Objectives: The aim of this study was to assess changes in cerebral haemodynamics and oxygenation induced by surfactant administration using near infrared spectroscopy (NIRS).
Methods: Eighteen premature infants, mean birth weight 960 g (range 550-1560 g), mean gestation age 28 weeks (range 25-30 weeks), were studied during 27 surfactant administrations. Porcine surfactant was administered to treat respiratory distress syndrome in a bolus of 100 mg/kg. Manual bag ventilation was performed for one minute after instillation. Heart rate, arterial oxygen saturation measured by pulse oximetry, transcutaneous PO2 (TcPO2), and PCO2 (TcPCO2), blood pressure, and cerebral oxygenated (O2Hb), deoxygenated (HHb), and total haemoglobin (tHb) concentration changes obtained by NIRS were registered every second from 15 minutes before until 30 minutes after surfactant administration.
Results: During surfactant administration, there was a short-lasting but significant drop in heart rate and arterial oxygen saturation. NIRS parameters remained constant during and up to 1 minute after administration. One to three minutes after administration, heart rate, oxygen saturation, and TcPO2 increased significantly concomitantly with an increase in O2Hb and a decrease in HHb. In 10 cases, TcPO2 increased above 100 mmHg. tHb--indicative of cerebral blood volume--did not change significantly. Five to 30 minutes after surfactant administration there was no difference of monitoring data from baseline levels. TcPCO2 and blood pressure remained unchanged during the measurement period.
Conclusion: Cerebral blood volume remained constant in very-low-birth-weight infants when surfactant was administered by bolus administration followed by manual ventilation according to our protocol. Attention should be directed towards rapid adaptation of inspiratory oxygen concentrations after surfactant administration to avoid hyperoxaemia.