. In half of them the colon was then enclosed in an impermeable bag to prevent transmural spread. (3) E coli (10(4)) was placed in the pancreatic duct in cats with and without acute pancreatitis. (4) In cats with acute pancreatitis 10(5) E coli was placed in the gall bladder. In half of them the common bile duct was ligated to prevent biliary-pancreatic reflux. After 24 hours, intravenous E coli infected the pancreas in six of nine cats with acute pancreatitis and three of 10 controls. After 72 hours E coli spread to the pancreas from the colon in six of nine cats with acute pancreatitis. This was prevented by enclosing the colon in an impermeable bag (p = 0.02). In five of six cats with acute pancreatitis and five of six controls E coli placed in the pancreatic duct colonised the pancreas within 24 hours. Pancreatic colonisation from the gall bladder occurred in five of six cats with a patent common bile duct and in three of six with an obstructed common bile duct. In conclusion, in cats E coli can spread to the pancreas by the blood stream, transmurally from the colon, and by reflux into the pancreatic duct.

Sources of pancreatic pathogens in acute pancreatitis in cats

The source(s) of pancreatic pathogens is uncertain, although the colon is usually implicated. We studied whether pathogens may spread from different sites in a feline model of the disease. Acute pancreatitis was induced using a standard technique and a distinctive clinical strain of Escherichia coli as the marker bacterium. E. coli were placed in the colon, gall bladder, main pancreatic duct, or obstructed renal pelvis of control cats (no pancreatitis) and acute pancreatitis cats. Pancreases were colonized from each source, whether or not pancreatitis was present. The pancreatic colonization rate was greater in acute pancreatitis only when E. coli had been placed in the colon. In conclusion, E. coli may spread to the pancreas from different sources. The high rate of pancreatic colonization in both control and inflamed glands suggested that, clinically, bacteria may spread to the pancreas more frequently than is currently thought.

Antimicrobial treatment of pancreatic infection in cats

An investigation examined the efficacy of antibiotics in a novel feline model of pancreatic infection in acute pancreatitis. Acute pancreatitis was induced in cats using an established technique. In control animals (no pancreatitis) and cats with pancreatitis, Escherichia coli (10(4) in 0.1 ml) was placed in the pancreatic duct. Reoperation was performed after 24 h in six controls and six cats with pancreatitis. E. coli was cultured from the pancreas in five control animals and five cats with pancreatitis. Reoperation was performed after 1 week in ten controls, in 11 cats with pancreatitis and in nine with pancreatitis that were treated with cefotaxime (50 mg/kg intramuscularly three times daily) started 12 h after the induction of pancreatitis and administration of E. coli. Pancreatic infection developed in eight cats with pancreatitis compared with none of the cefotaxime-treated animals and none of the controls (P < 0.05). Cefotaxime reached bactericidal levels in pancreatic tissue and juice. In conclusion, ductal administration of E. coli caused pancreatic infection only in cats with acute pancreatitis. Early administration of an appropriate antibiotic was effective in treating pancreatic infection in acute pancreatitis.

Combined laparoscopic and endoscopic treatment of gallstones and bile duct stones: a prospective study

In patients with symptomatic gallstones the management of choledocholithiasis has been controversial since the introduction of laparoscopic cholecystectomy. A prospective study was made of 300 consecutive patients with symptomatic gallstones managed by laparoscopic cholecystectomy and preoperative endoscopic retrograde cholangiography (ERC) over 2 years. Fourteen patients were excluded either because urgent surgery was required or because they were unfit for laparoscopic cholecystectomy. ERC was performed on 96 patients (34 per cent) who were at risk of choledocholithiasis. The presence of bile duct calculi was confirmed in 59 patients (21 per cent of the total, 61 per cent of those undergoing ERC); stones were removed endoscopically in 53 cases (90 per cent of attempts). The remaining six patients underwent open cholecystectomy and bile duct exploration. Laparoscopic cholecystectomy was attempted in 280 patients (98 per cent); it was necessary to convert to open operation in only three (1 per cent). There were no deaths, no retained stones and no bile duct injuries, and only three patients (1 per cent) developed a significant postoperative complication. Symptomatic gallstones can be managed by preoperative ERC and laparoscopic cholecystectomy with minimal morbidity and mortality.

