Principles of Small Mammal GI Surgery Flashcards
How do you determine if an animal is fit for anesthesia and surgery?
Obtain complete history, complete PE, Check HCT/TP, Check electrolytes (K and Na), Check acid-base status, Complete hematology and biochemistry (if clinically indicated)
Why might an animal present for GI surgery?
Disease of wall or structures of GIT
Partial or complete obstruction of GIT
What effect does gastric vomiting have in a patient that is important to consider pre-sx? How do you correct this prior to sx?
Loss of gastric HCl = metabolic alkalosis, hypochloremia, decreased Cl
Dehydration = poor tissue perfusion, metabolic acidosis
Insufficient food intake = hypokalemia
Correct this by administering IV fluids (replacing electrolytes) and IV K+ supplement as body cannot autocorrect potassium deficiency
What is the difference between high and low small intestinal complete obstruction?
High intestinal obstruction - mimics gastric vomiting = loss of HCL –> Metabolic alkalosis –> Hypochloremia
Low intestinal obstruction - Loss of pancreatic sodium, HCO3-, Metabolic acidosis, decrease in Na
What are the effects of small intestinal complete obstruction? How do you correct these effects prior to surgery?
Dehydration = poor tissue perfusion
Obstruction in jejunum leads to lack of digestive enzymes, which leads to metabolic acidosis
Insufficient food intake/decreased absorption = hypokalemia
Correct with IV fluids + supplement K+
What effects does small intestine PARTIAL obstruction have? How do you correct prior to surgery?
Chronic vomiting, diarrhea, weight loss
Bacterial proliferation and nutrient metabolism (maldigestion/malabsorption), Intestinal mucosal damage
Correct with IV fluids + supplement K+
What % anaerobic bacteria does the stomach vs. small intestine vs Colon contain? Which part of the GIT does E. coli commensally inhabit?
Stomach - acid kills most enteric bacteria
Small intestine - 10^2-10^9 units bacteria/ml (50% anaerobes)
Colon - 10^9 units bacteria/ml (79% anaerobes) - E.coli
In what % of cases is septic peritonitis fatal? What does this indicate in terms of prophylactic abx use?
50% of septic peritonitis cases are fatal
Prophylactic abx use most indicated when septic peritonitis risk is highest (large intestine/colon surgery, long surgical time, severe necrosis Ex. torsion/voluvulus)
Are antibiotics indicated in surgery of the stomach? If so, which abx is best to use and why?
Not always, if dog is healthy then no. If needed use single broad spectrum antibiotic with anaerobic coverage (Ex. 2nd generation cephalosporin or amoxy-clav)
Are antibiotics indicated in surgery of the small intestine? If so, which abx is best to use and why?
Antibiotics are always indicated (50% anaerobes)
Single broad spectrum antibiotic with anaerobic coverage (Ex. 2nd generation cephalosporin or amoxy-clav)
Are antibiotics indicated in surgery of the large intestine?
Surgery of the large intestine is not indicated in general, most surgery of colon is elective and requires extensive planning
What are some other methods you can use to decrease bacterial contamination during GI surgery?
Isolate GI site of entry
Use a separate set of instruments for contaminated part of Sx
Lavage GI wound after closure
Change gloves
Lavage abdomen with sterile saline
What questions should a surgeon be able to answer for a client about wound healing?
How quickly will a wound heal?
Is there a risk of wound breakdown?
Is there a higher risk in some animals compared to others?
How long is the strength of the wound dependent on the sutures or staples used to appose the wound edges?
Which layer of smooth muscle should ALWAYS be included when closing wound after GI surgery? Why?
Submucosa - strongest layer in intestinal wall due to high collagen content
Describe the 4 phases of intestinal wound healing (Days, Name of process, etc. )
Phase 1 - Hemostasis Days 1-4
Phase 2 - Microbial Killing and Wound debridement - Days 1-5
Phase 3 - Proliferation or Granulation Days - 3 weeks
- Fibroblast proliferation, collagen synthesis
(increase in wound strength), Angiogenesis
Phase 4 - Remodeling or Maturation weeks - years
During which days of intestinal wound healing is risk of wound breakdown the highest? Why?
