Gastrointestinal Flashcards
The major and minor duodenal papilla are the openings for what?
Major: Bile and pancreatic ducts Minor: Accessory pancreatic duct
What provides the blood supply to the ileum? a) Cecocolic artery b) Ileocecal artery c) Caudal mesenteric artery d) Cranial mesenteric artery
b) Ileocecal artery NB. It is a branch of the cranial mesenteric artery
Which cell type makes up the majority of small intestinal epithelium? a) Paneth cells b) Goblet cells c) Columnar absorptive cells/enterocytes d) Enteroendocrine cells
c) Columnar absorptive cells/enterocytes
What cells are the pacemakers of the intestine?
Interstitial cells of Cajal (ICCs)
Which option correctly matches the phase of activity with the type of activity of small intestinal motility? a) I: NSA, II: ISA, III: RSA b) I: ISA, II: NSA, III: RSA c) I: RSA, II: ISA, III: NSA d) I: RSA, II: NSA, III, ISA
a) I: NSA, II: ISA, III: RSA
What are the borders of the epiploic foramen
Visceral surface of caudate process of liver (dorsal and craniodorsal) Portal vein (cranioventral) Gastropancreatic fold (ventral)
Describe the procedure for a functional end-to-end jejunojejunostomy
Bowel ends lined up in antiperistaltic fashion Stoma created with GIA along opposing surfaces Bowel ends closed
Mesenteric rents can be congenital in origin but what structure is the cause
Mesodiierticular band
The prognosis for mesenteric rents is lower than for other strangulating lesions. What are the reasons for this
- Inability to reduce hernia 2. Long segments of bowel involved 3. Haemorrhage from mesentery 4. Failure to close entire mesenteric defect
What is the difference between direct and indirect hernias
Indirect: Small intestine passes through naturally occurring ring (eg. vaginal ring) Direct: Small intestine passes through acquired defect in musculature
What are the risk factors for enteroliths
1.California, Florida, 2.Arabians, Morgans, American Saddlebreds, donkey and Minis 3. feeding alfalfa hay 4.
For how long should feed be withheld following a jejunocolostomy
36-48 hours
What is the mortality rate for large colon volvulus (according to Auer)
56-65% (although one study reported 84%
List the complications associated with large colon resection
- Perstent endotoxemia 2. Peritonitis (contamination or bowel) 3. Continued bowel devitalisation 4. Post-op pain 5. Post- op diarrhoea 6. Weight loss 7. Colon ileus 8. Haemorrhage
How should small colon enterotomy incisions be closed
2 layers Full thickness simple continuous Seromuscular inverting pattern 2-0 polyglactin 910 Careful not to invert too much
Describe the post-op care following esophagotomy
Withheld feed 48 hours (can be immediate if incision closed and separate esophagostomy tube placed) Small quantities pelleted feed over next 8 days Parenteral electrolytes - can as deficiencies can happen Attention to hydration status Will heal by first intention and intraluminal suture will slough within 60 days
List the options for fixing rectal tears
Indwelling rectal liner Loop Colostomy: Single incision - high flank/low flank/ventral midline. Double incision - high flank/ventral midline End Colostomy Direct suturing Medical treatment
Describe the mechanism of action of the following prokinetics: a. metoclopramide b. lidocaine c. erythromycin d. neostigmine
a. metoclopramide dopamine 1 (DA1) and 2 (DA2) receptor antagonism and through 5-HT 4-receptor (5-HT4) agonism and 5-HT3 receptor antagonism b. lidocaine - Basically a sodium channel blocker but Auer has a bunch of info: reducing the level of circulating catecholamines through inhibition of the sympathoadrenal response, (2) suppressing activity in the primary afferent neurons involved in re ex inhi- bition of gut motility, (3) stimulating smooth muscles directly, and (4) decreasing in ammation in the bowel wall through inhibition of prostaglandin synthesis, inhibition of granulocyte migration and their release of lysosomal enzymes and cyokines, and inhibition of free radical production. c. erythromycin motilin agonist that in u- ences motility partly by acting on motilin receptors on GI smooth muscles and motilin and/or 5-HT3 receptors to stimulate the release of acetylcholine. d. neostigmine cholinesterase inhibitor
List the grades of rectal tear and describe them. Also give the prognosis for each (based on the two papers mentioned in Auer)
I - mucosa and submucosa only 93% (medical) 100% (medical) II - muscular only (mucosa intact) 100% (medical) IIIa - mucosa, submucosa, muscular (serosa remaining) 70% (medical) 38% (medical) 81% (suturing) IIIb - tear into mesorectum or retroperitoneal tissues 69% (medical) IV - everything (communicates with abdomen) 6% (medical) 2% (medical) 50% (suturing)
