Evaluation of Oxygenation Index Compared With Oxygen Saturation Index Among Neonates Admitted to the NICU

Abstract

Oxygenation index (OI) based on arterial blood gas (ABG) test is an invasive procedure and requires indwelling arterial lines. However, the oxygen saturation index (OSI) assessed by the pulse oximetry method is simple and noninvasive for monitoring oxygenation saturation in newborn neonates with chronic lung disease. This study aimed to evaluate and compare OI and OSI among neonates in NICU who underwent mechanical ventilation. A cross-sectional study was carried out among fifty neonates (term and preterm) who were admitted to the NICU of Abuzar Hospital in Ahvaz, Iran. All neonates were examined by both ABG and pulse oximetry methods. Approximately 2 cc of arterial blood sample was taken and sent to the laboratory to determine blood gases. At the same time, the level of peripheral capillary oxygen saturation (SpO) was recorded using a pulse oximeter. OI and OSI were calculated according to their formula. Spearman’s correlation, linear regression, and Bland-Altman scatter plot were used to determine the correlation, association, and agreement between OI and OSI, respectively. Of the total 50 neonates, 26 were female. The mean (range) gestational age was 35.28±3.01 (28-39) weeks, and post-neonatal age was 6.05±7.04 (1-25) weeks. There was a linear and significant association and correlation between OI and oxygen OSI (P<0.001), while the Bland-Altman scatter plot confirmed the agreement between them in mean values. Therefore, OSI utilizing pulse oximetry as a noninvasive method can be a substitute for OI in neonates with respiratory failure. It can also reduce workloads and costs.