Cerebral Oxygenation and Oxygen Extraction in the Preterm Infant during Desaturation: Effects of Increasing FiO2 to Assist Recovery

Abstract

Background: In the clinical setting, episodes of desaturation in newborn infants are often treated by increasing the fraction of inspired oxygen (FiO₂). Objectives: To study the effect of an increase in FiO₂ on cerebral oxygenation during recovery from desaturation, as measured by near-infrared spectroscopy (NIRS). Methods: Peripheral arterial saturation (SaO₂), NIRS-monitored cerebral saturation (rScO₂), and fractional cerebral oxygen extraction (cFTOE) were analyzed in the first 3 days of life during 6 episodes of desaturation (SaO₂ <75%, >30 s) in each of 24 otherwise stable spontaneously breathing preterm infants (gestational age 29.8 ± 1.5 weeks, birth weight 1,215 ± 280 g; mean ± SD), during 3 episodes without and 3 episodes with increased FiO₂ during recovery from desaturation. Results: Post-recovery SaO₂ with increased FiO₂ was significantly higher than post-recovery SaO₂ without increased FiO₂. Post-recovery SaO₂ and rScO₂ were significantly increased over baseline saturations when FiO₂ was increased. Post-recovery rScO₂ was very high for several minutes in some cases, while cFTOE was highly suggestive of oxygen delivery that exceeded consumption. Conclusions: Assuming that NIRS-measured rScO₂ is an indicator of cerebral oxygen content, an increase in FiO₂ to assist recovery from desaturation may cause hyperoxygenation of the brain in relatively stable preterm infants. This procedure may be particularly harmful in the sick very preterm infant with limited regulation of brain circulation and poorly developed antioxidant defenses.