Dopamine in models of alcoholic acute pancreatitis

Acute oedematous pancreatitis and acute haemorrhagic pancreatitis were studied using the low pressure duct perfusion models of alcoholic pancreatitis in cats. After creating either form over 24 hours, each pancreas was histologically graded and assigned an inflammatory score (0-16; absent-severe). Urinary trypsinogen activation peptide concentrations were also used as a measure of severity. Using the model of acute haemorrhagic pancreatitis, it was previously shown that low dose dopamine (5 micrograms/kg.m) reduced the inflammatory score at 24 hours and that this effect was mediated by a reduction in pancreatic microvascular permeability acting via dopaminergic and beta adrenergic receptors. Further studies were conducted and are reported here. In experiment 1 different doses of dopamine in established alcoholic acute haemorrhagic pancreatitis were studied. In group 1 control cats (no dopamine), the inflammatory score was 10.5 (interquartile range (IQR)4). In groups 2, 3, and 4, haemorrhagic pancreatitis was induced. Twelve hours later dopamine was infused for six hours, in the doses of 2 micrograms/kg.min, 5 micrograms/kg.min, and 50 micrograms/kg.min respectively. The inflammatory score in group 2 was 7 (IQR 0.5, p < 0.05 v group 1), in group 3 it was 7 (IQR 2, p < 0.05 v group 1), and in group 4 it was 7 (IQR 4, p < 0.05 v group 1). This was matched by significantly lower levels of urinary tripsinogen activation peptide at 24 hours. In experiment 2 (group 5) we tried to reduce microvascular permeability further by combining dopamine with antihistamines, but there was no improvement in the inflammatory score. As oedematous pancreatitis is the commoner and milder form of acute pancreatitis in clinical practice, in experiment 3 we looked at the effect of dopamine in this model. In group 6 control cats (no treatment), the inflammatory score was 7 (IQR 3, p < 0.05 v group 1). In group 7 cats given dopamine (5 micrograms/kg.min for six hours) from 12 hours after the onset of actue oedematous pancreatitis, the inflammatory score was reduced to 4(IQR 2, p < 0.05 v group 6). This was matched by a significant reduction in the 24 hour urinary tripsin activation peptide concentration.

Compartment syndrome in experimental chronic obstructive pancreatitis: effect of decompressing the main pancreatic duct

Chronic pancreatitis is characterized by persistent and severe pain, which can be relieved by decompression of the main pancreatic duct (MPD). Both ductal and interstitial pressures have been shown to be increased in chronic pancreatitis in patients. A study was carried out of pancreatic interstitial pressure and pancreatic blood flow in normal cats and those in which chronic obstructive pancreatitis had been induced 5 weeks earlier to determine the effect of decompression of the MPD. In the normal pancreas, median(interquartile range (i.q.r.)) basal interstitial pressure was 0.05(1.2) mmHg and median(i.q.r.) basal pancreatic blood flow 58.3(24.3) ml per min per 100 g. Secretory stimulation did not change the interstitial pressure significantly, but was associated with a 40 per cent increase in median(i.q.r.) blood flow to 81.8(45.8) ml per min per 100 g. In contrast, in chronic obstructive pancreatitis, the median(i.q.r.) basal interstitial pressure was 2.0(1.5) mmHg, which was significantly higher than in the normal gland, and median(i.q.r.) pancreatic blood flow was 38.3(9.8) ml per min per 100 g, significantly lower than in the normal pancreas. Furthermore, secretory stimulation was associated with a significant increase in median(i.q.r.) interstitial pressure to 3.3(1.6) mmHg and a simultaneous decrease in median(i.q.r.) blood flow to 31.5(13.7) ml per min per 100 g. After decompression of the MPD in cats with chronic obstructive pancreatitis, the median(i.q.r.) basal interstitial pressure was 2.0(1.4) mmHg and on secretory stimulation 1.8(1.5) mmHg. Decompression thus prevented the increase in interstitial pressure seen in the animals with obstruction. In contrast, ductal decompression improved the median(i.q.r.) basal pancreatic blood flow to 45.9(38.4) ml per min per 100 g and, furthermore, this increased significantly on secretory stimulation to a median(i.q.r.) of 81.4(47.8) ml per min per 100 g. Decompression thus restored the normal pattern of secretory hyperaemia. Within the confines of this model, these observations demonstrate that chronic obstructive pancreatitis exhibits a compartment syndrome that is relieved by duct drainage.

