Surgical Patients

Postoperative sepsis

Patients commonly develop SIRS in the immediate postoperative period 2° to ↑cytokine levels caused by the surgical tissue trauma. This is normally a self-limiting response that subsides within 48 hours. Persistent SIRS, or the development of end-organ dysfunction, should prompt examination and investigations to elucidate the cause.

Causes

A number of factors predispose patients to developing postoperative sepsis, including:

Preoperative:
- Infection unrelated to the operation (e.g. LRTI, UTI)
- Infection requiring surgery (e.g. bowel perforation, abscess)
- Immunocompromised patients (e.g. RhA, malnutrition)
Intraoperative:
- Peritoneal contamination
- Gut ischaemia (e.g. thromboembolism, volvulus)
- Reperfusion injury (e.g. aortic cross-clamping)
- GU surgery (especially if indwelling catheter/stent and/or mucosal damage by calculus or instrumentation)
- Surgery of infected area (e.g. debridement of burns, incision and drainage of abscess)
Postoperative:
- Pneumonia (e.g. following thoracic/upper-GI surgery, prolonged immobility, or inadequate pain relief preventing deep breathing/coughing/mobilization)
- Surgical wound infection

Presentation and assessment

(See also

p.322.)

Pyrexia may be associated with other evidence of infection, including:
- Tachypnoea, tachycardia, rigors, sweats
- Complications of sepsis (see p.322)
- Raised WCC and inflammatory markers
Features of sepsis and end-organ dysfunction may be present.
After contaminated gut surgery, sepsis should be monitored for, particularly in the first 72 hours.

Investigations

ABGs (metabolic acidosis, lactataemia suggest impaired perfusion).
FBC (↑/↓WCC, ↑/↓ platelets).
Coagulation screen (↑ APTT/PT and ↓ fibrinogen if DIC).
CRP (raised in response to inflammation).
Cultures:
- Blood from indwelling lines and peripheral ‘stab’
- Samples from all drains and any effusions that can be tapped
- Sputum: consider bronchoscopy/BAL
- Urine: dipstick, MSU/CSU
- Stool: C&S, C. difficile toxin if diarrhoea present
- Wound swabs, if wound inflamed
U&Es (raised urea/creatinine may suggest sepsis-induced AKI).
LFTs (deranged if sepsis-induced hypoperfusion).
Serum glucose, phosphate, magnesium, calcium.
Serum amylase (raised in pancreatitis and other acute upper intra-abdominal conditions, e.g. cholecystitis).
ECG (new onset AF).
CXR (new shadowing/consolidation).
Further imaging: consider US/CT of abdomen, pelvis, or chest (looking for evidence of perforation or collections) and plain films of joints if appropriate.

Differential diagnoses

SIRS (no evidence of infection).
MI (hypotension, tachycardia, hypoxia if LVF present, cool peripheries).
PE (hypoxia, hypotension, tachycardia, cool peripheries).
Haemorrhage (hypotension, tachycardia, cool peripheries).
Ongoing ischaemia (e.g. bowel ischaemia).

Further management

(See also sepsis,

p.326.)

Institute sepsis care management.
Consider:
- Open wound drainage
- Continuous wound irrigation
- Multiple laparotomies for repeated washouts
In some conditions (e.g. necrotizing fasciitis) repeated surgical debridement may be required.
Monitor for, and treat, complications of sepsis (e.g. AKI).

Pitfalls/difficult situations

Multiple organ failure may occur if the source of infection is not aggressively treated.

Further reading

Monkhouse D. Postoperative sepsis. Curr Anaesth Crit Care 2006; 17: 65-70.

Rivers E, et al. Early Goal-Directed Therapy Collaborative Group. Early goal-directed therapy in the treatment of severe sepsis and septic shock. N Engl J Med 2001; 345: 1368-77.

Wound dehiscence

This is partial or complete opening of the surgical wound. Presentation and management vary with the site.

Causes

Predisposing factors include:

Wound infection.
Poor surgical technique.
Tension in the surgical incision site (ascites, ileus, obstruction).
Bleeding/haematoma formation.
Reduced tissue perfusion/oxygenation (‘shock’).
Tissue oedema/poor tissue strength (obesity, hypoalbuminaemia, uraemia, heart failure, liver failure, chemotherapy, radiotherapy).
Persistent coughing/vomiting.
Diabetes.
Smoking.
Long-term or high-dose steroid use.
Patient age >65 years.

Presentation and assessment

Early

Open wound noticed at dressings change or removal of clips/sutures.
Excessive soiling of dressings.
Inappropriate pain.

Late

Signs of shock: hypotension, tachycardia.
Generalized sepsis.
MOF/DIC.

Investigations

ABGs (metabolic acidosis/↑ lactate suggest impaired tissue perfusion).
FBC (↑/↓WCC, ↑/↓ platelets).
Coagulation screen.
U&Es (raised urea/creatinine may suggest sepsis or excessive fluid loss).
LFTs (↓protein/albumin may occur with SIRS/malnutrition).
Wound swabs.
Blood cultures if there are signs of generalized sepsis.
CXR or AXR may help identify alternate sources of infection.
Further imaging: a CT scan or a US scan of wound area may detect any fluid collection, or other source of infection.

Immediate management

Give O₂ as required to maintain SpO₂ ≥ 95%, support airway, breathing, and circulation.
Invasive monitoring may be required to guide fluid management and deliver vasoactive support.
Keep the patient NBM initially in case surgery required.
Inform surgical team as urgent wound closure may be indicated.
Assess blood loss and crossmatch blood for transfusion if necessary.
Cover wound with sterile dressing.
In mechanically ventilated patients consider deepening sedation or commencing neuromuscular blockade to decrease likelihood of expulsion of abdominal contents.

Further management

Identify/avoid/treat any predisposing factors.
Continued invasive monitoring and correction of:
- Fluid status
- Electrolytes
- Coagulation status
Antibiotic therapy may be required.
Surgical management will be required:
- Dressing changes as appropriate
- Wounds may require debridement and/or closure (which may have to be delayed)
- Drainage of any associated collection
After re-closure of abdominal wound, pain relief will be extremely important; consider epidural infusion of local anaesthetics and opioids:
- Involve the pain management team early
Re-closure of abdominal wound may also cause splinting of diaphragm—respiratory support is likely to be required.

Pitfalls/difficult situations

Sepsis and multiple organ failure may occur because the open wound is prone to infection. Strict sterile precautions are required.
Insensible fluid losses may be difficult to assess.
Patients are at high risk of developing resistant infections (e.g. MRSA, VRE, C. difficile).