Cerebral oxygen saturation in neonates: a bedside comparison between neonatal and adult NIRS sensors

The majority of neonatal NIRS literature recommends target ranges for cerebral saturation (rScO₂) based on data using adult sensors. Neonatal sensors are now commonly used in the neonatal intensive care unit (NICU). However, there is limited clinical data correlating these two measurements of cerebral oxygenation.

A prospective observational study was conducted in two NICUs between November 2019 and May 2021. An adult sensor was placed on infants undergoing routine cerebral NIRS monitoring with a neonatal sensor. Time-synchronized rScO₂ measurements from both sensors, heart rate, and systemic oxygen saturation values were collected over 6 h under varying clinical conditions and compared.

Time-series data from 44 infants demonstrated higher rScO₂ measurements with neonatal sensors than with adult sensors; however, the magnitude of the difference varied depending on the absolute value of rScO₂ (Adult = 0.63 × Neonatal + 18.2). While there was an approximately 10% difference when adult sensors read 85%, readings were similar when adult sensors read 55%.

rScO₂ measured by neonatal sensors is typically higher than measured by adult sensors, but the difference is not fixed and is less at the threshold indicative of cerebral hypoxia. Assuming fixed differences between adult and neonatal sensors may lead to overdiagnosis of cerebral hypoxia.

In comparison to adult sensors, neonatal sensors rScO₂ readings are consistently higher, but the magnitude of the difference varies depending on the absolute value of rScO₂. Marked variability during high and low rScO₂ readings was noted, with approximately 10% difference when adult sensors read 85%, but nearly similar (58.8%) readings when adult sensors read 55%. Estimating fixed differences of approximately 10% between adult and neonatal probes may lead to an inaccurate diagnosis of cerebral hypoxia and result in subsequent unnecessary interventions.