95.Liver_biliary Flashcards
pringle manuever
20 minutes occlusion of hepatic artery and portal veinfinger in epiploic foramen(dorsal–CVC, ventral–PV, cranial–liver, caudal–hepatic artery)
blood supply to liver
hepatic artery (br celiac artery): 20% blood 50% oxygenportal vein: 80% blood 50% oxygen
where does the cystic artery arise from
branch of the left branch of the hepatic artery
most proximal draining veins into the portal vein prior to liver branching (prehepatically)
splenic veingastroduodenal vein (most proximal–absent in cats)
T/Fthe most cranial hepatic vein entering the caudal vena cava arises from the left hepatic lobe
TRUEleft branches are the most cranial, then central branches and then the most caudal are right branches located within the parenchyma
lobes of the liver
6 lobesleft medialleft lateralright medialright lateralcaudate —caudate and papillary processesquadrate
biliary flow
canaliculiinterlobular ductslobar ductshepatic ducts (2-8)CBD*at the point where the first hepatic duct meets the cystic duct= CBDenter at major duodenal papilla, sphincter of Oddi (adjacent to but not conjoined to pancreatic duct—conjoined in cats)80% cats do NOT have minor duodenal papilla for accessory pancreatic duct
functions of liver (6)
dysfxn occurs with 70-80% loss of liver–protein synthesis (20% of TP)–CHO metabolism (glucose homeostasis)–Lipid metabolism (makes cholesterol, stores fat in the form of TG from free FA)–immune system:reticuloendothelial phagocytic function of harmful substances, Kuppfer cells (macros)–all coag factors including vit K dependent factors 2, 7, 9, 10 (liver does not make VIII, vWF) and vit K, TPO, fibrinogen–bile production: made up of bile acids, bilirubin (80% from Hb), cholesterol, phospholipids, water, bicarb, ions
physiology of Hb breakdown
reticuloendothelial function of liver (extravascular) breakdown of Hb–bilirubin is bound to alb and taken to liver–conjugated in liver to glucuronic acid and secreted into bile –combine with bile acids (taurine–cats, taurine or glycine–dogs WITH cholesterol)–conjugated bili and bile acids travel to GB for storage–SI stimulated release of CCK causes GB to contract and sphincter of Oddi to relax–bile salts emulsify fats (miscelle formation) and bind endotoxin to prevent their absorption–bilirubin is degraded to urobilinogen by bacT–urobilinogen is converted to urobilin or stercobilin (brwn color feces)–90% passage in feces; 10% re-circulation within portal system
regenerative capacity of liver
incredible regenerative capacity–begins within hours and peaks at 3 daystolerates removal of 65-70%BUT NOT >80%compensatory hypertrophy and hyperplasiahepatic arterial buffer response–change in portal pressure with massive resection will increase hepatic arterial perfusion (portal vein embolization can increase liver volumes 25-30%)cytokines also enhance regeneration (insulin, estrogen, growth factors, PG, etc)
factors that impede liver regeneration
diabetes mellitus (decr insulin which is a major hepatotrophic hormone)male genderbile obstruction agemalnutrition
common location of trauma biliary tract rupture
–CBD (body)–hepatic ductsRARELY from GB itself
most common causes of EHBO in dogs
–GB mucocele–pancreatitis–neoplasia–cholangitis–cholelithiasis(can also have FB or mass in duodenum)
most common causes of EHBO in cats
–complex inflammatory dz (pancreatitis,cholangiohepatitis, cholecystitis with or without stones)–neoplasia(less common: parasites–flukes, diaphragmatic hernia)
after acute ligation of CBD in dogs, how long does it take for dilation to occur
dilation of CBD occurs within 24-48 hrs (along with an increase in serum bilirubin)dilation of lobar/interlobular ducts takes 4-6 days
pathophysiologic consequences of EHBO
absence of bile salts in SI leads to increase bacT overgrowth and endotoxin absorption, impaired clearance of endotoxin through RE system of liver so systemic endotoxemia ensues–hypotension–coagulopathy (DIC)–GI bleeding (endotoxemia related gastric ischemia and incr acid production)–delayed wound healing (decr fibroplasia/angiogenesis)–decreased myocardial contractility –acute renal failure (endotoxemic = renal vasoconstrictor, acute tubular necrosis)
bile peritonitis causes in dogs
–trauma–necrotizing cholecystitis–ruptured GB mucoceleRARE in cats –think traumacan also have a proximal duodenal perf with bile peritonitis if near major duodenal papillabilirubin in ab fluid 2x > peripheral blood bilirubin
