Cardiac arrest and therapeutic hypothermia: Prognosis and outcome

University dissertation from Lund University, Faculty of Medicine

Abstract: Abstract Therapeutic hypothermia (TH) is the only treatment available to reduce neurological sequels for unconscious patients following cardiac arrest (CA). TH requires sedation and muscular relaxation, obscuring the clinical neurological examination for estimation of prognosis, and clinical decision making. Continuous amplitude-integrated EEG (aEEG) has been used to predict outcome in neonates suffering from asphyxia. In adults following CA and TH, the novel observation was made that a continuous aEEG-pattern prior to or at normothermia strongly correlated to return of consciousness, while other patterns strongly correlated to continued coma. A status epilepticus aEEG-pattern carried a poor, but not desolate prognosis. Biochemical neuronal-markers (neuron-specific enolase (NSE) and S-100B) have previously been assessed in non-TH CA patients. In TH, an NSE level of 28 μg/l 48h after CA, or an increase of more than 2 μg/l between 24 and 48h were strongly associated to a poor outcome. Five days after the CA, one third of the patients remained in coma. They either had multimodal signs of extensive brain damage (high NSE levels, ischemic changes on MRI or neurophysiological evidence of advanced brain damage (bilateral lack of SSEP)), or showed sustained unconsciousness and a status epilepticus aEEG-pattern. Unconscious patients without these signs of brain injury eventually regained consciousness. Approximately 50% of hypothermia treated patients regained consciousness. Ninety-eight percent of surviving patients had an independent lifestyle six months after the CA. The dominant cognitive problem was a disturbed memory function. Taken together, aEEG appears superior in early neurological prognostication in these patients.