Neurological consequences of cardiac arrest

Abstract

An out-of-hospital cardiac arrest is a life-threatening event with very high early mortality. More than 50% of the patients who reach the emergency ward die, showing clinical signs of brain damage during the first weeks after admission. Survivors may suffer from post-ischemic encephalopathy, which influences their future lives. Predicting the outcome is difficult, but it is important to estimate the brain damage as early as possible. Repeated physical examinations, including coma level determination and registration of pathological brain-stem reflexes, are essential clinical instruments. The present study was undertaken to investigate whether the quantification of brain damage markers in serum and cerebrospinal fluid reflects the extent of the anoxic damage and can be used to predict the outcome.In all, the study comprised 82 patients resuscitated from cardiac arrest and referred to Sahlgren's University Hospital. A neurological examination was performed about four days after admission and thereafter at specific time points: 14, 45, 90 and 365 days. Serum samples were drawn on the first three days. Concentrations of S-100 and NSE were determined with immunoassays. In 22 cases, a lumbar puncture was performed during the second or third week. The contents of NFL were determined with an ELISA method. At one year, the outcome was categorised as good or poor according to the Glasgow Outcome Scale. Functional capacity was evaluated using the Mini Mental State Examination, Katz ADL scale, Barrow Neurological Institute Screen and Functional Independence Measure. Serum levels of both S-100 and NSE were increased during the first three days after the arrest. The concentrations were strongly associated with traditional clinical parameters indicating anoxic brain damage. The levels were higher among patients with a fatal outcome within two weeks compared with survivors. Both serum markers were increased among patients with a poor outcome at one year compared with those with a good one. CSF levels of NFL at two to three weeks were increased and related to poor outcome according to the GOS, MMSE and Katz. Furthermore, the serum levels of S-100 were related to outcome according to the BNIS and FIM at one year.The present study reveals that the extent of brain damage after a cardiac arrest can be estimated by measuring S-100 and NSE in serum, as well as NFL in the CSF. These brain damage markers can be used to predict the outcome.