The effect of acidosis on cerebral function was evaluated by computerized online EEG monitoring in 14 ventilated preterm infants less than 32 weeks’ gestation at the Department of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK. All episodes of acidosis were associated with periods of EEG discontinuity (attenuated activity between bursts of EEG activity). In more than half a pH <7.20 was recorded, but EEG changes were noted even with acidosis levels of pH 7.20-7.25. In 21 of 32 episodes, EEG activity returned to pre-acidosis levels after therapy for acidosis. Duration of EEG discontinuity was related to severity of acidosis. Recovery of EEG was quickest for pure-respiratory acidoses that required only simple ventilatory adjustments. 
COMMENT. Increases in the amount of discontinuity in the EEG of infants may reflect disturbances in neonatal cerebral function caused by acidosis, hypoxia, or low cerebral blood flow. These changes are reversible in contrast to EEG suppression associated with hemorrhage that is persistent. EEG discontinuity may be used as a sign of acute neonatal cerebral dysfunction requiring immediate therapeutic intervention. This apears to be the first report of EEG changes in the neonate associated with acidosis.