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Comparison of pulse oximetry and earlobe blood gas with CO-oximetry in children with sickle cell disease: A retrospective review

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Michele Arigliani, Sean Zheng, Gary Ruiz, Subarna Chakravorty, Cara J. Bossley, David Rees, David Rees, Atul Gupta, Atul Gupta

Original languageEnglish
Article numbere000690
JournalBMJ Paediatrics Open
Issue number1
Published15 Jun 2020

King's Authors


Objectives To investigate the agreement between pulse oximetry (SpO 2) and oxygen saturation (SaO 2) measured by CO-oximetry on arterialised earlobe blood gas (EBG) in children and adolescents with sickle cell disease (SCD). Design and setting We retrospectively reviewed 39 simultaneous and paired SaO 2 EBG and SpO 2 measurements from 33 ambulatory patients with SCD (32 subjects with Haemoglobin SS and one with Haemoglobin Sß +, 52% male, mean±SD age 11.0±3.6, age range 5-18). Measurements were performed between 2012 and 2015 when participants were asymptomatic. Hypoxaemia was defined as SaO 2 ≤93%. A Bland-Altman analysis was performed to assess the accuracy of SpO 2 as compared with EBG SaO 2. Results The mean±SD SpO 2 and SaO 2 values in the same patients were, respectively, 93.6%±3.7% and 94.3%±2.9%. The bias SpO 2-SaO 2 was-0.7% (95% limits of agreement from-5.4% to 4.1%) and precision was 2.5%. In 9/39 (23%) cases, the difference in SpO 2-SaO 2 was greater than the expected error range ±2%, with SaO 2 more often underestimated by SpO 2 (6/9), especially at SpO 2 values ≤93%. Thirteen participants (33%) were hypoxaemic. The sensitivity of SpO 2 for hypoxaemia was 100%, specificity 85% and positive predictive value 76%. Conclusions Pulse oximetry was inaccurate in almost a quarter of measurements in ambulatory paediatric patients with SCD, especially at SpO 2 values ≤93%. In these cases, oxygen saturation can be confirmed through EBG CO-oximetry, which is easier to perform and less painful than traditional arterial blood sampling.

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