Cerebral tissue oxygen desaturations and increased fractional oxygen extraction events vary by gestational age in preterm infants.

Background and objectives Cerebral tissue oxygen saturation (SctO2) and cerebral fractional tissue oxygen extraction (cFTOE) changes with GA in preterm infants. This study examines changes in frequency, duration, and severity of SctO2 desaturation and increased cFTOE with GA. Study Design The lower limit of normal SctO2, the event threshold, was calculated using a tolerance interval method with 95% confidence interval (CI) and 90% probability. Cerebral desaturation events were defined as: 1) a drop below event threshold for at least 30 seconds (s), 2) preceded by a period above the event threshold for at least 30s, and 3) followed by a period above the threshold for at least 60s. Results 86% of infants <28 wk experienced one or more SctO2 desaturation event compared to 57% in >28 wk, odds ratios (OR) 4.5 (CI:1.3-15.3, p=0.016). The severity of SctO2 desaturation events decreases at a rate of 77.9 units per wk increase in GA (p<0.001). 39.3% of infants <28 wk experienced one or more increased cFTOE events compared to 28.6% in >28 wk, OR 1.6 (CI:0.6-4.4, p=0.35). The severity of increasing cFTOE events decreased by 69.7 units per wk increase in GA (p<0.001). Conclusion Cerebral tissue oxygen desaturation events decrease in frequency and severity with increasing GA. The severity of increased cFTOE episodes decrease with GA.