Principles of GIT surgery 1, 2 + 3 Flashcards
List Halsted’s 7 principles of surgery
- Gentle tissue handling
- Meticulous haemostasis
- Preservation of blood supply
- Strict asepsis
- Minimal tension
- Accurate tissue apposition
- Obliteration of dead space
Once in the abdomen during surgery, what is the first step?
- Systematically explore the abdomen before you do anything else.
- Complete the whole exploration even if you find an obvious lesion, otherwise you might miss something.
- Evaluate the size, shape, location, colour, consistency and surface contour of organs/tissues.
What is the duodenal dam manoeuvre?
Useful when exploring the abdomen
Grasp the duodenum and retract most of the intestines over to the left to expose the right abdominal roof.
What is the best instrument to use for mobilising/examining gut?
Hands
Why should excess handling of the gut be avoided?
Can cause ileus: temporary lack of the normal muscle contractions of the intestines
Before making an incision into the stomach what should you do?
Use 3-4 stay sutures to stabilise the stomach
Which tissues in the abdomen require extra care when handling? Why?
Liver capsule and parenchyma - friable
List some instruments specialised for use in abdominal surgery
- Self-retaining abdominal retractors.
- Malleable retractors.
- Suction: this is essential for adequate lavage
- Doyen bowel forceps or Allis tissue forceps padded with swabs can occlude the gut lumen when an assistant isn’t available
Describe/name the type of forceps used on abdominal tissue
- Debakey thumb forceps are the least traumatic forceps for handling gut: don’t use large “rat-tooth” types. Use the tip of the forceps on the serosa of the organ or adventitia of vessels, don’t grab a section and crush it
- Use crushing forceps to occlude the lumen of gut that is to be resected but never use them on tissue that you aren’t going to excise.
What abdominal structures / organs do you need to evaluate in an exploratory coeliotomy?
What order should you look at them in?
- Parenchymatous organs first: liver, spleen, pancreas, right kidney and adrenal, left kidney and adrenal
- Intestines: stomach, duodenum, colon, caecum, ileum, jejunum, mesenteric lymph nodes
- Bladder and ureters, reproductive tract (if present)
- Anything else specific to the patient’s problem
When incising into the GI tract you want to incise the least vascularised part of the gut wall, where is this in each part of the gut?
Stomach = Midway between the greater and lesser curvatures
Duodenum, jejunum or colon = the antimesenteric border
Ileum = approximately 2/3 of the way from the mesenteric to the antimesenteric border
Do you need to worry about ‘capillary ooze’ bleeding?
Usually stops spontaneously when the incision is sutured, if not before
How are larger blood vessels vigated?
Synthetic absorbable suture material or vascular clips
Which vessels should be ligated in the SI?
Both the branches of the cranial mesenteric artery running up the mesentery and the terminal arcade vessels running along the mesenteric border of the intestine
In dogs which artery of the colon should not be ligated?
Cranial rectal artery
In dogs, which arteries of the colon can you ligate?
Vasa rectae
Left colic artery
Name some topical haemostatic agents that you may use in the liver
Absorbable gelatin foam or collagen felt can halt diffuse parenchymal haemorrhage
Why is electrocautery of limited use in the liver?
Can ablate the parenchyma, making bleeding worse
Describe the pringle manoeuvre
Can occlude blood flow to the liver for up to 15 minutes by applying pressure to the celiac artery and portal vein at the epiploic foramen
Haemostasis near the border of liver lobes may be achieved using …?
Bulk ligation of tissue (the “guillotine method”)
Which technique is used for a partial lobectomy away from the border of the lobe or for a total lobectomy? Why?
The “finger-fracture” technique
- It allows large vessels and bile ducts to be identified and individually ligated: safer
How is the “finger-fracture” technique carried out?
Carefully incise the liver capsule (or score with the blunt end of a scalpel handle – probably safer) along the line of resection then crush/separate the parenchyma along that line with fingers to expose the large vessels and bile ducts so you can ligate them.