Name the methods for repairing chronic incising hernias
Subperitoneal Mesh Placement with Fascial Overlay Subperitoneal Meach Placement with Hernial Ring Apposition Subcutaneous Mesh Placement with Hernial Ring Apposition Laparoscopic Intraperitoneal Mesh Onlay
What mesh materials are available for repairing incisional hernias
Knit polypropylene mesh (Marlex): Strong, elastic, inert, resists infection Coated polyester (Mersilene) Polyglactin 910 Absorbable mesh; may not need to be removed, even if infection
What suture size, type and patterns would be used to close umbilical hernias in foals
Simple continuous appositional pattern recommended using appropriate size (USP 1,2,3) absorbable, monofilament suture
What are the predisposing factors for prepubic tendon rupture
Hydrops allantois Hydrops amnions Trauma Twins Fetal gaints Normal pregnancy Draft breeds Older mares
What material, patter, bite size, etc is used to repair acute total dehiscence of an abdominal incision
Monofilament stainless steel wire Through and through interrupted vertical mattress pattern Sutures 2-3cm apart Suture through skin, fascia, rectum abdominal muscle 5cm from wound edge Hard rubber tubing used as stents Second bite 2.5cm from wound edge Preplace sutures and close by applying tension on all sutures Wires twisted Cut ends bent back into lumen of tubing Leave skin unsutured if infected
Name 2 drugs, their function and their doses that can be used to treat gastric ulcers
Histamine (H2) antagonists:
Ranitidine (6.6mg/kg PO q8hrs or 1.5-2mg/kg IV q6-8hrs)
Proton pump inhibitors:
Omeprazole (2-4mg/kg PO q24hrs)
What is the fancy term for migration of epithelium across gastric ulcers
Epithelial restitution
What methods can be used to treat gastric impactions
Medical:Nasogastric intubation:
Water
Reflux contents
Carbonated cola
Surgery:Infusion/Massage
Massage
Infuse impaction via insertion of needle adjacent to greater curvature
Infusion of balanced polytonic fluid
Gastronomy:
Pack of abdomen with towels
Incision parallel and caudal to attachment of omentum on greater curvature
Evacuate contents
Double layer inverting closure
Rarely necessary to open stomach
Describe the arterial supply and venous drainage of the spleen
Arterial supply:
Splenic artery (branch of celiac artery)
Within hilus
Branches to supply spleen and greater curvature of stomach
Venous drainage:
Affluent of portal vein
List the possible approaches for splenectomy
Left side. Standing or right lateral recumbency
Incision caudal to 18th rib in left paralumbar fossa:
Difficult to assess primary vessels
Between ribs 17-18
Resection of 18th/17th/16th rib
Removal of distal aspect of last 3 ribs
Removal of 17th and transecting of 16th and 18th ribs
Laparoscopic-assisted
Describe the ventrolateral approach to the oesophagus
GA, right lateral or dorsal recumbency or standing
Place feeding tube
5cm skin incision just ventral to jugular vein
Sternocephalicus and brachiocephalicus muscles separated
Deep cervical fascia incised to expose oesophagus
May be necessary to incise cutaneous colli muscles in distal cervical area
List the methods of treating oesophageal stricture
First 60 days:
Bougienage - not useful
Pneumostatic/hydrostatic dilators - no useful
Balloon dilation
Initially low-bulk diet, NSAIDs and antibiotics for first 60 days
Then surgical options:
Esophagomyotomy
Partial or complete resection and anastomosis
Patch grafting
What suture material/patterns should be used in an oesophageal resection and anastomosis
Submucosal layers apposed with 3-0 simple interrupted monofilament non absorbable polypropylene placed 3cm from cut edge, 2-3mm apart, with knots tied in lumen
Oesophageal muscle apposed with interrupted horizontal mattress sutures, 2-0 polydioxanone or monofilament non absorbable suture material (relief incision - circular myotome 4-5cm proximal or distal to anastomosis may help)
List the complications of oesophageal surgery
Dehiscence and stricture
Acid-base electrolyte alterations
Laryngeal hemiplegia
Carotid artery rupture
What are the 4 layers of the oesophagus
Tunica adventitia (fibrous layer)
Tunic muscular (muscular layers)
Tela submucosa (submucosal layer)
Tunica mucosa (mucous membrane)
How can you treat diastemata
Cleaning out periodontal pockets with diastema forceps, dental picks, long forceps or high pressure-pneumatic or water instruments and filling periodontal defects with antibiotics in plastic impression material
Use diastema burr to wide to 4-6mm (clear periodontal pockets and diastema for feed first). Stop burr at 5 second intervals. Spray water continuously. Remove more from rostral aspect of caudal tooth as pulp horns located towards caudal aspect of tooth