Differential effects of experimentally induced chronic pancreatitis on neuropeptide immunoreactivities in the feline pancreas

The distribution and concentration of calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), and gastrin-releasing peptide (GRP) immunoreactivities in the pancreas of cats with experimentally induced chronic pancreatitis and of age- and sex-matched controls were investigated. By narrowing the main pancreatic duct between the head and the body to approximately 25% of its normal diameter, we induced within 5 weeks chronic pancreatitis restricted to the body and tail. In control animals, peptide immunoreactive nerves were distributed to the islets, acini, and ducts; the latter were predominantly innervated by fibers immunoreactive for NPY, VIP, or CGRP. The vasculature received an abundant supply of NPY-, CGRP-, and, to a lesser extent, SP-containing axons. Within intrapancreatic ganglia, peptide immunoreactivities were identified in fibers and ganglion cells, with the exception of CGRP and SP immunostaining, which could be visualized only in fibers. In animals with chronic pancreatitis, the innervation pattern of each peptidergic system was comparable to that described in controls. However, there was a remarkable increase in the density and staining intensity of VIP and NPY immunoreactive fibers in the exocrine parenchyma and fibrous septa of the body and tail, where chronic pancreatitis developed. Fibers immunoreactive for CGRP and SP also were moderately denser than in controls, whereas those containing GRP immunoreactivity did not show any detectable changes. In addition, a marked increase of the immunostaining for VIP and, to a much lesser extent, for NPY and GRP, was observed in neurites supplying the head of the pancreas, which appeared devoid of histologically detectable pathological alterations. Radioimmunoassay analysis confirmed the immunohistochemical observations. The increased density of distinct peptidergic nerves in the pancreas with induced chronic pancreatitis might be the result of compensatory phenomena in response to the inflammatory process.

Survey of guidelines for antimicrobial prophylaxis in surgery

One method of making optimal use of prophylactic antibiotics is for interested parties to agree on guidelines. A postal survey was undertaken to determine the prevalence of this practice within UK hospitals and details of any guidelines used. Eighty-one of the 160 respondents (51%) stated that guidelines were available or in preparation. Prophylaxis was recommended by 100% of respondents for colorectal surgery and prosthetic joint replacement and by 96% for gastro-oesophageal surgery, procedures where it has been proven to be of benefit. Prophylaxis was recommended for the following procedures for which its efficacy remains controversial: cholecystectomy (100%); peripheral vascular grafting (93%); hysterectomy (95%) and noncardiac thoracic surgery (63%). Although 35 combinations of 22 different antimicrobials were recommended, 63% included a cephalosporin; the greatest variety of antibiotics recommended was for peripheral vascular grafting. In 88% of policies it was advocated that prophylaxis be started preoperatively and in 79% that it be continued for less than 24 h. When surgery involved the implantation of a prosthesis the duration of prophylaxis tended to be prolonged. Policies for the prescribing of antimicrobial prophylaxis in surgery are available in many hospitals and for the most part conform with established principles.

