Principles of GI Surgery 1 + 2 Flashcards
For what 2 reasons would GI surgery be performed?
- DIsease of the wall of the GI tract
- Partial/complete obstruction of the GI tract
Of what clinical significance are the GI lesions wrt surgery?
Dependent on location may compromise fitness for aneasthesia
- Gastric disease may -> gastric vomiting
- SI complete obstruction may -> acute vomiting
- SI partial obstruction may -> chronic VD and weight loss
- GI bleeding may -> heamatemesis, meleana
How may gastric disease and vomiting comproise the animal pre-surgery?
- Loss of HCl -> metabolic alkalosis and hypochlorinaemia
- Dehydration -> poor perfusion and metabolic acidoisis
- insufficient food intake -> hypokalaemia
How may complications from gastric vomiting be corrected prior to surgery?
IV isotonic crystalloids, IV K+ supplement (sometimes)
How may SI complete obstruction and vomiting compromise the animal pre-surgery? What is this dependent on?
Dependent on location of obstruction
- high = mimics gastric vomiting
- low = loss of pancreatic Na+, HCO3- -> metabolic acidosis and hyponatraemia
> dehydration -> poor perfusion and metabolic acidosis
> Insufficient food intake and absorption -> hypokalaemia
How may complications from complete SI blockage be corrected prior to surgery?
IV isotonic crystalloids, IV K+ supplements
How may SI partial obstruction (VD and weightloss) compromise an animal pre-surgery?
- Vomiting -> electrolyte loss and dehydration
- Bacterial proliferation and nutrient metabolism -> malassimilation and mucosal damage -> diarrhoea, weight loss, hypoalbumenaemia
How may complications from partial SI blockage be corrected prior to surgery?
IV isotonic crystalloids, IV K+ supplementation, hypoalbumenaemia cannot be corrected but normotensive state should be maintained
How may GI bleeding (-> heamatemesis and meleana) compromise an animal prior to surgery?
-> anaemia and hypoalbumenaemia
How may GI bleeding be corrected prior to surgery?
Blood transfusion, Fe supplements
What should especially be noted on the physical exam prior to anaesthesia and surgery?
Dehydration status - if in doubt, IV fluid therapy!
What should be checked to determine that the animal is fit enough for surgery?
- complete history
- physcial exam
- heamatocrit and TP
- electrolytes esp K+ Na+
- acid base status
- complete biochem/heamatology IF CLINICALLY INDICATED ONLY
How does the distribution of GI bacteria differ along the GI tract?
- V in stomach (acid kills majority of bacteria)
- SI: 10^2 - 10^6 CFU/ml, 50% anaerobes
- Colon: 10^9 - 10^11 CFU/ml, 80% anaerobes
Which organism is responsible for the majority of post-surgical infection? What type of organism is this?
E coli - Gram -ve rod
For what reasons are use of prophylactic antibiotics encouraged for GI surgery?
- immune defences may be compromised (debilitated animals eg. VD+, GI injury, extensive resections, >90min surgeries)
- septic peritonitis fatal in 50% cases
> indicated for use in ALL SI and Colon surgeries
For what reasons may prophylactic antibiotics be discouraged?
- animals have an immune system
- although contamination is inevitable, will not definitely progress to an infection
- antibiotics may NOT v risk of infection
> not indicated for use in stomach surgery if no prior pathology is present (eg. FB removal)
What classes of antibiotics would be indicated for use in gastric surgery (IF indicated)? eg.?
Single broad spec with anaerobic coverage
eg. 2nd generation cephalosporin OR amoxycillin clavulanate
What classes of antibiotics would be indicated for use in SI surgery (IF indicated)? eg.?
Single broad spec with anaerobic coverage
eg. 2nd generation cephalosporin OR amoxycillin clavulanate
What classes of antibiotics would be indicated for use in colon surgery (IF indicated)? eg.?
Combination of 2 antibiotics, including an anaerobe specific drug
eg. Metronidazole PLUS 2nd gen cephalosporin or amoxycillin clavulanate
Other than ABs, how may bacterial contamination be minimised (5 ways)?
- Isolate site of GI entry
- Use separate instruments for contaminate surgery
- Lavage abdomen with sterile saline (dilutes conc of bacteria)
- Change gloves
- Lavage wound after closure
How may the colon be prepared for surgery? How does this differ to human medicine?
- Humans routinely enema-ed prior to surgery
- No evidence to support this in vet (liquid ^ likelihood of leaking through incision site)
- Low residue diet and 12-24hr starvation recommended only
Outline the layers of the intestinal wall. Which is strongest and why?
Adluminal: Mucosa - submucosa - muscularis (circular) - muscularis (longitudinal) - serosa(sub) - serosa :Outside edge
> Submucosa strongest due to collagen so MUST BE SUTURED
What stages of wound healing are solely active during days 1-3? How long do these continue?
Heamostasis (formation of platelet-fibrin clot) and inflammation (microbial killing and wound debridement)
- will continue until day 5
What stage of wound healing begins on day 3?
Proliferation of granulation tissue (fibroblast^, collagen synthesis, angiogenesis -> ^ wound strength)