Correlation of Oxygen Saturation Index and Oxygenation Index in Hypoxaemic Respiratory Failure among Neonates

Abstract

Introduction: Hypoxaemic Respiratory Failure (HRF) is severe arterial hypoxaemia that is refractory to supplemental oxygen. Oxygen Saturation Index (OSI) can be an alternate method of diagnosing and assessing the severity of HRF as it uses Oxygen Saturation (SpO2) in place of Partial Pressure of Oxygen (PaO2) and may be utilised with reasonable sensitivity and specificity. Aim: To evaluate the correlation between OSI and Oxygenation Index (OI) in HRF in neonates. Materials and Methods: The prospective observational study was conducted in Kempegowda Institute of Medical Sciences and Hospital, Bengaluru, Karnataka, India, from December 2016 to July 2018. Fifty neonates who were admitted to Neonatal Intensive Care Unit (NICU) and conventionally ventilated in view of HRF were included. Arterial blood gases in the first 24 hours of life and corresponding oxygen saturations and ventilator settings were recorded. OI and OSI was calculated using the standard formula and their correlation was analysed. Results: The neonates were all on first day of life at admission to NICU and were invasively ventilated due to HRF. The mean birth weight was 1.89±0.84 kg. Of the 50 neonates, 22 (44%) were preterm babies (<34 weeks), 17 (34%) belonged to late preterm group (34 weeks to 36 weeks +6 days), 9 (18%) were term babies (>37 weeks), two neonates were extremely preterm (less than 28 weeks). In this study, OSI and OI significantly associated and correlated (p-value <0.01) with a correlation coefficient r=0.727. Area under the Receiver Operating Characteristic (ROC) curve for OSI was 0.912 which indicates that OSI is an excellent test to assess the severity of HRF. Conclusion: That OSI can be used to diagnose and assess the severity of lung disease in neonates having HRF.