Preparing Your Patient

Many potential postoperative crises can be prevented by adequate preparation, following basic principles for intestinal surgery and recognising the high-risk patient.

When to Operate?

Immediate surgical intervention is indicated for complete gastric or proximal intestinal obstructions, displacements, intestinal perforation, strangulation or penetrating abdominal wounds. Resuscitative efforts are instituted simultaneously. For lower or partial obstructions, surgery can usually be delayed to allow for fluid, acid-base and electrolyte corrections. Surgery should be performed within 12 hours of diagnosis.

Fluid Therapy

Many patients requiring gastrointestinal surgery are dehydrated. The hypotension associated with anaesthesia, as well as evaporation from the open abdomen and the anaesthesia circuit will compound the fluid deficit, so aggressive fluid therapy is generally continued throughout surgery and into the postoperative period. As a rule, 10 ml/kg/hour of an appropriate crystalloid should be administered during surgery (unless cardiac or renal failure is evident). Oncotic support and/or blood products may be indicated in critical cases.

Fasting

Fasting the patient before surgery is recommended: it will decrease the incidence of reflux, decrease ingesta volume in the intestinal lumen and will also decrease bacterial numbers. A 12-hour fast is normal for adult patients, and a 6-hour fast for paediatric patients (monitoring blood glucose).

Anaesthesia

Some anaesthetists will premedicate with atropine or glycopyrrolate to counter vagal effects of the bowel being handled. If there is evidence of gas-filled loops of bowel, or free gas in the abdomen, nitrous oxide should be avoided. Critical cases will require more intensive monitoring under anaesthesia and postoperatively, with a urinary catheter, central line and possibly an arterial line.

Principles of Intestinal Surgery

Warmth

Hypothermia is a huge concern with any open cavity surgery. Circulating water heating blankets should be routinely used, and supplementary safe forms of warming are warranted in small dogs and cats. Core temperature should remain above 35°C.

Antibiotic Prophylaxis/Antibiotic Therapy

When a hollow organ is entered, prophylactic antibiotics are indicated. A first-generation cephalosporin is appropriate for upper gastrointestinal surgery, administered as a slow intravenous bolus around induction and repeated every 2 hours until close. A second-generation cephalosporin (such as cefoxitin) is preferred for the colon or rectal procedures.

Instrumentation

Appropriate instrumentation greatly facilitates surgery of the gastrointestinal tract:

 Self-retaining abdominal retractors are essential (e.g., Balfours).

 Hand-held retractors to expose deeper structures (e.g., malleable, Faraboeufs, Army-Navy).

 Doyen non-crushing intestinal forceps for occluding the lumen of the bowel without compromising perfusion.

 Regulated suction is useful - Poole suction tip for draining abdominal fluid; Yankaeur and Frasier tips for finer suction.

 Metzenbaum scissors and Babcock forceps should routinely be included in the surgery pack.

 Fine, multitoothed forceps such as Debakey or Cooley are the least traumatic for handling bowel edges - avoid large-toothed forceps.

 Intestinal stapling equipment, automatic ligating staplers are quick, fun and secure.

 Ceiling-mounted, articulated, double lighting system is invaluable.

Assistance

Assistance facilitates many gastrointestinal procedures. A sterile assistant will enable enhanced exposure due to accurate retraction, improved apposition of bowel ends, decreased contamination and shorter surgical times.

Sponges

The use of large laparotomy sponges is highly recommended, rather than traditional small gauze squares. All sponges should have a radio-opaque stripe and numbers must be reconciled on closing.

Surgical Technique

Always handle bowel gently. Excessive handling and drying of the intestines may cause postoperative ileus. The abdominal contents should be kept moistened with warm, sterile saline at all times, as they have a tendency to dry out. Hands are excellent for examining the intestines and occluding the bowel lumen. Electrocautery should not be used on the bowel wall - haemorrhage from transected or incised bowel will soon clot with gentle pressure from moistened gauze. Bleeding from vasa recti or arcuate vessels should be attenuated with fine ligatures of 1 metric (5-0 USP) monofilament suture. Tension should be minimal on any suture line.

