Small Animal GI Surgery Flashcards
What MUST you do before performing GI Surgery on a patient?
ASSESS IMMEDIATE NEEDS
Is it fit for surgery, if not how can we correct it?
A patient presents with gastric vomiting. How is that likely to affect its metabolic status?
loss of gastric HCl —metabolic alkalosis (losing H+) —hypochloraemia (losing Cl-) Dehydration —Poor tissue perfusion —Metabolic acidosis as a result of anaerobic metabolism Insufficient food intake —Hypokalaemia
How can a patient with gastric vomiting be stabilised before surgery?
Give IV fluids
Can self-correct acid-base imbalance
Need to give K+ in severe cases
A patient presents with a high intestinal obstruction, how would this affect its metabolic status?
Mimics gastric vomiting
Metabolic alkalosis and hypochoraemia, loss of HCl
Metabolic acidosis from dehydration
Hypokalaemic from low food intake
A patient presents with a low intestinal obstruction, how will this affect their metabolic status?
Loss of pancreatic Na+ and bicarbonate
- metabolic acidosis and hyponatraemia
Dehydration - metabolic acidosis
Low food intake and POOR ABSORPTION - hypokalaemia
How can a patient with acute vomiting due to a high or low intestinal obstruction be stabilised prior to surgery?
IV fluids
IV K+
How would chronic vomiting (and diarrhoea) due to a small intestinal partial obstruction affect the metabolic profile of a patient?
Vomiting — dehydration and electrolyte loss
Bacterial proliferation
- bacteria absorb nutrients therefore —maldigestion and malabsorption
- Intestinal mucosal damage
Diarrhoea, weight loss, hypoalbuminaemia
Why would you only expect bacterial proliferation to occur in partial blockage cases?
In complete obstruction, vomiting is acute
Therefore bacteria don’t have enough time to accumulate
How could you correct the metabolic status of an animal presenting with small intestinal partial obstruction?
IV fluids
Intravenous K+
What is meant by the terms haematemesis and melena?
Haematemesis - vomiting blood
Melena - Passing blood in faeces
How might GI bleeding affect a patient?
Anaemia - regenerative/non-regenerative
Hypoalbuminaemia
How can animals with GI bleeding be stabilised prior to surgery?
Blood transfusion
Iron supplementation so they can regenerate their RBCs.
What information do you need to check if an animal is fit for anaesthesia and surgery?
Complete history Complete physical examination Check haematocrit and total protein Check electrolytes: Na+ and K+ Check acid base status Complete haematology and biochemistry if clinically indicated
How long does it take to correct metabolic imbalances with IV fluids?
Between 1 and 6 hours
What is the relationship between number of bacteria and % anaerobes as you progress through the GIT?
Increasing number of bacteria, increasing number of anaerobes.
Where is the most bacteria found in the GIT?
Colon
What is the most common bacteria in the large intestine which can result in surgical complications?
E. Coli
Why is it important to appreciate the number of anaerobic bacteria present in a given area?
Determines the type of antibiotic you would use.
When might prophylactic antibiotics be important?
When immune defences are compromised: Debilitated animals GI surgery Extensive GI resections Surgeries more than 90 mins
What could be a potential risk if prophylactic antibiotics are not used prior to GI surgery in immunocompromised animals?
SEPTIC PERITONITIS
Fatal in 50%
When might you not use prophylactic antibiotics when doing gastric surgery?
In a healthy dog e.g. with a ball in its stomach.
What prophylactic antibiotics might you use when doing gastric surgery?
Single broad spectrum antibiotic with anaerobic coverage
E.g. second generation cephalosporin OR Amoxycillin- clavulante
When are prophylactic antibiotics always indicated?
Small intestine and colon surgery
What prophylactic antibiotics might you use for Small intestine surgery?
Single broad spectrum antibiotic with anaerobic coverage
E.g. 2nd generation cephalosporins or amoxycillin -clavulante
What prophylactic antibiotics might you give for colon surgery
COMBINMATION
Broad spectrum plus anaerobe specific
Metronidazole
PLUS 2nd gen cyclosporine or amoxycillin-calavulante
Other than antibiotics, how can you minimise bacterial contamination when doing GI surgery?
Isolate site of GI entry
Use separate set of instruments and gloves for contaminated part of surgery
Lavage abdomen with sterile saline
Lavage GI wound after closure
What additional measures could be taken to minimise bacterial contamination in colon surgery?
A low diet and at least 12-24 hours starvation
Results in decreased faecal volume
Which layer of the intestinal wall is strongest?
Why?
How does this affect suturing technique?
Submucosa
High collagen content
Suture/staple needs to go through submucosa.
What are the phases of intestinal wound healing?
