Global Cerebral Hypoxia

The concept of global cerebral hypoxia and subsequent hypoxic encephalopathy (HE) has become increasingly important due to the aging population as well as the growing acceptance and use of resuscitation after cardiac arrest. Therefore, more patients reach the hospital after cardiopulmonary resuscitation (CPR). The present review summarises the current knowledge on HE. The actually valid rules for CPR are as follows: Untrained bystanders should concentrate on cardiac compression (100/min). Trained or medical personnel should use a 30: 2 ratio of compression to ventilation in adults as well as children. Early defibrillation is recommended. After hospital admission, a mild therapeutic hypothermia (TH) treatment (32-34 degrees C) is recommended for the first 24 h. TH improves the prognosis significantly. From the neurological point of view, an important part of HE is an evaluation of the prognosis. Unfortunately, there is no proven algorithm for the prognostic evaluation of patients with HE after the use of TH. No clinical or technical test is able to predict a poor prognosis within the first 24 h. Excluding sedation and hypothermia, a deep coma with loss of pupillary reaction und corneal reflexes for 3 days after HE is highly predictive of a poor prognosis. Loss of the oculocephalic reflex after 24 h or a GCS motor score under 3, i.e., no motor reaction or merely extensor posturing after 72 h, are less predictive. Validity has not been shown for other clinical signs, including myoclonus. Proven loss of SEP on both sides within 2-3 days following HE is a valid measure confirming a poor prognosis, if sufficient experience with the method has been gained by the examiner. Blood NSE values correlate with the amount of damage to brain structures. Nevertheless, no proven limits are defined up to which a relevant recovery could still be possible. Using TH leads to enlarged time intervals between HE onset and the clinical and technical evaluation of prognosis. Clinical and technical findings have to be interpreted with great caution in patients after TH. Great emphasis has to be given to the congruence of the findings, i.e., that the clinical and technical results are in accordance and interfering parameters can be fully excluded. The combination of loss of pupillary reaction and loss of corneal reflexes together with a motor GCS under 3 and a complete loss of the N20 of the medianus-SEP or an areactive EEG on day 3 after HE is a very strong indicator of a poor prognosis. After successful resuscitation with documented ventricular fibrillation the implantation of an ICD is mandatory, unless it is a rare case of a self-limiting heart disease.