May require extraction of a displaced cheer tooth
Do not widen diastema in young horses
Name lots of methods of removing cheek teeth and which teeth they are appropriate for
Oral (anything)
Minimally invasive transbuccal (anything but more difficult caudally as may not be able to get sufficient angle)
Repulsion (any)
Lateral buccotomy (Upper 6,7,8; can also be used for lower 6,7,8)
How do you close a partial (decent size that needs repair but not needing partial glossecomy) thickness tongue laceration
GA/Standing and local
Debride
Lavage
Multi layer closure
Vertical mattress sutures replaced deep in muscular body of tongue with absorbable or non-absorbable size 0 or 1 monofilament suture
Buried rows of simple interrupted 2-0 to 0 monofilamter absorbable suture subsequently used to appose muscles, obliterating dead space
Vertical mattress sutures tied and lingual mucosa apposed with simple continuous or interrupted vertical matters sutures
What are sialoliths made of
Calcium carbonate and organic matter that develops within salivary duct (or a gland)
How do you treat a laceration of the parotid duct
Most close spontaneously in 1-3 weeks
Anastomosis techniques:
Suture over intraluminal tube
Three sutures opposing two cut ends as a triangle and suturing between apices
(Size 2 nylon threaded normograde through distal laceration; guide tubing over nylon to cannulate duct before suturing)
Use 4-0 to 7-0 absorbable or non-absorbable suture in simple interrupted pattern
Leave tube in place while duct heals
If only one side lacerated, do not need to leave tube in place after closing defect
If anastomosis not possible, interposition polytetrafluoroethylene tube graft may restore duct continuity
Can create fistula from duct to oral cavity proximal to injury
Duct translocation
Surgical removal of gland, duct ligation or chemical ablation of gland
What are the normal peritoneal fluid values day 6 post-op?
40,000 WBC/ml; 6g/dL TP
What are the normal peritoneal fluid values day 4 post-op?
200,000WBC/ml
What are the most common organisms found in septic peritonitis?
Streptococcus
Rhodococcus equi
Esherichia coli
Staphylococcus
Bacteriodes (anerobic)
Clostridium (anerobic)
Fusobacterium (anerobic)
In what percentage of cases does recurrences of a right dorsal displacement of the large colon occur?
15%
What are the predisposing and protective factors for incisional complication?
Predisposing factors:
Repeat laparotomy
Increased duration of surgery
Use of near-far-far-near
Chromic catgut
Leukopenia
Incisional edema
Post-operative pain
>300kg weight
>1 year age
Staple
Closure by less experienced surgeons
Protective factors:
Abdominal bandage
Short surgery time
Adequate draping
Isolating enterotomy incision
Minimize trauma to incision during exploration
Minimally reactive suture material
Do not take overly large bites
Avoid excessive force when tightening sutures
List the uses of buscopan
Anti-spasmodic for colic
Choke
Rectal exam
Uterine movement during pregnancy
What side effect of buscopan may affect monitoring for colic/pain
Increases heart rate
Which laxative is anionic?
DSS
Which laxative can form an oil embolus when administered with mineral oil?
DSS
On incision, the oesophagus separates into 2 layers, what is in each layer?
Mucosa and submucosa:
Inner
Elastic
Muscular layer and adventitia:
Outer
Inelastic
Describe the arterial blood supply to the oesophagus
Cervial part:
Carotid arteries
Thoracic/abdominal part:
Bronchoesophageal and gastric arteries
Vascular pattern arcuate but segmental
Minimal collateral circulation (preservation of vessels important)
Describe the ventral approach to the oesophagus
GA, dorsal recumbency
10cm skin incision exposes 6cm esophagus
Skin and subQ fascia divided used scalpel blade
Paired steronothyroid, sternohyoid and omohyoid muscles are separated along midline to expose trachea
Blunt separation of fascia on left side of trachea permits identification of esophagus containing NG tube
Retract trachea to right
Gentle sharp dissection of overlying loose adnentitia to expose ventral wall of esophagus
List the possible diagnostic tests for choke (even the funky tests)
Clinical exam
Palpation
Ultrasound
Radiography
Contrast radiography
Negative/double positive contrast radiography
Bloodwork: WBC, electrolytes, hydration
Cineradiogrpahy
Electromyography
Manometric evaluation
Functionally distinct regions:
Cranial esophageal sphincter
Caudal esophageal sphincter
Fast (cranial 2/3)
Slow (caudal 1/3)
What drugs does Auer like to use for choke?
