Background: Permissive hypercapnia is routinely practiced in neonatal intensive care units. The effect of permissive hypercapnia on the preterm brain and brain electrical activity is unknown. In this study, we aimed to determine the effect of chronic changes in partial pressure of blood carbon dioxide (PcO2) on brain electrical activity in preterm newborn babies born at or before 32 wk gestation.
Methods: Eighty-three 1-h long digital electroencephalography (EEG) recordings were performed once a week for 4 wk on 25 babies with median gestational age of 29 wk (range: 23-32) after 48 h of age. Capillary blood gas measurements were performed midway through EEG recordings.
Results: There are associations between EEG parameters and blood pH, PcO2, and blood glucose concentration. However, there are also strong and complex associations with gestational age and substantial individual patient effects that make it difficult to demonstrate predictive associations. PcO2 and bicarbonate are significantly correlated with relative power of θ EEG band and Δ EEG band respectively after adjustment for age and intrababy correlations, but after allowing for multiple testing these relationships are of borderline statistical significance.
Conclusion: Compensated respiratory acidosis may affect EEG by increased delta wave activity in preterm babies born before 32 wk gestation.