Effect of temperature on the EEG

Brain temperature cannot be measured directly during deliberate hypothermia on cardiopulmonary bypass. Temperature measured within the NP or ear canal near the tympanic membrane is often used as a surrogate indicator of brain temperature. Hypothermia produces characteristic changes in the EEG that can also be used as a physiologic surrogate of the degree of suppression of cerebral metabolism. Electrocortical silence on the EEG occurs at an average NP temperature of 18°C in adults, but a NP temperature of approximately 12°C is necessary to ensure electrocortical silence in >95 percent of patients.