Haemostasis
Inflammation
Proliferation or granulation
Remodelling or maturation
What happens during the inflammation stage of intestinal wound healing?
Microbial killing and wound debridement (enzymes released which break down tissue)
What happens during the proliferation or granulation phase of intestinal wound healing?
Fibroblast proliferation and collagen synthesis
Increased wound strength
What is the typical timeline for wound healing in the intestine?
Days 1-4 - Haemostasis
Days 1-5 - Inflammation
Day 3 onwards (few weeks) - Proliferation or granulation
Weeks/years - Remodelling or Maturation
When might there be increased risk of wound breakdown?
Overlap between inflammation and proliferation or granulation phase.
Collagenase produced in inflammation phase may prevent healing
What is the relationship between progression along the GIT and rate of wound healing?
Rate decreases as you progress along GIT.
Why is healing faster in the stomach?
Abundant blood supply
How long does it take for the small intestine to regain 75-80% of its tensile strength post-surgery?
14 days
How much of its normal tensile strength would the colon have regained 14 days post surgery?
50%
RISK OF WOUND BREAKDOWN GREATEST
NEED A GOOD REASON TO PERFORM SURGERY
Which factors impact negatively on intestinal wound healing?
Compromised blood supply Traumatic surgical technique Hypoproteinaemia Chemo and radiotherapy Steroids
Can you normally correct for hypoalbuminaemia prior to surgery?
No - takes too long
What surgical technique should you NOT use for GIT surgery?
ELECTROCAUTERY
Need to use atraumatic techniques/instruments.
How could you minimise the amount of bruising you cause to the intestine?
Reduce the amount of times you pick it up
Use sutures to hold it
What are the goals of gastrointestinal wound suturing?
Restore normal anatomy
Promote rapid healing
What methods of suturing are appropriate for gastrointestinal wounds?
Full thickness appositional
Simple interrupted or simple continuous
What suture material would you use?
Why?
Monofilament
Retains strength for long enough to permit wound healing - >5 days
Absorbable - dissappear after wound healing
PDS II - lasts longer than monocryl
What are the pros and cons of using staples vs sutures,
Titanium is inert and permanent
Results in wound edges turning in or out
— not exactly where we found it
What incision do you make for an exploratory laparotomy?
Is the approach the same for males and females?
Ventral midline
Males, go to the right of prepuce and cut through preputial muscle.
— Ligate blood vessel on caudal edge
How can you hold open the abdomen during an ex lap?
Retractors
Balfour or Gossett
What is the difference between Balfour and Gossett Retractors?
Balfour has a ‘spoon’ which holds open cranial edge.
How can you repair an incision made in the stomach to take a biopsy?
Repair in two layers.
Mucosa and submucosa - simple continuous
Muscularis and serosa - simple continuous (or inverting Lembert)
Describe the blood supply of the jejunum.
Why is this important during an ex lap
Radiating blood supply from one side that sits within the mesentry.
Don’t ligate at origin as you cut off blood to whole jejunum (can ligate branches though)
Describe the blood supply of the ileum
Blood supply on both sides
- mesenteric and antemesenteric
Describe the blood supply of the large intestine.
How is this important during an ex lap
Parallel blood vessels along one side.
Only ligate vessels which sit DIRECTLY against the intestine
What should you consider before you do an ex lap to investigate the liver?
Fine needle aspirates,
Ultrasound guided biopsy
What do you need to be careful of when doing a punch biopsy of the liver?
What do you have to do after you’ve taken the biopsy?
Don’t go too deep
More bleeding
Plug hole with haemostatic agent
What in the history of a patient would indicate a gastric foreign body?
Any age, but common in young Previous foreign body ingestion Known foreign body ingestion Vomiting Lethargy Abdominal pain Depression Anorexia
What clinical signs are associated with gastric foreign body’s?
Dehydration Abdominal pain Gastric distension Melaena and haematemesis Dyspnoea if aspiration pneumonia
How can you image the stomach?
What technique isn’t useful?
X ray, endoscopy
Ultrasound isn’t good
How can you treat gastric foreign bodies?
Endoscopic retrieval of foreign body
Gastrotomy
What post- op care is required after a gastrotomy?
Feed,
Antacids,
Gastric protectants
What decision making factors should be made prior surgery for gastric neoplasia?
— is there any metastasis (e.g. to lungs)
— is resection and reconstruction achievable?
When is resection of the stomach achievable?
When the following structures can be preserved:
— Cardia
— Common bile duct
— Common pancreatic duct
What factors affect the prognosis of patients with gastric neoplasia?
Benign tumour LEIOMYOMA resection - good prognosis
Malignant tumour (ADENOCARCINOMA) - poor prognosis - symptoms often recur within weeks
In intestinal resection and anastomosis, when is enterotomy not enough?
