Principles of GI Surgery 1 + 2 Flashcards

1
Q

For what 2 reasons would GI surgery be performed?

A
  • DIsease of the wall of the GI tract

- Partial/complete obstruction of the GI tract

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2
Q

Of what clinical significance are the GI lesions wrt surgery?

A

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
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3
Q

How may gastric disease and vomiting comproise the animal pre-surgery?

A
  • Loss of HCl -> metabolic alkalosis and hypochlorinaemia
  • Dehydration -> poor perfusion and metabolic acidoisis
  • insufficient food intake -> hypokalaemia
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4
Q

How may complications from gastric vomiting be corrected prior to surgery?

A

IV isotonic crystalloids, IV K+ supplement (sometimes)

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5
Q

How may SI complete obstruction and vomiting compromise the animal pre-surgery? What is this dependent on?

A

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

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6
Q

How may complications from complete SI blockage be corrected prior to surgery?

A

IV isotonic crystalloids, IV K+ supplements

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7
Q

How may SI partial obstruction (VD and weightloss) compromise an animal pre-surgery?

A
  • Vomiting -> electrolyte loss and dehydration
  • Bacterial proliferation and nutrient metabolism -> malassimilation and mucosal damage -> diarrhoea, weight loss, hypoalbumenaemia
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8
Q

How may complications from partial SI blockage be corrected prior to surgery?

A

IV isotonic crystalloids, IV K+ supplementation, hypoalbumenaemia cannot be corrected but normotensive state should be maintained

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9
Q

How may GI bleeding (-> heamatemesis and meleana) compromise an animal prior to surgery?

A

-> anaemia and hypoalbumenaemia

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10
Q

How may GI bleeding be corrected prior to surgery?

A

Blood transfusion, Fe supplements

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11
Q

What should especially be noted on the physical exam prior to anaesthesia and surgery?

A

Dehydration status - if in doubt, IV fluid therapy!

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12
Q

What should be checked to determine that the animal is fit enough for surgery?

A
  • complete history
  • physcial exam
  • heamatocrit and TP
  • electrolytes esp K+ Na+
  • acid base status
  • complete biochem/heamatology IF CLINICALLY INDICATED ONLY
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13
Q

How does the distribution of GI bacteria differ along the GI tract?

A
  • 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
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14
Q

Which organism is responsible for the majority of post-surgical infection? What type of organism is this?

A

E coli - Gram -ve rod

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15
Q

For what reasons are use of prophylactic antibiotics encouraged for GI surgery?

A
  • 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
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16
Q

For what reasons may prophylactic antibiotics be discouraged?

A
  • 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)
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17
Q

What classes of antibiotics would be indicated for use in gastric surgery (IF indicated)? eg.?

A

Single broad spec with anaerobic coverage

eg. 2nd generation cephalosporin OR amoxycillin clavulanate

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18
Q

What classes of antibiotics would be indicated for use in SI surgery (IF indicated)? eg.?

A

Single broad spec with anaerobic coverage

eg. 2nd generation cephalosporin OR amoxycillin clavulanate

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19
Q

What classes of antibiotics would be indicated for use in colon surgery (IF indicated)? eg.?

A

Combination of 2 antibiotics, including an anaerobe specific drug
eg. Metronidazole PLUS 2nd gen cephalosporin or amoxycillin clavulanate

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20
Q

Other than ABs, how may bacterial contamination be minimised (5 ways)?

A
  • 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
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21
Q

How may the colon be prepared for surgery? How does this differ to human medicine?

A
  • 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
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22
Q

Outline the layers of the intestinal wall. Which is strongest and why?

A

Adluminal: Mucosa - submucosa - muscularis (circular) - muscularis (longitudinal) - serosa(sub) - serosa :Outside edge
> Submucosa strongest due to collagen so MUST BE SUTURED

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23
Q

What stages of wound healing are solely active during days 1-3? How long do these continue?

A

Heamostasis (formation of platelet-fibrin clot) and inflammation (microbial killing and wound debridement)
- will continue until day 5

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24
Q

What stage of wound healing begins on day 3?

