Can Noninvasive Oxygen Saturation Index Match Invasive Oxygenation Index to Monitor Respiratory Disease in Critically Ill Children?—A Prospective Study

Abstract

Respiratory illnesses are common indications for mechanical ventilation in children. The adequacy of ventilatory support for oxygenation is measured using arterial blood gas analysis and calculation of oxygenation index (OI). Due to invasive nature of arterial blood sampling needed to calculate OI, several researchers have replaced blood gas-derived partial pressure of oxygen values with oxygen saturation (SpO₂) obtained from pulse oximetry. This noninvasive index called oxygen saturation index (OSI) is found to be useful in neonates. Studies in pediatric population is lacking. In this prospective study on mechanically ventilated children, both OI and OSI were determined and compared against alveolar–arterial oxygen difference (AaDO₂). A total of 29 children were studied. Both OSI and OI had good correlation of 0.787 and 0.792 with AaDO₂, respectively. OSI of 7.3 and 9.4 had good sensitivity and specificity for AaDO₂ cutoffs of 344 and 498, which represents moderate and severe respiratory illness, respectively. The correlation coefficients of both OSI and OI are similar against AaDO₂. OSI can be used instead of OI for constant monitoring of children on mechanical ventilation. Arterial blood gas analysis and calculation of OI can be reserved for situations where SpO₂ measurement is unreliable.

Keywords

oxygenation - oxygenation index - arterial–alveolar oxygen difference - mechanical ventilation - children - critical care

Ethical Approval

The institutional ethical committee approved this study. Informed written consent was taken by the parents for the participation of their ward in this study.

Authors' Contributions

S.M.D. generated the research question and did the study design. He was involved in statistical analysis and fine tuning of manuscript. S.C. collected the data and did the literature search and initial analysis. J.K.K. helped in study design and preparation of manuscript.

Publication History

Received: 25 August 2021

Accepted: 15 January 2022

Article published online:
21 February 2022

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