pathophysiology bile peritonitis
bile salts are hyperosmolar in ab cavity (fluid shifts)inflammation, necrosis, hemolysis occurnormally sterile but can have bacT from ascending GI, colonization of liver bacT, bacT translocation, or from direct inoculation with penetrating injury septic biliary effusions greatly worsen px
T/Fwhen bile salts are not present in SI to bind endotoxin, systemic endotoxemia may develop
TRUEin the GI, bile salts emulsify fats (miscelle formation) and bind endotoxin to prevent their absorptionwhen they are not available INCR bacT and INCR endotoxin
hepatobiliary imaging
–survey rads (not SN/SP: mineralization (may be incidental, gas, liver size, mass effect, stones)–ab US (FNA, biopsy, centesis, color flow doppler, contrast enhanced harmonic US w gas microbubbles)–hepatobiliary scintigraphy (quantifies liver function; technetium iminodiacetic acid accumulate within biliary tract; if not seen in SI in 3 hours== EHBO; limitation of mechanical vs functional obstruction and location)–CT/MRI–Endoscopic retrograde cholangiopancreatography (ERCP)–contrast, stone removal or stent placement
cholelithiasis composition in dogs and cats
50% opaque dogs (calcium bilirubinate)80% opaque cats (calcium carbonate)usually found near major duodenal papilla–can do sphincterotomycholecystectomy preferred after retrograde flushing stone back into GB and ensuring patency (recurrence is not reported if GB removed)other options (especially if CBD is not patent): cholodochotomy (dehisce! and stricture) or cholecystoenterostomy (recurrence seen)
normal CBD diameter on ab US
CBD normal diameter dogs and cats 3-4 mm
typical US appearance of GB mucocele
immobile stellate or finely striated GBkiwi fruit
method to monitor EHBO with serial ab US
can give synthetic CCK (sincalide) IVnormally, GB should empty 40% within 1 hrEHBO if empty <20%
coagulation testing of liver patients prior to surgery
CBC (blood smear, platelets), Chem, UAcoag panel (PT, aPTT, ACT)PIVKA (most SN)blood type cross match57% dogs with confirmed liver disease will have at least one abN coagulation parameterMayhew it al 2013 TEG for EHBO suggest HYPERCOAGincreased tendency for hemorrhage in dogs with natural liver disease has not been demonstrated
surgical liver cultures
sx and lap liver cultures had sign more positive results than percutaneous needle biopsyintraop biliary culture was significantly more likely to have positive culture than liver culture (30 vs 7%)Ab recommendations1. fluoroquin, penicillin, metro2. fluoroquin, amoxi-clav3. fluoroquin, clindamycin
methods to control extensive hemorrhage during liver surgery
maintenance of CVP < 5 cm H20 is essential for minimizing blood loss1. inflow occlusion–Pringle Manuever (hepatic artery and portal vein 20 min occlusion)–dogs have less collateral circulation than humans2. total hepatic vascular exclusion–simultaneous occlusion of cranial and caudal VC–with concurrent inflow (hepatic artery and portal vein) occlusion–dramatically reduces cardiac preload; brief occlusion only3. hepatic artery ligation–supplies only 20% to liver but generally it is the major (95%) supply to liver tumor–give ANTIBIOTICS–attempt to ligate lobar arteries if possible–consider cholecystectomy–ensure portal vein flow
overall agreement with FNA and histopath of liver lesions in dogs and cats
dogs 30%cats 50%
liver biopsy
punch biopsies bleed the mostligature and harmonic scalpel may bleed the least(other options: lap biopsy forceps, lap endoloop or extracorporeal loop ligature, biopsy needle/Trucut, vessel sealing device)obtain enough for histopathology, culture, and toxicology
methods of exposure for partial or complete liver resection
- midline celiotomy—may extend into caudal thorax/median sternotomy2. puncture the diaphragm3. lap sponges btwn diaphragm and liver lobes to retract caudally4. cut triangular ligaments5. paracostal incision
contributions of liver volume from each lobe
tolerate 65-70% resectionright lateral and caudate make up 28%right medial and quadrate make up 28%left lateral and left medial make up 44%
methods of regional tumor control for diffuse or metastatic or not amenable to surgery tumors
percutaneous ablation techniques1. radiofrequency ablation2. microwave ablation3. laser thermal ablation4. cryoablation5. ethanol ablationintravascular tumor embolization/chemoembolizationintra-arterial (lesional) chemotherapy