Atropinization (0.02mg/kg)
Acepromazine
Oxytocin (0.11 and 0.2IU/kg)
Xylazine
The left carotid sheath is super close to the oesophagus - what structures does it contain?
Carotid artery, vagus and recurrent largngeal nerves
Describe the procedure for a cervical esophagostomy
Lateral recumbency and GA or standing and local anesthesia
Pass NG tube
Skin over left jugular furrow prepped (can occasioanlly be right)
5cm skin incision ventral to jugular vein
Esophagus sharply incised lonitudinally for 3cm down to indwelling NG tube
NG tube removed and polyethylene NG tube (outer diameter 14-24mm) placed into stomach (make sure placed through both layers of esophagus)
Place sutures in mucosa to form a seal around tube (likely unncessary as saliva will still leak)
Secure tube firmly with butterfly tape bandages sutured to skin, then elastic tape bandages
Large diameter tubes preferred
Cap tube between feedings; flush with water at end of each feeding
Tube should remain in place for minimum of 7-10 days to allow stoma to form (longer if in area of rupture or perforation)
Can feed normally when tube removed
Large portion of swallowed feed lost through stoma when fed from ground (feed a withers height)
Stoma heals spontaneously
Fistula formation rare
Complications:Fatal infection:
Drain and infection early
ABs for 7-10 days, until mature stoma develops
What do I cells release and what does it do?
Cholecystokinin (CCK): Released in response to protein and fat in duodenum. Stimulates pancreas to secrete amylase, lipase, trypsin, chymotrypsin, carboxypeptidase, elastase and colipase.
What is the effect of high Mg on Ca absorption?
Decreases Ca absorption
Describe the neural stimulation of motility of the small intestine
Vagus nerve, components of sympathetic NS, enteric NS
Enteric NS: ganglia in myenteric (Auerbach) plexus and submucosal (Meissner) plexus - independent of CNS
Myenteric neurone: innervate longitudinal muscle and outer lamella of circular muscle
Submucosal neurons innervate inner lamella of circular muscle
Apart from WBC and TP, which 6 factors in peritoneal fluid have a strong correlation with a strangulating lesion?
Gross appearance
Peritoneal chloride
pH
Lactate (peritoneal better than blood; also good for prognosis)
Myeloperoxidase (MPO) - potentially useful to indicate neutrophil activation
D-dimer concentration - potentially for fibrinolytic activity
What 4 issues in the GI tract can Parascaris equorum lead to?
Obstruction
Intussusception
Abscesation
Rupture
What is a Littre hernia?
Protrusion of a Meckel diverticulum through a potential abdominal opening
What is a Richter hernia?
Antimesenteric wall of intestine protrudes through defect in abdominal wall
Between which bands (for the cecum and colon) do you perform a cecocolic anastomosis
CCA between dorsal and lateral bands of cecum and lateral and medial free bands of RVC
List the causes of cecocecal or cecocolic intussusception
Dietary changes
Cecal wall abscess
Salmonella
Eimeria leuckarti
Strongulus vulgaris arteritis
Organophosphate exposure
Parasympathomimetic drugs,
Tapeworm
What type of laxative is Polyethylene glycol 3350?
Osmotic laxative
What is DCAB? What is the equation to calculate it and what is the target in horses?
Dietary cation anion balance (DCAB)
Target DCAB +200-300 mEq/kg
Grass hay/cereal grains ok
Not alfalfa - important in enterolith formation
List the Ddx for meconium impaction
Bladder rupture
Atresia colic
Ileocolonic aganglionosis
Enteritis
List the factors that predispose to post-op ileus
Intestinal ischemia
Distention
Peritonitis
Electrolyte imbalances
Endotoxemia
Traumatic handling of intestine
R&A
Anesthesia
>10yrs
Arabian
PCV>45%
High serum protein and albumin
Elevated serum glucose
>8L reflux at admission
Anesthesia >2.5hrs
Surgery >2yrs
High pulse rate
Strangulating lesions of SI and ascending colon
Length of SI resection
Obstruciton of SI
Ischemic SI
List 2 factors that protect against post-op ileus (presuming the horse had SI surgery)
Pelvic flexure enterotomy
Intra-operative lidocaine
What is the mechanism of action of bethanecol
Muscarinic cholinergic agonist
Stimulate Ach (M3 and M2) recetors at level of myenteric plexus
Affects duodenum, jejunum, cecum emptying, pelvic flexure, gastric emptying
List the complications that can occur with abdominal drain placement
Partial obstruction of drain (26%)
Leakage of fluid around drain (16%)
Subcutaneous fluid accumulation (12%)
I guess peritonitis too but not listed in Auer
