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.
- 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)
- patients who became brain dead due to cerebral herniation, and
- 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Active treatment could be withdrawn prior to 72 hours after the intervention period for ethical reasons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)