ANAHEIM, CALIF. – Withdrawal of life-sustaining systemic therapies in comatose patients after out-of-hospital cardiac arrest as advised in current guidelines often occurs too early, resulting in the death of many patients who could potentially survive with good outcome, according to the results of NORCAST, the Norwegian Cardiorespiratory Arrest Study.
“The take-home message is to be patient and wait. Three days may be too early to make decisions on the patient,”
The European Resuscitation Council and European Society of Intensive Care Medicine have jointly recommended a prognostic algorithm in which a multimodal assessment is made on patients who are still comatose on day 3 after cardiac arrest. But this advice is based on expert opinion and has never been validated. This was the impetus for the prospective NORCAST study.
Current practice in the management of out-of-hospital cardiac arrest patients who are comatose upon hospital admission is to induce therapeutic hypothermia, with targeted temperature management to 33° C for 24 hours under deep sedation. The study hypothesis was that this strategy delays the time to awakening and that, as a consequence, the recommended prognostic tests that are usually done on day 3 after withdrawal of sedation are rendered insufficiently reliable. Thus, decisions to withdraw life-supporting therapies at that point will reduce the survival potential of this population, Dr. Sunde explained.
NORCAST was a prospective observational study that included 259 patients admitted to Oslo University Hospital in a comatose state after out-of-hospital cardiac arrest. In this unselected group, 81% had a cardiac cause for their arrest; the remainder had hypoxic arrest. All patients underwent therapeutic hypothermia, then a period of nonhypothermia followed by sedation withdrawal.
All of the widely used multimodal prognostic tests were ordered, including serial measurement of serum neuron-specific enolase; neurophysiologic testing using EEG and sensory-evoked potential readings obtained both during hypothermia and again at least 3 days after sedation withdrawal; a standardized clinical neurologic exam including assessment of brainstem reflexes and a Glasgow Coma Scale rating 3 days after sedation withdrawal; and a transcranial Doppler study and cerebral MRI on day 5-7. However, the treatment team was blinded to the results of these tests and was encouraged to delay withdrawal of life-supporting therapies as long as possible.
Out of 259 patients who were comatose upon admission, 54% were alive at 6 months – and 91% of them had a CPC of 1 or 2.
The final tally at 6 months: 44% of patients were CPC 1, 5.5% were CPC 2, 4% were CPC 3, meaning severely disabled, and 46.5% were CPC 5, which is brain dead.
Withdrawal of life-supporting therapies occurred in 73 patients, or 28%, and 71% of those patients died, few of them in the early days.
Among patients with a CPC score of 1 or 2 at 6 months, only 20% were awake on day 1-3 following admission. Fifty-seven percent awoke on day 4-7, but importantly, 23% of patients with a good outcome at 6 months were not yet awake on day 8.
Three days after withdrawal of sedation, 49% of patients were rated as having a Glasgow Coma Scale score of 3-8, while 51% were Glasgow Coma Scale 9-15. Moreover, at that time 26% of patients with a good outcome as defined by a CPC of 1 or 2 at 6 months were still in a coma.
“So a lot of patients were still affected by their disease or by sedation at that point. That’s an important finding,” Dr. Sunde said.
Some prognostic tests were highly unreliable
A standout in poor performance was the widely utilized standard of a time to return of spontaneous circulation greater than 25 minutes as a predictor of poor cerebral outcome. In fact, it had a 34% false-positive rate.
“I think it’s really useless to use that. I would rather have return to spontaneous circulation after 40 minutes of good-quality CPR than not have it with 25 minutes of lesser-quality CPR,” he commented.
Similarly, a Glasgow Coma Scale score of 9 or less or a Glasgow Coma Scale-Motor score of 1-3 upon assessment 3 days after sedation withdrawal had false-positive rates of 30% and 34%, respectively.
During hypothermia, EEG abnormalities had a high false-positive rate, and sensory-evoked potential findings were difficult to interpret.