A

Proliferation of granulation tissue (fibroblast^, collagen synthesis, angiogenesis -> ^ wound strength)

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25
Q

At what stage post-surgery is the “danger zone” for wound failure? Why?

A

Day 3-5

> overlap of inflammatory and granulation processes

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26
Q

How does the rate of wound healing differ along the GI tract?

A

> Stomach - rapid healing due to ^ blood supply, rarely complicated
SI - by day 14, regained 75-80% normal tensile strength
LI - by day 14, regained 50% normal tensile strength (Poss ^ collagenase production? risk of wound breakdown greatest)

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27
Q

Is colonic surgery often indicated?

A

NO! Only perform colonic surgery if there is a definite indication to do so.. even biopsies should be avoided if possible

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28
Q

What surgical factors impact -vely on wound healing? How may these be overcome?

A

Compromise to blood supply and traumatic surgical technique (avoid electrocautery, use atraumatic debakey forceps, atraumatic bowel clamps and stay sutures in lieu of handling stomach/intestines)

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29
Q

Which commonly used instrument should NOT be used in GI surgery?

A

Rat-tooth forceps

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30
Q

What physiological factors impact -vely on wound healing? How may these be overcome?

A

> Hypoproteinaemia (rarely correctable prior to surgery)
Chemotherapy and radiotherapy (delay for 3 weeks post surgery)
Steroids (discontinue use if possible)

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31
Q

What type of suture should be used to repair gut lining and why?

A

Full thickness appositional to allow separate layers to repair individually

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32
Q

Which suture patterns may be used in the SI?

A

Simple interrupted or simple continuous

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33
Q

Which type of suture material should be used for GI surgery? eg.?

A

Monofilament as is resistant to infection (cf. multifilament)
Material that maintains strength long enough to permit healing (>5d) but is absorbable
eg.PDS II (or Monocryl though this is too weak really, loses strength ~7 days)

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34
Q

What are staples made from?

A

Titanium - inert and unreactive so can be left in the abdomen

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35
Q

How does the reconstruction of gut wall with staples differ from sutures? Are staples advocated?

A

Appositional not possible - lining must be everted or inverted.
> may be less likely to break down/burst cf. suturing, so is advocated

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36
Q

When is ex lap indicated?

A
  • to diagnose the cause of intra-abdominal disease if all other diagnostics have been unsuccesful
  • to correct the cause of intra-abdominal disease
    > eg. to remove FB, investigate chronic vomiting, liver biopsy
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37
Q

If no discrete lesion is found on ex lap what next steps should be taken?

A
BIOPSY
- stomach
- SI
- +- liver
- +- pancreas
-+- LNs
>NB: NOT colon unless indicated
38
Q

Where should the incision for an ex lap be made? What may get in the way and how should this be dealt with?

A
  • From xiphersternum to pubis midline (linea alba, should not cut abdo muscles)
  • Preputial muscle will be on the midline in males - cut this and stitch at end of surgery - No problem!
39
Q

What 2 types of retractors can be used for GI surgery?

A

Balfour - have an extra scoop for diaphragm and bowed side arms
Gossett - straight side arms

40
Q

What should be the first step in an ex lap?

A
  • Protect wall from drying with moist swabs

- Palpate entire GI tract - run through hands in a logical manner

41
Q

What is an incision into the stomach referred to as? Where should this ideally be made?

A

Gastrotomy - on side between lesser and greater curvature, away from blood supply etc.!

42
Q

How should the stomach be repaired following a gastrotomy?

A

2 layers

  • first mucosa and submucosa (simple continuous suture; appositional)
  • then serosa and muscularis (simple continous suture, appositional or inverting lembert)
43
Q

Outline 4 steps of SI biopsy

A
  1. isolate intestine
  2. milk contents away and close intestine with atraumatic clamps/fingers
  3. incise ANTImesenteric border
  4. Ellipse shaped biopsy - cut with metzenbaum scissors
  5. Trim excess mucosa to ensure sutures placed through SUBmucosa.
  6. Suture 3-5mm apart, 3-5mm from cut edge
44
Q

How does the blood supply to the SI and LI differ?

A

SI: radiating supply from root of mesentry
LI: parallel supply

45
Q

How may SI and LI be differentiated grossly?

