Ch 28 (s28.16); Ch 23; Ch 24; Ch 29; Ch 37
Chapter 23 routed the enolase-plus-haemolysis-index requirement to Chapters 29 and 37; this guideline supplies the number those chapters need, which is that there is no validated number.
Four of the six standard indicators are individually confounded on ECMO (pupils by adrenaline, N20 by the ECMO series in which it was intact in every patient who did badly, enolase by haemolysis, and magnetic resonance imaging by being unavailable). The rule requires two concordant indicators and on ECMO it is difficult to assemble two that are not confounded. Do not apply the 60 micrograms per litre threshold to an ECMO patient.
An unfavourable neurological outcome in patients without ECMO is strongly suggested by at least two indicators of severe acute brain injury: absence of pupillary and corneal reflexes at 72 hours or more, bilateral absence of N20 cortical waves on somatosensory evoked potentials at 24 hours or more, highly malignant electroencephalographic patterns after 24 hours, neuron-specific enolase exceeding 60 micrograms per litre at 48 or 72 hours, status myoclonus within 72 hours, and extensive diffuse anoxic injury on brain computed tomography or magnetic resonance imaging. This approach has not been validated in ECMO patients and has limited evidence. Neuron-specific enolase values are often higher in ECMO patients due to ongoing haemolysis, and the most accurate threshold for predicting an unfavourable neurological outcome in extracorporeal cardiopulmonary resuscitation remains unknown, possibly exceeding 100 micrograms per litre. Clinicians must exercise caution to mitigate the self-fulfilling prophecy bias; confounders such as sedatives, electrolyte disturbance and hypothermia must be excluded first, and in patients undergoing targeted temperature management the most crucial assessment is performed after rewarming. Where an apnoea test is not feasible, a cerebral angiogram or radionuclide brain scan is preferred. Routine ethics consultation within 72 hours of cannulation can mitigate ethical conflicts.
Neurological prognostication on ECMO