Background: Wired pulse oximetry is a critical tool for monitoring neonates but the probe wire can become dislodged or entangled with movement, and requires frequent replacement. Wireless pulse oximetry is an emerging technology that has the potential to simplify monitoring of hospitalized term and preterm infants, but has not previously been studied. Objective: To compare oxygen saturation (SpO2) and heart rate (HR) values recorded by a reference wired pulse oximeter (Nonin 8500M™) with a wireless oximeter (Owlet™ Smart Sock) in full term and preterm neonates. Design/Methods: Healthy full term infants born ≥ 37 weeks and preterm infants born ≤ 35 weeks gestation were enrolled during birth hospitalization in this prospective, comparative trial. Concurrent oximeter recordings were obtained in full term infants recorded for 20 minutes in the newborn nursery and in preterm infants recorded in the NICU for 60 minutes. To account for differences in averaging times between oximeters, data over the preceding 15 seconds were averaged and matched data pairs were generated. Results: We enrolled 50 infants in this study; 30 full term, median (IQR) gestational age 39 weeks (38,40) and birth weight 3427g (3105,3670) and 20 preterm, median birth weight 1632g (1361,1994), and weight at recording 2096g (1820,2563). A total of 9116 matched data pairs were analyzed. There was excellent correlation between the two oximeters for HR (R= 0.953; Fig. 1) among all 50 infants, with no difference in r values between full term and preterm infants. There was no significant difference for SpO2 between the full term and preterm groups (Fig. 2) although the correlation coefficient was less than for HR (r =0.683). Linear mixed effects models showed that mean differences were not significant between the two oximeters (Nonin-Owlet™) for HR (+0.75, SD=±5.2 BPM) and for SpO2 (1.01, SD= ±2.3%). Conclusions: Compared with the reference wired pulse oximeter, the Owlet™ Smart Sock showed good accuracy and correlation for HR in both full term and preterm infants. The overall mean difference in SpO2 between the two oximeters was not clinically significant, but there was greater variation in preterm than full term neonates. However, the sock size was not designed for preterm neonates and may be a significant limitation to the correlation data in preterm neonates. Although these results appear promising overall, studies are needed with larger sample sizes and especially with a smaller sock size appropriate for preterm neonates
Scatterplot Heart Rate (full term and preterm neonates)
Scatterplot of 9116 paired heart rate data points obtained in 50 infants comparing reference Nonin™ oximeter (x-axis) and Owlet™ Smart Sock (y-axis), with identical values superimposed (r=0.953).
Scatterplot Oxygen Saturation (full and preterm neonates)
Scatterplot of 9116 paired oxygen saturation data points in 50 infants comparing reference Nonin™ oximeter (x-axis) and Owlet™ Smart Sock (y-axis), with identical values superimposed (r=0.683).