Assay of trypsinogen activation in the cat experimental model of acute pancreatitis

An enzyme-linked immunosorbent assay for trypsinogen activation peptide (TAP) was used to measure urinary TAP levels in standard feline models of acute oedematous pancreatitis and acute haemorrhagic pancreatitis. It has been shown that the extent of pancreatic damage as assessed histologically is significantly greater in the model of acute haemorrhagic pancreatitis. This increase in damage has been found to be associated with a significantly greater increase in the excretion of urinary TAP.

Pancreatic infection complicating acute pancreatitis

Pancreatic infection is the leading cause of death from acute pancreatitis. Patients with severe necrotizing pancreatitis are most at risk. Early computed tomography and percutaneous fine-needle aspiration microbiology of areas of pancreatic necrosis enable early diagnosis. Pancreatic infection should be treated surgically, although sterile necrosis may be managed conservatively. The role of antimicrobial drugs is uncertain.

Species differences in the immunoreactive patterns of calcitonin gene-related peptide in the pancreas

In the pancreas, calcitonin gene-related peptide (CGRP) immunoreactivity has been described in nerve fibers and in distinct types of islet cells. This unique, apparently species-specific cell-type expression prompted the present investigation to clarify further the pattern of CGRP immunoreactivity in different mammalian species (i.e., different strains of rats, mice, guinea pigs, rabbits, cats, dogs, pigs, and humans) commonly used for functional and anatomical studies of the pancreas by means of immunohistochemistry using three different CGRP antibodies. In each species, CGRP-immunoreactive neurites innervate the exocrine and endocrine compartments, the vasculature, and the intrapancreatic ganglia, where they form dense networks encircling unstained cell bodies. The only exception is the pig pancreas, where the islets appear to be devoid of immunoreactive fibers. The overall density of immunoreactive pancreatic axons in different species is as follows: rat, mouse, and rabbit greater than guinea pig greater than or equal to pig and cat much greater than dog and human. CGRP-immunoreactive endocrine cells appear to be restricted to the rat pancreas, where they form a subpopulation of somatostatin-containing D cells. In contrast, in mouse, guinea pig, cat, dog, and human pancreas, a homogeneous staining of the core of the islets, where insulin-producing B cells are located, was visualized in sections incubated with the rabbit CGRP antiserum at 4 degrees C, but not at 37 degrees C (an incubation temperature that does not affect the islet cell staining in the rat nor the fiber labeling in any species). Furthermore, the staining of islet B cells was not reproducible with all the CGRP antibodies used, all of which comparably stain nerve fibers in each species, and islet D cells in the rat. Immunoreactive islet cells were not visualized in pig and rabbit pancreas. These results are consistent with the hypothesis that the expression of CGRP in nerve fibers is a common feature of mammalian pancreas, whereas its expression in endocrine cells appears to be restricted to the D cells of the rat pancreas.

Pancreatic blood flow in cats with chronic pancreatitis

Pancreatic blood flow and its relationship to pancreatic interstitial pressure were investigated in a model of chronic pancreatitis in cats using a hydrogen gas-clearance technique with an intraductal electrode. The intraductal technique correlated well with blood flow measurements made using gamma-labeled microspheres (r = 0.88, P less than 0.001). In control cats, the basal blood flow of 69.1 +/- 9.5 mL.min-1.100 g-1 increased by 25% to 86.2 +/- 11 mL.min-1.100 g-1 with secretory stimulation (P less than 0.05). Interstitial pressure was -0.02 +/- 0.3 mm Hg and did not change significantly with stimulation. In cats with chronic pancreatitis, basal interstitial pressure was 1.8 +/- 0.5 mm Hg and basal blood flow 39.9 +/- 4 mL.min-1.100 g-1 (P less than 0.05). Stimulation of the chronic pancreatitis gland increased the pressure to 3.0 +/- 0.4 mm Hg (P less than 0.01) and reduced flow 15% to 34.2 +/- 4 mL.min-1.100 g-1 (P less than 0.05). Papaverine increased blood flow in control and chronic pancreatitis cats without altering tissue pressure, suggesting that despite the reduced basal blood flow, the ability to increase blood flow was preserved in chronic pancreatitis. The increased interstitial pressure associated with secretion appeared to limit the gland's normal hyperemic response in this model of chronic pancreatitis.

