Preservation of the metabolic rate of oxygen in preterm infants during indomethacin therapy for closure of the ductus arteriosus

BACKGROUND:The aim of this study was to assess and quantify the effects of indomethacin on cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2) in preterm infants undergoing treatment for a patent ductus arteriosus (PDA). METHODS: CBF and CMRO2 were measured before and after the first dose of a 3-d course of indomethacin to close hemo-dynamically significant PDA in preterm neonates. Indocyanine-green (ICG) concentration curves were acquired before and after indomethacin injection to quantify CBF and CMRO2. RESULTS: Eight preterm neonates (gestational age, 27.6 +/- 0.5 wk; birth weight, 992 +/- 109 g; 6 males:2 females) were treated at a median age of 4.5 d (range, 4-21 d). Indomethacin resulted in an average CBF decrease of 18% (pre- and post-CBF = 12.9 +/- 1.3 and 10.6 +/- 0.8 ml/100 g/min, respectively) and an OEF increase of 11% (pre- and post-OEF = 0.38 +/- 0.02 and 0.42 +/- 0.02, respectively) but no significant change in CMRO2 (pre- and post-CMRO2 = 0.83 +/- 0.07 and 0.76 +/- 0.07 ml O-2/100g/min, respectively). Corresponding mean blood pressure (BP), arterial oxygen saturation (SaO2), heart rate, and end-tidal carbon dioxide tension levels remained unchanged. CONCLUSION: Indomethacin resulted in significant reduction in CBF but did not alter CMRO2 because of a compensatory increase in OEF.