Necrotising fasciitis

It is 1 a.m. A 65-year-old diabetic male presents with a painful red swelling in his right thigh and groin. He is pyrexial, hypotensive and dehydrated. How will you treat him?

• Resuscitate the patient with oxygen and IV fluids and take baseline bloods, BM, urinalysis and arterial gases.

• Take a history and examine the patient.

• Check for trauma, IV drug use, symptoms of bowel obstruction.

• Consider differential diagnosis—cellulitis/abscess/necrotising fasciitis/strangulated hernia.

What is necrotising fasciitis?

• It is polymicrobial infection of skin and fascia with necrosis of subcutaneous

tissue, sparing the underlying muscle.

• It can progress rapidly to severe sepsis, multiorgan failure and death.

• Primary necrotising fasciitis is due to bacterial entry from mild skin trauma.

• Secondary necrotising fasciitis is due to prior infection (e.g., deep abscess/

visceral perforation).

• Risk factors are diabetes, immunosuppression, steroids, old age, malnourishment

and renal failure.

What are the clinical signs?

• Erythema, swelling, and pain

• Warning signs: dusky blue skin, crepitus (indicating gas in the tissues),

patchy areas of necrosis, bullae and signs of systemic sepsis

How would you confirm the diagnosis?

• Blood tests: leucocytosis, acidosis, deranged clotting, hypoalbuminaemia, abnormal renal function

• Imaging: soft tissue gas on x-ray or CT (if the patient is stable)

• Stab incision over crepitus releases murky fluid from skin.

How would you treat the patient?

• IV broad spectrum antibiotics are used against Streptococcus, Gram-negative aerobes (E. coli and Pseudomonas), anaerobes (Bacteroides):

• Start with augmentin/metronidazole initially and consult with the microbiologist on call.

• Take patient to theatre following initial resuscitation (may need HDU/ITU) because this is a life threatening emergency.

• Incise down to deep fascia; debride all nonviable tissue.

• Take back in 24 hr for a second look and further debridement.

• Some studies report the benefit of hyperbaric oxygen (controversial and not

widely used).