The influence of ethanol on pancreatic blood flow in cats with chronic pancreatitis

BACKGROUND

The mechanism by which ethanol predisposes to acute pancreatitis, especially in established chronic pancreatitis, is not known. Here we studied the effects of acute ethanol ingestion on pancreatic blood flow in chronic pancreatitis, a setting characterized by diminished basal blood flow to the pancreas.

METHODS

Obstructive pancreatitis was created by partial duct ligation for 3 weeks in nine cats. Controls (n = 8) were not operated on. Blood flow was measured in anesthetized animals with a hydrogen gas clearance technique and an intraductal electrode. Pancreatic interstitial pressure, systemic and portal blood pressures, and serum ethanol levels were recorded, and pancreatic vascular resistance was calculated. Measurements were made before and for 2 hours after 20 cc of 40% (wt/vol) ethanol was instilled into the stomach.

RESULTS

Basal flow was reduced in the obstructed pancreas to 51% of normal. Both groups showed an acute decrease in blood flow when ethanol was given. A more steep (50% of baseline) and a more prolonged (120 minutes) fall was observed in the pancreatitis group than in controls (31% and 60 minutes, respectively). The decline in blood flow correlated with increases in interstitial pressure and vascular resistance.

CONCLUSIONS

Acute ethanol ingestion sharply reduces pancreatic blood flow, especially in glands with chronic pancreatitis.

Patterns of innervation of vasoactive intestinal polypeptide, neuropeptide Y, and gastrin-releasing peptide immunoreactive nerves in the feline pancreas

In this study, we performed a detailed analysis of the immunoreactive (IR) patterns and tissue distribution of vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), and gastrin-releasing peptide (GRP) in the feline pancreas by means of immunohistochemical and radioimmunological techniques. Immunoreactivity for each peptide is localized to varicose nerve fibers distributed throughout the exocrine and endocrine pancreas, with some differences in the density and pattern of fiber distribution. In the acinar and stromal compartments, VIP-IR processes have a higher density than NPY- and GRP-containing fibers, the latter being the least abundant. The vasculature receives a particularly prominent NPY innervation, while GRP- and VIP-IR fibers are found occasionally in association with blood vessels. Around ducts, NPY- and VIP-IR nerves are more numerous than those positive for GRP-IR, which are quite sparse. One of the most interesting findings of the present work is the visualization of all peptide-IRs both in neuronal cell bodies and fibers within the intrapancreatic ganglia. VIP-IR is observed in virtually all ganglion cells, while GRP- and NPY-IRs are seen in a few neuronal cells. VIP and NPY tissue levels are much higher than GRP concentrations in all regions of the pancreas. VIP content in the head and body is greater than in the tail. The morphological relationship of VIP-, NPY-, and GRP-IR fibers with different pancreatic structures is consistent with specific peptidergic neural inputs in the regulation of pancreatic functions.

Pancreatic ductal and interstitial pressures in cats with chronic pancreatitis

We investigated the etiology of interstitial hypertension in chronic pancreatitis by examining the relationship between pancreatic ductal and interstitial pressures in cats. The main pancreatic duct was cannulated in the tail of the gland and perfused at 1, 2, or 5 ml/hr, to simulate pancreatic secretion. Intraductal and interstitial pressures were measured in four groups of animals: (1) normal cats; (2) normal cats after acutely narrowing the main duct to 25% of its original diameter; (3) normal cats after encasing the body and tail in a rigid latex capsule; and (4) cats with chronic pancreatitis created by narrowing the main duct five weeks earlier. Duct perfusion increased intraductal pressure in all of the cats, but significantly more in groups 2, 3, and 4 compared to group 1. Pancreatic interstitial pressure was unchanged by duct perfusion in groups 1 and 2, but increased in groups 3 and 4. We concluded that the compliant tissue of the normal pancreas expanded to effectively dissipate the increase in duct pressure associated with duct perfusion. In chronic pancreatitis, the inelastic parenchyma and capsule limited the distensibility of the gland, which resulted in elevated interstitial pressures during duct perfusion.

