Tasty Morsels of Critical Care 022 | Necrotising fasciitis

25 Jan

Welcome back to the tasty morsels of critical care podcast.

Continuing along a theme of words with with too many i’s in them, (see TM 007 for more) today we look at necrotising fasciitis or “nec fasc” to its friends.

What clinical signs might help us find this?

  • necrotic skin
  • bullous changes
  • dishwater coloured drainage from the bullae/tissue
  • everyone’s favourite: POOP or pain out of proportion
  • crepitus
  • people with DM, immunosuppression, lines in situ or water exposure
  • the other thing I’ve found useful over the years is that whenever you see a cellulitis with hypotension or a cellulitis going to ICU then you should be strongly considering nec fasc that you just haven’t found yet.

Many of you will have heard of the LRINEC score but, like many of these scores for uncommon critically illnesses, it’s not that useful for making decisions but does highlight some of the features that should prompt you to think about it.

You can diagnose it clinically with plain film, ultrasound, with CT or god help us all… MRI. (it’s not that MRI isn’t good, but any time you combine “time dependant surgical diagnosis” with MRI you’re in for diffs…)

First amongst the lesser known facts about nec fasc comes the various types it is split into.

  • Type 1: polymicrobial infection affecting the trunk perineum, typically in poorly controlled diabetics.
  • Type 2: monomicrobrial infection (usually a beta haemolytic strep), mainly affecting the limbs of usually fairly normal patients
  • Type 3: Clostridial infections or gram -ve, possibly even vibro. Can affect limbs, trunk, perineum and be associated with trauma or water exposure
  • Type 4: candida, typically in the immunosuppressed as you might expect

Obviously types 1 and 2 are what we see most of. There are some identifiable risk factors for nec fasc but type 2 infections, being mainly group A strep often have no risk factors so this list is more for the other types.

  • Diabetes
  • Alcohol misuse
  • PVD
  • Renal failure
  • Recent surgery or trauma
  • Malignancy/immunosuppression
  • Injection drug use
  • VZV is an unusual but well described risk factor in kids

If you weren’t already aware then a key take home point is that surgical debridement is of the essence here. Surgery involves removing everything where the fascia pulls away when it’s not meant to. Generally a second look at 24-48 hrs to see if there’s been any progression is good idea.

Medical treatment lies more in our domain as intensivists. Antibiotics are the mainstay and recommendations will vary by country and hospital. For example my current hospital’s empiric recommendations are

  • ben pen and flucloxacillin
  • ciprofloxacin
  • gentamicin
  • clindamycin

MRSA is relatively uncommon so simple penicillins are often fine. Clindamycin is used as it inhibits protein (ie toxin) synthesis, though it is worth adding there are no high level data supporting this. I’ve heard similar physiological reasoning for linezolid against the staph PVL toxin in this regard.

IVIG is frequently given (again with little data supporting). IDSA makes no recommendation on IVIG, the World Federation Emergency Surgeons give very weak recommendation to consider its use.

Hyperbaric oxygen is much more complicated to deliver in a crashing critically ill patient. It is not recommended by IDSA.

References and rationalisations

Tasty Morsels of EM 012

Oh Chapter 72

Stevens, D. L. et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the infectious diseases society of america. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 59, e10-52 (2014).

Sartelli, M. et al. World Society of Emergency Surgery (WSES) guidelines for management of skin and soft tissue infections. World Journal of Emergency Surgery 9, 403–18 (2014).

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