# Noninvasive estimation of oxygenation index in pediatric critical care: an independent retrospective observational validation

## TL;DR

This study validates a noninvasive algorithm to estimate oxygenation in critically ill children, showing it is accurate but not highly precise.

## Contribution

The study introduces and validates a new noninvasive algorithm for estimating oxygenation index in pediatric ICU patients.

## Key findings

- The eOI algorithm showed minimal bias in both PICU and CTICU populations.
- Discrimination performance was excellent across multiple hypoxemia thresholds.
- Noninvasive OI monitoring may have clinical utility despite limited precision.

## Abstract

To independently validate an empirically optimized algorithm for calculating estimated Oxygenation Index (eOI) using noninvasive parameters from pediatric intensive care populations.

Retrospective observational cohort study using an integrated patient data repository spanning over 12 years (August 2012-December 2024).

Single tertiary children's hospital with general pediatric ICU (PICU) and cardiothoracic ICU (CTICU).

Arterial blood gas measurements were paired with coincident SpO2, heart rate, pulse rate, FiO2, and mean airway pressure measurements. The primary analyses used SpO2 observations between 80%–100%. Using these values eOI was calculated. The primary outcome was the Bias and Limits of Agreement of the difference between measured OI and eOI. Discrimination performance of eOI for severity of hypoxemia was evaluated using receiver operating characteristic curves at OI thresholds of 4, 8, and 16.

Analysis included 68,915 observations from 7,109 subjects (44,133 CTICU, 24,782 PICU observations). Bias was minimal in both populations: PICU 0.06 (95% CI; 0.03, 0.10) and CTICU 0.12 (95% CI; 0.09, 0.14). Limits of agreement were −5.2 to 5.4 (PICU) and −4.9 to 5.2 (CTICU). Discrimination performance was excellent, at 3 hypoxemia thresholds (AUROC; 0.91–0.98), and in the CTICU for OI ≥4 when SpO2 >97% (AUROC; 0.83).

The new eOI algorithm provides accurate, but not precise, estimation of OI in both general pediatric and cardiothoracic ICU populations. Noninvasive OI monitoring may be shown clinically useful.