Evaluation of Oxygenation Index Compared with Oxygen Saturation Index among Neonates admitted to the NICU

Oxygenation index (OI) based on arterial blood gas (ABG) test is an invasive procedure and require indwelling arterial lines. However, oxygen saturation index (OSI) assessed by pulse oximetry method is simple and non-invasive for monitoring of oxygenation saturation in newborn neonates with chronic lung disease. This study aimed to evaluate and compare OI and OSI among neonates in NICU underwent mechanical ventilation. A cross-sectional study was carried out among fifty neonates (term and preterm) who admitted to NICU of Abouzar Hospital in Ahvaz, Iran. All neonates examined by both ABG and pulse oximetry methods. Approximately, 2-cc of the 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 (SpO2) was recorded using a pulse oximeter. OI and OSI were calculated according to its 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 non-invasive method can be a substitute for OI in neonates with respiratory failure. It can also reduce workloads and costs.