Cerebral oxygenation and oxygen extraction in the preterm infant during desaturation: effects of increasing FiO(2) to assist recovery.

Background: In the clinical setting, episodes of desaturation in newborn infants are often treated by increasing the fraction of inspired oxygen (FiO(2)).

Objectives: To study the effect of an increase in FiO(2) on cerebral oxygenation during recovery from desaturation, as measured by near-infrared spectroscopy (NIRS).

Methods: Peripheral arterial saturation (SaO(2)), NIRS-monitored cerebral saturation (rScO(2)), and fractional cerebral oxygen extraction (cFTOE) were analyzed in the first 3 days of life during 6 episodes of desaturation (SaO(2) <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 FiO(2) during recovery from desaturation.

Results: Post-recovery SaO(2) with increased FiO(2) was significantly higher than post-recovery SaO(2) without increased FiO(2). Post-recovery SaO(2) and rScO(2) were significantly increased over baseline saturations when FiO(2) was increased. Post-recovery rScO(2) 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 rScO(2) is an indicator of cerebral oxygen content, an increase in FiO(2) 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.