The purpose of this study was to investigate the effects on cerebral hemodynamics of administering modified natural surfactant (Curosurf, 200 mg . kg-1) to infants requiring mechanical ventilation for hyaline membrane disease. Observations were made using near infrared spectroscopy on 20 infants for between 26 and 109 (median 57) min before and 22 to 112 (median 46) min after surfactant instillation. Changes in cerebral oxyhemoglobin concentration and cerebral blood volume (CBV) were monitored continuously; cerebral blood flow, oxygen delivery, and the response of CBV to changes in arterial carbon dioxide tension were measured while the infants were stable shortly before and after surfactant was given. Cerebral oxyhemoglobin concentration fell transiently in all infants immediately after surfactant by a median of -0.21 (range -0.46 to 0.05) mL . 100 g-1, but quickly recovered so that the median change during the 10 min after surfactant was 0.0 1 (-0.46 to 0.46) mL . 100 g-1. Alterations in CBV also occurred ranging from -0.44 to 0.40 (median 0) mL . 100 g-1, which represented -12 to 16% of total CBV, these changes rapidly resolved. When the infants were stable before and after surfactant, the values for mean (SD) cerebral blood flow were 20.5 (7.5) and 23.1 (5.2) mL . 100 g-1 . min-1, respectively (n = 9); for mean cerebral oxygen delivery, values were 2.71 (0.89) and 3.15 (0.73) mL . 100 g-1 . min-1 (n = 9); and for response of CBV to changes in arterial carbon dioxide tension, they were 0.14 (0.09) and 0.11 (0.11) mL . 100 g-1 . kPa-1 (n = 16); these changes were not statistically significant. We conclude that (1) surfactant administration caused small, transient perturbations in cerebral oxyhemoglobin concentration and CBV, and (2) no important alterations in cerebral blood flow, cerebral oxygen delivery, or response of CBV to changes in arterial carbon dioxide tension were detected.
