CICM SAQ 2015.1 Q20

Prognostication after cardiac arrest may be very difficult and involve a number of modalities.

It involves consideration of:

History

• Underlying cause of the arrest
• Co-morbidities
• Use of therapeutic hypothermia
• Features of the arrest – down time, CPR, ROSC

Clinical assessment

• Timing:Neurological assessment timing will be determined by the use of therapeutic hypothermia and the duration and type of medication for sedation but is most reliably performed day 3 without therapeutic hypothermia – probably day 5 with TH. Suggestion is to wait 72 hours after return of normothermia.
  With new TTM trial suggesting 36C then 72 hours post arrest may again be appropriate.
• Examination:
  Clinical – off sedation and neuromuscular blocking agents
  Cranial nerve abnormalities – absence of pupillary response and corneal reflexes are bad prognostic indicators.
  Best Motor response at 72 hours with absent or extensor response associated with poor outcome.
  Status / Generalised and repetitive myoclonus (as opposed to sporadic myoclonus)

Biochemical parameters

•  Nurone specific enolase >33mcg/L at days 1-3 indicates poor outcome
• S100, CSF CKBB not accurate enough for prognostication

Electrophysiological features

• EEG: generalised suppression, burst suppression or generalised periodic complexes strongly associated with poor outcome.
• SSEPs: Bilateral absence of N20 component of SSEP with median nerve stimulation within 1-3 days is strongly associated with poor outcome.

Imaging

•  CT appearance – catastrophic changes with obvious pathology. Diffuse oedema has not been formally assessed as an indicator. 
• MRI may be more sensitive

Predictors of better outcome are:

• Recovery of brainstem reflexes within 48 hours
• Return of purposeful response within 24 hours
• Hypothermia at the time of arrest
• Young age