97. Pancreas Flashcards
two functional units of the pancreas
98% exocrine (acinar cells/duct system)–>digestive functionEndocrine (islet cells of Langerhans)–>hormonal function
islets of langerhans cells
alpha = glucagon (increases glucose)beta = insulin (decreases glucose)delta = somatostatinF or PP = pancreatic polypeptide
vascular supply to pancreas
celiac–>hepatic, and splenic artery branches which give pancreas brancheshepatic also gives rise to gastroduodenal artery and then cranial pancreaticoduodenal artery cr mesenteric artery–>caudal pancreaticoduoudenal
innervation to the pancreas
enteric nervous system–vagus nerveceliac and superior mesenteric plexusesacinar/islet cells–cholinergicstimulated by PSNSinhibited by SNS
major pancreatic duct in dogs
accessory pancreatic duct (duct of Santorini) into the minor duodenal papillapresent in < 20% catsCBD and pancreatic duct (minor contributor–duct of Wirsung) enter major duodenal papilla
Major pancreatic duct in cats
pancreatic duct (duct of Wirsung) into the major duodenal papilla combines/fuses w/common bile duct at MDPthis is the only pancreatic duct in 80% of cats
insulin functions
B cellsanabolicdecrease blood glucosepromotes IC conversion into glycogencontrols glucose efflux from EC spaces and puts INTO cells
glucagon functions
Alpha cellsincrease blood glucosecontrols glucose influx from hepatocytes and takes OUT of cellsmobilizes energy stores by increasing gluconeogenesis, glycogenolysis, lipolysis
digestive enzymes from the pancreas exocrine acinar cells
bicarb/water—to neutralize stomach pHintrinsic factors to incr absorption of cobalamin–vit B12 (distal ileum), Zn, colipase C (promotes action of pancreatic lipase)antibacterial factors inhibit bacter prolif in duodenomzymogens (trypsinogen, chymotrypsinogen, proelastases, procarboxypeptidases)–trypsin activated by active peptide enterokinase from duodenal enterocytes, then activates other zymogens into enteropeptidase TABLE 97-1
three mechanisms to prevent auto digestion
- secreted as proenzymes/zymogens (inactive)2. zymogens are packaged as membrane bound granules within rough ER of pancreas3. acinar cells secrete pancreatic trypsin inhibitor to prevent premature activation
pancreatic exocrine secretions are under what regulation
stimulation from vagus nerve and food presence in duodenum which stimulates the release of CCK and secretin from duodenal enterocytesCCK–stimulates secretion of digestive enzymessecretin –stimulates secretion of bicarbbiphasic response1. initial spike digestive enzymes 1-2 hr after meal2. second phase rich in bicarb 8-11 hr after meal
anesthetic drugs to avoid in pancreatic patients
avoid alpha2 agonist (xylazine, medetomidine)–produce hypoinsulinemia and hyperglycemia–vasoconstriction (poor pancreatic perfusion)
two techniques for pancreatic biopsy
most often RIGHT limb pancreas (accessible, distance from duct system, blood supply is not primary source to other organs)–suture fracture technique (guilloteine)–for lesions near extremity of pancreas (may have more inflammation on histopath, but not clinical differences)–blunt dissection and individual ligate/divide–for lesions anywhere is pancreas–laparoscopic biopsy (punch, guilloteine pretied suture, hemoclips, harmonic scalpel, VSD)
how much pancreas can be resected so long as there is an intact pancreatic duct
75-90% resection is possible if there is an intact duct remainingthis can be resected without impairment of exocrine and/or endocrine functionregenerative capacity available (production of insulin like growth factor)
post op complications requiring life long mgmt following total pancreatecetomy or pancreaticoduodenectomy
tx diabetes mellitustx EPItx gastrointestinal ulcerbiliary diversion (cholecystojejunostomy) with gastroenterostomy (BIllroth 2 or Roux en Y) for pancreaticoduondectomyhigh MM
methods for pancreatic drainage in cases of abscesses and/or cysts
- US guided percutaneous aspiration/drainage2. open abdominal drainage (for severe pancreatitis)3. closed section JP drain4. omentalization
define acute, recurrent and chronic pancreatitis