Describe how to perform haemostasis in the pancreas
- Pass a ligature around the area of pancreas containing the lesion or haemorrhaging vessel and tighten, crushing tissue and occluding vessels and ducts. Excise tissue distal to ligature.
- Bluntly separate pancreatic lobules around lesion, isolate blood vessels and ducts supplying affected part and ligate or cauterise, excise tissue.
How can planning your incisions help preserve blood supply to tissues/organs?
When removing a section of gut, incising at approximately 30° to the transverse ensures adequate blood supply to the antimesenteric border and increases the luminal diameter at the anastomosis
How can you assess the viability of intestine?
- Colour should be a healthy pink.
- Arterial pulsations should be present.
- Peristalsis should be present.
Describe the blood supply to the oesophagus and how to preserve it
Segmental blood supply
Rich submucosal plexus
Preserve this by:
- Avoid excessive cautery
- Handle tissue gently
- Place sutures carefully
The blood supply to the the stomach, duodenum, pancreas and spleen arises from which artery?
Celiac artery
Resection of the descending duodenum may compromise the blood supply to where?
The pancreas
When performing a splenectomy which artery should be preserved?
Left gastroepiploic artery - terminal branch of the splenic artery
When working around the pylorus take care to preserve which 2 arteries?
Cranial pancreaticoduodenal and hepatic arteries
List the ways of minimizing contamination of the peritoneal cavity when you open the intestine
- Use moistened abdominal swabs to isolate the area you are working on from the rest of the abdomen before making your incision
- Before opening the intestine, gently “milk” the contents away from the incision site orally and aborally then keep them away by occluding the lumen with atraumatic forceps or an assistant’s fingers
- Elevate the oesophagus and stomach with stay sutures to reduce spillage.
- Discard contaminated instruments and gloves and use clean ones for abdominal closure
Once you have finished an abdominal procedure what should you do before closing up to reduce contamination?
Lavage the abdomen with 1-3L of warm saline before closure.
“Dilution is the solution to pollution.”
Prophylactic antibacterials should be used in which procedures?
Clean-contaminated or contaminated procedures (e.g. gastrotomy, enterotomy or enterectomy, colotomy or colectomy) and in hepatic surgery
When should prophylactic antibacterial be administered?
Give them intravenously just after induction of anaesthesia, continue through the operative period then stop before 24hrs postoperatively
Which antibiotic has good activity against the common GIT contaminants?
Clavulanate amoxicillin
For colonic or hepatic surgery, add an antibacterial effective against anaerobes e.g. …?
Metronidazole
In which parts of the GIT can tension be a problem?
Oesophagus
Colon during subtotal colectomy
Which layer of the intestine is the strongest?
Submucosa - high collagen content
Why must the submucosa be considered when suturing a wound?
Accurate submucosal alignment in the sutured wound is required for adequate healing, ensuring rapid re-
epithelialisation as early as 72 hours post-op and preventing leakage
Describe the two methods of making and closing incisions into the intestine to facilitate accurate apposition
- Longitudinal incision, longitudinal closure – good general-purpose technique.
- Longitudinal incision, transverse closure – maintains luminal diameter very well, useful in small patients.
Why are transverse incisions not used?
May cause stricture formation
If a section of intestine has been removed how is it closed up?
By end-to-end appositional anastomosis
What features of the GIT make it heal rapidly?
- Rich vascular supply
- Regenerative capacity
- Presence of the omentum and peritoneum
Which heals faster the LI or SI?
SI is faster
Which factors contribute to poor/delayed healing in the oesophagus
Incomplete serosal covering
Poor tissue mobility
Tension
Limited exposure of the surgical site
Poorly vascularised
Describe the choice of suture materials used in GIT surgery
2 metric or 1.5 metric (3 metric to 2 metric for stomach) monofilament synthetic absorbable suture material
Which suture material should be avoided in GIT surgery?