Assessment of Intestinal Viability

A decision to resect bowel requires an accurate assessment of viability. The standard subjective criteria for viable intestine are colour, arterial pulsations, peristalsis and bleeding from a cut edge. The bowel should be moistened and warm when assessing these characteristics. If viability is questionable, resection is the prudent choice. Around 75–80% of the small intestines can be resected before permanent short bowel syndrome is seen.

'Packing Off'

Following initial exploration of the abdomen, the affected area of bowel should be isolated and packed off from the remaining abdominal contents. Large laparotomy sponges moistened with warmed sterile saline are placed around the affected area. These sponges act to protect the packed-off abdomen from contamination in case of inadvertent leakage, they keep abdominal contents moistened and decrease heat loss.

Stay Sutures

Stay sutures are loops of suture material passed through the bowel wall, and held with forceps. They are atraumatic and can be used to provide traction and reposition the bowel as needed. Stay sutures are removed by snipping one end of the suture close to the bowel, so that drag through the tissues is minimised.

Suture Material

A monofilament, absorbable suture material with a consistent, known rate of absorption and minimal reactivity is suitable for use in the small intestine. Polydioxanone and polyglyconate are most commonly used. Non-absorbable monofilament sutures such as nylon, polypropylene and polybutester are also suitable choices. Braided sutures tend to harbour bacteria and cause more trauma as they pass through the tissue and are not generally recommended. Chromic gut is not indicated due to its unpredictable rate of absorption, especially in the presence of inflammation. Gut will also incite a significant inflammatory response. A fine suture material is always indicated, usually 1–1.5 metric (4-0 or 5-0 USP), and occasionally 2 metric (3-0 USP) in size.

Suture Patterns

Single-layer, direct apposition of the bowel is recommended over an inverting, everting or two-layered suture pattern. This is true for small and large bowel, but stomach wall is usually sutured in two layers - a simple continuous full-thickness layer, followed by an inverting layer in the serosa and muscularis. Gastrointestinal sutures need to be tied snugly. Accurate apposition is difficult to obtain, due to the tendency for the redundant mucosa to bulge outward from the lumen. Mucosal eversion can be minimised by mucosal trimming, modifying a simple bite to a modified Gambee bite, and using a simple continuous suture pattern.

Abdominal Lavage and Suction

Copious quantities of warm, sterile saline followed by suctioning before closure is essential following gastrointestinal surgery. Thorough abdominal lavage will reduce contaminating bacteria and debris, remove residual blood, warm the abdomen, moisten all organs and enable a final check of the cavity. (Water-impermeable barrier draping should be consistently used as part of the draping protocol.) The addition of antibiotics or antiseptics to the final lavage solution has no proven benefit, and can be irritating to serosal surfaces.

Recognising the high-risk patient

Although complications of gastrointestinal surgery can occur in any patient, there are some patients at increased risk of dehiscence, or other complications. Patients with pre-existing peritonitis, hypoproteinaemia, uraemia, hyperadrenocorticism, immunosuppressed state, advanced liver disease, negative nitrogen balance, coagulopathies, septis, etc., may not heal as quickly or effectively. These patients should be aggressively prepared for surgery and will require critical postoperative care. Intestinal suture lines should be augmented with serosal overlay or omental wrap, thus bringing in blood supply, a source of macrophages and mesothelial cells to the sutured area. A serosal overlay pexies two sections of healthy bowel over the suture line, carefully avoiding kinking of the jejunal festoons. An omental wrap covers the suture line with a 'wrap' of omentum, held in place with several tacking sutures. Both these techniques effectively reinforce the suture line. The abdominal wall closure needs to be secure and long lasting in these cases. An interrupted or continuous, carefully spaced linea closure with a monofilament (slowly absorbable or non-absorbable) suture should be placed. Subcutaneous and skin layer should follow.

References

1.  Stanley BJ. Small intestinal surgery. In: Williams J, Niles J, eds. BSAVA Manual of Canine and Feline Abdominal Surgery. Gloucester: British Small Animal Veterinary Association, 2005:96–111.

2.  Tobias KM. Gastrointestinal system. In: Slatter DH, ed. Textbook of Small Animal Surgery. Philadelphia: WB Saunders, 2003:499–762.