Clinical quantification of SpO2 instability using a new histogram classification system: a clinical study



Oxygenation instability is not quantified or documented despite being common and correlated with neonatal morbidities, retinopathy of prematurity, and adverse 18-month outcomes.


We developed a five-type SpO2 histogram classification system based on the SpO2 difference within the 10–90th cumulative time percentile (A) and the time percentage with SpO2 ≤80% (B). In type 1, A is <5% and in type 5, A and B are ≥10%. We then studied consecutive 12-h SpO2 frequency histograms in all infants ≤34 weeks gestation receiving respiratory support on day 1, over 6 months.


Six thousand and sixteen histograms were obtained in 73 infants, 28.9 ± 3.0 weeks gestation, and birth weight (BW) 1318.5 ± 495 g. All types were common and did not overlap. Type 3–5 (“unstable”) histograms were more common in oxygen or any intubated support. Time in SpO2 <85% and <80% progressively increased in types 3–5. Among histograms in oxygen, the mean (±SD) of SpO2 medians was 92.8 ± 1.9. Infants ≤28 weeks exhibited three phases of SpO2 instability (stable–unstable–stable). Those developing unstable histograms during the first week received longer ventilatory support (median [IQR], 101 [66] vs. 62 [28] days) and supplemental oxygen (62.5 [72] vs. 40.5 [40] days), and more were on ventilatory support at 40 weeks (7/15 vs. 0/10).


Classified SpO2 histograms quantify and document SpO2 instability and identify early infants at risk of prolonged respiratory support, while median SpO2 does not.

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All authors take responsibility for the reported findings and have participated in the concept and design, analysis and interpretation of data, drafting or revising, and approval of this manuscript as submitted.

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Correspondence to Liron Borenstein-Levin.

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Borenstein-Levin, L., Konikoff, L. & Solimano, A. Clinical quantification of SpO2 instability using a new histogram classification system: a clinical study. Pediatr Res 87, 716–720 (2020).

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