Presented as a poster at the Neonatal Society 2016 Summer Meeting.
Karunatilleke AS, Cheung CK, Liddle N, Davies M, Evans HJ
University Hospital Southampton NHS Foundation Trust
Background: Nocturnal pulse oximetry (NPO) is used to investigate infants for sleep disordered breathing (SDB). Reference ranges are based on data from older children (1). Infants spend proportionately more time in REM sleep, when SDB occurs, and are more prone to central apnoeas than older children. Hence normal values in older children may not be applicable to infants. Our aim was to use NPO to collect data on saturation indices in healthy infants at one month and again at 3-4 months to report a normal reference range.
Methods: With NRES ethical approval and parental consent healthy infants were recruited from postnatal wards. During the first month of life (study 1), oxygen saturations were monitored at home using NPO (Masimo Rad-8). This was repeated at 3-4 months (study 2). Sleep times were recorded. Visilab software (Stowood Scientific) was used to interpret the data as well as to remove artefacts and wake periods. Mean (SD) for saturations (SAT50), desaturation index >4% from baseline per hour (DI4), delta index 12s (DI12s) and median (range) for minimum SpO2 (SATmin) were calculated. Additionally, cumulative frequency curves were constructed from the merged data sets.
Results: For study 1 of the 52 infants recruited, 46 studies (M:F 21:25) were successfully completed. To date 35 of these babies have completed Study 2 (collection ongoing).
Participants who completed both study 1 and study 2 (n= 32) had significant increase in SAT50 of 0.96% (96.71 – 97.67) p=0.002, 95% CI [-1.55, 0.37]. Participants who completed both study 1 and study 2 (n= 32) had significant decrease in DI4 of 7.96 events/hour p=<0.001, 95% CI [5.72, 10.20].
Conclusion: The initial study shows that neonates have similar mean saturations but higher desaturation indices than older children, where a DI4 over 4 is considered abnormal (p<0.01, one sample t-test). The follow up study suggest that these values significantly decrease by 3-4 months of age but remain elevated as compared to older children.
Corresponding authors: ckc2g11@soton.ac.uk and ask2g11@soton.ac.uk
References
1. Urschitz MS. Reference Values for Nocturnal Home Pulse Oximetry During Sleep in Primary School Children. Chest 2003;123(1): 96-101. doi:10.1378/chest.123.1.96