Paediatr Anaesth. 2025 Jul 21. doi: 10.1111/pan.70014. Online ahead of print.
ABSTRACT
AIMS: The Oxygen Reserve Index (ORI) is a novel, noninvasive parameter that reflects moderate hyperoxic states. However, its relationship with PaO2 in the pediatric population remains poorly understood. We investigated the ORI-PaO2 relationship during pediatric cardiac surgery and identified its influencing factors.
METHODS: This prospective observational study included 98 pediatric patients (< 7 years of age) who underwent cardiac surgery for congenital heart defects. ORI and PaO2 were measured at FiO2 levels of 0.21, 0.5, and 0.8, both before and after cardiopulmonary bypass (CPB). Linear mixed models and regression analyses were used to examine the relationship between ORI and PaO2 by incorporating covariates such as hemoglobin (Hb), ejection fraction (EF), and perfusion index (PI). Locally weighted regression analysis was conducted to identify potential PaO2 thresholds influencing this relationship.
RESULTS: A total of 487 data samples were analyzed. A nonlinear relationship between ORI and PaO2 was observed, with a threshold of 245 mmHg dividing the data into two distinct ranges. Pearson correlation coefficients between ORI and PaO2 were significant in both ranges: 0.516 (PaO2 ≤ 245 mmHg, p < 0.001) and 0.151 (PaO2 > 245 mmHg, p = 0.035). Although Hb level and EF showed no impact, only PI had a mildly negative relationship with ORI before CPB. The relationship between ORI and PaO2 remained consistent across both pre- and post-CPB periods (r2 = 0.304 and 0.337, respectively).
CONCLUSION: ORI consistently correlates with PaO2 in children undergoing cardiac surgery, is unaffected by Hb or EF, and may serve as a useful tool for monitoring oxygenation trends.
TRIAL REGISTRATION: ClinicalTrials.gov: NCT03130023.
PMID:40686277 | DOI:10.1111/pan.70014
