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.

Cerebral Oxygenation during Intermittent Hypoxemia and Bradycardia in Preterm Infants

“…Although some groups have studied the influence of apnea of prematurity on cerebral oxygenation [14,15,16,17,18,19,20,21,22,24,25], only two of them have focused on different types of events [18,22] and neither of the two reported cerebral StO 2 , but instead reported hemoglobin concentrations as a measure of cerebral blood volume. …”

“…However, little is known about the impact of different event types on cerebral StO 2 . Published studies focused on one type only or did not differentiate between event types [14,15,16,17,18,19,20,21,22]. …”

Evaluation of Neonatal Regional Cerebral Perfusion Using Power Doppler and the Index Fractional Moving Blood Volume

“…There is currently no simple way to measure how well the neonate is perfusing regional areas of the developing brain. Currently, a number of neonatal units use near-infrared spectrophotometry to evaluate global cerebral oxygenation and blood flow [16][17][18][19] . This apparatus uses oxygenated haemoglobin, reduced haemoglobin, oxidised cytochrome a3 and total haemoglobin concentration to derive values for cerebral blood volume, mixed venous central saturation and changes in cerebral blood flow [20] .…”

Brain oxygenation monitoring during neonatal resuscitation of very low birth weight infants

“…It has been used in preterm infants for various healthcare conditions such as respiratory distress syndrome, 7 red blood cell transfusion, 8 desaturations, 9 indomethacin therapy 10,11 or ligation of a patent ductus arteriosus 12,13 and during the critical first days of life. [14][15][16][17] Major determinants of the regional tissue oxygen saturation are changes in SpO 2 , regional perfusion, regional blood volume and metabolic rate of oxygen utilization.…”