There are multiple things that need to be considered with managing a septic peritonitis patient, though here are 10 (well 11) to consider.

Diagnosis

If you are concerned about a patient having a septic process then identifying the source of sepsis is important. If there is abdominal pain, or peritoneal effusion then the patient should be screened to assess for septic peritonitis. All peritoneal fluid should be evaluated under microscopy for neutrophils with intracellular bacteria, dilute samples might require centrifugation to concentrate the cells, or even evaluation by a clinical pathologist. It depends on the site of the gastrointestinal lesion whether a bacterial load might be identified, for example a patient with a perforated gastric ulcer might have no obviously identifiable intracellular bacteria, however, a patient with a colonic lesion would have a marked load. It was reported in 2003 retrospectively that a difference in concentration of >20 mg/dl (1.11 mmol/L) between blood and peritoneal fluid glucose concentration can differentiate a septic peritoneal effusion from a non-septic peritoneal effusion (Vet Surg. 2003;32:161–166). Koenig and Verlander re-examined this using a point of care glucometer in cases with confirmed septic peritonitis and found the following: >20 mg/dl, sensitivity 41% and specificity 100%, however, the difference >38 mg/dl (2.11 mmol/L) supported a more accurate diagnosis.

A diagnostic peritoneal lavage, if there is no obvious free peritoneal fluid visible can be used to see if there are any neutrophils with intracellular bacteria. To do this you need to insert 10 mL/kg of sterile saline, prior to sampling.

Radiographs, ultrasound, and even CT might be able to identify free peritoneal gas, which would merit an exploratory laparotomy.

Pre-Operative Stabilisation

It is likely that some fluid resuscitation is required if there is a hypovolaemic component to the patient’s shock. Though if the patient is hypotensive then some fluid might be required prior to starting vasopressor therapy. Although there is limited evidence in our species, norepinephrine should be started if after a sensible bolus the patient’s blood pressure remains ≤65 mm Hg. Once the source of sepsis is identified then broad-spectrum antibiotics should be given intravenously. A pre-operative serum albumin concentration of <25 g/L, a left shift prior to surgery and dogs that required a resection and anastomosis due to an intestinal foreign body were more likely retrospectively to leak (J Am Vet Med Assoc. 2003;233:73–77). Foreign bodies have not been shown to be a risk factor in all studies.

Anaesthesia

Care is required to maintain blood pressure and minimise the amount of anaesthetic agents used. Often fentanyl, midazolam might be all that is required for endotracheal intubation. Maintaining the patient’s body temperature and minimising heat loss is important. Hypotension should be avoided as this is a risk factor for leakage (J Am Vet Med Assoc. 2011;238:486–494).

Surgery

A full exploratory laparotomy is important when trying to locate the source of GI leak, and retractors are invaluable for making sure that you have adequate visualisation. Pyloric ulcers can be tricky to identify. If an enterotomy, enterectomy, or resection and anastomosis is required care should be taken to make sure that the closure is appropriate and secure. Care should be taken if the surgeon is suspicious of a neoplasia as the underlying cause of the leak, as this has been identified as a cause of leakage following surgery. Pre-operative septic peritonitis is a risk factor in itself for dehiscence (Vet Surg. 2018;47:125–129) in intestinal resection and anastomosis. Staples in that study were less likely to dehisce compared with hand sewn, however, this was not found in a previous study (Vet Surg. 2016;45:100–103). It is probably evidence enough that large prospective studies are required to evaluate if there are any consistent identifiable factors in leakage following surgery, however, identifying one solitary factor is unlikely.

Postoperative Care

Blood Pressure

Maintain MAP ≥65 mm Hg. It is likely that some vasopressor would be required to help maintain perfusion to the vital organs, however, care must be taken when deciding upon a target, e.g., blood pressure. There is little evidence in dogs and cats for a preferred vasopressor though norepinephrine (noradrenaline) seems to be the most appropriate currently.

Antibiotics

Depending on the clinical picture of the patient antibiotics might not require changing even if a resistant bacterial species is cultured. However, initial appropriate antibiotic therapy is likely to be a major factor in having a successful outcome.

Fluid Therapy

Fluid therapy should be based upon the hydration status of the patient, monitoring the patient’s urine output and drain output, if abdominal drains are used. Recording these findings on the patient’s clinical record and calculating the ins and outs, and if possible, the patient’s weight regularly can give some objective information for assessing hydration status. It is not uncommon for sick, septic peritonitis patients to become oedematous, and it should prompt the clinician to think about the fluid balance of the individual patient, particularly if the patient’s albumin is low.

Drainage

A variety of different abdominal drains have been used and it might make some sense to remove the peritoneal fluid although there is no evidence that it improves outcome. It was reported that closed suction drainage: left in place for a median of 6 days (2–11), had a survival rate of 85% in a referral population (Adams et al. Vet Surg. 2014;43:843–851). Open abdomens might be the surgeon’s preference based on visual appearance of the abdomen, though there is no evidence that this improves outcomes, however, it will mean that the abdomen will be examined and flushed again prior to closure.

Dehiscence

Often occurs within 5 days though can be longer. Leakage <24 hours is likely to occur from surgical failure. It is important if there are drains in place to not look at fluid collected in them to identify leakage, as often these receptacles will be colonised and, therefore, abdominocentesis is preferred. It is more common that if dehiscence and leakage occur that the patient will become tachycardic, pyrexic, and likely have abdominal pain.

Kirby’s Rule of 20

Twenty things to consider when looking after critical patients, it includes what is listed above. Nutrition is key.

Going Back In

This might be the 11th thing. Repeat surgery following dehiscence carries a higher mortality though can be effective in approximately 50% of cases. Although hypotension, hypoalbuminaemia, and initial appropriate antibiotics are important they were not shown to be significant when examined retrospectively.

References

References are available on request.