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G426(P) How reliable are pulse oximetry saturations? A prospective study in a neonatal ICU
  1. V Balodima1,
  2. V Patel2,
  3. S Sen2
  1. 1Department of Paediatrics, University Hospital of Wales, Cardiff, UK
  2. 2David Ferguson Neonatal Unit, Royal Gwent Hospital, Newport, UK

Abstract

Introduction Pulse oximetry is an easily available, non- invasive continuous method for assessment and management of oxygenation. However, previous studies have reported discrepancies between pulse (SpO2) and arterial hemoximetry saturations (SaO2) with SpO2 overestimating SaO2 especially at low saturations. Whether new generation SpO2 monitors are less prone to such discrepancies is not known.

Aim To prospectively assess correlation between SpO2 and SaO2 in term and preterm infants.

Methods Infants admitted to NICU over a period of 11 months, with an arterial line and SpO2 monitoring were eligible for this study. Infants on iNO were excluded. During routine arterial blood gas analysis, measured SaO2 was compared with stable SpO2 value just prior to initiating blood gas draw. Data was analysed using Bland-Altman method to assess measurement agreement.

Results 221 paired measurements were obtained from 36 neonates. 77.8% were fit for analysis. Of these, 6.4% SpO2 values were between 85–89%, 42.4% between 90–95%, 47.6% between 96–100% and the rest 3.6% were <85%. On an average, SaO2 was lower than SpO2 with a mean difference of -1.056. The 95% limits of agreement were –7.216 to 5.014 (SD =3.08). For the SpO2 categories between 85–89%, 90–95%, 96–100%; 73%, 53% and 73% respectively correlated with the SaO2 measurements. However, SaO2 was lower than SpO2 in 18%, 21% and 27% respectively.

Conclusion Though the study showed that SpO2 and SaO2 measurements did not correlate completely, the observed difference was not clinically significant. This could be because of small sample size or due to improved SpO2 technology.

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