Neuroprognostication from the TTM Trial

Excerpted from Life in the Fast Lane CCC

The TTM trial (Nielsen et al, 2013) used a standardized protocol for neurological prognostication to guide decisions regarding treatment withdrawal following targeted temperature management post-cardiac arrest:

All patients in the trial were actively treated until a minimum 72 hours after the intervention period, i.e. after rewarming, when neurological evaluation was done on patients not regaining consciousness.

1. patients with myoclonus status in the first 24 hours after admission and a bilateral absence of N20-peak on median nerve somatosensory evoked potentials (SSEP)
2. patients who became brain dead due to cerebral herniation, and
3. because of ethical reasons described below.

At that time-point, limitations in and withdrawal of therapy could be instituted by the treating physicians. The neurological evaluation was based on:

• Clinical neurological examination (including Glasgow Coma Scale (GCS), pupillary and corneal reflexes)
• SSEP and electroencephalogram (EEG)
• Biomarkers for brain damage were not used for operational prognostication

Findings allowing for discontinuation of active intensive care:

• Brain death due to cerebral herniation
• Severe myoclonus status in the first 24 hours after admission and a bilateral absence of N20-peak on median nerve SSEP
• Minimum 72 hours after the intervention period: persisting coma with a Glasgow Motor Score 1-2 and bilateral absence of N20-peak on median nerve SSEP.
• Minimum 72 hours after the end of the intervention period: persisting coma with a Glasgow Motor Score 1-2 and a treatment refractory status epilepticus (see TTM trial supplement for definition)

Patients with Glasgow Motor Score 1-2 at 72 hours or later who had retained N20-peak on the SSEP, or patients in hospitals where SSEP was not  available were:

• re-examined daily
•  the limitations/withdrawal of intensive care considered if GCS-Motor did not improve and metabolic and pharmacological affection was ruled out

Active treatment could be withdrawn prior to 72 hours after the intervention period for ethical  reasons

• for instance: previously unknown information about disseminated end-stage cancer  or refractory shock with end-stage multiorgan failure
• However assumptions of a poor  neurological function were not allowed be the sole reason for withdrawal of active treatment  prior to 72 h after the intervention period (exception: brain death and early myoclonus status including a negative SSEP)