A

LI paler, longitudinal striations, blood supply

46
Q

Which side of the liver does the caudal vena cava pass?

A

Right

47
Q

How should the liver be manipulated?

A

Carefully - very friable and easily damaged

Use palms of hands

48
Q

When would liver biopsy be indicated?

A

Clinical signs and bloods indicative of liver disease
Generalised abdo appearance - ultrasound or surgery
Presence of liver nodules/masses

49
Q

What alternative procedure to an open biopsy of the liver should be considered?

A

FNA (fine needle aspirate) or Trucut biopsy under ultrasound guidance

50
Q

What are the clamps that are used to crush tissue and initiate haemostasis referred to as?

A

Heamostats

51
Q

When would a peripheral biopsy of any liver lobe be indicated?

A

Generalised liver disease

52
Q

When may skin punch biospy tools be used for liver biopsy?

A

Specific nodule or local disease process (skin biopsy good as prevents going too deep)

53
Q

What may be used to encourage heamostasis other than clamps?

A

Collagen sponges initiate platelet clotting

54
Q

Where can gastric resections be performed?

A

Fundic region - cardia cannot be detroyed neither can pylorus - biliary and pancreatic ducts would have to be rerouted.

55
Q

What does the pancreas share its blood supply with?

A

Descending duodenum

56
Q

How are pancreatic biopsies performed?

A

Tie ligature round section before cutting

Do not remove form near pancreatic ducts

57
Q

Where does the left limb of the pancreas lie?

A

Stomach wall

58
Q

What history and clinical signs are associated with gastric FBs?

A
  • Young
  • Previous FB ingestion
  • Vomiting -> dehydration
  • Lethary
  • Abdo pain and gastric distension
  • Depression
  • Anorexia (sometimes)
  • Mealeana or heamatemesis
  • Dyspnoea if 2ndry aspiration pnumonia
59
Q

How may gastric FBs be treated?

A

Endoscopic removal or gastrotomy

60
Q

What postop care is required following gastrotomy? What is the prognosis?

A

Feed straight away, antacids if ulcers present and gastric protectants anyway
Prog: excellent

61
Q

When investigating gastric neoplasia, what other diagnostics should be investigated first?

A
  • Radiograph esp thorax to check for metastases
  • Position of gastric neoplasia: a large part of the stomach can be resected (fundic region) BUT cardia must be preserved and common bile and pancreatic duct must be preserved or rerouted.
62
Q

What treatment is required if the pancreas is removed?

A

Pancreatic supplements for life

63
Q

Give two types of gastric neoplasia

A

Leiomyoma (benign smooth muscle/connective tissue tumour)

Adenocarcinoma (Malignant)

64
Q

What is the prognosis for gastric neoplasia?

A

Complete resection of benign leiomyoma : good

Adenocarcinoma: poor, clinical signs often recurring after weeks

65
Q

What closure method is recommended for partial gastrectomy?

A

Staples (staple gun with inbuilt knife secures in 6 places, eversion of tissue)

66
Q

When is intestinal resection and anastomosis indicated?

A
> Ischeamic necrosis
- ^ intralumenal pressure 
- disrupted blood supply
Would -> breakdown of gut, spillage of contents -> peritoneal cavity -> septic peritonitis 
> Neoplasia
67
Q

How can you distinguish viable intestine form necrotic?

A
  • pulse in arterial blood vessels
  • peristalsis
  • normal colour
  • normal wall thickness
68
Q

How do you carry out an intestinal resection?

A
  • Milk out intestinal contents
  • isolate intestine with atraumatic clamps
  • Ligate mesenteric vessels
  • Incise mesentry
  • Incise intestine close to clamps
69
Q

Why may ligating blood vessels be difficult?

A

Hidden by fat

70
Q

How may luminal disparity following resection and anastamosis be overcome? How should the two section be rejoined?

A
  • Space sutures further apart on large side (leaky)
  • Transect small side at an angle to match diameter of large side
  • Reduce small side with sutures (leaky)
  • Spatulate small side (advocated)
    > suture mesenteric border first
    > 2nd in anti-mesenteric border
    > repair mesentry to prevent further strangulation of intestine
71
Q

How may GIT wound healing be improved?

