Clinical validation of a continuous intravascular neonatal blood gas sensor introduced through an umbilical artery catheter.

Introduction: Arterial blood gas (ABG) values are a necessary diagnostic measurement in the management of critically ill neonates. We hypothesized that a fiberoptic intravascular blood gas sensor, adapted for use through an umbilical artery catheter, would produce blood gas results with clinically acceptable bias and precision, in comparison to laboratory values, but with no blood loss.

Methods: We evaluated a fiberoptic intravascular blood gas sensor (Neotrend) in 23 consecutive neonates suffering respiratory failure. The sensor was inserted into the descending aorta via a 4.0 or 4.5 French umbilical artery catheter and extended 20 mm beyond the catheter tip. Arterial blood samples were drawn as clinically indicated and analyzed using a standard laboratory analyzer. Sensor measurements were recorded at the time of arterial blood sampling. Additionally, we recorded and evaluated data related to umbilical artery catheter placement (low position [L3-L4] vs high position [T8-T10]), duration of sensor functioning and use, and sensor bias and precision compared to the laboratory analyzer (using Bland-Altman technique and linear regression analysis of pH, P(aCO2), and P(aO2)).

Results: Duration of sensor use ranged from 1 to 304 hours (3-304 h in high position and 1-91 h in low position). Nine sensors were used for > 72 h (1 in low position and 8 in high position). Nine sensors were placed in low position, with a placement success rate of 56%. Eighteen sensors were placed in high position, with a placement success rate of 89%. The sensor values for pH, P(aCO2), and P(aO2) were strongly correlated (p < 0.0001) with the laboratory-determined values. Bias and precision for all values met standards for discrete analyzers for laboratory use.

Conclusions: The Neotrend device was accurate and reliable in the neonatal setting, allowing blood gas assessment with no iatrogenic blood loss. Catheter placement in high position may increase the likelihood of successful sensor placement and sensor duration of function.