Indicators of poor neurological prognosis in patients with anoxic coma: a systematic review and critical appraisal of the evidence

Purpose: To determine the neurological clinical signs predicting poor outcome in patients with coma of hypoxic/ anoxic origin through a systematic review and critical appraisal of the literature. Data sources: A structured search was performed using MEDLINE; search terms were 'prognosis' and 'coma'. Study selection: Articles published since 1980 were selected if they studied an adult population, had a sample size greater than 50 patients, focused on bedside clinical signs, and addressed long-term recovery and functional status. Data extraction: We reviewed all selected articles and abstracted pertinent information. Results: The overall outcome in hypoxic/anoxic coma is quite poor, with 65% of patients dying within two weeks and 10% surviving to one year. In particular, the absence of pupillary light reflexes, corneal reflexes or motor response to pain, at three days post-injury, can predict poor outcome with apparent 100% accuracy. Conclusions: The absence of any of three simple clinical signs correlates strongly with a poor neurological outcome. These signs can aid the intensivist in prognosticating, although certain methodological limitations of the studies limit inferences that can be drawn.