when is clinical icterus present
with serum bilirubin >1.5-2.0 mg/dL
preparation of hepatic patient for liver surgery
–fluids–vitamin K 1-2 mg/kg SQ q 12 hr–FFP, whole blood, pRBC if needed–Ab perioperatively–GI protectants +/-(based on prep PE, imaging, and bloodwork/coag panel/blood typing)
surgical decision making for extra hepatic biliary tree
–check patency (normograde or retrograde* choledochal flushing)–if NOT patent: reroute: cholecystoduodenostomy* (preferred), cholecystojejunostomy (suture or EndoGIA)–if PATENT and potential reversible disease (pancreatitis, cholangitis, +/- trauma to CBD) or palliation for malignancy: stent or cholecystotomy tube–if PATENT but NOT reversible disease (stones, neoplasia, GB mucocele, trauma to GB, necrosis of GB): cholecystectomy (open, laparoscopic)
T/Fdiversion of bile from the duodenum (as with cholecystojejunostomy) can lead to duodenal ulceration in dogs
TRUEwithout bile in duodenum, duodenal ulcers occurnormally when bile is present in SI, gastric acid secretion is inhibitedif bile is gone and inhibitory feedback is loss, gastric over secretion may occur leading to ulcer formation in the duodenum
stoma size created during a cholecystoenterostomy
antimesenteric SI incision with longitudinal incision in GBcreate stoma as long as possiblesmall stomas < 2.5 cm may predispose to obstruction and stricture formationeach side is sutured with simple continuous single layer+/- apical suture at each end to relieve tension3-0- 4-0 monofilament absorbable(double layer may invert and decrease lumen–stricture)
possible complications following rerouting cholecystostomy
–hemorrhage–gastric/duodenal ulceration–stricture–re-obstruction–dehiscence/bile peritonitis–ascending cholangiohepatitis
most common indication for surgery management of EHBO in dogs
GB mucocele–cystic mucosal hyperplasia and hypersecretionshetland sheepdogs (GB disease) predispositionhypoT (14% vs 5%)hyperadrenocorticism (risk 29x GB mucocele–21% vs 2%)cholecystectomy (check patency first!)
ab US sensitivity for detecting GB rupture
86%
medical mgmt for GB mucocele
- ursodial: choleretic, immunomodulatory2. S-adenosyl-L-methionine (SAM-e): anti-inflammatory, antioxidant3. famotidine: H2 receptor antagonist4. vitamin E: antioxidant, anti-inflammatory 5. Silymarin (milk thistle): anti-oxidant, choleretic, antifibrotic/anti-inflammatory
complications following cholecystectomy for GB mucocele removal
- leakage/peritonitis2. pancreatitis3. reobstruction if congealed bile in CBD
prognosis following cholecystectomy for GB mucocele
Worley et al JAVMA 2004 (22 dogs)70% survivalPike et al JAVMA 2004 (30 dogs)22% mortality (80% survival)GB rupture was NOT associated with increased mortality
what constitutes “triaditis” in cats
–IBD–pancreatitis–cholecystitis
4 types of primary hepatobiliary tumors
- hepatocellular adenomas and adenocarcinomas (massive, nodular, diffuse)2. cholangiocellular adenomas and adenocarcinomas3. neuroendocrine carcinomas (aggressive, diffuse, poor px)4. mesenchymal (HSA, leiomyosarcoma, OSA, FSA): poor px(mets to liver are more common than primary liver tumor #1 hematopoetic/lymphoid #2 epithelial/mesenchymal)
paraneoplastic condition related to variety of hepatic neoplasms
hypoglycemia
T/Fcorrelation with ultrasound live appearance and tissue histopathology is poor
TRUEways to enhance correlation:contrast enhanced harmonic US (microgas bubble)MRI
hemorrhage/hematoma formation complication rate following percutaneous needle core liver biopsy
<6%
T/Flaparoscopic liver biopsy contains fewer portal triads and hepatic lobules than traditional open technique
true
most common hepatocellular liver tumor in dogs
hepatocellular carcinoma 70%; 30% adenomas)–massive (60%)–usually L sided; favorable px with resection; MST 1400d–nodular (30%)–higher met rate–diffuse (10%)–higher met rate
prognosis with liver resection and massive hepatocellular carcinoma according to Liptak 2004 JAVMA 48 cases
1400 days MSTperiop mortality 5%poor px associated with R sided tumors NOT with incomplete resection (10%)
T/Fin cats, hepatocellular adenomas is more comma than hepatocellular carcinomas
truein cats, bile duct tumors are the most common primary hepatic neoplasm–benign cyst adenomas (good px) are TWICE as common as bile duct carcinomas (100% mortality)