The low-pressure duct perfusion model of acute pancreatitis

The low-pressure duct perfusion model reliably produces acute pancreatitis in cats. The main pancreatic duct is made permeable in one of several ways: the perfusion of glycodeoxycholic acid along the main pancreatic duct, the administration of intragastric ethanol, the stimulation of pancreatic secretion into an obstructed duct, or the creation of acute hypercalcemia. Active pancreatic enzymes are then perfused through the main pancreatic duct via a catheter inserted into the duct in the tail of the gland, and acute edematous pancreatitis results. Simultaneous infusion of 16,16-dimethylprostaglandin E2 converts acute edematous into acute hemorrhagic pancreatitis. Histologically, the characteristic changes of human acute pancreatitis are manifest 24 h later: necrosis, polymorphonuclear leukocyte infiltrate, hemorrhage and edema.

Influence of levamisole on pancreatic infection in acute pancreatitis

We investigated the effect of levamisole on pancreatic infection in a model of acute pancreatitis (AP) in cats. Animals with and without AP received Escherichia coli intravenously. Blood was then taken at intervals for culture. AP reduced phagocytic function by 28% as measured by the rate of bacterial disappearance from the blood (p less than 0.03). In other cats, AP was induced, and E. coli were placed into the pancreatic duct. Levamisole was given orally in some cats; the remainder were untreated. Control cats (neither AP nor levamisole) also received E. coli. Seven days later, pancreases from all control cats were sterile. In AP cats, the pancreatic infection rate was 73%. Levamisole reduced the rate of infection to 22% (p less than 0.03). We concluded that phagocytic function was impaired in cats with AP. Levamisole reduced the rate of pancreatic infection.

The antiinflammatory effect of dopamine in alcoholic hemorrhagic pancreatitis in cats. Studies on the receptors and mechanisms of action

Hemorrhagic pancreatitis was induced in cats by perfusing pancreatic enzymes through a pancreatic duct after the administration of intragastric ethanol. Dimethyl prostaglandin E2 was administered concurrently. In the first study, dopamine's antiinflammatory effect on the pancreas was determined in the presence of haloperidol, propranolol, or both. Next, dopamine's effects on blood flow in the normal and inflamed pancreas were compared using a hydrogen gas-clearance technique. In the final study, the effect of dopamine on fluorescein isothiocyanate-labeled dextran leakage from the pancreatic duct to portal venous blood was investigated. It was found that blockade of either dopamine or beta-adrenergic receptors reduced, and blockade of both receptors completely eliminated, the antiinflammatory effect. Dopamine had no effect on pancreatic blood flow in normal cats. In pancreatitis, although dopamine transiently reduced blood flow, after an hour flow had returned to normal. Dopamine reversed the leakage of fluorescein isothiocyanate-labeled dextran from the pancreatic duct caused by ethanol and by ethanol and prostaglandin E2. It was concluded that dopamine ameliorated pancreatitis by reducing pancreatic ductal and/or microvascular permeability rather than by altering pancreatic blood flow. The antiinflammatory effect was mediated by both dopamine and beta-adrenergic receptors.

The effect of dopamine in a model of biliary acute hemorrhagic pancreatitis

Perfusion of the main pancreatic duct in cats with a dilute solution of bile salts increases ductal permeability. Subsequent perfusion of a permeable duct with activated pancreatic enzymes results in acute edematous pancreatitis. Simultaneous infusion of 16-16 dimethyl-PgE2 converts edematous pancreatitis to acute hemorrhagic pancreatitis (AHP). AHP may be associated with a reduction in pancreatic blood flow; it is certainly associated with increases in microvascular permeability. Low dose dopamine is a splanchnic vasodilator and may also reduce pancreatic microvascular permeability through beta agonist effects. In these studies, we investigated the effect of dopamine in an established feline model of biliary AHP. We also studied its effect on blood flow in both normal pancreas and after induction of AHP. We found that dopamine significantly reduced the degree of pancreatic inflammation, even when administered up to 12 h after onset of biliary AHP. However, the drug had no significant effect on blood flow either in normal pancreas or in the gland affected by hemorrhagic pancreatitis. We concluded that the effect of dopamine was most likely due to its ability to reduce pancreatic microvascular permeability.

