Cerebral oxygenation in preterm infants at high altitude: a prospective pilot cohort study

Abstract Introduction: Near-infrared spectroscopy (NIRS) is a non-invasive technique for measuring regional oxygen saturation. Because preterm infants are susceptible to brain injury secondary to immaturity of the central nervous system (CNS) and cerebral vasculature, there has been significant interest in using cerebral NIRS monitoring to predict and/or decrease the risk of brain injury. Methods: Preterm infants born at <32 weeks’ gestational age at high altitude were monitored with cerebral near-infrared spectroscopy (NIRS) throughout the first 96 postnatal hours. Regional cerebral oxygen saturation (rcSO2) and cerebral fractional tissue oxygen extraction (cFOTE) were measured. Additionally, we evaluated for possible correlations between cerebral oxygenation and fraction of inspired oxygen (FiO2) received. Results: 20 infants were studied, with a mean birth weight of 1124 grams and gestational age of 28 5/7 weeks. Median rcSO2 was 73.5% on day of birth, 75.0% at 24-48hrs of age, and 73.0% at 48-72hrs and 72-96hrs of age. Median cFTOE was 23.8% on day of birth, 18.8% at 24-48hrs of age, 21.5% at 48-72hrs of age, and 23.6% at 72-96hrs of age. These patterns of rcSO2 and cFTOE and the median values for rcSO2 are consistent with those obtained in the largest sample of preterm infants reported to date at sea level. FiO2 correlated positively with cerebral oxygen saturation (r = 0.23, p < 0.001 for rcSO2) and inversely with cerebral oxygen extraction (r =−0.25, p < 0.001 for cFTOE). Conclusion: Cerebral oxygenation at high altitude appears to be similar to that at low altitude in preterm infants in the first 4 postnatal days. Cerebral oxygenation appears to be influenced by FiO2 received.