Prognostication after cardiac arrest and hypothermia: a prospective study

Area of Science:

• Neurology
• Critical Care Medicine
• Neurophysiology

Background:

• Current American Academy of Neurology (AAN) guidelines for predicting outcomes in comatose cardiac arrest (CA) survivors were established before the widespread use of therapeutic hypothermia (TH).
• The efficacy of TH in modifying neurological prognostication necessitates re-evaluation of existing predictive models.

Purpose of the Study:

• To validate the prognostic value of clinical and electrophysiological variables in comatose CA survivors treated with TH.
• To assess if TH impacts the accuracy of established neurological outcome prediction guidelines.

Main Methods:

• A prospective study of 111 comatose CA survivors treated with TH.
• Neurological examinations, electroencephalography (EEG), and somatosensory evoked potentials (SSEP) were performed post-TH.
• Neurological recovery was assessed at 3-6 months using Cerebral Performance Categories (CPC).

Main Results:

• Certain clinical variables (incomplete brainstem reflexes, myoclonus, absent motor response) showed higher false-positive mortality predictions than AAN guidelines.
• Unreactive EEG background strongly correlated with in-hospital mortality and poor long-term neurological recovery (CPC 1-2).
• A combination of 2 out of 4 predictors (incomplete brainstem reflexes, myoclonus, unreactive EEG, absent cortical SSEP) accurately predicted poor neurological recovery (PPV=1.00), with EEG reactivity improving prognostication.

Conclusions:

• Therapeutic hypothermia (TH) significantly influences outcome prediction in cardiac arrest (CA) survivors.
• Clinical variables previously used for prognostication require cautious interpretation in the TH era.
• Electroencephalography (EEG) background reactivity is a valuable tool for determining prognosis in CA patients treated with TH.