Predictors of poor neurologic outcome in patients after cardiac arrest treated with hypothermia: a retrospective study.

INTRODUCTION: Outcome studies in patients with anoxic-ischemic encephalopathy focus on the early and reliable prediction of an outcome no better than a vegetative state or severe disability. We determined the effect of mild therapeutic hypothermia on the validity of the currently used clinical practice parameters.
METHODS: We conducted a retrospective cohort study of adult comatose patients after cardiac arrest treated with hypothermia. All data were collected from medical charts and laboratory files and analyzed from the day of admission to the intensive care unit until day 7, discharge from the intensive care unit or death using the Utstein definitions for the registration of the data.
RESULTS: We analyzed the data of 103 patients. The combination of an M1 or M2 on the Glasgow Coma Scale or absent pupillary reactions or absent corneal reflexes on day 3 was present in 80.6% of patients with an unfavourable and 11.1% of patients with a favourable outcome. The combination of M1 or M2 and absent pupillary reactions to light and absent corneal reflexes on day 3 was present in 14.9% of patients with an unfavourable and none of the patients with a favourable outcome. None of the patients with a favourable outcome had a bilaterally absent somatosensory evoked potential of the median nerve. The value of electroencephalogram patterns in predicting outcome was low, except for reactivity to noxious stimuli.
CONCLUSIONS: No single clinical or electrophysiological parameter has sufficient accuracy to determine prognosis and decision making in patients after cardiac arrest, treated with hypothermia.