acute–sudden and reversiblerecurrent–repeated episodes, no permanent histological changechronic–continuous, may be subclinical at times, irreversible histologic changes (seen in cats with IBD and cholangitis–triaditis)
comparison of SN of diagnostic testing for pancreatitis
most SN–serum cPLI (82% dogs) and semiquantitativeleast SN–serum cTLIcTLI < lipase < ab US < cPLI
hallmark clinical sign of pancreatitis
vomiting in dogs!only 40% cats with pancreatitis vomit (most cats were anorexic)
minimum data base abnormalities in dogs with pancreatitis
–dehydration (incr HCT/TP)–azotemia (prerenal or AKI)–hyperbilirubinemia (EHBO)–increased liver enzymes (EHBO or severe liver dz)–hypercholesterolemia/hyperTG–hypoCa (saponification of fat)–hyperglycemia (necrotizing pancreatitis–incr cortisol–incr glucagon from pancreas)–incr amylase/lipase (NOT pancreatic specific, can incr with decr GFR)–TLI (SN/SP for EPI but NOT pancreatitis)–cPLI most SN 82% dog 100% cats with sever disease but only 50% in cats with mild dz
Thompson et al JVECCS 2009surgical outcome of pancreatitis patients
overall 63% survival80% survival if EHBO with cholecystoenterostomy64% survival if necrosectomy40% survival is pancreatic abscess
pancreatic abscess
–most often sterile (take multiple samples from pancreas–15% and ab cavity–60%)–most common sequel following pancreatitissurgery–debride +/- partial pancreatectomy or duodenal R&A +/- cholecystoenterostomy if EHBO severe/irreversible–drainage and/or omentalizationprognosis poor (50% survive range 14-60%)
pancreatic pseudocyts
nonepith lined fibrous sac; usually sterilemajority in LEFT limb if small—monitor with serial ab USFNA US guided aspiratesurgery drainage: omentalization, cystoduodenostomy, cystojejunostomy, or complete excisiongood prognosis
most common tumor of the exocrine vs endocrine pancreas
exocrine—carcinomaendocrine–insulinoma (beta cell tumor)–60% of which are M carcinoma
serum lipas and pancreatic carcinoma
serum lipase»_space;25 times the upper limit is suggestive of pancreatic carcinomaextremely poor px
% of dogs with insulinoma have mets at the time of diagnosis
50% (detected via histopath) but suspected to be 100%biopsy LN and liver
diagnostic testing for insulinoma
presence of insulin or hyperinsulinemia in presence of hypoglycemia < 60 serum insulin to blood glucose ratio > 30(insulin x 10)/(glucose -30)decreased fructosamine
solitary nodule in pancreas is seen in how many insulinoma patients
80% solitary20% multiple nodulesvery few are diffusemost often in right (35%)or left (44%) limbs»_space; pancreatic body (14%)
methods to find pancreatic nodule intraoperatively
–intraoperative ultrasonography–sterile methylene blue 3 mg/kg diluted in 250 ml saline given over 30 min (acute renal failure, heinz body anemia)–biopsy left limb (majority of nodules 44%)
medical treatment for persistent or recurrent hypoglycemia in cases of insulinoma
–streptozocin: nitrosurea Ab, destroys B cells, nephrotoxic(maintains euglycemia 163 days)–prednisone and diazoxide: inhibits insulin, stimulates hepatic GNG–Octreotide: somatostatin analogue to bind receptors and inhibit insulin synthesis and secretion
T/FLonger survival times are seen in dogs treated surgically for insulinoma regardless of mets and complete excision
TRUEsurgery is palliative and reduces tumor burden which improves survival381 days with surgery74 days without surgery(surgery improves medical therapy)
MST insulinomas undergoing partial pancreaticetomy
12 monthsmay be less if mets present at time of surgery
main negative prognostic indicator for insulinomas
post op hypoglycemia
Polton et al 2007 JSAP MST insulinoma with surgery alone and surgery with med rx
surgery alone 785 dayssurgery + rx 1300 dayssmall numbersand may represent earlier diagnosis and intervention
Gastrinomas
pancreatic islet cell tumors that secrete excessive gastrin—results in gastric acid hyper secretiontumors can arise in pancreas or duodenummets 70%
define Zollinger–Ellison sydrome
NON beta cell islet tumorhypergastrinemiagastrointestinal ulceration