Multifilament sutures - act as a nidus for bacterial growth and may wick bacteria from the mucosal to the serosal surface of the intestine and promote inflammation, delaying healing.
Why are appositional suture patterns good for use in the GIT?
Technically easy and quick
Preserve blood supply
Maintain lumen diameter
Minimise adhesion formation.
Name some appositional suture patterns
Simple interrupted or continuous
Which is better, simple continuous sutures or simple inturrupted?
Simple continuous cause less mucosal eversion, post-op adhesion formation and give more precise submucosal apposition than simple interrupted
In which part of the GIT would you use inverting sutures? Why?
Stomach
Not used anywhere else as they narrow the lumen size
Which suture pattern is recommended in the colon?
Simple interrupted
List the practical steps you can take to minimise the risk of postoperative infection if you’re removing a foreign body from the jejunum
- Exteriorise and pack off the incision site
- Incise distal to the foreign body
- Close the incision securely with a monofilament suture
- Check for leakage after closing the gut Lavage the abdomen before closure
- Give prophylactic antibacterials
- Change instruments before abdominal closure
Sections of intestine to be anastomosed are often different diameters, how can this be dealt with surgically?
- In cases of moderate luminal disparity, eliminate gaps or puckers by spacing sutures further apart on the larger side.
- With moderate luminal disparity, transect the smaller segment of bowel at a greater angle to create a lumen of a larger diameter
- Perform end-to-side anastomosis if the luminal diameters are grossly unequal, suturing the end of the proximal segment to the side of the distal segment
- Can also make a small incision along the antimesenteric border to increase the available lumen
If you have incised the mesentery, how should you close it? Why does it need to be closed?
- Simple continuous suture of fine synthetic monofilament absorbable suture (e.g. 1.5 metric poliglecaprone).
- If you don’t do this, intestines may herniate through the hole in the mesentery, become strangulated, go necrotic and perforate causing septic peritonitis.
Is dead space a major or minor problem in GIT surgery?
Dead space is not as much of a problem in abdominal surgery as it is in other types of surgery e.g. reconstructive surgery.
How is the omentum used in GIT surgery?
The omentum is a mesothelial sheet with a rich vascular and lymphatic supply and large surface area.
It is angiogenic, immunogenic and adhesive and induces vascularisation, acts as a natural haemostatic agent and adheres to compromised organs to support healing.
Describe the importance of fluid therapy in GIT surgery cases
GIT surgery cases often have large fluid losses due to vomiting, diarrhoea and sequestration of fluid in the intestinal lumen
Unless fluid deficits and acid/base or electrolyte imbalances are partly or totally corrected before surgery, the animal may not survive anaesthesia
Define peritonitis
Inflammation of the peritoneum (the serosal lining of the abdominal cavity)
Describe primary bacterial peritonitis
Rare in animals. Cats get primary viral peritonitis due to FIP
Describe secondary peritonitis and its causes
More common
Chemical or septic
Local or Diffuse
Describe local peritonitis
Restricted to one area of the abdomen by omentum and adhesions
Describe diffuse peritonitis
Involves the whole abdomen
List the causes of chemical peritonitis
Due to escape of bile, pancreatic enzymes, urine or gastric or duodenal contents.
It almost always progresses to septic peritonitis.
List the causes of septic peritonitis
Occurs after bowel necrosis or perforation, pyometra, pancreatic or prostatic abscessation, foreign body penetration, contamination at surgery or gut wound dehiscence.
Most wound dehiscence in the gut occurs within 72-96hrs of surgery.
Describe the pathophysiology of peritonitis
- Hypovolaemia due to decreased fluid intake, losses from vomiting and diarrhoea and sequestration of fluid in the peritoneal cavity, gut lumen and splanchnic vessels.
- Metabolic acidosis due to decreased tissue perfusion.
- Electrolyte imbalances.
- Endotoxic shock.