Days 3-5 - Overlap between inflammation and proliferation, Fibrin clot formed during healing breaks down during proliferation/granulation phase, Presence of inflammatory enzymes counteract the buildup of collagen which creates instability
What is the rate of wound healing in stomach vs. small intestine vs. large intestine? Why?
In which of these locations is wound breakdown the highest risk?
Stomach - rapid healing due to abundant blood supply, healing rarely complicated
Small intestine - By day 14 ~50% normal tensile strength regained
Large intestine - By day 14 ~50% normal tensile stength regained, possibly increased collagenase production, risk of wound breakdown after surgery greatest in the colon
What should you consider prior to entering colon for surgery?
Consider if there is a real INDICATION for LI surgery prior to attempting
Why is a laparotomy better than surgery when it comes to large intestine foreign body?
Better to perform laparotomy and gently massage foreign body out of colon, but to never open up the colon (high risk of post-surgical infection)
Small intestine limiting factor to digestion of FB material (smaller luminal size than LI) so once FB is in the colon it will eventually come out, just might need to help it along
What are the factors which negatively impact wound healing? Why?
Compromise to blood supply - slower healing
Traumatic surgical technique - Ex. electrocautery (damaging to delicate intestines)
Hypoproteinemia - may delay fibroplasia, decrease wound strength, and produce edema
- can rarely be corrected prior to surgery
Chemotherapy/Radiotherapy - must delay chemo 3 wks post-surgery (immunosuppressive)
Steroids - immunosuppressive (discontinue steroid use when possible)
What are these 3 suture patterns?
Label these intestinal smooth muscle layers
Which suture pattern (inverted vs. everted) is preferred for keeping liquid contents IN?
Inverted (Lembert)
What is the preferred suture material filament type for GI surgery and why?
Monofilament - resistant to infection (preferred)
Multifilament - bacteria can get trapped between filaments
What do you need from suture material to compliment healing in the intestines?
Sutures must retain strength >5 days (must overcome overlap between inflammatory and proliferative phase)
Sutures must disappear after wound healing (absorbable)
Which 2 suture types are typically indicated in GI surgery and what are the differences in strength between them?
Monocryl - monofilament absorbable, loses 33% strength in 7 days
PDS II - monofilament absorbable, loses 26% strength in 14 days
- better for delayed wound healing (stays in longer) but not always necessary for every patient (can cause irritation in some patients)
What is the difference between suture and metal staples?
Staples are always permanent while sutures can be absorbable
What is ex-lap?
Exploratory laparotomy - direct visual and tactile examination of abdominal organs at surgery via incision into the abdomen
What are the indications for ex-lap?
To diagnose cause of intra-abdominal disease
To correct cause of intra-abdominal disease
Give some examples of situations when ex-lap would be indicated?
Dog with foreign body on x-ray
Animals with chronic intermittent vomiting and all other tests have not yielded diagnosis
Animal with suspected liver disease to obtain biopsy
Name these retractors
Label this stomach - What does the purple line indicate?
Purple line indicates where incision into the stomach should be made, away from major blood supply
Why is inverting lembert ideal for repair of stomach after GI surgery?
Inverting Lembert - prevents leakage of stomach contents
- Inverts lip of wound and never passes through submucosa, preventing passage of infection
Label this image of the large intestine
What is this (surgery of small intestine)? Where is it located in relation to SI?
What must you be careful not to do during surgery?
Pancreas! Its located in mesentery of duodenal loop and transverse colon and in greater omentum close to the stomach and spleen
Must be careful not to incise during surgery!
What does this purple arrow indicate and what is the importance of this structure?
Major duodenal papilla
Major and minor duodenal papilla have ducts coming into the tissue (important to remember when incising tissue in this area)
What is this? What are the predisposing causes for this condition?
What are the symptoms/signs?
What is the prognosis?
Intussusception
Predisposing factors:
Parasites, GI disorders which affect motility of the gut
Symptoms and signs:
Dehydration, Depression, Abdominal pain
Palpable tubular mass
Protrusion of intussusceptum from anus
Prognosis: good in healthy, young animals
- 6-27% recurrence 3 days - 3 weeks post-op
How do you correct luminal disparity in the small intestine?
Space sutures farther apart on large side
Transect the small side at an angle to match diameter of large side
Reduce large side with sutures
Spatulate small side