A
  • Omentalisation: Wrap omentum round incision site.
  • Serosal patch: Tack healthy intestine over wound (only advocated when wound has failed and is being sutured for the second time
72
Q

What history and clinical signs would be associated with intestinal FBs?

A
History: Persistent vomiting, frequently projectile 
- anorexia
- depression 
- no defeacation 
Exam: dehydration
- abdo pain 
- intrabdominal mass
- string etc. stuck in mouth esp cats
73
Q

When performing an enterotomy where should the incision be made?

A

As close to healthy tissue as possible.

74
Q

How may intestinal string FB be diagnosed and treated?

A

Radiograph: intestines “stacked”
Tx: multiple enterotomies, cut string and remove in sections

75
Q

What types of intestinal neoplasia are possible?

A

> Adenoma/adenocarcinoma (->local LN and liver) 12m
Lymphoma (esp cats)
Leiomyoma/leiomyosarcoma (->local LN and liver) 20-21m
Mast cell
Duodenal polyps

76
Q

Which breed are predisposed to intestinal adenocarcinom? What is the median survival time?

A

Siamese

- 12m

77
Q

What margin should be left when removing a growth?

A

3cm

78
Q

How may intestinal neoplasia be noted in the history/clinical signs?

A

Partial obstruction while growing
-> chronic intermittent VD+, weight loss
> radiograph:
-dilated intestine and ingesta backed up behind obstruction
-“gravel sign” where mineralised fragments and large food pieces are stuck behind the obstruction
> ultrasound shows loss of 5 layers of normal intestine wall

79
Q

Give 4 common causes of intessuception

A

Intestinal growth, parasites, bacteria, IBD

80
Q

What are the two portions of intestine either side of an intussuception referred to as?

A

Intussusceptum invaginates into Intussescipiens

81
Q

Which blood flow is affected first by gut problems?

A

Venous, then arterial

82
Q

How may intussesceptions be diagnosed?

A
  • dehydration, depression abdominal pain, palpable tubular mass
  • potential protrusion form the anus (distinguish from anal prolapse by passing thermometer to the side of the protrusion)
  • Ultrasound: parallel lines or concentric rings - double thickness (ie. 10 rings instead of 5)
83
Q

What are the 3 surgical treatments for intussception? What is the prognosis?

A

Reduction: push rather than pull
Resection: if irreducible, ischeamic, or if a mass is present
Enteroplication: suture all intestine to each other! - treat underlying disease as well (check feacal bacteria and parasites, deworm if in doubt) [minimal evidence base, causes cramps and VD in humans, still performed]
Prognosis: good in young, 6-27% recurrence between 3 days - 3 weeks

84
Q

How soon after surgery should enterotomy/enterectomy patients be given food?

A

Straight away ASAP

85
Q

What are potential complications of enterotomy and enterectomy?

A
  • persistent ileus (VD, pain, diarrhoea, abdo distension)
  • Stricture at anastomosis site (presents as partial obstruction)
  • Short-bowel syndrome if >70% resected -> Malassimilation
  • Intestinal incision dehiscence (7-16% cases for biopsy)
86
Q

How does septic peritonitis occour?

A

Bacteria and inflamatory cells enter peritoneal cavity-> cytokines, endotoxin release - vaodilation, ^ capillary permeability, diaphragmatic lymphatics bloacked with fibrin - ^fluid and protein in peritoneal cavity - Hypovoleamia and decreased vascular oncotic pressure-> hypovoleamic shock = Systemic Inflammatory Response Syndrome - DIC - Death

87
Q

What is the prognosis for septic peritonitis?

A

50% mortality

88
Q

What are the clinical signs for septic peritonitis?

A
  • VD+
  • anorexia and depression
  • abdo pain and enlargement
  • hypovolaemic shock (^HR, vBP)
  • pyrexia
  • discharge from abdo wound
  • Heamatohezia, meleana, haematemesis
89
Q

How is septic peritonitis treated?

A

Surgery

90
Q

How is septic peritonitis diagnosed?

A

Abdominocentesis - look for neutrophils containing bacteria