Background: Patent ductus arteriosus (PDA) is a common problem in preterm infants and a risk factor for brain damage. In an earlier study we reported a lower regional cerebral saturation (rScO₂) during PDA (62 ± 9% vs 72 ± 10% in controls), recovering after treatment with indomethacin. Surgical ligation of PDA should pose a higher risk for neurodevelopmental impairment (Kabra et al. J Pediatr 2007).

Objective: To investigate the impact of surgical closure of PDA (rescue therapy) on cerebral oxygen saturation, measured by near infrared spectroscopy and fractional tissue oxygen extraction (cFTOE).

Design and Methods: In 12 preterms (gestational age 27 ± 1.6 weeks, birth weight 925 ± 203 g) mean arterial blood pressure (MABP), arterial saturation (SaO₂) and rScO₂ were continuously monitored up to 24 h after surgery. cFTOE was calculated as a ratio: (SaO₂ − ScO₂)/SaO₂. 5–10-minute periods of reliable monitoring were used, before surgery, just before clipping, just after clipping and 60 minutes, 120 minutes and 6 h, 12 h, 24 h after clipping and averaged for MABP, SaO₂, rScO₂, cFTOE.

Results: Before surgery rScO₂ and cFTOE were 53 ± 6% and 0.43 ± 0.7. During surgery up to clipping rScO₂ and cFTOE further decreased and increased: 49 ± 8%; 0.46 ± 0.1. After ligation of the ductus these values showed a sustained increase and decrease, respectively, to 62% ± 9 and 0.34 ± 0.1 (24 h).

Suggestion: The surgical ligation procedure of PDA induced a further decrease of the cerebral oxygenation to very low values. These unexpected findings may be related to the suboptimal neurodevelopmental outcome recently reported in preterm infants undergoing surgical ductal closure.