Cerebral blood flow and plasma hypoxanthine in relation to surfactant treatment

We have previously reported reduction in EEG activity in preterm babies after tracheal instillation of Curosurf. To elucidate the cause of EEG depression, we have examined cerebral blood flow (CFB), amplitude-integrated EEG (aEEG), mean arterial blood pressure (MABP) and plasma hypoxanthine (Hx) concentration in a group of preterm babies before and immediately after administration of surfactant. No change occurred in CBF immediately after surfactant treatment despite a significant decrease in MABP. At 60 min after surfactant administration, a significant reduction in CBF occurred (p < 0.05). However, when CBF values were corrected for changes in PaCO₂, no reduction in CBF was observed. Mean plasma Hx concentration was 11.6 (SD 7.3) μmol/l before surfactant therapy, which decreased significantly to 8.1 (5.8) μmol/l (p < 0.05) 15-30min after treatment. No correlations were found between plasma Hx concentration and FiO₂ a/A pO₂, PaCO₂, SaO₂, arterial blood pressure, CBF or the degree of EEG depression. This study indicates that EEG depression observed after surfactant instillation is not caused by cerebral ischemia.