Predictors showing utility
Several clinical factors predicted poor cerebral outcome with low false-positive rates: Unwitnessed cardiac arrest had a false-positive rate of only 4%; initial presentation in asystole or with pulseless electrical activity had a false-positive rate of 6%; and no bystander CPR had a false-positive rate of 13%.
Abnormal sensory-evoked potential or EEG findings 3 days after sedation withdrawal had low false-positive rates as prognosticators of poor cerebral outcome. An EEG showing burst suppression or epileptiform activity had a “pretty good” false-positive rate of only 7%, Dr. Sunde noted. Bilaterally absent N20 sensory-evoked potential findings, while uncommon, had a false-positive rate of zero. A serum neuron-specific enolase level greater than 80 mcg/mL had a 3% false-positive rate, in sharp contrast to the previously recommended cutoff of more than 33 mcg/mL, which had an unacceptable 38% false-positive rate.
“We should avoid using single predictors in decision making and be patient, especially if we have a witnessed ventricular fibrillation with bystander CPR, independent of time to return of spontaneous circulation,” he concluded.
Dr. Sunde and his coinvestigators plan to present numerous further follow-up studies from NORCAST, including the results of comprehensive cognitive function testing 6-9 months after cardiac arrest in all survivors, coupled with interviews with their close relatives, as well as cognitive function and quality-of-life measurements 3-6 years after cardiac arrest along with interviews with relatives.
Several audience members rose to declare that they’ve been waiting for data such as this for a long time. Session chair Karl B. Kern, MD, professor of medicine at the University of Arizona, Tucson, and codirector of the University of Arizona Sarver Heart Center, commented, “We’ve been talking about whether 3 days is too early for a number of years, and clearly from your data it is. It was twice as long before most of them woke up.”
Dr. Sunde reported having no financial conflicts of interest regarding the NORCAST study, which was sponsored by Oslo University Hospital.