A study of the time course of conversion of edematous to hemorrhagic pancreatitis

We studied the conversion of acute edematous pancreatitis (AEP) to acute hemorrhagic pancreatitis (AHP) in an experimental model in cats. In the model, 16,16 dimethyl PgE2 effects this conversion by increasing microvascular permeability. First, we induced AEP in cats and then gave PgE2 at increasing intervals after the induction of AEP to see how long an interval would still allow conversion. In 6 groups of cats, PgE2 was administered for 2 h, starting at 2, 4, 6, 8, 10, or 12 h after the creation of AEP. Twelve h later, the cats were sacrificed and the pancreases were graded for inflammation and hemorrhage. Significant pancreatic hemorrhage did not occur when the PgE2 was administered at 12 h compared to 2 h. Next, we determined that PgE2 still retained its ability to increase pancreatic vascular permeability when administered 12 h after the creation of AEP. This was done by perfusing a marker molecule through the MPD (fluorescein isothiocyanate labeled dextran: FITC-D, mol wt 20,000) and then finding it in portal venous blood (PVB). The presence of FITC-D in PVB signified increased vascular permeability, since normally none was present. We concluded that conversion of AEP to AHP was possible during the first 12 h after induction of AEP. Lack of conversion at 12 h was not caused by a lack of vascular reactivity at that time.

New perspectives in the surgical management of chronic pancreatitis

Although the etiology of pain in chronic pancreatitis remains uncertain, that symptom remains the most common indication for surgery in these patients. Current endoscopic and imaging techniques now permit accurate definition of the morphology of the disease. Thus, surgical intervention can be more selectively applied to address specific abnormalities. Pancreaticojejunostomy should be the first line of surgical therapy if the ductal system is dilated. When, in addition, the head of the pancreas is enlarged and inflamed, the operation should include a localized resection of the head, preserving the stomach and duodenum. If the duct is not dilated, some form of pancreatic resection is indicated. The resection should be limited to the most severely diseased part of the pancreas. Efforts should be made to preserve as much pancreatic tissue as possible, while maintaining normal gastrointestinal continuity. In this way, the nutritional and metabolic consequences of pancreatic resection will be minimized.

Ketamine and the guinea-pig ileum: possible opiate agonist and antagonist actions and effects of peptidase inhibition

The effects of ketamine and its interaction with naloxone were studied on the transmurally stimulated guinea-pig ileum preparation. Ketamine (at concentrations between 10(-4) and 10(-3) M) depressed the contractions of the ileum, showing a very steep log concentration-effect curve. Naloxone partially reversed the depressant effect of ketamine at slightly higher concentrations (between 10 nM and 1 microM) than those normally required to reverse opiate depression in this tissue. Naloxone did not affect pentobarbitone-induced depression, suggesting that ketamine has specific actions on opiate transmission. Phentolamine and propranolol did not affect the ketamine-induced depression, whereas acetylcholinesterase inhibition did not alter the action of naloxone on this depression. Ketamine showed some reversal effect on the depressant action of morphine and caused contractions of the morphine-tolerant ileum, suggesting that it may have opiate antagonist activity. Inhibition of peptidase enzymes by a mixture of dipeptides potentiated the depression after high-frequency stimulation of the ileum, but did not affect the action of ketamine. The results suggest that ketamine may interact with opiate mechanisms in the ileum to produce part of its depressant action and may also have some opiate antagonist activity.