Question 10

College comments

Syllabus topic/section: 2.1.3 Sepsis and Infections. Necrotising soft tissue infections L1

Discussion: 

Most candidates answered the question appropriately as per the glossary term. Candidates scored well if they provided a structure and contextualised the answer to the given scenario.
Candidates who considered a broad differential and tailored their request (from the resident) for assessment, accordingly, were awarded more marks.

In Part a), history and examination questions directed to form a differential diagnosis for hypotension in the context of cellulitis was expected. Candidates that asked for history including past history and examination features to differentiate between cellulitis and necrotising fasciitis, sepsis versus cardiac failure and end organ effects of hypotension scored high marks.

In part b) candidates gained more marks if they categorised the criteria for admission.
For example: the admitting criteria would depend on variety of factors such as disease factors, patient factors, logistics of the ward/ICU.
Candidates were given credit for mentioning resident seniority, experience, and reliability as factors that would affect diagnosis and admission.
 

Interpretation

Considering how often the "decision to admit this patient to your ICU" seems to be based on vibes, it was curious to see this question appear in an exam paper.

a) Assessment details:

History:

• Chronicity: cellulitis typically evolves over 2–3 days
• Pruritis: it should not itch
• Wound
• Progression despite antibiotics
• Previous cellulitis:
• Systemic unwellness out of proportion to signs (nec fasc)
• Symptoms out of proportion to signs (nec fasc)
• Recent surgery or travel (DVT)

Examination

• Features of shock: cellulitis rarely causes profound shock
• Unilateral: very rare to get cellulitis in both legs
• Fluctant mass? - it's an abscess, or septic bursa
• Well-demarcated, raised, shiny plaque: typical of erysipelas
• Exquisitely tender, bullae, crepitus: necrotising fasciitis
• Palpable cord like structure: thrombophlebitis
• Circumferential limb involvement, peau d’orange: cellulitis

Investigations:

• FBC, CRP, procalcitonin: inflammatory markers would be only modestly raised in DVT
• Lactate: a cellulitis should not have a lactate of 6. That's more in keeping with necrotising fasciitis.
• Blood cultures: 
• CT: gas locules would suggest a necrotising infection
• Skin biopsy

a) Decision to admit to ICU

Patient factors:

• Fraily and baseline function, comorbidities
• Likelihood of survival and good functional outcome
• Patient preferences, family preferences, "consumer partnership"

Disease factors:

• Support requirements, response to ward-level interventions like fluids
• Intervention requirements (eg. need for CVC)
• Disease severity (eg. if nec fasc is recognised)

Referrer factors:

• Ward staffing, capacity for closer monitoring
• Experience and seniority of the assessing ICU resident  
• Experience and seniority of ward staff

System factors:

• ICU bed status
• ICU workforce characteristics (eg. acuity, medical cover)
• Availability of necessary interventions (eg. can the patient undergo debridement locally or do they require transfer)