Principles of small animal GIT surgery Flashcards
What are the consequences of gastric vomiting (3)? How is this corrected prior to surgery (2)?
- Loss of gastric HCl (metabolic alkalosis, hypochloraemia)
- Dehydration (poor tissue perfusion –> metabolic acidosis)
- Insufficient food intake
CORRECTION:
- IV isotonic crystalloids
- IV K+ supplementation
What are the consequences of SI complete obstruction induced acute vomiting (4)? How is this corrected prior to surgery (2)?
- High intestinal obstruction - mimics gastric V
- Low intestinal obstruction - loss of pancreatic Na, HCO3 leading to metabolic acidosis and decreased Na
- Dehydration - poor tissue perfusion causing metabolic acidosis
- Insufficient food intake and deceased absorption leading to hypokalaemia.
CORRECT:
- IV isotonic crystalloids
- IV K+ supplementation
What are the consequences of SI partial obstruction induced chronic vomiting, diarrhoea and wt loss (3)? How is this corrected prior to surgery (2)?
- V–> dehydration and electrolyte loss
- Bacterial proliferation and nutrient metab –>maldigestion, malabsorption, intetinal mucosal damage
- Diarrhoea, wt loss, hypoalbuminaemia
CORRECTION:
- IV isotonic crystalloids
- IV K+ supplementation (can’t correct hypoalbuminaemia but ensure normotensive)
What are the consequences of GIT bleeding causing haematemesis and melaena? (2) How is this corrected (2)?
- Anaemia - regenerative (acute bleeding) or non-regenerative (if blood loss is chronic as body loses ability to regenerate its RBCs)
- Hypoalbuminaemia
CORRECTION:
- Blood transfusion
- Iron supplementation
How do you check that an animal is fit for anaesthesia and surgery? (6)
- complete history
- complete PE
- check haematocrit and total protein (if anaemic)
- check electrolytes (K+ and Na+)
- check acid-base status
- complete haematology and biochem (if indicated)
How do the levels of bacteria within the GIT change? (2) Which bacteria most commonly causes infection after GIT surgery?
- Increased number and increased % of anaerobes the more caudally you travel
- E.coli
When might you want to use prophylactic ABs (2)? Why?
- When immune defences are compromised (debilitated animals from chronic V/D, GIT injury, extensive GIT resections, surgeries >90 minutes).
- Consider the location of the surgery (stomach - ABs aren’t necesarily indicated in healthy young dog. SI and LI - ABs are always indicated).
- Septic peritonitis is fatal in 50% cases
What prophylactic AB might you use when indicated for stomach surgery?
Single broad spectrum with anaerobic coverage e.g. 2nd generation cephalosporin OR amoxycillin-clavulante
What prophylactic AB might you use when indicated for SI surgery?
Single broad spectrum with anaerobic coverage e.g. 2nd generation cephalosporin OR amoxycillin-clavulante
What prophylactic AB might you use when indicated for LI surgery?
Combination of 2 ABs including and AB specifically targeted to anaerobes. e.g. Metronidazole PLUS 2nd generation cephalosporin OR amoxycillin-clavulante
How can you decrease bacterial contamination? (6) How is it different for the LI?
- ABs
- Isolate the site of GI entry (swabs)
- Use a separate set of instruments for contaminated part of surgery
- Lavage GI wounds post-closure
- Change gloves
- Lavage abdomen (sterile saline)
- In the LI, there is no veterinary evidence that mechanical preparation of the bowels (i.e. enemas) decreases contamination risk. Liquid faeces may be more likely to bypass atraumatic clamps and purse string sutures. A low residue diet and at least 12-24hr starvation is recommended.
What is the strongest layer in the GIT wall? Why?
Submucosa because high collagen content (despite this layer not being the thickest).
What are the stages of intestinal wound healing?
Haemostasis (d1-4), Inflammation (d1-5), Proliferation or granulation (day 3 - weeks), remodelling or maturation (weeks to years)
When When is the chance of wound breakdown greatest?
Overlap between inflammation and proliferation
How does the rate of wound healing change along the GIT?
Stomach - rapid healing (many BVs) so healing rarely complicated
SI - by d14, 75-80% normal tensile strength returned
LI- by d14, 50% normal tensile strength returned. May be that there is increased collagenase production. Be SURE there is a real indication for entering the colon before performing colonic surgery.
What impacts negatively on intestinal wound healing?
- Compromise to BV
- Traumatic surgical technique (avoid electrocautery)
- Hypoproteinaemia (rarely correctable prior to surgery)
- Chemotherapy and radiation (delay chemo for 3 weeks post-surgery)
- Steroids - discontinue steroid therapy where possible)
Which surgical tools can you use for the GIT? (3)
Atraumatic debakey forceps
Atraumatic bowel clamps
Stay sutures (to handle stomach/intestines)
DON’t use rat-tooth forceps
What are the aims of GIT sutures (2)? Which suture patterns do you use for GIT wounds (2)?
Aim = restore normal anatomy and promote rapid healing. SUTURE = full thickness appositional. 2 types = simple interrupted and simple continuous.
Which suture material would you use?
Monofilament - yes
Multifilament - no (multiple fibres intertwined means grooves may support bacterial infection).
Must retain strength long enough to permit healing (> or equal to 5d)
Disappear after wound healing (absorbable).
Monocryl - no - loses 33% strength in 7 days
PDS 2 - yes for GIT - loses 26 % strength in 14 d
What would a staggered row of titanium staples do in terms of repairing a GIT wound?
Cause eversion or invesion (depending on how stapled). Not appositional healing. But the bursting strength) potential for wound to break down) will be less with staples vs. sutures.
Name 2 indications for exploratory laparotomy. What should be done if no discrete lesion is found?
Diagnose cause of intra-abdominal disease. OR correct the cause of intra-abdominal disease.
Next step: biopsy (stomach, SI +/-liver/pancrease/any enlared LNs).
How does the surgical approach for exp. lap. differ between males and females?
Both along linea alba between xiphisternum adn pubis. In males you perform a para-preputial approach and cut through the preputial muscle.