Acute Anoxic Injury and Therapeutic Hypothermia in Adults

Acute anoxic injury is common in the adult population, occurring most commonly due to sudden cardiac arrest. In patients that remain comatose after resuscitation, there is a period of uncertainty, accompanied by high morbidity and mortality. Therapeutic hypothermia (TH) has been used for neuroprotection during this time period, though its true benefit remains uncertain. As a result, the focus shifts to determining prognosis, with EEG being one of the most widely used, well-studied resources available. From the time EEG became available, specific findings after acute anoxic injury have been detailed and correlated with outcomes. Multiple grading scales have been proposed to simplify clinical decision-making. As clinical protocols have evolved, and TH has become the standard of care, specific EEG patterns, including nonreactivity, low-voltage output pattern, and nonconvulsive seizures (NCS) and nonconvulsive status epilepticus (NCSE) remain worrisome. When combined with complementary clinical data, EEG remains a powerful tool for predicting prognosis after acute anoxic injury. In this chapter, the pathophysiology of anoxic brain injury and value of TH will be presented. Various EEG features that are associated with anoxia and TH and their prognostic value will also be discussed.