Principles of SA GI surgery Flashcards
What are some of the problems associated with gastric vomiting and how can they be corrected prior to surgery?
Loss of HCl - metabolic alkylosis/hypochloreamia
Dehydration - poor perfusion, metabolic acidosis (lactic acid production due to poor perfusion anearobic metabolism)
Insufficient food intake - hypokaleamia
Isotonic fliud therapy/addition potassium
What are the additional complicaitons with a SI complete obstruction leading to acute vomiting?
May have the same problems as gastric vomiting if high up
Low intestinal obstruction may lead to pancreatic Na/HCO3- loss and therefore metabolic acidosis .
Dehydration
How do complications differ for chronic vomiting?
Dehydration/electrolyte loss severe
Diarrhoea - weight loss and hypoalbuminaemia
Bacterial proliferation - maldigestion/malabsorption
- mucosal damage
Can hypoalbuminaemia be corrected?
What can be done?
Not really unless the animal can eat protein as this is how the body gets albumin. Blood protein contributes to maintaining BP so this needs to be monitored and the animal can be made normotensive with IVFT.
If there is evidence of GI bleeding then what is a possible consequence and how can it be treated prior to surgery?
Aneamia - give blood transfusions or iron supplementation
How can an animal be assessed prior to surgery?
History
Physical exam - hydration status
Check Na and K + acid base status
CBC and Biochem only if clinically indicated
How does gut bacteria vary along the length of the GI tract?
Stomach - little/no anearobes
SI - 50% anearobes
LI - 79% anearobes
Is prophylactic antibiotic therapy always indicated prior to GI surgery?
In what animals is the risk of peritonitis increased?
No as most healthy dogs will have an immune system to deal with the bacteria.
Animals which are debilitated, have large gastric resections, have GI injury, have surgery >90 mins are at greater risk.
Bear in mind septic peritonitis has a 50% mortality rate!
When is prophylactic treatment always indicated? When is it not neccessary?
SI or LI surgery always indicated
Young, healthy dog with gastric FB it may not be needed.
What type of AB would one use for:
a) SI surgery?
b) LI surgery?
a) single broad spectrum with anearobic coverage
b) combination of 2 ABs with one specific to anearobes
- e.g. metronidazole + 2nd gen. cephalosporin / amoxycillin clavulante
How else can bacterial contamination be prevented during GI surgery?
Use moist swabs to isolate area of gut/prevent leakage
Seperate instruments/gloves for contaminated part
lavage wound after closure
lavage abdomen with sterile saline
How is the LI prepared prior to surgery in a VETERINARY environment?
Enemas rarely used as liquid faeces may bypass clamps and no evidence for efficacy in vet med.
Use low residue diet and starve 12-24hr prior to surgery.
What are the layers of the GI tract?
Mucosa, submucosa, muscularis (circular, longitudinal), serosa (subserosa & serosa)
Which layer is it important to go through when repairing?
The SUBMUCOSA
Outline how an intestinal wound heals.
Phase 1 - in days 1-4 a platelet-fibrin clot forms to elicit heamostasis
Phase 2 - in days 1-5 Inflammation for wound debridement and microbial killing
Phase 3 - day 3 to weeks is where proliferation or granulation occurs which includes collagen synthesis and angiogenesis
Phase 4 - remodelling weeks-years.
Which of the phases of wound healing is key to wound strength and therefore, when is a wound most likely to break down?
Phase 3 as collagen synthesis. The wound is most likely to break down in the overlap of inflammation and proliferation which is between 3-5 days.
Which part(s) of the GI tract take longest to heal/are most likely to break down?
The stomach heals quick and rarely breaks down. The SI is less quick and the LI is the least quick. Li has the most risk of breaking down.
ONLY ENTER THE LI IF ABSOLUTELY NECCESSARY!!
What impacts negatively on GI wound healing? How can these be minimised?
Compromised blood supply. Traumatic surgery -Avoid electrocautary -Atraumatic (doyens) clamps -Atraumatic forceps - Use stay sutures Hypoproteinaemia Chemotherapy/Radiotherapy - delay these 3w prior to surgery Steroids - discontinue use if possible.
What suture patterns should be used?
Full thickness appositional techniques:
-Simple interrupted & simple continuous
Which suture materials are best?
Monofilaments as they dont have grooves which are hiding places for bacteria. E.g. Monocryl and PDS II - PDS II is the best.
n.b. need to be absorbably and retain strength for >5 days