Introduction: Pulse oximeters are valuable non-invasive tools for monitoring peripheral blood oxygen saturation (SpO2) in neonates, the most commonly used being the Masimo SET. New devices, including the NONIN SenSmart, have the capability of simultaneously monitoring SpO2 and regional tissue oxygen saturation which could aid clinical management of sick preterm infants. This study aims to assess accuracy and reliability of NONIN SenSmart compared to Masimo SET in preterm infants (<32 week’s gestation).
Methods: Arterial oxygen saturation (SaO2) and peripheral SpO2 were simultaneously recorded by NONIN SenSmart and Masimo SET pulse oximeters from 18 preterm infants admitted to the IWK Health Centre NICU within 72 hours after birth. SaO2 from umbilical arterial blood gas samples were obtained as clinically indicated. Post-ductal SpO2 from NONIN SenSmart and Masimo SET pulse oximeters were recorded as arterial blood gas sample was drawn. Analysis of the difference between SaO2 and SpO2 (SaO2 – SpO2) for each pulse oximeter was completed using Wilcoxon paired t-tests and mixed model analysis. Measurement agreement was assessed by plotting the difference of SaO2 and SpO2 (SaO2 – SpO2) with 95% limits of agreement and 95% confidence intervals.
Results: 101 measurements (18 infants) were obtained between January and September 2019. Both NONIN SenSmart (r= 0.92) and Masimo SET (r=0.91) were highly correlated with SaO2. SaO2 – SpO2 (+/-95% limits of agreement) values were 0.3(+/-7.8) and -1.4(+/-8.1) for NONIN SenSmart and Masimo SET respectively (p < 0.01). Sensitivity of NONIN SenSmart and Masimo SET within 3% of SaO2 were 60% and 68% respectively.
Conclusion: NONIN SenSmart and Masimo SET provide reliable and accurate measurements of SaO2. NONIN SenSmart SpO2 has greater statistical accuracy, but the clinical significance is unknown. NONIN SenSmart, with additional capability of measuring regional tissue oxygenation, provides an attractive alternative to the currently used Masimo SET pulse oximeter in preterm infants.
Souvik Mitra– Assistant Professor and Neonatologist, Faculty of Medicine, Dalhousie University AND Division of Neonatal Perinatal Medicine, IWK Health Centre