Flashcards in Principles of SA GI surgery Deck (52)
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 .
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?
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?
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.
-Atraumatic (doyens) clamps
- Use stay sutures
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
How do staples affect the wound pattern?
They can cause inversion or eversion but there is decreased risk of wound breakdown.
When is an exploratory laparotomy indicated and what should be obtained?
To correct the cause of GI disease
To determine the cause of GI disease/obtain a biopsy
If no discrete lesion found then biopsies of everything should be obtained (except the LI)
What should be considered when making the incision for an ex lap?
If a male animal then cut through para-preputal muscle and be careful of the central ligament of the bladder.
What are the different types of retractors?
Balfour and gosset retractors
What should be done in an ex lap?
the entire length of the GI tract should be observed and palpated.
Where should one enter the stomach?
The body in the middle between the blood vessels.
How is the stomach repaired following gastrotomy?
Repair mucosa and submucosa with simple continous and then the muscularis and serosa possibly with inverting lembert to prevent leakage.
What should one be careful of when examining the SI during an ex lap?
Blood supply - need to be careful when biopsying LNs
Pancreas - anatomically related to descending dueodenum
What is the procedure for obtaining a small intestinal sample for biopsy?
1. Isolate with swabs
2. Milk contents away and clamp with atraumatic clamps/fingers
3. Incise on anti-mesenteric border.
4. Use metzenbaum scissors to cut away an elipse of material.
5. Suture - may need to trim excess mucosa if it bulges out then suture 3-5mm from the edge 3-5mm apart.
6. After releasing clamps then assess for leaks! If not sure then wait 10-15 mins.
How is the LI distinguished from the SI?
By following the GI tract and looking at the blood supply. Size is not a good indicator as some diseases cause increased size of the SI.
Is the liver easily biopsied? What methods should be considered prior to ex lap liver biopsy?
It can be challenging especially on the right size. Knowing which lobe is which is very useful if referring. Laproscopy, FNA and trucut under ultrasound should be considered.
How can the liver be biopsied during an ex lap?
Use heamostats to isolate the liver area then cut away.
Use a punch biopsy tool
Use heamostatic agents if excessive bleeding.
How is the pancreas examined and biopsied?
Check both limbs, lift omentum to see the left limb. Bare in mind the panc shares blood supply with the SI. Tie around the area to be biopsied to crush and ligate the area. Take care not to damage duodenal papilla.
What are the post op care routines for a gastrotomy?
Feed, antacids if there is ulceration and gastric protectants.
What needs to be considered with gastric neoplasia surgery?
Is there metastasis? - If so then not much point
Can the cardia, pancreatic duct and common bile duct be preserved?
What is the prognosis for gastric neoplasia following gastrotomy?
Benign - good
Malignant - poor
When is intestinal resection and anastamosis neccessary?
When there are areas of ischaemia - IMPORTANT as risk of septic peritonitis if the wall becomes compromised
How can intestinal viability be assessed?
Look at arterial pulses
Thickness (will be thin if necrotic)
What is the procedure for an enterectomy?
Ligate the mesenteric blood vessels (can bunch ligate with fat)
Incise intestine close to clamps
Will need to repair mesentery as well as intestine so another piece of intestine doesn't pass through the hole and itself become necrotic.
What can be done if one part of the si is larger than the other end to be put back together?
Space sutures farther apart on the large side
Reduce large side with sutures
Spatulate the small side (this is best)
Place the bottom stitch first.
How can a SI anastamosis be supported?
What is a common appearance of the SI with a cat who has eaten string?
Concertina of the SI. May need to perform multiple enterotomies and check for little holes in the SI.
Which intestinal neoplasias are common:
a) in dogs
b) in cats
What is intussusception?
When one part of the intestinal tract invaginates into another.
What disease process is intussusception associated with?
Enteritis (e.g. IBD, parasites, infections)
How is intussusception diagnosed?
Gas distension on radiography
Ultrasound will see 10 layers of intestinal mucosa.
How is intussusception corrected?
Reduce it - push rather than pull
Resect if not viable, irreducible or mass present
Treat the underlying disease - worm etc. may need to enteroplicate (although not necessarily proven in vetmed)
Outline the post op care and complications that may arise following enterotomy/enterectomy.
Encourage oral nutrition asap.
Short bowel syndrome (if large resection)
Intestinal incision dehiscence
What is septic peritonitis?
Bacteria cause inflammation & release of inflammatory cytokines. This causes vasodilation, and blockage of diaphragmatic lymphatics with fibrin. Increased fluid and protein in the peritoneal cavity reduce vascular oncotic pressure and cause hypovolaemia => hypovolaemic shock. Systemic inflammatory response syndrome, disseminated intravascular coagulation and death can result.
What are the clinical signs of septic peritonitis?
Vomiting soon after surgery
abdominal wound discharge
evidence of bleeding e.g. heamatemesis.
What is the most important test for SP?