ISCHAEMIC NECROSIS
NEOPLASIA
What is ischaemic necrosis and how can it happen?
Death due to loss of blood supply
Excessive pressure within the lumen of the intestine (e.g. due to wedged foreign body).
Disruption of blood supply
Breakdown of gut wall, leakage of gut contents into the peritoneal cavity and SEPTIC PERITONITIS
How can GIT viability be assessed?
Look for:
Pulsations in the arterial blood vessels
Peristaltic muscle contractions
Normal colour
Normal wall thickness on palpation
How would you resect a piece of intestine?
Milk out intestinal contents from intestine to be resected
Isolate intestine with atrumatic clamps
Ligate mesenteric vessels
Incise mesentry
Incise intestine close to clams on the intestine to be resected
How can you tell if some clamps are atraumatic?
Space between ‘fingers’ of clamp
How can you deal with luminal disparity once you’ve resected a piece of intestine?
Space sutures further apart on the large side
Transects the small side at an angle to match the diameter of the large side
Spatulate small side (cut slit in small)
How far apart should sutures be?
3 to 5 mm from the edge and 3-5 mm apart
How can you further support the wound after you have performed an end to end anastomosis?
Wrap it with omentum
- do every time
Tack together with other bits of intestine
-do when you’re more worried
What history would indicate an intestinal foreign body?
Persistent vomiting, frequently projectile
Anorexia
Depression
No defecation
What would an intestinal foreign body present as in clinical exam?
Dehydration Depression Abdominal pain Intra abdominal mass String around tongue - string foreign body
When performing an enterotomy, where should you cut?
Antemesenteric side
How would a string foreign body appear on a radiograph?
Stacking of intestines
String causes concertina of intestines
How can string foreign bodies cause problems?
String can cut through the mesenteric side of the small intestine leading to SEPTIC PERITONITIS
Cut string where its tethered then take it out in pieces and check for holes in the gut - REFER
What are the possible types of intestinal neoplasia?
Adenoma/adenocarcinoma
- local lymph node and liver
Lymphoma
Leiomyoma/leiomyosarcoma
Mast cell
Duodenal polyps
What can intestinal neoplasia result in?
Partial obstruction:
Chronic intermittent vomiting
Diarrhoea
Weight loss
What is intussuception ?
Invagination of one portion of the gastrointestinal tract into the lumen of an adjoining segment
How do patients with intussuceptions present?
Acute onset problem Dehydration Abdominal pain Palpable tubular mass Potential protrusion of intussuceptum from anus
How can you investigate intussuceptions?
Ultrasound
— Parallel lines or concentric rings
Radiography
— Gas distension of loops of small intestine
What are the likely causes of intussuception in young and old animals?
History of V+D - particularly parvo puppies or young animals with worms
Older animals - more likely to be neoplasia
What surgical intervention can you perform to treat intussuception?
REDUCTION - push rather than pull
Resect if:
Irreducible, ischemic, or mass present
How else can you treat intussuception?
Treat the underlying disease
DEWORM
How should animals be fed post op?
Encourage oral nutrition as soon as possible
What are complication of enterotomy and entree to my?
Persistent ileus
Stricture at anastomosis site - partial obstruction
Short bowel syndrome (if more than 70% has been resected) - malabsorption and malnutrition
Intestinal incision dehiscence
How would a patient with persistent ileus present?
Vomiting
Diarrhoea
Pain
Abdominal distension
What happens when bacteria enters the peritoneal cavity?
SEPTIC PERITONITIS
Inflammatory cells enter the peritoneal cavity and release cytokines
Bacteria release endotoxin
- Diaphragmatic lymphatic blocked with fibrin
How do inflammatory cells in the peritoneal cavity cause problems?
Release cytokines
Vasodilation and increased capillary permeability
Increased fluid and protein in peritoneal cavity
Hypovolaemia and decreased vascular oncotic pressure — HYPOVOLAEMIC shock
SIRS and DIC
DEATH
What do SIRS and DIC stand for?
SIRS - Systemic inflammatory response syndrome
DIC - Disseminated intravascular coagulation
What clinical signs are associated with septic peritonitis?
Vomiting Anorexia and depression Abdominal pain Abdominal enlargement Hypovolaemic shock Pyrexia Discharge from abdominal wound Diarrhoea Haematochezia, melaena, haematemesis
How can you diagnose septic peritonitis?
Abdominocentesis
Diff quik stain under oil, look for:
Toxic (hypersegmented neutrophils)
Intracellular bacteria (rods)
Background red blood cells
How can you treat septic peritonitis?
Pre-op stabilisation inc. antibiotics
Ex lap - find and correct leak
Peritoneal lavage and drainage
Intensive post-op care, IV fluids and nutrition