List the clinical signs of peritonitis
- Depression
- Anorexia
- Vomiting
- Abdominal pain
- Abdominal distention
- Ileus
- Pyrexia
- Shock
How does a peritonitis appear on radiography?
Loss of abdominal detail , “ground glass” appearance, presence of free gas, evidence of ileus
Describe the haematology and serum biochemistry results of a patient with peritonitis
Neutrophilia with left shift, often degenerate
Azotaemia, often degenerate
How can abdominal fluid samples be used for a peritonitis diagnosis?
- Cell count, protein level and cytology: exudate containing abundant degenerate neutrophils with intracellular bacteria.
- Biochemistry: an abdominal fluid to blood glucose difference of >1.1mmol/L (with the blood glucose higher) and a blood to abdominal fluid lactate difference of > 2mmol/L (with the abdominal fluid lactate higher than that in the blood) are highly sensitive and specific indicators of septic peritonitis.
- Abdominal fluid culture and sensitivity.
Describe the treatment methods for peritonitis
- Correct fluid and acid/base imbalances.
- Broad spectrum systemic antibacterials
- Correct primary cause e.g. by exploratory coeliotomy and repair of wound dehiscence.
- Copious peritoneal lavage with ≥ 200-300ml/kg saline – dilution is the solution to pollution!
- Drainage of abdomen
What are adhesions?
Fibrous or fibrinous bands between two or more surfaces normally covered with serosa and not normally attached to each other
When do adhesions form?
- Due to tissue anoxia
- Serosal injury
- Presence of foreign material e.g. swab
What are restrictive adhesions?
Cause visceral strangulation and obstruction
How are adhesions minimised?
Appropriate tissue handling
Prevent serosal injury (e.g. avoiding drying)
Removing blood clots prior to abdominal closure
Appropriate suture placement.
What is short bowel syndrome?
Removal of more than 80% of the small intestine
What are the consequences of short bowel syndrome?
- Maldigestion due to reduced pancreatic secretion.
- Malabsorption due to rapid gut transit and reduced mucosal surface area.
- Bile salt deficiency due to impaired enterohepatic circulation.
How is short bowel syndrome medically managed?
- Frequent small low-fat meals.
- Diet supplements (vitamins, minerals, pancreatic enzymes)
- Medium-chain triglyceride oil.
- Oral antidiarrhoeals, antibiotics, antacids and bile salt binding agents.
The prognosis for these cases is generally poor.
What is ileus?
Inadequate peristaltic activity of the entire GI tract leading to functional obstruction
What are the clinical signs of ileus?
Vomiting, anorexia, fluid and gas distension of the entire GI tract
How is ileus treated?
Difficult.
- Address underlying disease.
- Correct fluid and electrolyte imbalances.
- Normalise gut motility with metoclopramide/ranitidine
How can ileus be prevented?
Early return to enteral feeding postoperatively as the The presence of ingesta stimulates parasympathetic tone
List 3 specific things you can do during your daily clinical examination to monitor your patients for postoperative peritonitis. Don’t include your general clinical examination (TPR etc.)!
- Check for abdominal pain by palpation - remember cats often don’t show this
- Ballotte the abdomen for a fluid thrill
- Weigh them
- Measure their abdominal circumference
Describe where strictures occur
Usually occur in the small intestine when the lumen has been narrowed by a surgical procedure e.g. inappropriate use of an inverting suture pattern, 2-layer closure or inappropriate incision of tissues during enterectomy.
How are strictures treated?
Resection of affected gut and anastomosis
Where can the oesophagus be accessed for surgery?
- Access the oesophagus to the level of the second rib via a ventral cervical midline approach.
- Access the intrathoracic oesophagus via an intercostal thoracotomy at the level of the lesion
The linea alba is a depression between which muscles?
Rectus abdominis
Which structure can sometimes restrict exposure of the cranial abdomen?
Falciform ligament
Laparotomy refers to an incision where?
Flank
Why are flank incisions less frequently used?
- More traumatic
- More restricted access to the abdominal contents
