Necrotising Fasciitis

Question 1

What is Necrotising Fasciitis?

Answer 1

• A bacterial infection that spreads along the fascial planes and subcutaneous tissue
• The bacteria multiply and release toxins and enzymes that result in thrombosis in the blood vessels
• Resulting in soft tissue and fascial destruction

Question 2

What is the main Cause of NEC Fasciitis?

Answer 2

• Group A Haemolytic Streptococcus

Question 3

What are the risk factors for NEC Fasciitis?

Answer 3

• Abdominal surgery
• Diabetes
• CKD
• Alcohol excess
• Age/ Fraility
• Immunocompromised
• Malignancy
• Obesity

Question 4

How does NEC fasciitis present?

Answer 4

• Severe pain out of proportion
• Erythematous, blistering and necrotic skin
• Pus oozes from the fascial planes
• Systemically unwell with fever and tachycardia
• Subcutaneous emphysema ( Crepitus)
• X-Ray = soft tissue gas

Question 5

What is the positive finger test?

Answer 5

• A 2 cm vertical incision is made in the affected skin
• An index finger is pushed into the tissue
• The test is positive if the finger passes through the subcutaneous tissue without resistance

Question 6

What investigations need to be done?

Answer 6

• Blood culture
• Blood Gas ( raised lactate = metabolic acidosis)
• Worsening renal function, low sodium, impaired liver tests, raised glucose, coagulopathy
• Tissue biopsy
• Imaging (X-ray, Ct scan )
• Bloods: WCC, CRP, CK, Urea all raised

Question 7

What is the managment for NEC fasciitis?

Answer 7

• Urgent Surgical Debridement - packed for 24/48 hours and then relooked at.
• Sent to ITU after surgery
• IV antibiotics
• IV fluids
• Catheter

Question 8

What is the Risk Scoring System for NEC fasciitis?

Answer 8

• LRINEC
• < equal to 5 = low risk
• 6/7 intermediate
• > equal to 8 = high risk

Question 9

What is indicative of damaged tissue?

Answer 9

• Dish-water fluid from the wound
• non-bleeding unhealthy subcutaneous tissue

Question 10

What are the two main types of NEC fasciitis?

Answer 10

• Type 1: polymicrobical infection, mixture of anaerobes and aerobes. More common in elderly patients
• Type 2: monomicrobial infection, caused by Streptococcus Pyogenes, common in healthy individuals with history of trauma

Question 11

What is Gas Gangrene?

Answer 11

• Form of Nec Fasciitis caused by Clostridium species
• Results in gas being produced by the bacteria within the tissues
• clostridial organisms produce alpha and beta toxins that lead to extensive tissue damage and large volumes of gas
• Tissue Crepitus present on light palpation